, '

,

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1

RATES OF PRlMARY PRODUCTICN AND DECOMPOSITION

IN SUBARCTI C PEA TLANDS

Ingrid Banach

'.

A th.al. aul:.ttted te the Faeulty of Qn.4uate StucU •• and R ••• m ln

partial fulf"11lMnt of t.he requ1reMnta t'or the Degree of

Maater of Science

~t. of Gec@lapl\1 MaG!ll Uniyeraity ..... u..l. ~ebee

Jul.7 '198)

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Abstract

The rates of plant production and t1ssue decomposltion ln four

subr.rcttc ll1!re ~ysteJ1ls wer~ exanined. '!'otal p~atlanè p'!'c.dur.ticn was

-2 -1 estimated at 114 to 335 g.J1l ·YT ,with sedges l'lB.king t.he ereatest

contribution. Product1vity by sedge spec1es was found to he weakly

correlated with peat temperature and trophic statua. Aithough the trend

15 toward increasing production wlth higher temperature and nutrient

levaIs, it 18 not possible to separate these effects from each other,

or from specifie differenees at each site. The litter beg te~hn1que

was utillzed to deter~ine the ~ss 1088 fro~ decomposing tissue over

time. First year lasses ranged from 6.4 to 26.6%. of wh1ch approxi­

III&teIy 6,5% occurred during the winter Months. Nutrlent releases from

decomposlng I1tter are slow, generally proeeedlng in the sequence

K>Mg>Ca>N. P. Tissue qual1ty appeara tO,e'xereise a greater influ-

enee on decay rates tban do envlronmental parameters, aithough some

slgniflcant variations between decompositlon rates exist within

tissue types, batween microhabltats.

(~ ---

Résu.'Tl~

Les taux de production vlgftal et de d~compo8i tion de tissus

chez quatre tourbUres subarctiques 5talen t ex&1ft1nfs. La production

totale des tourbUres • 'i'chelonne de 114 1. 335 g l'II -2 a -1, les

herbac6es faisant la plus grande contribution. lA production par

les espaces herbacfes (ftat t t'ai blement relt6e à la. tel1lpê"rature et.

statut trophique 4e cNLque e.place.ent. Quoique la. tendance est

envers une augmentation d" production avec les tempfratures et niveaux

trophiques élev'., 11 n'elt pas po.sible de .'parer ce. e'ffet. l'un

de 1" au tre, ni de. di 'f'f'rence. entre esplce. 1 chaque e.placemen t •

Des enclos en 'filet ont été utll1a~. pour ... urer la perte de poids

des tissu. avec le teaps. Ces pertes s"chelonnent. de 6.4 a 26.~

pendant. 1& prellilre année, cOllprenant environ 6~ durant l'hiver.

IA dfch&rge d "léaents pendant la d~olllposl tion est lente, su1vant

l'ordre potassiu. > a@n"iua > calc1ua> azot.e, phosphore. 1.& qual1 té

de tis.u .. able exercer une pluè grande 1nt"luence sur les taux de

d'~rl."eaent que le. &gentil envlronnelllentals, quoique quelques

variation •• lsnif1cante. exi.tent ent.re microenvlronnel'lent.e. parmi

les types de ti.au.

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Âcknowledgements

Several people have been instrumental in th9 coapletton of'

this study. l wish to ttank Dr. T. R. Moore for consistently provldlng

pos1 tive cri tical supervision st a11 stages of.' the researoh a.nd

wrlt1ng, and Dr. T .. C. Meredith for helpful crlt1c1s11 of the final

draft of this the.i ••

l alll gratef'ul to Ja_hed Merehant tor lnvalua.ne asaistance ln ,

la.boratory _ttera, Dr. D. Morton (University ot AI1»rt&) for identi-

fyin! SPh!lmU1 8I.çle., Sldth for pee.t_ter analyse., and K. Bart&eh

for the t'inal dra1't of Table 1. J.

Th, field work in Sehefferv1 ~l • .... .. de possi ble through a

D.I .N.A. graftt t'ro. th. Centre for Northern Studle. and R .... rch,

McGill Uni ver.ity, and through support rra. the Meelll Subl.rctie

Res_roh Station (and'~ .rr ln aotual tact).

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Table or Contents

page

Introduction 1

Clw.pter 1. Literature Revlew

1.1 Pea t lAnde J

Origln and dev.lop_nt J Cla.ei fi cation 5 Dtetri butlœ 6 Phyaleal propert1.,. 8

&. Morphclocy 12 b. Hydroloc 13 c. V •• tation 15

Ch.lI1eal propertles 20

&. Total and avallable ,nutrlente 21 b. V&ter ch.ll1ltry 26 c •• u~ent cycl1ng 27

1.2 Pri.ar, production J4

1.) DrecollpOtll tlœ ri

1.4 Âccu.ulat.lon 42

Chapt.er Z. Inv.et.lsat1one and Met.hodolQli ••

2.1 R.~ch al_ 47

2.2 General char&cterteUc. of the et.u4y 48 rectœ

2.3 Locat.lon and defln1t1on of eallp1ing Il tee 49

2.~ 11'1.14 .... ureMftt. 52

a. S1te properile. 52 b. Pri .. ry productlvlty 5" c. Li t ter 'ta&' .tudie. .5.5

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2.5 Analytical methods

Chapter 3. Results and Analyses

3.1 Site properties

3.2 Production

J.) Mass 108ses from decomposing tissue

, 61

12

15

).4. Testa for signif1cant dlfferencea between 79 10s8ea in the varioua site and litter categories

• 3.5 Nutrient changes during li tter deco.poal tion 8)

).6 Influence of litter quallty on deco.posltion 9)

Cha pter 4.. Di seuss! on

4..1 Peatlanda in the Schefferville ara 95

4..2 Production "Dy mire vegetation 99

4..) Factors influenclng a peci es producti vi ty 105 in 8ubarctic peatlanda

4..4 L1 tter decoaposl tian in lubarctie peatlands 110

Conclus1ona 117

Li terature eited 119

c: Humber

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

1.10

1.11

" 1.12

2.1

2.2

J.l

J.2

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List of Tables

Hydrol~lc and base status'propert!es assoclated wi th the major peatland types.

Physlcal propert1es of humie, mesic, and f1br1c peat peat J'IIIlter1als.

Specles distribution accorllng to grad~ents of trophic and moisture status.

Total nutrtent contents for a range of peatland types.

Rat10s of total ta availablA nutrlents of: flve major peatland types.

Mean values of the concentration of najor ions in waters from seven !l11re types.

Coaparison of d!seolved nutrient changes w1 th ::iepth for Houghtcn Lake fen, M1chigan.

Bio_s8 and production values for gram1noid, cha!lll\e­phyte. and bryophyte species.

Annual vascular, non-vascular, and total produc tion for peatland vegetation.

SUJU8ry of decollposi tion rates' of 11 tter for northern peatlan::is.

Rate. of peat Incrftment for nor~hern peatlandA.

Rates of organlc Natter accret1on.

Location, ' depth, area, and general che1'd.cal properties of the t6ur etudy si te ••

Tissue. collected troll! the tour atudy a1 tes for li tter bLg lnveat18atlona.

"-n value. ot ttHÇtrI'&ture. redox potential. 1J.nd COz evolutlon for ach ot the atudy si tes.

Production by vaaeular sPftcles a t the four si tes 1n­vest1.ted.

Page

7

11

19

22

28

29

35

38

41

.53

6)

73

i t

(; Number

J.)

J.4

1.5

).6

J.7

3.8

3.9

3.10

3.11

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Page

Mean leneth incremen te and production by Spha,rnum 74 mosses.

Proportion of original MSS lost over the winter 76 period and one year a t each site.

Calcula ted llnear (ls..) and exponen tlal (~) decay 78 constants for the ten tissue types at each site.

Mean values of IMSS lasses a t all s!. tes, and the 80 proportion attr1butable ta winter decol'lposltlon.

Results of tests for slgnlflcant di~!erences ln 81 mass lORS between tissue types, within sites.

Resul ts of tests for di "ferences in mass 10S$ W'i thtn 82 tissue types. between sl tes.

Chemical COMposi tlon of the orle1na1 tissues. 84

Percentage nutrients remalnlng ln Il tter tissues 86 follow1ne one year of dp.col'lpos1tlon ..

Correlation coeffic1ents and regresslon equat10ns for the relatlonshlp between decay rate and the original chelll1 cal compos1 ~1 on of th~ litter tissues.

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NUJllber

1.1

1.2

1.3

2.1

2.Z

3.1

3.2

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).3

3.6

3.?

3.8

List of' Fl.r;ures

Changes ln peatland development along latltudlnal, and continental to mari tlme gradients.

Hodels deplcting annual nitrogen, phosphorus, and calcium flux and pools fOT a central Mlchiean bog.

Seasonal NO -N, NHiJ,-N and total dissolved phospho!:'us concentrat16ns of surface water from a central Michigan fen.

Location of study 51 tes.

Procedures used ln process':'nl!, tissue st\rnplps for l'lea~urement of inorganic constl twmts.

Seasonal patterns of tenperature, redox potent~al. and COZ evolutlon ln the study sites.

Changes in temperature and redox potent1al withln the pea t prof! les of the four s tudy si tes.

Seasonal patterns of conductivity in su:r-face waters from the study sites.

Seasonal patterns of reduced 1ron in surf'a~e wat~rs,

trom the study sites.

Seasonal patterns of total dissolved phosphorus ~n surface waters fro", the study s~ tes.

Sea~onal pIltterns of aVl'llll'\hle ni trogr·m 1n surface waters from the study sites.

Seasonal patterns of aval1able nltrogen in surface waters collected ~rom the l'\rea harvest1ng p.lots of each study site.

Chan~es in mass of the ten tit'lsue types, !)lus cellu­lose, contalned in the Utter bags.

Changes in the quant1ty of K in the ten litter types durlng the first year of decomposi tion.

Page

9

32

33

51

59

62

66

68 f

71

77

87

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( .URber Pase

).10 Changee ln the quanti ty of Ca in the tan 11 tter types 88 durtng t.he tint year o~ decOJIpOsl tion.

J.11 Changee ln tj'le quant! ty of Mg ln the ten 11 t ter types 89 dur1~ the ~lrst year o! deconposlt!on.

J.12 Changes ln the quanti ty of' P ln the ten 11 ~tl!lr types 90 durtng the f1rst year of de~ollposi t! on.

J.13 Changee ln the quan t1 ty of N ln the ten Uttar types 92 durlng the firat year of deco~poeltlon.

1

1.

INTRODUCTION

( Peatlands are common and distinctive features of temperate and borea1

regions of the northern hemisphere. World peat resources have been estimated

at 420 million ha~ and may approach 500 million ha vi th the inclusion of

tropical and subtropical pea.t deposi ts (132). Recent figures for Canada.

range from 130 million ha (178) to 170 million ha (251), approximately 35%

of global peat resources.

Man has exploi ted peat deposi ts throughout the '\7orld for many years.

Tradi tionally. peat employment has included in si tu use for crop production.

in addition to materials created or synthesized from extracted peat, such as

industrial alcohols, insulation, fertilizers, and fuels. Much of the effort

in peatland management and research has been applied to the production of

agricultural and silvicul tural crops, and raw peat and peat products, or to

the prob1ems of transportation and construction on peat terrain.

The intensive in situ utilization of peatlands, or extraction of peat

materials, has resul ted in depletion of peat reserves i.n several areas. In

northern circumboreal regions, hovever. a great maJority of peatlands remain -,

intact (up to 99% in Can&da. (132». In a vorld of limi ted J;esources. i t i5

unlikely that this condition will persist. As the economic potential of

peatlands increases, they may be drained for timber production ~ cleared for

agricultural purposes, or harvested for industrial use" and their ecosystems

totally altered. Thus, there exists a need for careful examination of tqe

ecology of these biocenoses, and some assessment of the impact of management

acti vi ty on the systems as a whole. This has been recognized in the U .S.S.R.

and several European countries. vhere conservation programmes, aimed to preserve

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2.

( area. for .cientific. hydrologie, economic, and recr.ational purposea,

have b .. n bpl_nted.

De.pite the abundance of orgenic terrain in Canada (18% of the total

land .urface). comparatively little'research has been directed tovard

coapreh.nsion of the physieal and biological processas within these systems.

Knowledge of ecosystem dynamics is a prerequisite to proper and efficient

uae of those resources lt possesses, and 15 a usefuI tool for managing the

environment, through prediction of the consequences of site modification.

The present study vas undertaken in order to achieve severai objectives.

Firat. ,and most directly, to document two fundamental biological processes

in subarctic peatlands. through direct measurement of species productivity

and lit ter decomposition rates. The applications are both of scientific and

practical interest, in terma of testing recently developed models of peat

growth (50, 127, 247), and increasin, comprehension of the peat accumulation

proca •• , partlcularly the rata at which it proceeds under various conditions.

Second, the results obtained may be utilized for comparisona with similar

European etudie., in order to establish trends and management applications

on a larger scale. Finally, this res.arch, in conjunct1on with concurrent

flori.tic and ,eoch.mical investigations, will provide a more complete

picture of tbe interactions batw.an various components within subarctic

peatlands, and a better understanding of how they function.

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Chapter 1. LlTERATURE REVIEW

1. I Pea tlaruts

Origin and development

Peat ia a general term applied ta that material, chiefly organic,

regarded as " ... the incompletely decomposed remains of plant and animal

life aecumulating at their site of growth under extremely wet conditions"

(152). The principal peat fonning plants are sedges, reeds, grasses, Spaagnum,

and other mosses (93), although ericaeeous speeies and dwarf shrubs often

play an important role in mire vegetation. The type of peat produced is

dependent on bath the nature of the plants from which it i8 derived, and

the templates of peat formation, where optimum conditions are provided by

cool, humid climates, and a physiography presenting relatively large areas

of poorly drained land (114).

Deposits of organic matter are classified as peatlaods (!! seg. mire,

moor, muskeg) when the accumulating material has attained a depth of at

la.st 30 cm (undrained) or 20 cm (drainad) (131). The origin and subsequent

formation of peatlande differs as a rasult of climatological and topographieal

variations, where maisture conditions are instrumental. Basically, two broad

groups are recognized~ ombros.nous mires, where growth is cootrolled by n,

aemasph.rie precipitation; and. topoganous mir", where development ia

madtateci by topography and the ground vater table (194).

On a geclogic time scale, peatlands are of recent origin, h.ving

developed in the post glacial (Holocena) périod, following the race.sion of

the ice sheets. In many instanc.s, glacial eventa have strongly inf:ueoced

the formation and distribution of peat deposits. through rupturing and

scarification of bedrock, thua creation of landscape. with physiographic 1

l

and hydrologie conditions condueive to peat initiation and development

(: (115). The wat elimate 1nstituted at the Boreal/Atlantic transition

(approximately 8,000 years before present) resulted 1n extensive peat

formation under favourable topographie situations (54).

Iwo types of mire formation oecur; by overgrowth of lakes (terrestrial-

1zation), and by waterlogging of supra-aquatie terres trial soi1s (pa1udifi-

cation) (82, 107). In the former, elassical model of peat initiation. plant

debris gradually aecUMulates, altering the drainage ragime of the area. With

an adequate supply of base-rieh ground waters, topogenous mires continue to

form. If, however, simultaneous lateral spread and vertical accretion of

peat reBults in a reduetion of the ground water effect, an inereasing

dependence on precipitation develops, and ombrogenous mires tend ta form.

Although it is probable that fev peatlands are the result of a single sueeess-

ional sequence, the s1milariti.s in origin and development, supported by

stratigraphie evidence, sugaest that topogenous mires may be an early stage

of succe.sion, later b.eo_ing oabros.noua mir •• (232. 241).

In soma e •• e., pest do •• DOt ow. its gen •• is to favourable and loealized

topographie conditions, but racher ta e1imatic f.ctors, pa~icularly an

iner •••• in effective precipit.tion. rhis type of mire has originated .t

differ.nt tfa •• iG ditferent plac •• (53. 54. 106, 150. 157), but it. initi-

ation i. a.aoei.t.d with"cliaat1c fluctuation. Th. gr.dual bÙild-up and

expan.ion of organic .. tter commonly oceur. on level and gently sloping

terr.in, in cool, moist .r •••• wh.re the v.t.r table 18 clo •• to the surface,

or vher. an incr •••• in th • .oi.ture r.gia. re.ults in an inv •• ion of

Sphasnua mo •••• (219). The product 1. g.nerally a .ballow, a.brogenoua p.at

depo.it.

5.

Based on stratigraphie evidence (103, 154), the peat deposits of the

interior Labrador-Ungava peninsula appear to fit the classical model of . ,

fo~ation through basin filling, and the conditions underlying the development

of peatlands in this region are similar in nature to those of other subarctic

areas (2).

Classification

The classification of peat and peatlands has long heen of concern to

peat ecologists and technicians alike. The literature contains a myriad of

terms describing both peat and peatland conditions. In the past:

" the lack of globally unified principles of classification of peat species and deposits has hampered, to some extent, the progress of peat science, and has led to the appearance of many differant, often ill­founded, conceptions of peat formation, the structure of peat deposits, and their geographic distribution." (162)

The need. for meaningful and consistent definitions of peat and peatlands

has led to the recognition of three systems, common to many count~ies, geared

to best serve those employing th .. (74):

1. A horticultural peat and peat IIIOSS classification based on fibre

content, botanical types, and degree of decOllposition.

2. A soil classification system bued on degree of deco1llpQsition

(b.!. fibric, _sic, and hUlld..c).

3. A peatland clas.ification system, wh.re vegetative types (open, forested,

moss, sedge, etc.). topographie type. (Ilopina. blapket, raised, basin),

hydrology (ombrophllous, transition, rheophiloua). and base status (ombro-

6.

trophic/oligotrophic, mesotrophic, eutrophlc/minerotrophic) are used as

criteria.

ln broad .cologieal terms, peatlands are divided into two types; bogs

and fens (160,210). In boreal and subarctlc regions throughout the northern

hemisphere, bogs and fens are the major types of organ~c terrain (234), In

order to place bogs and fens in the context of classification, the general,

widely reeognized properties associatad with, and used to differentiate

between, these two peatland types are presented in Table 1.1. Any mire can be

placad with1n the continuum of variation between these two extremas (152).

In practice, and for the purposes of this investigation, the classification

of peatlanda may be conaidered hiararchical: level one establishes the major

peatland types, such .s bog and fen; leval two subdivides them into morpho-

. logical .ubtype., such as raised bog and slope fen; level three identifies

the major vegetation types; and, level four identiftes the specialized needs

of variou. diaciplines (252).

This brief ovarvlav .. phaslze. the iaporeance of clasaifieation and

tenatnology in distinsuishinS real and ~portant dtfferenee. aaong highly

ca.plex ecologic&! si~uations. The dilferentiating charaetertstics are useful

in de.cribins factor •. that accoUDt for the pre.ent phyaical f .. tures and

vesetation pattema of p .. tlands.

Distribution

A major proportion of the world'. peatlaads occur in bor .. l and

e .. peraee (oceanie and cont1neaeal) resions of the northeru h .. isphare. The

zonation of peatland types t. probably of gr .. ter iaportance in terms of ~ire

1

{

Peatland type Gradient Peatland type

Bo6 Ecologie Fen

Oabrophiloua Hydrologie Rheophl1ous

o.brotrophle Base statua Minerotrophle Oll@'otrophi'c Eutrophie

Tabl. 1.1 HydrolOSie and ba •• statua propertl •• associa ted w1 th the _jor pM tland type ••

7.

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8.

ecology than is the global distribution of peat resources. The geographic

variation in peatland types reflects, in part, changes in development along

a climatic gradient (59). Regional differences in hydromorphological mire

types are associated with three zonal characteristics; macr~imate, length

of the vegetative period, and frost action (23). Local variations in peatland

features, particularly the nature of the plant cover, may be due to edaphic

conditions or floral history of the area. Both local and regional conditions

impart not only physical, but also ecological changes within and between

peatland types (68). The climatic and developmental changes along north-south

and east-west gradients are illustrated in Figure 1.1.

Regions of raised bogs, and those which replace them under maritime

condit~ons (~. blanket bogs) , are widespread on both the Atlantic and Pacifie

coasts of North America (57, 181, 182, 241), Europe (14, 169), and Asia (129,

236), where they axtead a. far as the 91st aeridian. An iocrease in contin-

entality resu1ts in a predominance of .utrophic peae types (129, 182), where

peat formation t.nds to b. intensive: To the north and south. peat accumulation

decr.aS8S, a. a re.ult of low tamperatures in th. north (r.ducing both

productivity .nd d.compoaition). and .n iocr •••• in the ratio of .vapor.tion

to pr.cipitation to the south.

Phy.ical prop.rti.s

Th. physical propareia. of peatlaDds (.arpho1olY aDd phy.ioaraphy) are

affected by the aurroundina .uviroDaeDt. and lt haa baen .uaa.st.d that

th ••• features .. , alao crea ce unique local an.iroa.ents (62, 114), s

di •• tall.r situation to tbat of .inaral so11s. The surface atructura •• hydrology, 1

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''::~~~V'*,~(~~'''''~ ~

~

~

? ...... -~ ~ ~"""~4= ;;;;:~

~ .~~~

... L ' ' ..... ~ ~IJ-~_~~~-+~

COttTlNaH1Al ---... MARITIME

Fl«u~ 1.1 Changes in peatland developaent along latitudlnal, and continental to .aritlme gradients.

(At'ter ra ... n (59)).

'D •

10.

and vegetation of peatlands are apatially variable. a1though interrelated at

tha microanvironmental level.

Comprehension of the relationship between peatlands and che environment

as a whole aecessitatas examination of the physical properties of the peat

material. Many of the Most important physical characteristics of peat depend

on 8tructural features. such as partiele size distribution and porosity whieh, "

in turn, rely largely on the na~re and origin of the composite plant remains,

and their degree of decomposition (173). Table 1.2 presents some general

physical properties of peat material.

One of the most evident and critical properties of peat is its capacity

ta absorb and retain large quantities of vater. This ia due ta high porosities

(average tocal values of 92%). which are augmented with an increase in'the

degree of decomposition of the material (234). The moisture holding capacity

Df pe.~ plays several important raIes. Soil aeration i8 a crucial factor, as

it influence. not only plant growth, but alao p'laat accuaulation. which tends

to be reduced undar driar (.erobic) condition •• s a re.ult of oxidation, u

thu. dacay, of organte sattar (59, 135, 232).

In addit1on, tba watar content of paat has baen found to be instrumental

ta its thar.ar propertia •• In ca.parison vith athar s011s, peat has a 10v

ther.al eODducciv1ty (k), whieh depend. on che vater contant where,

k.= 2.61(x )1.39 • 10-6 w

and Xy 18 the voluaetric v.tar content (75). This reduced thenaal conductiv1cy

ta 1aportant .s:

1. Soil t .. per.ture. influenca tbe .atabolic activity of plant roots and 5011

IJ

11.

( 1"- -

Fi bre con t8l'l t &.

P_t type ( 0.15 _) ~

Hydraul1c b. Haxiw. saturated conduct1vl ty Bulle dens1 tyc. _ter content

(Clio sec -1 ) (g.c.-J ) (aven dry basis)c.

%

Hume JJ 10-6 0.2 450

Mesie )J-67 0.1-0.2 450-850

Fibr1c 67 10-1_10-J 0.1 850-)000

a. Walaaley (2)t&.) b. ltycroft .!1!.l. (189) c. Day (6),

...

....

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organi ... (65, 249).

2. Peat tends ta rematn frozen for longer periods than the surrounding

mineraI soils (2. 22, 114), thus sail waters are unavailable to root systems.

3. Mass tranafer of unfrozen water 18 decreased as the ice content of the

peat increases, due to les8 free porosity (75).

a. Morphology

The way in which peat accumula tes varies in response ta different

coabinations of anv1ropmental and btottc factors. The development of peatland

topography is due, in part, to plant gravth, and to differential rates of

pest accumulation and decay (115).

In many cases, peatland surfaces possess morphological characteristtes

or patterns, most commonly:

1. Convexity, generally as.ociated with raised bogs. and Most frequently due

ta the growth of Sphagnum mosses (155. 183). particularly the concept of

lenticular regeneration where hummocks exist (93. 152).

2. Strings, which have bean attributed to the action of trost at the surface

and the depth ta which peat is thawed in the spring (2. 220), and ta the

.. tablishaent of water tracks, or elongatiou of microhummocKs created by the

clona! growth of some sedge species (85). Despite the theories put forth ta

explatn the orlgio of strings and hollows (flarks), the genesis of these

f .. tures remains unresolved, ~lthough once Inltiaced, appear to be self-

perpetuating (199).

The maintenance of specifie mire patterns 1. mediated.by surface

•

13.

drainage patterns. These are often used as diagnostic features, as, they are

apparent from aerial photographs. Several principles, applicable to most

tempera te , boreal, and subarctic peat1ands are suggested (115):

1. Ombrogenous mires, particu1ar1y raised bogs, have divergent, or radiating ..

waterflow patterns.

2. Topogenous mires are éharacterized by confluent (converging toward drains)

flow patterns.

3. Strings of patterned mires are oriented at right angles to the direction

of water movement, thus, aspect of the underlying terrain.

b. Hydrology

Water and peat are inseparable by virtue of the nature of peat formation.

Properties of climate and soil hydrology combine to produce conditions in

which organic matter acc,umulation exceeds decomposition. The hydrologie

- status of a peat1and i9 a produet of physiographic and climatic factors, as

weIl as of properties of the peat substrate itself (114).

Three hydrologie situations are common in peatlands (152):

1. Rheophilous mires, developing in mobile ground waters.

2. Transition mires, either rheophilous mires with an insufficient ground

water supply. or mires ~hich are in the proeess of changing from a rheophilous

to an ombrophi10us water regime.

3. Ombrophilous mires, developing in immobile gr~und waters, their entire

water supply provided by precipitation.

Under ideal conditions, hydrologie conditions might gradually change from the

first to the third situation, thus, playing an important role in peatland (

[

1

14.

evolut10n.

The water wh1ch 8at~rates the peat of mires i8 ultimately derived from

the atmosphere, as rain or snow, but depending on local climate and topography,

the fate of this precipitation differs between one mire and another. Seasonal

water budgets are set by the balance between precipitation and evapotransp1r-

ation, and by spring runoff patterns (12, 121). Uneven distributions of runoff,

and reduction in or lack of sustained water flow from peatlands are commonly

observed, although short term delay of storm runoff may occur, part1cularly

when water tab1e~ are low (8,13).

Mavements of water occur horizontally, a~d may be correlated with

microtopography (190), as weIl as from one horizon to another. Water table

fluctuations are influenced primarily by vegetation, local hydrogeology,

precipitation, and type of peat material (12). ~e maximum eleva'tion of the water table dep~ds on the mois~ure balance, the size of the mire, and the

distribution of rainfall, as weIl as the topography of the surrounding

terrain (247).

Both lateral and vertical transfers of water are governed by the peat

substrate, particularly the hydraulic conductivity of the medium (121),

although specifie application of Darcy's law may pertain only to unhumified

pe.t materials (123). Several trends have been observed with regard to the i\-

rate of water mavement in peat:

1. Fibric pests are most conductive. and humic"peats least conductive (21).

The size and continuity of pores, as affected by the arrangement of the parti-

cles, creates a wide range of hydraulic conductivies in peats.

2. The lateral spread of water decreases with depth: this may be attributed

to reduced porosity (increased humification) and horizontal orientation of

, ;'

l r

! i

1

1

\~ J • •

c pores with depth, as weIl as proximity ta mineraI s01l layers which retards

percolation (190).

3. Water quality (oxygen concantra~1on and pH) is increased as vater mavement

increases (207).

Properties of the soil water system (i.e. source, velocity, and renewal

rate) are important, as transfers of water directly control the spatial

heterogeneity of peatlands, and the nutrient, oxygen, and toxin load of the

sed~ents. These factors, in turo, modify characteristics such as species

diversity, primary productivity, organie deposition and flux, and nutrient

cycles (101). In the literature of peatland ecology, references ar~ made as

ta the importance of ground water movement as a factor determining the

distribution of mire vegetation (91.114, 121, 152, 198), particu1arly

floristic differences betwean vater tracks and the surrounding mire expansa.

1 c. Vegetation

~

Vegetation play. an ~portant raIe in proeeaaes within mire biogeocenoses.

In both ombrotrophic and minerotrophic mires, there exists a mosaie of

vagetation. In general, however, tha vegetation of ombrotrophic types (bogs)

i8 depauperate, the Sphagnaeeae and Ericacea. being Most prominent, while

the vegetation of minerotrophic types (fena) ia comparatively r1ch in grasa,

sedge, herb, and shrub speeies. The change from one extreme to another 1a,

for the MOst part, continuous, with a number of floristiea11y simi1ar sites

containing common species in diff.rent proportions (61).

Sphagnum masses and their remains form a large part of Many peat deposits,

/ ( thereby hav1ng a significant funetion in peat formation, and giving some

16.

iDdicat1.on of site quality. Sphagna have low nutrient requirem.nts (4~) t

and experimental results indicate that these plants absorb cations selectively.

fro. the environment (46, 166). The ,structure of Sphagnum is intermediate

betveen a planktonic al gal population and a vascular plant. in both distribu-

tion of chlorophyll cells and dependenee on moisture (48). These unusua1

futures May account for the sueeess of this genua in habitats where many

plants are exeluded.

The conditions of aeidic (particularly in bogs) and often waterlogged

(in peatlands in general) subStrates poses some unique eeologieal problems

for vascular plants. Plants whieh grow in these habitats have adopted various

physiologieal and morphologiesl strategies to compensate for the lov nutrient

and oxygen availabilities within tllese systems. Of importance are the

adventitious root systems (renewed growth fram perenniating rhizomes) of many

cypeneeous graminoid spec1es (15, 19, 99), and the development of sclero-

phy1lous le.f tissue in Erieaceous species (henee, increased cutinization and

lignification, and increased fibre ta protein ratio), vhieh may reflect a

spactalizad metaboHslll tolerant of 10w nutrient levels (144). "

Floristie comparisons show siJailarities betveen mire vegetation on a

large scale, such that most spacies have boreal affiliations, and several

specie. are commonly regarded as mire plants. These include: (herba) Drosera

rotundifolia, D. anglica, Empetrum nigrum, Menyanthes trifoliata, Potentilla

paluatris, ~ chamaemorus; (graminoids) Rhynchospora Alba, Eriophorum

(cotton-grass) and Carex (sedge) species; (shrubs and voody vines) Andromeda

..

glaucophylla, Betula pumila, !. ~, Chamaedaphne calyculata, Kalmia (!olifoHa,

K.. angustifolia, ~ groen1andicum. M'ydcs gale, and Vaecinfum spp •. Picea

III&riana and Laru lar1cina may also invade peatlands. Amang the non-vascular

)

1

i

l

17.

plants commonly associated with peatlands are Sphagnum, Hypnum, Calliergon,

Hylocomium, Polytr1chum, and Drepanocladus mosses.

Differences in peatland vegetation oecur at several levels. On a broad

scale, continental and maritime mires possess different vegetation patterns

(57), where Sphagnum mosses play a greater role in the latter type (182). The

flora of coastal bogs 18 generally richer than that of those inland (68),

which has been attributed to a more favourable climate (57, 124), as weIl as

higher nutrient inputs from sea spray and lower acidity due to permanently

waterlogged conditions in the peat (60).

Floristic variability also occurs between oligntrophic and eutrophic

mires. That is to say that species density (or riehness) of vaseular plants

is related to the degree of influence by water that has percolated through

mineraI soi1 or bedrock (195). Efforts to distinguish between bog and fen

utilize acidity and base status of the medium as properties whieh may restrict

vascular plants to eertair. sites. Attempts have been made to define indicator

species, i.e. species with a narrow amplitude of adaptability to giv~

environmental factors. According to sorne reports (57, 85, 170, 205, 241, 242)

several species (Carex chordorrh1za, ~. diandra, Eriophorum angustifolium,

Molinia caerula, Triglochin maritima, Betula michauxii, Lonicera villosa,

Potentilla fruticosa, Scorpidium scorpioides, and Drepanocladus spp.) are

regarded as indicators of minerotrophic conditions. In most cases, however,

the ecological amplitudes of species varies. so that the vide distribution

of a single component might indicate that it was a tolerant species, and not

that a specific set of conditions exist in a number of locations.

Finally, within bogs and fens, distinct plant communities or associations

(both based on vegetation of more or less homogenous composition and structure)

lB.

( often change within rather short distances. This may be aftiliated vith

evident variations in microtopography (raised versus depressed areas),

reaulting in complex ecological gradients in accord with different water

levels, nutrient status, and microclimate (60, 68).

Mosses and hepatics are often more accurate indicato~s of small scale

(hummoek/hollow) variation than vascular plants (165). In addition, Sphagnum

mosses are believed to exercise a selective influence on the distribution of

vaacular plants (62, 181). Sphagnum species show remarkably consistent trends

in relation to microtopography. In raised bogs of (a) Europe, (b) Canada, and

(c) eutrophie peats, the following organizations of mosses were noted (from

drisst ta wettest sites) (165):

(a) Sphagnum fuscum > rubellum > imbriea tum > magellanicum > pap illosum > bal ticum,

lindbergii > pulchrum > maj us > cuapida tum;

(b) Sphagnum fuscum > capillaceum (rubellum, nemorum) > magellanicum>

angustifoI1U11l (recurvum) > annuIatum (jensenH);

(c) Pleurozium schuberi> Sphagnum fuaeum> warnstorfi! > subfluvUIII > Drepanoeladus

revolvena, .Q.. badiua > Caapylium stellatua > Seorpidium scorpioides.

Table 1.3 sumaarizea some speciea alliances provided through several

North American and Euraaian investigations (23, 60, 62, 73. 85. 112, 114, 115.

128. 139, 155, 170, 171, 185. 224, 236. 241). Thi. i. not a complete 5peeies

list, but ~ather a stmpli.tic synthesls of those plants found to he common or

predominant under given conditions in a number of isolated cases. Of special

interasc are the extenaive, often eircuaboreal, distributions of many genara,

and the broad .cologieal amplitu4e of soae .paci ••• Certain species, then. can

ba aean to occupy dry oligotrophic, wet oligotrophle, dry eutrophie, or wat

eutrophie aite. preferentially, although the •• groupings are not mutually

(

.. :q.-~i

HU .... OCI<S LAWNS MMotro hic Eutro hic OU MeIOtro hic Eutro hic

110"0 ~ S.11I1o /HIllfilll .. Car.x rD.lralD ..

.'1110 mu:1f1lllJl11 e IHJIIfllMlllpltll' cDlyculo la Car.x IO!llocorpa .. AMlro." t/OIIcopllylltJ " AMlr .... pilollll Cor.., dloRdro V«cl." o.qcM:f:fl. .. l'rK"c_''' IIl1gilttl._ ""cc ... vlfi.-1tIoIJII .. V~ tII9I.,ilDlillm Vocc __ IItyrl ••

Lonlctlrtl VllknD .. Po/M/ilo hl;co.1I Polfllllllll pMI.lrh

SC"f/ItI' C'.'DSIU .. L __ "."IIIItdH;". K ........ IlIoNIl Dr .... rohIMIlDlIII E.,IW"."", III /lu.,. ~".".GI'II' ~

LiIdwe ,.,..". .. Erio"..,... 1IfIIIIMI11l1If .. CM,. ,Vii, III Cllr,. oI~rlllll .. C ,,11,.,. rrI/tIOri. Mo/~ -.rulll ..

MY/ID DIttNlMlItl Sp/ttlfll#llll 1#I.eUM ---- --- -----Ill SphIIgtHIlIf ~/lIInlc_ .. SpItognum mll(l.lonie"", .. $pu,- ptIpII/o$ulII .. " III S,.., ... INIlliClllIf Sp/HIfIWIJI ballicum Sp/IofIHItII rub.nu. .. SphtlfllUm r/lH1I1HII ..

SpIIo(/lHlm _ndDr'" .. SphafllHltrl I",db.rf/II .. SphlllfNlm pU/Cltf"'" ..

SplHlllnu", rlpaf/"'" .. SphOfnum "oclum

l'olylrlCltIJ,,, slnelUIIII Dlcra~ ~.onl .. S./tI(IIlI./lO s"ogmoldtl'

AuklcOIIIIIHlIIf pohl"" .. Thalle/rum polYl/fllllum Pl#lIfOlIIlM ,cltrdlfl ~

Hypnum Jclt"b.o .. Table 1.3 SplCi .. distributions accordlng to gradientl of trophic and moilture statui.

~.

HOLLOWS hic MMotr hic Eutro le

CfU •• /ùno,o CII"X rD.'ralfl ..

C,,,,,, /Ivlda .. CIIT.X IlI!IIOCIUpll ..

Cllf •• pollclll«tI " Cllr •• o/igo,pflrllfll .. Cllr.JI •• /1" ..

Ci/,.JI clHlrdtNrllull

Sclf~chz"JQ polu.'f'. ~

Rlf.yndwsporo albll .. Call1tnOgro.lI. "".110 •• ..

TrIQltx:llIll "'Mfi.o ~nnlllOM

ErlDpltorum ,pin •• E napllo,um CIloIltl$$Dlt/'

ErlDpluNum allfll/.,ifDlilllll II'

IH"YIIRIIf" Idlolllllo ------. UlriClilorlo 'pp. DrD!lflrll IIII.rln.dIa

Dros.rll rolu"dlla/io Nuphor vOrlfl(lOlum ..

Va',,,,,,,m m(/,rOCtlfpOn B"lulo mlclt04lxiI

Spltllgnu", ,.".l1li", .. Splto(Jl1fl'" clI!lPldalum . .. Sp/llIgnum mll/f/' .. SphOfIlUltl fflCf/rvl/III .. Sphognum mIlg.lllllllcum ..

Sphaflf"IfI .b .. cundllm .. Sphll(llfllm '''.0.", Spltllgnum j.tt'tlnlt

Spl/ognu.'" pil/chr"m .: ,

SpltallRUIIf "pllrtum .. SplHJ,IRIIII4 oblu.",. ------. SphollRllm 'quarrolU'" .. E(lu/Slllum 'hholli. .. Dr.panoclodl.ls tlxannulolu$ ..

Campylllm .,./lalll" Scorpldlum sCDrplDldfl' III

Cal/ltlr(lon .pp

.... \0 .

20.

exclusive. This seems particularly applicable to vet hollows ln bogs where,

due to some degree of mineraI influence, weakly eutrophie conditions may be

present vithin otherwise oligotrophie mires. Despite the Many existlng

eeologieal gradients, a two dimensionalordinate (vith trophic status and

moisture status as components) May present a relatively satisfactory and

informative analysis of characteris tic vege tation patterns (112).

Chemical properties

Chemically, peat i8 a variable mixture of complex organic compounds,

includlng celluloses, lignins, cutlns, waxes, reslns, alkaloids, pectins,

fats. proteins, sugars. starches, and thair decomposition products (114).

Normally, over 90% of peat materials consiat of organic substances. The chemical

status of a given sample depends, in part, on the original botanical con-

stituents, and the nature and degree of their alteration by microorganisms

and chemical reactions.

Mineralization or breakdown of organic mate rials tends to be a contlnuous

process, producing nev compounds, and forming carbon dioxide, water, and

en.rgy. Cblloidal organic, or huaic, subatanc •• (particularly acids), vhich

constitute tbe bulk of organic material in put, are a rouIt of tbe ebeulieal

and biologieal degradation of plant and animal reaidue. (1.e. gmœ ,hemicellulose,

and lignins) (193). The re.iatance of vario" organic compound. to decomposition

Is reflected in the distribution of verious organic fractions in put profiles.

In accordance vith the high organic .. tur content, the aah content of

peat is lov, generally 1 ••• than 5% (173). The inorganie elements of peat are

\ primarily derived from th. initial peat forming plants, as weIl as from

(

21.

extraneous (atmo.pheric and ground water) sources (234). Although the

organic carbon content i8 similar for a variety of peat types, carbon ta

nitrogen ratios differ. and tend to be charaeteristic for aedge and moss

dominated peat material. In general, C:N ratios of moss peats exceed 20:1.

whereas those of sedge peata are le88 than 20:1 (234).

a. Total and available nutrients

Nutrients entering peatlanda via some external .ource will be atored

in the peat, or transloeated or removed to some axtent. The capacity of peat

to bind cations (raterred to as the cation exchange capacity, CEe) is high

(152). The CEe of organic material i8 the reBult of dissociation of hydrogen

ions in certain organic group., such as tbe aeidic carboxyl (-COOH) and

phenolic hydroxyl (-OH) groups of humic acid •• and .ubsequent substitution

by positively charg.d cations. The supply of aobU. aniona limita cation

transport to soma utent. so t~at the addition of hydrosen ions without a

mobile anion cou.ld decre .. e cation transport by shifting the equilibrium

of organie acida to the .. societad fortll (100).

Total. nutrient contenta of pest soila vary with the particular type of

peat, generally 1nqrea.ing from bog to fen (241). (Table 1.4). Altnouah stTict

limits are unlikaly. the ionic balance and acidity of peat have heen utllized

as indice., 'characterizing differant peat type. (98, 211), and cal.cium to

magnea1uaa raUo. of le •• tban 1.0 ara de_ed an indicatlou of ombrotrophy

(44). Nutrients retained in ombrotrophic and fen p.st. dacrease S.n the order

N > Ca> Mg > Fe> K> P> Mn and Ca" ~ > Fe .. MS> lC" P, Mn re.pectlvely (58, 237).

Law total phoaphorua il an intria.ic fe.ture of peaU (140, 170).

22.

..::~ P. tl&nd type Total Nutrlenta (% dry welght) Source

If p K Mg ca

Rich fen 2.54 0.09 0.08 0.14 1.33 (180) \

Marginal f'an 2.50 O. CYl (140)

Ralsed bog 1.80 0.02 0.40 0.10 0.07 (235)

Blanket bog 0.04 O.OB 0.12 (90 )

o.brotrophic bog 1.10 0.03 (140)

Table 1.4 Total nutrlent contents fOT a ra.nt;e of peatland types.

(

23.

reflecting its limlted external supply (89). Phosphorus in peat ls present

mainly in the form of mineraI compounds, i.e. aluminum, iron and calcium

phosphates (248). Nitrogen, whieh is perhaps the Most critieal element in

terms of total productivity of the system, is present in a number of forms

and valence states (NII4+ , NH). NO; , N0ï ' N2 , and organic nitrogen) (78).

Inputs of nitrogen are derived from:

1. Nitrogen mineralization (overall conversion of organic nitrogen ta

ammonium, nitrite, and nitrate) (l87);

2. Absorption and fixation of atmospheric ammonia (NH 3-N) (34, 142);

3. Decomposing 1itter (70, 152); and,

4. Nitrogen fixation, probably by a1gae intracel1ular1y or eplphytica11y

assoclated with Sphagnum mosses (11, 102, 238).

Organie so11s tend to be low in total potassium, as humus colloids are

essentially unable ta fix this element (197); chis, together with the highly

mobile nature of potassium (248) results in removal from, rather th an storage

in, the system.

As nutrients are incorporated into the peat, they are rendered unavailable.

The amount of adsorbed metallie cations in the peat substrate may be of the

order of one hundred Cimes that whieh is available in che peat water (93).

-Table 1.5 presents ratios of total to available nutrients for five peatland

types. Thus. despite the potentially high fertility of peat, severe nutrient

defieienciea may exist. as available forma of easential elements are limiting

(109, 141, 200). The ratio of exehangeable nitrogen (ammoniacal and nitrate)

ta total nitrogen ia generally 1%, and chat of available phosphorus (HPO~2 and

H2P04 ) 1 to 2% of the total phosphorua pool (180).

The pattern of available nutrients (decreaaing from Ca> Mg> K> Mn > ~l > P)

1

1 .

Aaaoci& tian

Blanket q

Raiaed 'tq

Treed fen

Rich fen

H.th fen

'!able 1.5

1....<3 ___ -'-"' __ .. t .nfès~f •• er

_1

Il P

186: 1 11: 1

247:1 22:1

)67: 1 11:1

281:1 45:1

)24:1 28:1

, ' 1

1

1.): 1

1.4:1

1~1.44

1: 2.79

1: 1.51

".

Ca M6 ,. Z.):l 1.41: 1 1: 5.41

1.78: 1 1.64~1

1

2.d4: 1 2.51:1 1.68:1

2.06:1 1.96:lr

2.71:1 2.)): 1 1.45: 1

Ratios of total to aY&llable nutrients of five .ajor peatland types. (After PoUett (110». '

/'

.... """,,t; o.ot.""..~ ... ,_~ ... ~ ....... ~ ..

~

,.... ~ "

CI

N ~ •

"·'''.~t~~

will d.pend on a number of factors, including the total content of the

.lement in the soil and the effect of pH (138), and the degree of anaerobism,

and the soil tamperature. In addition to having poor mobility (248), nitrogen

and phosphorus tend ta be released slowly from the peat substrate. Reducing

(anaerobie) conditions increase the solubility, thus potential availability,

of phosphorus and iron, while higher concentrations of available nitrogen

are present in aerated zones created by water table fluctuations, as a result

of higher rates of nitrogen mineralization and oxidation (180). Summerfield

and Rieley (214) noted that phosphorus and cations adsorbed on peat became

several fold more available for a twenty four ho ur period following 80il thaw.

The distribution of elements differs between ombrotrophic and minerotrophic

sites (93). In poorly drained soil situations (redox potential 0 ta 400 mV) 1

ammonium ions predominate in the sail solution, as nitrification ls lnhibited

(78,180,237). This may explain the hlgher concentrations of available

NH4-N in peat from some bogs (237). Rates of nitrate accumulation in aerobic

layera depinâ on both temperature and moisture characterist1e of the sail (7).

Concentrations of extractable P04-P (phosphate) may a180 be greater in bogs,

whieh Waughman (237) has attributed co phosphate fixation vith 1ron, aluminum,

and c:.aleium phosphates in fena. Virtually aIl uchangeable potassium, calcium,

and "anesium ia water s~luble (42), thus, tends to be rapidly and completely

reaoved by wat.rs percolating through the system.

Differences in nutrient supply between bogs and fens may be reflected in

th. nutrient contents of mire plants (218). although the ab11ity of various

speeie. to take up and tran.locate el.ents under waterlogged conditions may

be of greater importance in so .. c •••• (4, 136). In .ddition, some species <. '

.. , coapen.ate for the d.pres.ing effects of low soil temperatures upon

1

i

26.

nutrient absorption rates by having higher absorption capacities (38), and

elements lim:1.ted in supply or availabili ty may be reeyc1ed within various

plant compartments (39, 58, 180, 201), and from 1itter to living biomass

(141) •

The elemental composition of above p,round biomass has been found to

decrease from ~ > K, P > Mg> Hn> Ca> Fe (58, 225), refleeting, in part. the

biologieal demand of the various nutrients: Deviations in mineraI concentration ,

may result from differences in storage and flux from various parts of the plant,

in addition to the inconsisteneies in the chemical behaviour of elements within

plants (39). Concentrations of nitrogen, phosphorus, and potassium represent

biologieal uptake (i.e. are most concentrated in actively growing parts of

both vascular and non-vascular species (141»), whereas leveis of calcium,

magnesium and manganese May result from physieal proeesses (166).

b. Water chemistry

A number of factors affect the chemistry of peat waters (152):

1. The chemical composition of precipitation falling on the catchment.

2. The geology of the watershed.

3. Topography and drainage systems of the basin.

4. Climate, affecting weathering rates, and the minera! concentration of the

resultant water body. "" \ ,-

5. Biotic modification brought about by biogeochemieal cycles.

6. The time over which the system has been exposed to weathering effects.

7. The rate of water movement through surface and subsurface routes.

The chemistry of peat waters varies with the type of peat deposit, as

l­i

27.

( shown in Table 1.6. Generally the specifie conductivity (representing

approxima te quantities of mineraI ions present in the water) of fens is

higher than that of bogs (98); and, fen waters are dominated by calcium and

bicarbonate ions, whereas bog waters are dominated by hydrogen and sulphate

ions (152). Water chemistry also varies with depth-below the peat surface,

which can be attributed ta changes in moisture-aeration conditions, and

plant uptake (180). The nutrient status of a peat profile ia presented,in

Table 1. 7.

Although relationships between ionic composition of mire waters and

peat and peatland characteristics have been extensively documented (91, 92,

94, 95, 98, 198, 224), it is difficult ta aS8ess whether or not peat waters

and substrates approach an equilibrium. If the acidity (which has an over-

riding influence on the availability of nutrients) and potentially exchangeable

cations of these media are compared, it would appear that they do note The

pH values of water samples are higher (as much as 0.57 units) (207), and

the potentially available elements lower than those of peats (91). The

difference in pH May simply be due to measurement of pH as a suspension, as

ia the case in soils, where the change in pH is about the same (Moore, pers.

comm). Nonetheless, water chemistry may be of greater importance in peatland

development and floristics, particular1y the regulation of elemental supply

to plants, than the underlying peat material.

'J

c. Nutrient cycling

( A modification of energy flow (such as the accrual of peat materi~l)

within terres trial ec08ystems is invariably associated with changes in the

r,

;~

\. . 1

Jt

<9

/'

"

III _ ... )

.J. Total Major Ions (.eq/l)

M1re type pH HCO 804 CI. Mg Na K H )

Extre .. ri ch "fan ?? 2.) 0.4 1.8 0.9 0.2 0.02 <0.01 0

Tranaltlonal ten 1 5.8 0.9 0.03 0.9 0.02 0.05 0.01 <0.01

Interaedlate fen 5.5 0.6 tI

0'.06 0.6 0.0) 0.08 0,01 0.02 )

Transltlonal poor fen 4.8 0.1 0.04 0.1 0.0) 0.06 <0.01 <0.01

Interaedlate poor fen 4.4 0 0.05 0.06 0.0) 0.08 <0.01 0.4

Ixtreae poor fen 3.9 0 0.01 0.07 0.02 0.05 <0.01 0.1)

Iba. ).8 0 0.1) 0.04 0.05 0.09 0.01 0.16 ('

"

fable 1.6 '1'

Meaa valu •• of the concentration of _jor ions in _tera ho. seven aire types. (After Sj6ra (198».

~

•

-. }-----

r--,

, L

N CD •

..

--­~/

,--'J

)

l

c

(

29.

..

Nutrient concentration (àean.t. a.d.)

Depth belo1f pee. t surface (ca)

Nutrient Surface water 15 45

IOft.-N (pg/1) ?l8:*: 818 2099 i:1572 1899 t:15J2

lfOJ-N (pg/1) 39:t 2U. 59 :1:.28 57. 3)

CI. (1IIg/1) 19.)% 10.? )0.2: 16.5 )2.) ~1?8

// Ms (118/1 ) J.9.t 1.8 5.6 :t2.8 .

6.0 ± ).4

TDP (ug/1) 19.6:t 9.5 4O.8.:t 35.5 29.)%2).5

'e (118/1) O.S~ 1.6 1.8.tl.5 1.8:t:.l.4

K (./1) O.?:t: 0.6 0.8 ± 0.6 0.5 1 0.4

Table 1.? Coaparilon of dlsso1ved nutrient changea 111. th depth for Houchton Lak. fell, It1chipD. (After Richardlon .n!l. (IBO)).

..

.'

f ,

~.

c paCteru of nutrient cycling vithin the .yst .. (152). Deepite the importance

of biogeocheaical transfers in ecological processe., and in linking ecoayetam

aad enviroaaent. the nutr1ent dynaa1ca of peatlands have rece1ved little

atcantion.

Quantitie. of variou. eleaants within Any one coapar~ent of the system

(peat, vater. or vegetation) are spatially and teaporally heterogenous. In

boch re.pects. ch .. ical budgets are affected by (100):

1. Input. (a) rock and 80il veatbering

(b) nitrogen fixation \

(c) particle t.pact10n and ga. abeorption. ,

2. Hydrologie proce.ses affecting output. 1

-: (a) 10 •• of dissolved substance.

(b) ero.ion

(c) r.gulation of radox pot.ntial ••

~. liololical proc ..... affecting th. balance of inputs and output.

(a) n.t ecosyatea production

(b) d.co.po.ition and elament aob1lization

(c) r.gulation of soil solution ch .. istry

(d) variability 10 utilization of al .. enta.

Relatively coap1et. analy ••• of ch .. ical inputs, outpuca. and a1àka in

parc1cular peat1aud. bava baen undertaken (35. 56, 58. 180. 218). Total output.

bava bean ob.erved to be greater than input. derived from precipitation (56).

altbough thi. i8 a 80aevhat unu.ual case, .s eroaion contributed a major

proportion of the yields ob.ervad. and inputs did not account for weathering

sourc... The observation that dia.olved el .. ent yield. tend to be within th.

ranae of di •• olved 10 .... fra. oCher tarre.trial eco.y.t ... (180, 229) appear.

1

r

•

)1.

ta be rea80nable. Variations in annual yield values May reflect. in part.

differences in streamflow rates between systems (229).

Figure 1.2 illustrates the nitrogen, phosphorus. and calcium fluxes

and pools for a peatland in central Michigan. Although the absolute elemental

values might vary from one region to another, these models are probably a

relatively accurate qualitative representation. Annual storagc rates of

41 to 56%. 41 ta 60%. 81%, 67%, and 4% for precipitation inputs of Mg. K,

N, P, and Ca respectively have been reported (35, 116).

Seasonal fluctuations in nutrient levels of the medium May be related

to changes in moisture conditions and plant growth, hence uptake of elements

(58, 180). There i6 also some evidence,that atmospheric inputs of elements

1 may vary on a temporal basis (83). Figure 1.3 shows the seasonal patterns

of available nitrogen and total dissolved phosphorua in surface waters of a

f~.

Recently. stud1es have been dlrected tavard the anthropogenic factor 1n

peat dynamlcs. auch as the accumulation of heavy metals by peat (166, 188),

and the role of peatlands in the global environment. The accretion of peat

represents a global organic carbon accumulation of 2.1 • 1014 g of carbon

per year, which has been 8uggested aa a p08sible mechauiam for moderating

the dlaturbed equilibrium be~een released 3nd fixed CO2 on earth (26).

Through biogenic em1ss10u of aulphur, believed ta be an ~portant part of

the global sulphur budget, peatlanda might even be iaplicated in the creation

of acid rain (97).

,

1 1

j

NfTROGEN

(aclu_te.bl. N (7.6 )

PHOSPHORUS .

A"ollaole P "

CALCIUM

'ac ... ",eû.e Co

\

32. ;;

Precipitation ( 5.2 )

Pr.c ..... ahon (0.3)

Fi..,.. 1.2 Mod. depictint GMUCII nttl'09'ft t phnptloru. and calcium flua and pool. fM a c ... tra' Mich.oan bol. AILvolu •• ,ft ktJha. Afttr RIC:f\ordsan ltil.(J80l.

1

f.

lO

.25

--..... r .20 -.Î -ct i .15

1 j .10 ... -~ Z

.05

.. .. J s

NO.-N -­TOP NH.-N ---

o

Floure 1.3 Seaonal NO.-N ,NH.-N, and total d .. aolved phosphoru. concentration. of lUI' fac. wattr from a central Mlchtgan tin. After Richard.,., et ~. (180 J •

•

JJ.

~ . l

\

,î i

~.

1.2 Priaary production

Prt.ary productivity i9 the rate at vhich organic matter is created

through photo.ynthetic processes, per unit area, per unit time. Climate. d r

min.~l nutrition, and vater su~~1y are major determdnants of plant productivity.

The effects of climate, particularly temperature and length of the groving

seaaon. are complex and differ for each species (202). Despite the extensive

distribution of wetl'ands, and the highly productive nature of some reed and

gras. dominated communitiea. thera 1a a 1ack of info~ation on the levels

and con troIs of primary production in these systems.

Individual speciea show different responses to miner al and water supply.

The net production by vascular species appears to be restricted by the

availability of nitrogen. phosphorus, and potassium (88, 113, 174), and

treatment vith N, P, and K fert11izers has been found to enhance plant growth

and vigour (52, 66, 119, 161). Sphasnum productivity is affected by the

depth of the vatar table, being reduced under relatively dry conditions (48).

Production .sttmate. of graminoid, chamaephyte, and moss species vary

videly. a. indicatad in Table 1.8. Primary production values of f!!!! spec1es

range from 1 to 10 g .• -Z.yr- l in the Yukon and Alaska (Z40), to 1580 g.m-Z.yr- l

in Upper New York State (17). Th. productivity by the foliar camponents of

8hrub. give. a ralatively accurat ......... nt of total plant production, as

the perennial .cructure. often ahow little or no signifieant change in biomas8

ov.r one y.ar (80). Value. for chamaephyte .pecies rang. fram 31 ta 187

, •• -2. yr-l. Eat1aat •• of SphagDua production range from 7.8 to 790 g.m-2.yr-1

(73, 175).

ln .. ny .tudie., oo1y abov.-ground productivity of plant populations

or a •• ociations la report.d, in .plte of the acceptad iaportance of below-

--

35.

Species Location Bio_SB Production Source

2 (g/rl ) (g/,.2/yr )

'Carex agua talls Alberta )80 J40 ~99) AlAaka 25 221 )

Carex ela ta Sweden 440-890 (153) Carex lacua tri a New York 1017-1400 857 (17~

New York 1145 965 (18 Wisconsin 1181

rJJ

! Sweden 530-6)0 153

Carex laalocarpa Erlgland 510 167

ou Sweden 300-170 153 or4 Sweden 182 168 0

1071 7)8 (16) c ~ roatrata Plinnesota il Alberta 640 515 (99) Il J.. Manitoba 116 i1?6j u Sweden 320-610 153

~land 420 (167 Sweden 1)6-173 (168)

Carex atrtcta New Jersey 955-1500 1492 (126)

Er1 ophoruJll Alaska. 29 ~221 ) &runlatlfol1 UII Ploor House 96 81)

i. vaglnatUl!! Yukon/Alaska 27-28 (240)

t Calluna vyJ,.garia Moor Houae 300 1)0 (80) ., Betula puail.a Pllchigan 151 (179) ~

~ Cb!!!!edanhne Michigan 187 ~179~ ~ calyculatl. Manitoba 106 175 ., 1 lAdY! uoenlandiCUJl .... nitoba 68 (175)

.! V&cclniUl !.-~ Manitoba 53 (175~ u Kal!1& poU!ol1a Manitoba 31 (175 t

Sphagnua rybellu. Hu_ock 4) (48) Lawn )2

~. ~auuzlda~u Pool 79 (48) I&wn )li

., ~. papilloaua Pool 61 (48) +'

J Hua.ock )1

§Rb. recurYWI! Pool 5" (48) Hwlaock )6

l Sphagnu. rubellua Moor Houae 45 !ftl ,. Pennine. 1)0 SDhuna t:3.!I~UI Manitoba 51.8 1.8 17,5)

Table 1.8 »1o .. a. and production valu •• for graœ1nold, cha.ephyte. and bryophyte specl •••

, \

-. •

36.

ground components within peatlands and other more or less extreme

environments (239). This is Most likely due to difficulties involved in

extracting roots, and identifying new root growth (174). The production by

roots is important in two senses. First, the magnitude of above-ground

production may be related to the availability of storage products (64), thus .

the quantity of Bubterrainean structures. In addition, roots and rhizomes

contribute to peat accumulation, through the addition of detritus to the "

system. Ratios of above- to below-ground biomass may deviate from 0.04 to

1.0 for a variety of northern mire and meadow-like systems (245).

Vascular plants appear to make a greater overall contribution ta production

than non-vascular plants, although masses may, at times, represent a great~r

proportion of the above-ground biomass. Thus, total community production may

decrease with increa.iug wetness, favouring the growth of Sphagnum mosses,

which only partially replace the reduced investiture by shrubs and grasses

(202).

Sedge dominated wetlands often form large, relatively mQnotypie stands,

although the different spec1es commanly have dissimilar environme~tal

r~quirements (15). The linkage between propertics influencing florieties and

those controlling production may be indirect, such that the ionie balance

will be instrumental in differentiating bog from fen on a broad scale, whereas

N, P, and K availability liait. production. Water depth and duration of

inundatian have also been shawn to be important controis vith regard to

produet1v1ty in theaA-systema (153, 23).

On a global scale, peatland. have a relatively low net production,

although it i8 comparable to other northern ecosystems. Net primary productiv- ~

!ties of 1000 ta 2000 g.Ill-2.yr-1 may be cansidered a "normal" range for

1,

11.

tarra.trial syst ... (243). This includ •• many fore.ts and .ome gras.lands.

Nat production of bor •• l for •• ts range. from 400 ta 2OQO g.m-2.yr-l , with

an average value of 800 g.m-2 .yr-1 (243). Thus, the values of 110 to 1943

g .• -2.yr-l obtained from several studi •• (Table 1.9) indicate that peatland •

• re "normal" for the latitudes in which they gener.lly occur.

Although global comparisons of production are lnherently difficult,

dua ta local variations caused by edaphic. cl~atlc, and ather as yet

UDdetarained factors, terminal standing crop (above-ground biamass) gen.rally

d.cr •••• s with iocreasing altitude aod latitude, and •• ems to relate to

t.-p.r.turea of the wara.st mooth (96).

1.3 DecoapoaitioD

T .. p.rature, moi.cure, aad .ub.tr.ta qù&lity .re tba prim.ry factors

controlliDg decsy raca. and pattern. (77). Bath .ccusl .vapotranspi!ation

( ..... ur. of the concurrent avail.bility of enerBY and moisture). and lignin

concentration of the sub.trate have be.n iodep.ndently shawn to be relatlvely

.atiafactory pr.dictora of spatial and temporal variability in decomposition

rates (79, 111, 146, 192, 227). In addition, the markedly different growth

and d.sth patt.rns of grasinoid, cna.a.phyts, and bryophyte species affects

the thr •• sain inputs (through standing dead, surface litter, and below-ground

litter) into th. d.campa.er cycle (31, 109).

Dacsy rates, comaonly .xpr •••• d as the loss in m&ss of a litter sampIs

ov.r a p.riod of time. integrate decrements due to leaching of soluble and

tnorganic .. terial, re.piration, and the removal of particulate matter by

.a11 faun. or by phyaic.l factor. (lll). Sunn.ll and Tait (32) proposed that

~

~ .. '

PRODUC1'HJf (g/al /yr) -,

Location ('11) Abave-,round BeloN-ground Total Sourc.

Description Vascul&ron-v&scular

Sedge-shrub NeN Jers.y (41) 1699 ~~~ Sedge NetlAnd N ... York ~4J~ 1.580 Leatherleaf-bog btrch Michigan 44 )41 n~~ Leatherleaf-cotton grass bog Veraont (44) 140-1980 Carex I18&dON S.W. Quebec (45) 820 Hl) Sedge Netl.&nd Minnesota ~45~ 180 197 m Fen "lnn.Bota 4i 700 ll?7l O.brotrophic bog Mani toba ~ 49 J20 55.4 1457 .5 1942.9 176 Lagg Manltot& 49 1026 513 1539 (176 Blank:et bog In~nd n 125 .50 141 )61

71 j Blanket bog England 54 547 45 .' 592 80

Blanket bog illgland 54 589 156 745 81 Blanket bog England 54 24) 659 202

1 Heath SNeden p.5~ 164 225 Vet raeadoN Norway 60 425 410 8J5 246 Vet .eadoN Yukon (64)- 42 121 169 240 Vet _adoN A~.1Ia t5l 18 J2 110

1~~l o.brotrophic IÛre SNeden 68 122 24 146 Vet .eadoN Alaska 71 101 221

~ Table 1.9 Annual va.cular. non-vaacular, and total production __ sur .... nt. tor peatland vtt«etat1on.

.. ~ • J

fi111I 7S:M nu n_--'''~- ------------ . 'l.:-:-IJo:,.~

(

(

,e

the total mass 108s as a function of time (M(t» might be more accurately

envisaged if the substrate vere to be divided into tvo compartments. These

vould consist of more and less readily decayed fractions, vith initial masses

~11 and H2 , and average annual loss rates of rI and r 2 respectively. Thus,

the total mass loss over time yould be expressed as: ..

The potentially leachable fraction of most plant remains is of the order

of 5 to 30% of the plant maherial (110). TIle expected and observed sequence

of elemental losses from litter (K>P>N) is related to the degree of the1r

incorporation into organic molecules. and is inversely proportional to their

importance as structural components (37, Ill). Leaching may account for

50 to 75% of the mass loss during the first year of lit ter decomposition,

while later stages rely alcost exclusively on microbial activity (37). Law

pH and anaerobic conditions have a significant influence on the microfaunal

element of the system (152. 230), and temperature serves to control the role

of microorganism8 in the processes' and rates of synthesis or decomposition

(231).

Le.ses attributable to respiration have been calculated directly from

measurements of carbon dioxide released by the surface (77). Some difficulty

exista in interpreting rates of CO2 evolution from surface lit ter as

temperature and moisture affect respiration rates in a non-linear fashion,

and the interaction betveen temperature and moisture is non-linear (32);

and, root metabolism and decay may contribute the bulk of CO2

production (27).

l i 1

(~-

40.

Abiotie and biotic elements exerclse controls on decomposition such

that loss rates between species appear to be as great as those among studies.

Although decay rates May range from 0 to 100% (110), first year dry mass

losses of 16 to 36% (for soft leaves) are commonly observed (37, Ill, 134).

Sclerophyl10us tissue is sornewhat less rapidly decornposed, wlth first year

losses of 6 to 24% (37, 192). In short, losses have been found to decrease

from; soft leaves > hard leaves, shrub shoots:> mo~ses, lichens, and wood;

dry to wet to rnesic sites; and higher pH (>4.5) to 10wer pH «4.5) conditions

(110).

The annual decompositfon rate of litter 18 common1y denoted by the

coefficient ~, which, under steady state conditions, may be derived from the

exponential decay formula:

-kt = ln (XIX ) o

where X and X are the initial and final 1itter masses after time t. Although o

the valid1ty of an exponential decay model for describing the course of lit ter

d.composition in peatlands has been questioned (147, 212), ~ values a~e

uaually reported in decomposition studies. The use of ~ in peatland studies,

if only to standardize data, may be jU8tified by the observation that the

difference between exp6nential and linear assumptions is small for short term

(one ye.r) studies, and i. negligible for low rates of loss (27). Table 1.10

pr •• ents annual decomposition rates (as~) for a number of sites and tissue

types. The aean annual decomposition coefficient for northern peatlands is

0.3, which 1s significantly differant from the value of 0.9 calculated for

other wetlands (27). The lower values for more northern latitudes are mast

',,,:\ ,.

-..../~

~ -1

41. 1 ~

.. "(

~

"

Wetland type Location (0Jf) LUter type* ~ k Source

Sedge-shru b bog Michigan (44) Carex 0.45 . ()7) §!il.! 0.46 ChamaedaRhne 0.17

1 Betula 0.47 1 ,

Bcg {ore st Manitoba <'50) _ LedUll 0.40 (176) 1 1

i

(50) (176) j

Muskeg Manitoba Ledum 0.20 1

Chamaeda :2hne 0.)4 :

1 Kalmia 0.15 Vacclnlum 0.42

Bcg Manitoba (50) Ledulll 0.15 (176) J - ' ) Challl& eda:2hn e 0.36 Kalm1a 0.44-

J -:; Vacclnlum 0.49 \ Oxycoccus 0.07

lagg Manitoba (50) Chamaed.a:2hne 0.19 (176) Cala~ostls 0.26 » Carex 0.25 Sal1x 0.)2

Shrub bog En«land (54) Calluna shoots 0'.16 (110) Erlo:ehorum 0.20

Monocot bog Irel.a.nd (54) TrichoEharulll 0.1) (110) \

Schoenu8 0.11 ~l

Holinia 0.36 j.

EriophoruJII 0.22 1

Monocot bog Norway (60) Mlxed vascular 0.40 (110) ~ 0.5) 1 ,

Monocot bog Alaska (71) Mlxed 0.06 (110) 1

,A,Du:20ntla 0.17 r' Monocot bog Canada (75) Carex 0.24 (UO)

* leaves unles. otherw1se Indicated .

~

Table 1.10 Summary of decomposltlon rates of l1tter (as k) for northern pea tlands (44 to ? 5 DM). Only studies using 1 lU JIl8sh are Included.

1 , C'

1 •

42.

likely the result 'of' reduced tap.ratures. On a smaller scale. decay rates

f1uctuate with peat depth, due to changes in, ~lon (127, 152).

Defomposltlon rates a1so vary ln time, belng most rapid ln 10itial

stages~ due to elevated leaching losses and metabo1ism of easily degraded

plant compounds (37). First year losses of 17.6 ta 36.1: accounted for 53 to

92% of the total mass lOBs over two years (111). Decay rates may cnange on

a seasonak basis, although signlficant winter time mas. lo.s.s have been ,-

observed (20, 145, 151).

\ /

1.4 Accumulation •

Rates of peat formation are detarm1ned by tbe ~10 betveen production

and decompodtion, and the interactive .ffecta of eU._te, topoaraphy, .. . nutrient supp1y on ~h .. e proc ...... Put aecwmlation ia the rqult of

retarded decomposition, rather than rap~d productivlty (57). Given the

'relative1y hlgh peak productivitles of plants subject to short-groving-seaaon

envlrolJllelltl, high put accretion rat.s in oorthem mires may be a r.flection

of pr1mary production bunt. that ovarwhela the decomposition capadty of the

syst_ (27). Tha overal1 rate of _ accwaulation for a givan clepo.it b contiD--~.

sent upou the rate at vhich .. t.rial.a enter the aaaerobic: zone, vh.1cb 1.a

clependent 00 .urface productioo of put, aDd the beJ.&bt of the _cer table

(152).

Peat d.posiU are neitber 'un1.fonl in ~.it1aa .ad structur., GOr are

they .ubject to identlc:al elblat1c 1I1flueac ••. Tbua, it ___ raaaooable ta

4

expect difference. in acc\8ul.at1on rat .. DOt ouly bec-n peatl.aad types, but

alao among types in different locatiaa.. WidMpreed tread.a df th1.a nature

r J

1

(

. ' 'd

(

/~ ~

ba~ "t to b.- detena1oed. aad v.l ..... of peat iocr __ t •• re quite v.riable

both '.t tbe iDtar anel iIltr. type aacl ra.ion 1eve1 (T.ble l.11). Although --, -Ua1~r (2~2) fouad...o grovth r.t •• of 0.65 ... yr-1 for both oabrotrophic

aac1 aiDerotrophie: aire.. this is a .ingle cas.. and 'there r ... in8 a need to 1

Wllder.tand the cilemlcal and mlcrobial factors regulating rates of peat

acc __ 'I.Uon and decay in a.brotrophie: as oppased to ainerotrophie: sit ...

Le~ '. (135) nat.-.ots that .ean pnual taperatura. a fev elagre .. above

or belov 7 oC, and conditiona at tbe Sphagnwa bog-bath stage favour the

.,st r.pid accœwlation requin substantiatiotl.

The proportion of net priury production that e:ontributes to or'ganic

r' _tter .ccretion varie. between 3 and 44% (176, 215, 222). Model. of paat j \ . v

acc~at1oD are ba .. d 00 present .urface· production r.te., anel best esistiD,

.. t1aa~ of elecoapo.itioD iD put profU .. (~. bulk denaitY). Tb .. a .odela

1Dcl .. the follovi.D& par_tera:

• 1. Cly.o (50)

~~'-V a) x =.E. (l-e

at)

a

'",---

, wbere x ta the total acc ... ulated dry .. tter per unit area.

P 1s the rate of acld1tion of dry .. tter per unit aru, â

&'-

la a elecay paralMter. and t is tille i

b) ü z LI(t) • vbere 1 18 the depth of put. and L is the instant.aneoua clt

l'au of adclit1.oll;

c) claptb of the vatel' tab1e.

2. ".... ad Core (U7)

4IIz1 -kW ~ v

.... ciL:- 1 - kt, vbere cbaD&e in cleptb (L) 1s ... uaed di l

proportiona1 to cbaa.ge in veight (W), 1 1. the

iDput. &Del k la the deCC*pOsition rate.,

..

1

1 <. ') 1

I~

~1.11 .... of peat 1Jw:I:1 nt far llartberD plAtlaMa

( 141 to 68 C;). ....t ncur- nU. ted by c11ylcl1.ns

ncur- for peat d.epth br nWlber of' 1-.ra required.

to attaln thi. d.epth. ~baMd an rad.1ocarban datln«.

44.

( 1 , . ( i

•

•

•

( 3. TolODell (223)

Â: r' Db • vbere A 1a the aec~atiOQ rate in S·.-2.yr-l, and r 1a the

rate of heiaht Ir~h iD ... yr-l •

Table 1.12 preaent. acc~atioD rat •• e.tt.&ted throuSh the •• .odel.,

iD addition to the fev value. deteraiDed throu8h verioua re ... reh efforts .

. '. .tud1 .. ett.-pt ta correlate bei&ht iller ..... v1th aceU1lUlatioa rates.

althouab ob.ervat1olUt by Tolonen (223) and Moore (149) that lacr .. ent. of

0.18 ta 1. 33 .·yr-1 and 0.4 .-yr -1 corre.pond ta Accretion value. of

2 1 -2 -1 18.6 to 68 8-.- .yr- and 32 a·. ·yr re.peetively. 1adicate that the

values iD Table. 1.11 aad 1.12 are c:o.patib!e .

...

...

,

..

------- --~ . - - ~---- .~------ "-- --- -

"

'Î

1 t •

~.

(

l

Peat,J:).Wth rate Seuree ( a2/yr)

Zl-52 ' (116)

6-96 (14)

40-50* Cf" (50)

40-50 (211)

89-1.58 (16)

69.) (21S)

2,5-4) (222) ,

18.6-68* (22)

"6-10* (lZl)

129-2()I4* (IZl)

*1ncl1catea values obta1ned throUCh one or .."ft"&l lIOd.la

, ... 'fable 1.12 Ratea or oquie _tter aeeretlOft.

--- -- .... ----~- ~-----

Chapter 2. ~STlGATIONS AND METHODOLOGIES

2.1 b ... reb ailu

In revlew1ng tha literature pertaining to peaclands, it i8 evident

that the factors gpvarning peatland ecology are both complex and diverse.

It i. also apparent that documentation of basic biological processes, such

as the rates of species productivity and tissue decomposition, is I1mited,

particularly with re.pect to the subarctie region of North America. As the

balance between th •• e proc.sses determines. to a large extent, the course

of development in peatlands, it is important to characterize local and

regional trends in production and deeay.

The Schefferville ares presents an intere.ting case, due to the quantity .. , and diversity of uodisturbed 'peatlands in this region. In other worda,

ecosyste. procaase. ean be exaœinad in a range of peatland types. while

eltalnating pocential variability due to climatic heterogeneity. Given this

f .. ture. in addition to the inheren~ differences between subarctic Quebec

and other regions, this investigation addreasea several fundamental quastions.

1. liow doea specle. productivity differ betveen peatlands in. this and other

ragions?

2. What factor. dateraine differential ratas of plant growth wlthin this aree?

3. How do deco.poaltion rata. compare with tho.e of other terre.trial ayst .. s

wlthin the subaretie, and between peatlaoda in thi. and other ragions?

4. Do eicher biotte or ablotie factors ___ rcis. a greater influence ln the

decay of plant remains?

5. Fro. the abova, which par ... ters migbt be utilized ta .stablish. or predict.

trend. iD specie. procluctivity and decay of org.nie material in peatlaDcis?

. \

j ,

--------~-----~ - -~

(

48.

2.2 General eharaeter1st1es of the study reg10n

The study region 1s loeated in central Nouveau-Quebec/Labrador, with1n

the Labrador Trough. The primary elements of the landscape are Pre-Pleistocene,

and Pre-Cambrian rocks underlie the entire area. During glacial periods, the

Quebec/Labrador Peninsula was an iee dispersal area. Retreat of the iee

sheets proceeded from the margins to the centre of the peninsula, causing

d1sordered drainage patterns. This feature of the landscape, including many

lakes and mires, i5 one of the most striking distinctions of the region.

The area W8S deglaciated 5,000 to 6,000 years ago (30), allow1ng little

time for soil formation or landscape modification. The main active geomorpllic

proeesses are peri:slacial, including solifluction, 7latterned ground, and less

weIl defined features produced by frost action and snow meltwater.

The clillll1te of the Schefferville area ia characterlzed by cold winters

and cool summers. The mean annual tamperature of -4.5 Oc i9 notably lover

than average for this latitude (54 oN). ;o{ean monthly temp(!ratures range from

12 Oc (July) to -22 Oc (January) (9). The growing season (mesn daily temper-

o ' atures greater than 6.1 C) ls about 102 days, although this period may only

last, on average, 76 days in mire systems due to the blanketing effect of

peat materials (2).

With the low aean annual t .. peratures recorded, perœafrost formation

might be expected. The occurrence of permafrost in the discontinuous zone

appears to be close1y related to drainage (28). or to areaa where the insu1attng j

î snow caver is removed by yind (159). Although mires are generally open terrain,

chus windblown, there is little evidence of extensive penaafroat features

(palsas and put plateaus) in thia region.

1

Meu amt.ual prec1pieatlon ia 785 _. of which 407 I11III talla aa raln,

prillarlly during June, July. and Auguat (9). Much of the win ter precipitation

La generated by Maritime Polar Atlantic air, although high snowfall in early . winter' 18 rel.tad Co modification of Polar air masses prior ta freezing of

Ouring the study period (Sept_ber 1981 to August 1982). temperatures

were 5%, and total precipitation lU higher than the tventy Uve year average.

The Schefferville area lies in a transitionai zone between the open

boreal woodland to the south, and the foreat-tundra transition to the north.

There exists con.iderable vegecative variation. from forest or mire in valley

bottou to open tundra on ridge tops. due to the diversity of habitats

re*,ulting from ,eologie and phy.iographic heterogeneity. The fla ra of the

area Inciude. about 375 vascular .pecies (120). of ,whieh 111 occur in mires

(Waterway, unpublished data). Vegetative diversity Is somewhat greater in

the Labrador Trough than in other area. of the peninsula, due to the prelence

of Pre-c.abrian .ed1.mantary rock. ( ... lnly ,la te. dolOlai te, quartzi te. breccia,

and cODlloaerace (108».

Kire. are •• t!aated ta eover 10 ta 15% of the terrain in this region.

thi. relatively high figure il partIy due ta aleeration of drainage sy.tem.

br retreatina glacial lee. and partly du. ta the iaperviou. clay-rich till "

clepoaited follovin8 dealaciation.

2.3 Location ad daf1nltioD of • ...,lina aite.

Tbe .t\ldy vu cOllductad at four ait ... loeatad vithln 30 ka of the

•

townsite of Schefferville (540 43' N; 660 42' W) (Figure 2.1). Sites were

selected on the bas!.s of their physical and chemical properties, such that ,.

each represents a particular, ecologically different type of peat deposit.

;1

Thus, a range of conditions for inter-site comparisons of productivity and

decomposition i8 provided.

Due to the sedimentary and often calcareous nature of the parent

substrata and the continental climate, truly oIIbrotrophic conditions are

not present, or at least not recorded, in this region . . ~l four sites are non-

forested, and exhibit the following vegetative and hydrologie conditions.

Site l

A relatively small, poor fen (~ Sjors), dominated by Carex l1mosa and

Carex rostrata, and mess carpets containing Sphagnum lindbergii, Sphagnum

riparium, and Sphagnum fallax. The somewhat drier, marginal areas contain

Scirpus cespitosus, and small Spbagnum hummocks, with which are associated

low Betula shrubs. Although there ia a weakly defined outlet. water tends

to pond (accumulate) at the northern end of the site, creating very wet

conditions.

Site 2

An extensive, shallO'W, rich fen (!.!!!!!! Sjors), with large standa of Carex

liaoaa, f. chordorrhiza, and f. aquat.lis. Carex rostrata ia often inter-

mixed. Brown mosses are lIlOst abundant, although Sphagnutn mats and humrJlocks

are present Along the margins of the mire. Batula and Salix shrubs are un-

cOIIUDOn. occurring ln the dry. marginal areaa, together with small Scirpus

ceseitosus tussocks. The site ia drained by two streams flowing along either

fringe of the fen, althougn only the eastern stream terœinates in an outlet.

(

.. ,

".

... '~ . . - . ~

, "'-...:..... - --. ~~ -f~~ .. ~~ ..

,./

:.::.~ ---: -~/

M-~ "- .. ''''''.'.'

+-' , . . -. - A

/

,;::?~ <P . 1".. ~\ \'~-'- ~ <~ ~'~~. -~- ~ ~. ~ .. ~ <;""""IÀ,?C' .. '-;:::--~:, c.· '. ,\./"', :.:-

~\ Q~/"';-:. '.,- .. ~ l_~, 00~~/' ~ ,-,

.Ar-"", ' , ~ l '\. ..: \.-:., ""-"') ~~ ....:: ~n " \\ ~--c~ . ~:;;:~~!~~ ~P;;-h \,

\'-~_~~.l\~~'"::l' . Loeat!.or. of the atudy a1 tes.

. . " ,""

,O • . . ~,

"~

" . '."

\

... a, ' . • • e.

~

'.

51.

,

,52. ! ! '

Sita 3

A large transitional fen (~ Sjors), with several distinct (altemating

shrub and sedge dominated) floristic changes. From south to north, the se are: ~

an area dominated by Carex rostrata, with Sphagnum carpets and hummocks, and

some larch (Larix lartcina) trees and Betula shrubs; a dense shrubby area

(lIl81nly Betula), with f-. rostrata, f. limasa, 'fa oligosperma, and Sc1rpus

c •• pitosus along che margins; a stand of f. aquatalisj and, an area of strings

and hollow8, vith Lontcera villosa on elevat10ns, and brown mosses in

clepressions.

Site 4

A .edg. MeadOW, separaced fra. slt. 3 by a SBa11. dry area (containing Carex

aguata1ia. Larix lar1ctna. and ~ .. ruu' crees). The peat material Is

hiahly huaifi.d, weIl consolidae.d, and probably underl.in by dolomite. The

da.inant spaeiea ara C. aquetalis, C. diaodra, Sphasnum, and variou. other

.o ••••.

Site. 3 and 4 are draiued by a .er ... locatad at the nortberu extr .. lty of

che air ... Furtber aite infor.ation ia provided in Table 2.1.·

a. Site propartie.

Durinl tha .~r of 1982 ..... ur..-Dt. of t.-perature. redoz potential.

8IId carbon diozid. evolutioD wer. -aade at approziaac:ely tvo ."..k !nt.rvals.

T.-peratur •• wera ... ~rad vit~ tbarai.tora ( at 5, 10. ,20, 60. 100. 150. and

200 ca daptb). radoz poc:.ntial vith platiDua al.etroda. (at 5, 10. 20, 60, aDd

105 ca d.ptn), &ad carbon dioxida output fra. the .urfae. v •• dat.rain.d by

1

-

.. ~ 1

0

Site StaD4ard Ml 11 tal'J 'PFon_ta ana Depth pH CQIlclucU Ii t1 Jutrient Grld Reference (ha) (ca) (uS. ca- ) Stat ...

1 42112) 4 4.62-S.SQ 10-20 Ol1gotrophlc

} 2 26S905 12 80-200 5.19-1. )8 50-90 Eutrophic

) S?0S88 9 60-290 5.11-?SQ 20-SQ .... otrophie

" 566S88 o., 100-200 60-2~ Eutrophic

----- '"

Table 2.1 Location. cl.pth. ana. and len.ral chea1cal propertle. ~r the rouz: peatlancl .1 t •• lnve.Upted. '

, ~

• Md' ,..... irA' _ .............. _~ ......... ~ .... .., ~ ~ - _A", __ ~

~ ~,,~ ........ _ .. ~~~....","' ..... ~ _ .. ~ ..

/

~

\1\ ~ •

-.... _-<~~"' .. -

•

1 j

~

J ,

- 1

\ ~

-------.---- ~ ----- ~~ ------. .... -......... ---- ' ... ,

.l

54.

abeorption iD alkal.i. fol.l.oved by Utration (33).

P .. "i vatar vaa collectad at two weell intervals at each site from both , ... tba aurfac. (0-10 ca depth) as vell as wlth d.!.pth (ta 1.0 m). Within each

-----aite, •• ple. of surface vater vere collected from the plots where productivity

aod decoaposition .. a.ur_ents vere being made. Water samplea were filtered

through Whaoun 142 paper. and the following analyses conduc ted:

pil- Odon Specif ie Ion Me ter, model ~O 7 A

coaductivity- YS1 .ade1 31; conductivity bridge or equivalent

optica1 deniliy- absorbance at 330 Dm; related to diaao1ved organic carbon (Moore. pers. eOlllD.)

total di.aolved phoaphorua- mo1ybdate Dl.chod (209)

nitrite- gri ... reaetion lIlechod (209)

nitrate- brucine-sulfanilie acid •• thod (125)

~ni_- phenol hypochl.orite _chod (203)

iran- hydroxylaaine hydrocblor1d./o-phananthro11ne .ethod (118)

calc1ua\.

-sneslua, ata.1c absorption apectrophota.atry

potaas~ i ..

b.,Pr1aary produetivity

Tbe differmc arovtb foru of tba Iraainoid. bryophyte. and dwârf shrub

epeci •• Dacesaitate different •• tbod. in tha e.tiaation of tbeir production. , .

Gas axchaoS. and barveac .. tbocl. are coa.only utilized to __ sure productivity.

Tb. barveat .. thocl offers ••• eral. ad.aou •• s: equipaent 1. co.pantively

.

l 1 ;_ .. -

1

1

)-·1 1

1 1

•

(

o -

- .......... ,. .. --~

55.

simple and inexpensive, and there is no prob1em with extrapolating short

te~, sma1l scale gas exchange measurements to longer term or larger scale ~

production values.

The above-g~ound productivity of sedge species was measured by the harvest

method. Specifie plots (10 x 10 m , divided-into 1 x 1 m quadrats with 0.5 m

buffer zones) were established in early June, 1982. These p1o-ts were chosen

on the basis of vegetative homogeneity. In mid 'August, fifteen 1 m2 quadrats

were randomly se1ected, and a11 above-ground tissues c1ipped. One additional

5 x 5 m plot was established at site 4,-and five quadrats sampled. This

~eriod was chosen as an optimum sampling date, as many sedge species; peak

in biomass from ear1y to mid August (6, 18, 204); and, show a high aegree of /,

synchrony in peak ::ermina1 standing crop (221). }fost 1e~yes appear to ·remain

functiona1 severa1 weeks following peak production.

Production by Betula and Salix was estimated on the basis of total foliar

ùiomass for entire shrubs, tnereby assuming ~"oody production to be neg1igib1c

(dO),' Sphagnum productivity \vas determined by the craoked w:!.re method (48).

Essential1y, this indicates leogth increment over ~ given period (12 weeks)"

which can then be converted to an aerial figure assuming a mean weight per

unit area per unit length of Rlant (stem plus capitulum) of 65 g.m-2.cm-l for

hummock species, and 48 g.m-2.cm-l for lawn species.

•

c. Litter bag studies o

Litter bags (approximate:ly- 20 x 20 cm) were made using mesh with 1 mm

hales. Selection of a 1 mm mesh size conforms ta other recent studies, and

---- -~'

/

''1

~

;:.

.. + n"H t1JHt Specl.,· ~ Site

1 2 _ 3 4 ,. Qu:u 1119- L. x x x Leav •• .. Qnu [Oltratl Stob,. x X Jt Çnu ag.Wlll "'hl. x le Qu:u cbordorrhla L.t. x

,-, .. 1 •

Leanl, 1

Laav., ,-, .. Sçl~1 CAIDltolUI L. x X X Il

ht.ula alanclu10ta Ml ehx. x x x ,

Leav •• .0 - ... Illll ptdlc,llltl' Pur.h. x x Leav ••

~)

Plant, SplNou l1n4btrcll Sehtap. U. Llndb. x x 0

leINn,,1 r1 Rl!rl '" AJ'«' t • -x , X 4t:

Plant, (la ... ) ",

Iphtcnyi l1n4btfll1 X Sph!cnua ~J.tlro lua (Ru •• ow.) C. Jen •• x

Planta (h~') IAhlcnul [UIIOMi1 "'m.t. X SDhainMI &nIultltoll~ x X ,

'J 8~u~ M&rn.tortl1 Ru •• ow. x x

'«

l

.' ~ Tabl. 2.2 Tt.,u., coll.cted rro. th. tour l'ud1 lit •• for 11tt.r bac lnv •• tl81t~on ••

tI

't9-•

\ "-br PS' fi 1 1 ... '''n'

r ~'

(

,

5"'.

r.flect. cOIlClua101l. tMt _11er ..ab tend. to exclude .011 fauna, vhUe

lar,.r bole ... y al10v 11tter to e.cape.

,. Ten eat.sorie. of ti •• ue vere eollected, representing the tbr.e daaiDant

fora. of veletation (Table 2.2). Sa.pl •• vere air dried 24 to 48 hour., and

Approximate1y 2 g of mono.pecifie material pIaeed in eacn litter ba_. Bec.uee

litt.r aa.ple. of aite. 1, 2.. and 3 COQ tained more than one Sphapl1.m .pec1u,

iD eitur the eaa. of tie.uas coU.eted frOli Iavns or h.-,clta. the.e group.

vere categoriud collectively as lwn or hUIDIIOck spedes. In addi tion.

5 x 5 CID .-quar •• of pbotocrapb1c: ceJlulo.e .... re placed 1n litter ba,s.

folleving oven dryiDg at 105 oC. Cellulo .. i. gener~llv waed as a .~rd

substrate in deea.posit1on studies (186), allowing c~ar1aon of decay rates

vith .t.ilar Love.ticationa.

The litter bas. vere plac.ed ou tbe peat eurfaee 1.n late Au.auat, 1981.

Care vas tak.aD co replace tiseuea iD the location troll whieh they vere

retriav.d, 1n ordar to .t.u1ate natural condition. a. far .. po •• ible. Littar

" , bqe vera collected in lace May ta .. rly JUDe, ad .id Iw&u.t, 1982. vic.b

, three replicacea per .peei .. per siU- at .. ch ....,liq clata.

2.5 Malytieal..etboù ... the t...,..a~1I1' •• redoa9 .... carboa dt.ai.de daca (col.l.ec:ud aolely fra.

ar ..

,,&1-. for cODClucU.1ty. a.a1.üble nitro' .... total dieaolved pho.phorua. and

reduced iroD iD the .urfaee vatere at uc:b .ite vara ealeùl.atad. and t.-pora1

patte.ru ·eoapared vith tho.e of tha plots lIbere produet1vity and 'd.c:oapo.ition

.... ur..-lt. vere baina reeorcled.

'.

..... "' ..

f

(

....... 1

Arter harv.eating, the vascular tissues of aedge Uld shrub species vere

separated into live and dead fractions. and the live (gr~n) mat~rial air

dried and veighed to obtain a value for biomass (g.m-2 ). This quantitative

measure represents the present year's grovth. and 80 vas utilized to estimate ~ , e

f -c;:. - ..... , product: V':. ~y g. œ . Y"!' • ?r?d~ctl?~ by sédge'spe~ies vas then ~orrelated

Vl 'th the mean surface tempe rat ure. avai lab':'e Dl trogen, and conducti V1. ty of

t~plots . Surface parlllDeters vere dei!JDed mast important. as IIlOst species

cycle so:utes ~hrough ~he top 2Q =m of, peat (~. œos~.plant roots occur

vit.hir). this region 1 ~ l8c. ::'9C'. "!'he Vlres :nserted .ln the 2RhagnUJ/1 =e.rpets

vere measured. and the lengt.h :ncrements converted te producti~ ty va.lùes.

Fallov!ng \ ""-

=?l::'ect:or.. ~e ::tter bags vere ?ven dried at ~5 21. hrs.

and the mater:a::' removed an1 ve:ghec t: the ~earest 2.:l g. The values

obta.1.~ed "'ere t.hen calculated as t.he proportion of' the or::..ginal tissue lost

~ins t.he vinter period, and over one year. Jsing Duncao's multiple-range '­,

test, th .. e data vere then tested for 81gnif1cant differenGes betveen .... ~

losses in the var::..ous s:te and ::':tter ~ateg~r:es.

~ract::..onal ~OS6 rate •

for the one year stu4J period. vére calculated ~~ng:

• • vbere Xo i. the initial tissue !DUS. and X lS t.he final: tissue 1I&8S.

In O~der to proTide rurther baais f~r campar~son vith other deca.po.ltlon

studies. k values Vere aIso dete!'ml ned us iog :

-kt z ln ,Xt

; Xo }

\ \

J

l .

J

-(

\

~

vbere Xt i. the aaount ot tissue rem&inina arter time t, Xo 15 the

original amount ot tissue, and t is the time, in this case, one year.

lut.~nt changes during litter decomposition vere &lso examined. 'Cl

The gener&l scheme for processing each sample is shown in Figure 2.2.

'" . Original and litter t:ss~es vere ml:led t~ pass thrcugh Il ~~ mesh (0.2 mm)

.creen, and digest.ed :n Il concent.rated E~SCI / HC:Cl. llUxture .lOtil clear . .:: ..

The co~centrations ~~ phosphor~ and oitrogen :0 the extract vere determined

by th • .alybdoveadate (130) and ne .. lerizat100 (253) .thoCÙI reepecUwly.

Cancentrat100a of pot ... i ua, calc1l.., and magnea1U11l 1n the extr.ct

were detend.ned by atome ab8orption spectrophoto.etry (Perk.1n Ellier

Spect ropho t o. te r, mode l 40'3).

, -1 \Il1g·g ).

and t.he mass ::f t:SSue rema.!!U.!lg g l, the ab8C~..lte :tuanti ty of ea.ch: element

r~n::1g a!'ter the tvo sampl1ng periods vas determined. '!'he aver~ quantity

<for eae!': set ~r t!:ree :,epllcates 'litter tlssue 'Jas ther. cLcu.:e.ted. and

expressea as ~ percentage of the amo~t contalne~ :n the orlgi~ tlssue.

!4orecver. Jr:g:..nL. tlssues vere analyz.ed ~or acid-detergent ~Tore (ADY).

" lignlC. and ce:1U:ose by the decahydronaphthalene l potassium ~rmanganate

igni tion method (86).

\ .

\ ,

ljeldlûll

1-'l'otal •

•

Q"n4 oven-4r1e4 ._,1. to .... fIO .. eh .cnen

Yo.. 1 11:10.. cllCHtlœ

1I0171:dCMlnada te

1 p

atOlde aNorpUoa apeet;rophoto_\rJ

1 I,OIl.'"

'\

Aclc1-4et-..t fibre proc .........

1 ~ Am'

1 Perwa ..... te-Upln .. th04

. 1 Usnln

1 Aah )00 oc. J hoare

1 CeUuloa.

rtcun 2.2 Procedure. ".ed ln proc ••• lne U •• ". 8&111»1" for ... eure..n\ or lnorsanlc con.tltuent ••

• 7 r ' 1 h 0' .----~-::- ' """ ... : .. --.,.,,... , ..

1'" J 1 .

) l

~"'-

;.

..

,{g

p; •

61. ~

Chapter 3. RESULTS AlfD ANALYSES

3.1 Site propert1e.

Tbe seasonal patterns of te.pcrature, redox potential, and carbon ~ ,

dlox1de evolut1on at cach aite are 111uatrated in Figure 3.1. The .ean value.

and .Landard deviation. of the •• propertie. are pre •• ntad in Table 3.1. The

f1r.t two par ... t~r. give some indication of site quality ln the upper 20

.. ca of peat, whl~e carbon dioxide .. la.10n valu.s repres.nt both root reapir-\

\

at10n, and short tcrm (litter) and long term (pe.t) decay intenalties.

Throughout the a .. son , site l appears to have the lawest me4n'temperaturc, ,

folloved by slte. 2, 3, and 4. Tbe dlffer~nc8 ln mean aurface temperature

baeveen slte. 1. l.rgest early Ln the •••• on. Teaperaturea are hlghesc at

aIL dte. becveen the beginnlng and Irlddle of JuIy •• t vh1ch tia. the

a 4iffereuce becwean slte. 1. 1 ••• tban 2 C.

In addition to havina the leve.t aean .urface t.-perature at any given

data durlng the greving .e.aon. .it~ l u.uelly h.s the narrowe.t tamperature

aradient wlth depth (FIBure 3.2). The t.-per.ture differential w1thin each

.ite geuerally 1ncr ..... froc .ite 1< slte 3 < site 2 < .ite 4. Both th. JlK)re

rap1d heatin& and cooling of the surface peat, and the more consistent teaper-

ature. wlthin the profile of site 1, are indic.tive of the saaller degree

of l.teral v.ter moveaent at thia .ite rel.tive to the other •.

Tbe t .. perature inver.ion whlch exi.ts vlthln aIL .1te. by October

reflec::u both the poor heat conductance of pe.t aaterl.I,.:lf8 vell •• the

Sp.tial and t.-por.l v.ri.bility ln redox value. 18 effected by vater

table fluctuation •. Redox i •••• entially a ... 1-quantitatlve aca.uret but

lU rel.U". behavlour 1U1 give aD 1ud.ic:ation of alcrobial ac tlvity. and the

L

alO .. Il

J4

JlI ., .-... 12 2400

.. U ... 1 1 .. t.

.J .. ~ 10 ! • ~ • .. ~ : .. 0 • l, ~

JI • 1-• .. •

2300 IITI '1 • 0 -;; , . a eeoo ..... 4 •

1 1aOO

1400 ' .. 8 "llCIO

• -10 1000

• " la

J "100

./ "la 400

"110 , J -. ---r --------. --- -" "n. .. -..- ._=~ ,q1 »18 __

lCIO

o ...

J ,,'"" "'"" ,--_.~

:IIWl M" ~ ----_.---DAT' DATE

OA~

rtp,ure ).1 Seasonal patterns of teaperature (OC), redox potentlal (aV), and carbon dloxlde evolutlon,

(~/a2/day) ln the etudy sites. Values of temperature and redox potentlal rppreeent· ... n.

for the top 20 Cil ~ea t.

. •

••

0-N •

'"

1

/1

Site 1 ..

Iàte 5/6 18/6 ~ 1/7 16/7 26/7 12/8 29/8 4/10 Te.perature 6'~6t1.9 11.)=*2.0 12.8*0.7 7.9=*0.4 ),).0.4 Redox potential -120*5 -9)t16 -109:t15 -72*16 -851i11 COz 49U·261 672j:75 684~09 591~255 1121~49 )47*62

Site 2

Date 7/6 118/6 29/6 )/7 , 12/7 2:l/7 17/8 28/8 4/10

Te.penture 9.7:t1.8 11.7*-3.1 12.2*2.9 11.8-1.5 3.2.z.J Red.ox potentlal ' - -1641:) -112:d9 -169.11 3 -124154 C02

1~424 101)%.)51 14)U: ))1 IJ72*267 261)t114 18491720 "84t2QO

:~

Site )

Date 3/6 18/6 29/6 21/7 30/7 14/8 ' )0/8 2/9 4/10 Te.perature 11.2 i O.9 11.)*1.1 1).8d .0 14.5*1.8 8.)*0.4 3.6*0.) Redox potenttal -108:17 -102:i-29 -102-*26 -119*-11 -115*'0 COZ 521%)0 1)66i217 1)161215 1581!:521 1))0i.)28 2505t-160 1)))·241 ,586*10)

Site 4 Date )/6 18/6 29/6 Z1/7 30/7 14/8 JO/8 , 2/9 4/10 , Te.penture 1).) .. 2.8 10.9%'2.0 13.6:12.1 14.*.t-2.8 9.).t0.8 Redox potential

1 105"'-93 217:.)~ 240*'317 2271 )81 CO2 1111*248 1984-i7)8 ,. 2666-307 146.5-444- 1241*24 177h:?17 1963*211 359*258

/

~

Table ).1 Mean values (t ~tandard dev1ation) of temperature (oc), redox potent1al (aV). and carbon dlollClde evolut1on (mg/m !day) for each of the study s1tes. Values of tenperature and redox potentlal represent avera~e5 of three measureMents taken with1n the top 20 cm of peat. 'aiues of carbon d'ox1de are der1ved from four r~p11cate read1ngs.

01-~ •

~

(

, ~.

d.pth ta vhich th. root. of v •• cul.r pl.ntl c.n p.n.tr.t •.

There .pp •• ra ta bs littl ••••• on.l vari.tion in r.dox potenti.l at Any

of th. sit ••. Although sit •• 2 and J ara more strongly 'flœ.~ad' than site

1 ( •• indic.tad by optical denaity values of the paat watec). aIl three sites

pr ••• nt r.ducing conditions (Eh -50 t~ -200 mV) over time, and within all

fr.ctions of the peat profiles (Figure J.2). The surface layer of site 4 is

oxidizad throughout the 8ummer (Eh 500 mV). and the transition from aerobic

ta an.arobic conditions lies between 10 and 20 cm depth.

Although aIl three properties show spatial varlabilitv (fram one site

ta another), only carbon dioxide outputs demonstrate dramatic changes with

tim •• This is no doubt associated with elevated respiration by plant roots

as biomass increases. in conjunction with increased activity of sail organ­

isms. Average carbon dioxide emission increasea from site 1< site J< site 2<

site 4. Standard deviations associated with replicate sampies at each site

are quite high, thus, the plots chossn for biomaas harvesting m.y be somewhat

microclimatically, if not v.getatively, het.rogenous.

The s.asonal changes in conductivity, reducad iron, total 'dis8olved

phosphorus, and available nitrdgan (a8 ~4-N and NOJ-N) st each site are

pra.ented in Figure. J.J. 3.4, 3.5. and 3.6 ra.pectively. This analy.is serves

two purpo •••• Fir.t, ta da.onatr.ta the p.ttarn. of conductivity. reduced

iron, total di •• olved phoaphorua, and availabla nitroS.n with changing,envlron-<

.. ntal condition., on a aicrocl1matic scala. Fur tb.r.o ra , Mean valu.s for

tha sita Ar. ganarally not far diffarant from tho.e of the study plots. Thua,

th. plata cho.en for inten.iva .tudy are prob.bly rapr •• entative of condition.

(ch .. ical) in th. antir. aita.

\

.'

-------

\.

, \

~l<dl""'-...j;-~-

r-

------

"

~

0

• .. tG

• H -a

1 0

• tG .. 20

I.Tt t IITI 2

• ·C ·C

0 • Il • 0 • Il Il 1 , , 1 , 1 1

"

...

.w .w oeo -tOC 10 0 100 -110 lOCI - 10 0

! -"

./

.-

lin , IITI • ·C ·c

0 • 10 Il 0 • Il • 10 1 1 1 1 1 1 1 , 1

.w rIN -.0 100 -.0 0 -100 6 100 100 MIO 400 100

"-«Un '3.2 C~ea ln teaperalure (OC) and. redox potent1al ( •• ) v1th1n the peat profil •• of the four study aites. Sa.pli~ dates are 1ndicated at the top of each profil ••

.,. , 1

~ .

"1

0-V\ •

~

.. , ~ ~ ~ \:;.:·i~+

(

..

..

\

--• ~

~rR.'''' - - -_LOts

!!!!..!

-----,

.'

- 1

,

~.

, , ,

-: i ~ ~--.".------- .. ---. -

toIT JO/.

... i~-::;;:·--""~:: •• ___ "'_~~._-..r • .!:' - _ ....

101. ./7

DATI

•

~e J.) Seasonal pattern. Or conduct1v!ty (US.c.-1) ln aurtace -tera t'ro. the atudy sl tea.

toi'

•

(

o.t

:1 .... • 1 , • !

C>

"

..

,

0.1 ~

~

..

.. GA

a

0 JOie .. ,., 10' •

-----' ,

.- ". , !.!!...!

;., ,

,

,

, .- ,

" , ';j. , , 1

, , 1 , , ,

1 , , 1 , , , ,

J ~

~ .. ..

IOta ..n 10 ..

UT.

...

• If

S.eaaal pattern. of nclucecl 1rœ .. ten frOla the at.1IdJ ai tee.

"

(

, 1

" ,

1

1

l'

, ,

-1) <.-1

67.

. -_ .. ~ .. ,""':--

'O/?

ln aurfac •

...

, ~

1 Î

1 ,

1

(

- ,.

::; "'-• -., 3 • :. 1 1 • 0

1 0

: a •• • Ci

• • .a

(

• ! ,

, \

.TI _ ••

--- "LOTI

/'

(

, " , \

1 \ l ,

1 .' \ ,~ , " 1 ~ ," \ ", \

h , '

" 1

" • • • •

68. 1

---.:=------:.. --_ ... _---

,

.. ,.. 1

,---------

~ . , .!J 1

,".anal patterns ot total cl1lÏlIOlvecl phoaphorua b"S°l" ) ln aurface _ tera rro. the .tu4~l te ••

...

J.

)

\ )

.....

... -/

• " ... ! .,

( -saTI MIAH

-- -PLOTS 0.1

1:. It~N ~

0 ,.....-M 0.1. 1 \ \

1

0.14 1 ,0 , 1 , ,

SITE 2" SITE 1 .- \

0.12 \

. 0.10

1.' 3011 10/7 JOli IOta JOIT 1011 -~--:

-- DATI

r

l' i 1

1

1

"«ure ).6 s.a~QG&1 patterns of avallabl.& n1trOS8ft < •. 1-1

) in l , 8\l%'faee '1& tera t'ro. the .t~ .1 te •• .. 1

/

l ... .,

"

.1>

70.

Throughout the seuoo, th~an conducti vit y values are lowest at si tes

1 (10 t:o 20 ~. cm- l ) and 3 (ZO-- -to 50 '-l5'cm -1), elevated at site Z (50 to 90

-1 1 ,..s·cm ), and higher still at site 4 (60 to 240 J,J5'cm- ).

-1 Levels of reduced iron range from 0.01 tlS! 1.8 mgol The values are

-1 similar at sites l, 2, and 3 (0.2 to 0.4 mg'l ) during j".üv and August. The

> - ...

somewhat e~vated quantlty of ~ron at sltes 1 and 3:-/ 0.7 mg'l, J in IlUd August

, probably reflects the slower rate of water. movement at these s1.tes, at this

time. The data supports the redox data ln that lroç 15 koown to form compounda

of low solubility under oxidized condl.t1.ons (~. low values at site 4),

becoming transformed to highly soluble salts in reducl.ng coodit1.ons (~).

The total quantity of disso1ved phosphorus 1.n the peat water ls slm11ar

-1 • at aIl sites duriqg most of the growl.ng season (10 to 2'0 ug'1 ), but levels

are variable in June, deere,asing in the sequence site 4> 1>3>2.

Leveis of nitrate nitrogen (N03-N) are comparable at aIl sites (0.1 to

0.2 mg'l-l). Levels of ammonium nitrogen (NH

4-N) are generally highest at site

-1 -1 l (0.1 mg'l ), and lower «0.1 mg'l ) at the remaining sites. The produc-

tivity plots of sites 1 and 3 usually contain greater quantitl.es of available

nitrogen (as NOZ-N, N03"'"l~, and NH4

-N) than those of sites 2 and 4 (Figure 3.7).

Several general statements can be made with regard to seasonal patterns

of the peatwater chemistry, although the magnitude of increases and decreases

in elemental compositio~'may vary between sites. The conductivity at aIl sites

increases durin~~uly and~ August. This may be a function of concentration by

evapotranospiration, as elevated water levels in June (from meltwater) would

tend to reducè ionie concentrations. Levels of reduced iron follow a similar,

albeit less weIl defined, pattem. Levels of total dissolved phosphorus are

... .

1 " i

•

\

\

, \

----------

.:::. • 1

Z III •

" 0 ~ !!

SIl'! 1 A

2 0

! C

4 •

.1:

\

. o.L._-~:::::==:::;:===:::L---. ~/7 3O/a

VA TE

71.

nsure 3.7 Seasonal patterns of aval1able n1 trogen

(as NOZ-N, NOJ-N, and NH4

-N) in surface

waters collected from the area ha.;-vesting

plots of each study site. '1

1 ..

r __ 1 '--

·. (

t ,

72.

~Ih. initially. decre.aing rapidlv early in the se •• on, and thereafter . ~ reaa1ning 1ow. This trend has been recordèd in a number of northern systems

-)

(laO. 214, 229). and is attributed to transfers of p-hosphorua fr01J1 organic , to inorganic forms following soil tnaw (41), and subsequen~ incorporation of

phosollorus by lZrOWl.ng vebetatl.on (18, 39, 40), The distrlbution of available

nitrogen appears to be haw tnroughout tne season at all sites.

3.2 Production

The production by v .. cular species (.edg~ and ahrub) rangad from 50 to "

350 g.m-2.yr-l , and i8 summar1zed 1n Table 3.2. Single 5p~ies are the

greatest contributor to biom8sS at each site, but not identical at all three

sitea. Carex species at site 2 nad the highest rate of production (233 t 26

g.m-2.yr-1), as well as the smallest deviation between replicates. Mean pro-

duccion values of sedges decreased from site 2> site 4> site 3> site 1.

Productivity by sedge species ,showed a weak, positive rela~ionship with

temperature and conductivity, and similar, negative relationship with

-- environmental nitrogen levels. Based on the results of Spearman rank statis-

'\ \

\ \,

tics. the correlations were not significant (p < 0.05) • , ,

Length increments and production by Sphagnum mosses were generally great-

est, as well 8S least variable, in species from hummocks (Table 3.3). Values

for hummock species at site l (Sphagnum russowii) vere comparable to those

at sites 2 and 3 (mixtures of Sphagnum angustifolium and Sphagnum warnstorfii).

Thus, production appears to be independent of specific differences~ and, due

to variability in moisture and nutrient status, more greatly influenced by

f

l

,f

."

l ,. ,

; ... ..

• f •

Site .".;

1 (n = 15)

2 (ft : 15)

3 (n = 15)

4 (n = .5)

1 (n::. 1)

• 2 (n: 1)

J. (n...= 1)

t> \ ,

Table ).2

)

Specles

Carex chordorrhl za

~ rostrata.

Carex aguatal1s

Betula gland'.llosa Sal\x pedlcellaris

Betula glandul.osa Sallx pedlcellarla

a

Betula glandul.oS3.

\

/

P!"oducti vi ty

21 ~ 12

233 * 2fT

90 * 25

167:t 9?

4)

.5.5

52 71

\--

Production by vascular 6pecL~ at the four sites "

1nveet1gatld (Illean 'value-; r---stAndard devtatiJons) •

•

•

\

7). ,

\

"

Il'

1 l 1

Î

,/

~ -

,

\

..

" S1te Poe1tlon Mean length 1ncre..nt Prod,t1on

(ca t s.4.) IV (gJ /yr)

1 0.95 t 0.28 61.8 t l?J

2 1.12. ± 0.U2 72.8 t 30.6

J : 0.89 t 0.25 57.9 * 14.8 /'

1 La. 0.)OiO.18 14.4 * 2.6

2 0.18 ± 0.15 8.6 t 1.3

3 \ O.~ t o. 'J4 '- 19.21:6.5

Table J.) Mean length 1ne~lI8nta and production by Sphaejnua

_oases (n: 4) at the study 51 tes.

,""

\

..

1

!

\ l-

I

[

.,c, _.

aicrohabitat. This is supported by evidence at site 3, vhic~ contained the

.&me species (Sphagnum angustifolium) in both the lavn and hummock positions.

Comparisons of stmilar species in similar positions indicate that pro-

duction by lawn species ia greatest under oligotrophic conditions (i.e.

Sphagnum riparîum at s1tes 2 and J), and somewhat greater for hu~~ock species

in minerotrophic sites (1.e. Sphagnum angustifo1ium and Sphagnum warnstorfii

at sites 2 and 3).

The mean total above-ground production by vascular and non-vascular

plants was greatest at slte 2 (335 g.m- 2.yr-l ), decreasing in sites 3 (176

g.m-2 .yr-l ) and 1 (114 g.m- 2.yr- l ).

3.3 Maas 10s8 frQm decomposing tissue

The proportion of tissue remaining following one year' of decomposition

varies between sites as weIl as tissue types. The results of tissue 1055 (dry

mass) at esch aite, from the ten tissue categories and cellulose, sre presented

in Table 3.4, and Figure 3.8. In most cases, variations between replicates

is 10w, such that standard deviations are within 107. of the mean.

At site l, rnass losses varied from 12.4 to 17.67. for Carex and Scirpus - .

leaves, 13.9 to 21.4% for Betula and Salix leaves, and 6.4 to 10.8i. for . Sphagnum tissues. The patterns for tissue loss were much the same at sites 2

and 3, with sedge and shrub leaves decomposing more rapidly than Sphagnum

mosses.

The calculated~' and ~ values support this trend (Table 3.5). Despite

the 8imila~ities between the constants, a linear function provides a more ,

') \

\ \

'>

Tissue type Site 1 Site 2 51 te. J and 4 (a) (b) (a) (b) (a) (b)

Carex 11 1I0sa. 14.3?! 1.)6 1?6J~0.29 10.))*0.85 16.?OiO.57 1). 7?t). 35 24.8)Jl.99

Carex ros tra ta 15.60i 1. 96 20.J7 i l..5? 9.5)21.25 1 ).40*0.8) 14.4)21.89 2). :J?tO.2~

Carex ~guat.al1s 10.4)tO.90 16.001 1.92 18.17H .80 26.60 i 2.4?

Carex chordorrhlza 11.9?t2.54 20.20:t2.19

Scirpus ces:Qlt98\1~ 9.00:*2.25 12.40i O.)8 ? .9JtO. 50 12.40*1.18 10.10tO.4) 15.60tO.59 ,~ ~

Betula glandulosa. 16.0)tl.82 21.4):11.)6 1l.50tO~4 20.0?~2.)) 10.6)tO.70 16.77:t2.25

Sallx 2eqicell~r18 i.17 i 2.61 1).90t 2.58 11.80t1.24 18.1 ?:t0. 56.

SphagrlUM lind~rgl1 6.0):10.90 10.71*0.94 5.77 2 0.64 7. 90t 1.10

la wn Sphagna 6.6)i1.22 7.)):11.98 5.90tO.57 11.5)iO.8? 4.27!O.76 7 .8)tO.)4 ::

HUal/lock Sphagna 4.6)tO.4O 6.40*0.?0 7.00JO.92 1l.25-tl .65 6.60*1.04 10.4 Jt2 .12

Cellulose 4.99*0.80 6.59 t O.7B 4.54i 1. )0 5.62tO.B6 6.)Ot2.B6 5.?4tl.1J

Table ).4 Proportion of orig1nal "88 lost (II8&n t standard deviatlon, n= J) over <a> the "inter periocl (J9 .,eeks) and, (b) one year'(50 .,eeks) at each aite, for each tIssue type 1

"-J 0\ ~ •

-' ~.

~"ly.!J'- .. ~,...,~ .. "" ".~ .. ~

~ ~ !..!!!!!!!

~

.lo A •

'?

• 100

80 ca c ë eo a E • .. • ~ ~ u.!Jl!! l!!l!!I tU!*I!I!J • eo 0 ~

50

~ 0 A A

100

eo

eo

70

~ .... ........ ....et, ....... 80

-L---- .---.

• J • TlWE

:::::::::::---------~ .....

~ .... I--r-- -,

A

-~'a ~

..... u .... "

A

c .......

------,----, 1 •

\

--- -, ~

~ ........ " .. - - ----- ----r---"'I

, A

~-=-=~~

-...- --A

!!!! SITf ---

2 --3 0-

4 .... -JUNE

AUGUST A

Figure 3.8 Chan~es ln maS6 of the ten tissue types, plus cellulose, conta1ned ln the l1tter ha!l.

\-

.. ,~._ _.:....'f~ .... , __ .. -'- ......... r_- ~

(j P

~

~ ,.

\

18.

"-"

.. Site 1 Site 2 Site. J and ~

Tia.ue type k' ! k' k k' :! -

9!!:!! 111108& 0.119 0.197 0.168 0.18) 0.2~5 0.281

Carex ro.t.rt ta 0.204 0.228 0.1 Jû 0.14) 0.2)2 0.264

Carex aguat.a118 0.160 0.174 0.267 O. )11

Carex chordorrhl za 0.201 0.224

Sclrpul!I ce.pi tOl!lua ... 0.12) 0.1 )1 0.121 0.129 0.156 0.110

Bet.ula glA.ndulosa 0.216 O.2~J 0.199 0.222 0.166 0.181

SaUx :2!tdlcellarls 0.139 0.150 0.182 0.201

Sphagnua 1~ndbergl1 0.108 0.115 0.079 0.082

I.&wn Sph&gna 0.079 0.07~ 0., 11 J 0.120 '0.078 0.082

HUl'lllock Sphagna 0.066 0.068 0.111 0.118 0.10'7 0.11} rt.

Table J.5 ca1.culat.ed l1near (k') and exponentlal (k) decay constants tor the' ten tlssue 'types at 84ch 'sl te. -

(

/

(

"'Q , .

satisfactorJ prediction of litter decomposltion in this instance. Values ,

of ~' range !'rom 0.;7 for several 3phae;n'..un tissues. ~o ')ver 0.27 for C:arex

aquate.J.1S le<:wes in the sedge meado .... ISl.te ;.). The mean k' ~alues ~or all

species at s::.. tes l, - and 3, 9.re l .. l. 3f.:J , -= .1 ~(, 9.nd J.166- respec:t!. vely, vi th ~ ,

• an average "/9.1 le J: ~ .1': -: f0!" '3.:'l 31:es. ~J",~0'l1rOS : ... r;' ;9.":es~ t'1",r. • ,..:~!1er':tll:1

InCreaS€ !'ro~ Sl:'e -,,-<31~~ 2<3::.te 3.

The data also ShO .... S that a slgnlficant portiJn of the mass ~ass o~c~s

during the vinter months (Le. from SeptellÎ>er to June). Included in Table 3.6

are mean ""inter and flrst year lasses (al1 three 51 tes) f')r each t:.ssue type.

and the proportion of first year losses attributable ta decompositlon from J . September to June. Winter losses account for 59 to '69% (inean of 65%) Qf first ~

·year lasses.

..

3.4 Tests for significant differences in decomposition in the v&rious site and litter categories

\ Dunean's multiple-range test vas used ta determine the differenee in

mean dPy mass 1055 bet .... een tissue typéS .... ithin sites, and .... ithin tissue types

between sites. The results of these tests are presented in Tables 3.7 and 3.8.

The test results show that variability in loss rates is more often

signifieant (p< 0.05) between entirely incongruous types of litter (Le. vasculal 1

plant leaves and Sphagnum plants) than between similar tissues of diverse

specifie composition. Statistically significant differences in tissue deeay do

not appear to be greater in number for .... inter than first year lasses. That is,

.... hen disparity occurs between tissue types during the first year, they are

usually significantly different during the winter months as .... ell. 1

f

) , /"--

" \

./

..

n •• u. type

9!!:.!! roe tn ta

Carex ag ua ta Ua

Carex chordorrhi za

Sclrpua ceapito.us

Bet.ula glanduloaa

Sallx pedlcellaris

SPhagnUM I1ndber5ii

14am Sphagna

HUlUlock' Sphagna

Â

Vin ter 10ee

12.82!1.78

1J.19!2.6J

14. JO! J.B?

1l.97!2.54

9.0l! 0.87

12.72!2.J7

9.49!2. )2

5.9Q!0.13

6.08!1.04

\

B F1ret. y_r 10ee Ratio A/B -..

•

20.20!2.19

1 ).47H. 51

19. 4 2!1.96

8.90!1.86

69.24

67.14

59.26

66.89

66.50'

59.16

63.17

62.92

66.52

Table 3.6 Mean value. of .a. lo88ee at al1 sl tee (~t standard 4evlatlon) during the nnter and over one year, and th. proportion attributab1e to wlnter deco~pO.ltlon.

\

\

80.

,1

o

4 '\

\

~

" 81. .... , . \ !l il J ; J j !l ~: 1 1 ~

Il

! ~ :1

J ...... 1 if J

.. ~ • 1' , .. 1" . .,.. ... ,- . -;.- ,,. \- .. - , ., t.,. . "" 1 ". 0..1 J.~ ~ • .1" ._- .. ,. "

,..., , .. . " . .- 1. .. t.a,.. 1.- 10_ 0.- -.. -n .... ) ., ... . ,. • 'J .- , .. -.'" .. ~ ..• .... l " ,,~ 1.11 '.te ~ .. ........ .0.,.. .J .... '" ~. , .. t ., '" z. ..

... --- 'l.l'~I)""". "'" . ,. ... ,..,

• !I 1

; ':1 i Il ~

il 1 ! Il SI .1 : J

!!!!...! ~ ~ il 1 J J

;.~ ••• '.10 ... , .. t." 1'" '.l" 1 no ....,.. i··'-· 1 )1

,. , .. . ... . ., 1.1' J.'" /.n -t

i·~ 1 .... , .. '" , ,. . .. lJl - n- ) .,.

j. •• ). ..... ..... '.- ... 0.11 . - . .... ~

.,. .110 1." .... J ""

1 .... 1.0' '" l!!IfIIe 1 11 ,,,,. . ., , " './Ir<' , li j.- ....

, " ! ... -yen. . - .... 1 17 1." 1 .... ... , ... .... '- ..... '.1"'" 1 •• .- ... O." f.,... .- lU --- , .. " 1.11 ".7,- 1 .. ',. 1" .... .. ,.. oJe

~ il ~ ~ ~ j J !!!!..2 J ] u. J • ... ., Jl .. ;" llII!! 1" ).'7 J.'- ..... ... ',7"

:. :!:!D1! '.oé . ') 1110 ! .... ta , ..... '7.'" j

!.~ '.n ,,., 0," • JJ '.Il J. ,.

y,~ ~.06 660 l ,. -.N . ,.. -.Cl

!!!!. / '-"'!O!J!' ,~ 9,. 1' .... '10 er 1.'" 0.11 ----La_I ....... 17 .... 1,.,..- , .,.., 5." 0," l,"'! --- , ...... li'" ,.17 6. '" 1." 2,"

Table J.7 Results (differences betwéen means) of multiple-range tests. * indlcates significant variation in mass 1088 between tissue types, with1n sites (p< 0.05). Upper right hand values for each site compare Mean winter losses, lower 1eft hand values losses over the first yea.r.

..

1

\ \ la

.. ( .

.. :

..

"

"

~bl~ 3.8 Results (d1~~erences between means) of multiple-range tests. * indlcates signif!cant variation in r.l&SS 108s within tissue types, between sites (p< 0.05). Upper values compare Mean winter losses, lower values compare Mean losses over the tirst year.

j

l

,.

o

. ,

•

J

)

.f)

, \

Deapite the large variations related to tissue quality, there are ~

.lao significant differeI.\~s Cp < 0.05) in 108s rates within li\tter cate ..

gories between sites. Some differences between sites, however, may be

confounded by differences in tissue quality, 'rather than actual site

differences. Significant contrasts are more frequent following a full year

-ofo

decomposition than after the winter months alone, particularly between

site 3 and the other sites. This reflects a more consistent microenviron-,

ment et aIl sites during the rinter months.

\ , \

3.5 Nutrient changes during litter d~composition.

The original çomposition of the ten tissue, types is shown in Table

3.9. The total macronutrient content of the vegetation is low in all c4Ses, c

ranging from i.25 to 4.04% of the tissue mass. Individual nutrient concen-

tr~tions are ge~erally lowest in Sphagnum masses, an~ higher in sedge and

shrub leaves. Macronutrient levels of vascular leaves generally decrease

in the. arder N> K > Ca> Mg~ P. Moss speeies are more variable in composition,

and no pattern is evident.

Marginal differenees in total elemental composit~on of identical tissues

enst between sites, usually inereasing from s:1.te· 1< site'!t3< site 2, with r

the exception of 'etula and Salix leaves where leveis are highes't at si te '1. )

This, tagether wrt~ the higher levels of calcium in Carex squatalis tfss~es ~

at site 4, indicate that the elemental concentration of the vegetation may

rèflect individual or total ionie concentrations in the peat or peat waters.

The percentage of organie eompounds 1s variable,' afthough siprl,lar for

st>ectfic tissue types. Vascular tissues contain 2 ta 8% lignin and 5 to 24% .....

/

r ...

ELEMENT (percent dry we1ght)

T1e,!Sue type Site P N K Ca Mg AD' Llgnln Cellulo •• - -~~-- ~ - - ~ ~--*-.~-_.~

Carex U.osa 1 0.05 1.04 O.g? 0.27 0.17 27.5 2.5 22.5 2 0.05 1.84 0.75 0.25 0.25 )2.0 8.0 18.0 J 0.07 1.47 0.73 0.35 0.27 )0.0 ,5.0 20.0

Carex rOB tra ta 1 0.11 1.10 0.38 0.)2 0.)0 )0.0 2.0 20.0 , 2 0.05 0.92 0.84 0.27 0.19 )2.0 2.0 22.0

) 0.10 1.14 1.)6 0.25 0.2) )2.0 2.0 24.0 Carex aquata118 2 0.09 0.74 1.95 (1.18 0.17 )O~O 4.0 24.0

4 0.10 0.93 1.12 0.60 0.20 )0.0 5.0 22.0 Carex chordorrhlza 2 0.15 1.80 1.09 0.36 0.25 )0.0 6.0 20.0 Sclrpue ç.,apltoau8 1 0.05 1.16 0.39 0.27 0.18 24.0 4.0 18.0

2 0.0,5 1.94 0.40 0.2) 0.23 22 .0 2.0 18.0 J 0.05 1 • .50 0.55 0.25 0.21 22.0 4.0 20.0

Betula glan~~lQ6& 1 0.10 1.96 0.6) 0.57 0.28 17.5 2.5 12.5 2 0.10 1.97 0.51 0.,3 0.2? ?o.o 2.5 12.5 J 0.10 1.84 0.67 0.50 0.29 1.5 1 2.5 5.0

Sallx 2!dlcellarl. 1 0.08 2.08 0.68 0.84 O. )6 20.0 6.7 1). ) '- -2 0.09 2.~ 0.65 0.81 0.31 22.0 6.0 15.0

Sph&gnu~.ll~~~~~ 1 0.02 0.24 0.29 0.50 0.20 42.5 12.5 40.0

f J 0.10 0.70 O. J1 0.41 O. )1 40.0 12.5 35.0

uum Sphagna 1 0.02 0.62 0.41 0.41 0.14 40.0 12.5 25.0 2 0.03 0.44 0.29 0.61 0.25 42.0 12.5 )2.0 J O.OJ 0.52 0.27 0.15 0.4) 42.0 10.0 )2.0

HUJUI\OCk Sphagna 1 0.05 0.54 0.47 O. )f, 0.16 î.~8 .0 2.0 )2.0 2 0.05 0.42 0.38 1.04 O.:n 50.0 8.0 )2.,

_0 :3 0.05 0.:36 0.79 0.48 0.1.0.0 50.0 7.5 35.0 -- -- -- - ~- ---- --~---

..

Table ).9 Che.ical co.position (percent dry we1ght) of the or1Ktnal ti •• uee. ~ •

r

"

• cellulose. Moss tissues have somewhat higher quantities of bath lignin

and cellulose, constltuting 2 to 1~.5% and 25 tv ~O% of the dry mass

respectively.

':hanges in n.ut~ient content ,Ji Htter tissuèS ùver time are presen­')

ted in Table 3.10. During Jecomposi tian, nutrients may be transferred from

compl.ex ta simple compounds or t,~ elemental forms, removed from che II ctet

bv leaching ..)r as .A gas, and taken up bv ;:' lant roots vI" synthesized :.n

lUcre !:Bunal :::!..ssue i l11). ~~hanges l,n elemental "::ùmposl t:ion may be relateJ

tO partL.:ular ,.ite ar tissue types in som'" l,liSes, especial1y for K, Ca,

and ~, although f0r the mast part:, nutrl.ent alteratlon appears to be

independent .:;,f elther vari able.

?otasSlIJll:l 15 the only element. which shows consistent losses for all

tissue types at all sites ,Figure 3.9). Elevated losges of potassium (60

ta 80: in the fint yeu) are .. sociated vith h1gh leaching losses.

Caleb.a and lManesium alao de.anatrate rel.tively rapid losses over

the firat y.ar of d.cay (Figures 3.10 and 3.11). Sa .. tissue types increased

in calcium and magoesium content during the SumDer montha, desp1te lasses

over the vinter. This is lDOre apparent at .. ites 2 and 4. SphaanUIII tissue

presents an exception in both the cases of calcium and mapesiUIR, vi th

either very .mall lasses or slisht incre_es in calcium and _gnesium con-

tent. Betula and ~ leaves &lso show small ovenU losses or gains in

calcium content.

The pattern of chanse for phosphorua 19 more cOlllplex than for K, Ca, or

Hg (Fiaure 3.12). Only Sc1rpua and f.. chordorrhiza show consistent, and

almost. identieal, lasses of phosphorua vith time, such that 30 CO 60% of

---------- ---

\ _2L

~-1

,

th,:',", -, -

:!

H\1'I'RliJ(T Tissue type - Site P H 1 Ca Mg

2!!:!! 11110_ 1 157.4& 11.4 150.5 t 23.0 21.6 * 1.8 75.0 t 9.9 40.2 t 1.8 2 171.4* 8.2 82.2 t 5.4 21.4 i 4.2 97.1 c ).) 71.2* 6.7 ) 1)2.) & 45.) ~.4 * 28.2 25.0 * 5. 4 68.6 *22.6 41.0*15.1

Carex r08t.ra!! 1 59 • .5 :t 10.8 61.4 t 8.1 1).7 t 2.8 55.8 :t 5.5 16.9 Il 0.9 2 102.6 & 19.) 71.0 Il 28.0 10.) .. 4.4 118.) t 4.0 )6.1 t 8.4 ) 87.0 t 6.5 ??2 * ).? 16.0 t 2.1 109.3 t 10.5 62.0 * 1.5

Carex &qua taUa 2 75.6*19.9 128.2 a 65.1 29.3 *33.8 95.6 • 35.7 22.8 i 7.8 4 85.1 t 8.2 109.2 * 34.5 10.8 * 2.6 31.6 * 2).6 40.7 * 7.1

Carex chordorrhl rA 2 jl.4 ~ 2.4 72.8 * 3.6 16.3 t 1.7 67.8:1 9.2 27.) * 3.5 Sc1:rwa c.ap1toeu~ 1 47.3 *29.9 88.8 t 3.4 22.3 • 1.8 74.4 t 10.0 28.4 -s: 2.5

2 41.4 *24.8 , 60.6 t 8.6 )3.2 " 6.) 90.0 *1).) 24.2 * 2.0 3 28.4 • 7.4 61.9 t 11.4 19.4 t 1.4 95.3 *13. 4 49.3 i 7.7

Betula gla~dulo~ 1 91.7 t 9.6 108.3" 21. 7 16.1 * 2.0 76.8* 7.5 38.6 :t 11 .6 2 100.0 t 28.9 148.8 t 7.) 23.0 i 2.4 180.5 a 6.1 51. 3:t 3.7 ) 73.)'18.1 122.9 i 19.8 19 • .5 t 4.0 94.3 *"1:7.7 45.3 *11.0

Sal1x pedicellar1s 1 60.9 l 4.1 151 • .5 * 3.4 10.7 * 0.7 87.5 t .5.8 32.8 i J.) 2 101.9 t 8.7 131.9 t 30.5 20 • .5 * J.J 76.8 * 2.5 35.5 1 .5.6

Sphagnua 11ndberg11 1 207.) t 56.1 347.6*12.4 )).8 * .5.0 140.5 t 8.9 114.5 t 8.3 ) 83.3 * 9.9 108.2*61.) 46.7 * ).9 105.7*11.7 tl1.8*13.2

lawnSphagna 1- 314.6 * 13.2 96.7 t 6.1 18.0 * J.5 184.5 * 11.9 172.5 s 20.4 2 186.4 t )2.6 186.2 • 66.1 17 • .5 1 1.9 108.0 i J.7 86.0 i 12.2 J JOS.2 t 22.9 10).0 :t 62.9 61.7 j 6.3 71.7 i 6.4 77.5 * 6.2

HUllllOCk Sp~ 1 192.6 *21.3 148.4 t 9.0 26.9 t 5.8 11 3.9 i 20.) 95.3 * 15.5 2 125.7 t ?:l. 9 165.9 * 15.2 26.7 * 2.3 59.0 t 2." S'7.5* 4.0 3 179.6 i 23.6 182.5 * 23.4 15.1 t 1.1 146.0 t 12.1 99.5 l 7.3

-~.- ---- ---_ ........ _----_ ..... -

Table ).10 Percent nutrlenta re.ainlng in litter tissues (~ean:t standard devlatlon) followlng one year of deco.position. - ('l)

0\

If

1 (

IlQ -c,,_. - --- c. ...... ..

c, ......... .. 100

10

ta

r" 120 -- ............

40 ---1. ...... 11_

?

Ot ] c:

5 CI E • i 1 ... J " -c:

! -" '~1

12Q c:

~ --c'I_ --s.a. ,,,''''"

0 ----s.~_ - ...... --- ...... 100 100

, 10 ... ,

~,

~, ... , 0 ~

\ " J A \ " 10 , \

10 " " \, , , , \ , , 9l: lITl 1 A ,

" \ ~ a 0 \, ... ' .... "0

~ 0

.~

1. , .. . 10

JUIll J 10

,,'*'ST " 0 0

A

TIME Tl ME

Figure 3.9 Changea in th. quant1ty of potassiua 1n the ten l1tter types dur!", the tint year o-t decompoa1tion.

__ ._ - - _4'--_____ -----------------_..:1'------

0

"

1

88.

110 --c..-..

JDO .... c. __ ..

.. /~ c. __

1.0 , l'

/ \

1.0 r \ ,-\

.-140

,

... ~ 100 ::::~= / 110

.0

~ .0 r:: c: ... ... ~ 40

, ... • .. ---.. ...

to

1 0 =1 - ......... fII

s eo '- ..... 1> i A ._--- .......

_0 1.0 6

~ 0

«)

-C.I'- .0 1

1&0 ----L Mlle_ 0 f

--~ ... . 0 __ -:. -:.. :. __ .0 ''6 J " .s.: _ ..

100

1 ~ "1'1 1 • • 0-1

~ 10 sa

•• .KIIII J

:1 ~ .-10

i 0 .1 "

TI .. t: TIME

Figure J.10 Chance. ln the quant1t7 of calei ua in the ten 11 tter typel durtnc the t"1nt 78&1' of deeoçoa1 tlon.

----

'. --. 'Cl , ... '0

J "

,

140 -c._ •••. c. ........

,ao c.. .... , ....

'00

" ... \ 210

\:JI ,,--- \ -L"-- - ............. c: .,

~ .......... - 100 -.......

5: ----......, "' ..... 0 40 e • .. .. 20 j ... 1 .. 1- «1

.••• s.....w- ao 100

0 ~ 10

~ .. " •• 10

JO 10

•• 0 1 MIl J

TINi ...., ..

TIME

P'1gure 3.11 Change. in the quanti ty of' 1IIiIlP •• 1wii ln the ten 11 tter type. duriDC' th. tint y ... r of deeollpoai tion.

.)

lA

A

0 --t D

"

'"

(

--~~ ..... - _.- ., ~ ~ -J ~

90.

-:----... s \- .......

P 140 ZlO

• , , - ........... -1 " ~

110 •••• a. ..... ...,.. 210 ... ... 1

'i .......... ..;' E .0 100 140 • ' ... .. " ---... ao 10 ao CI • .. 0 10 .... -- .. aoo -::1 CI

A

1110 40 '10 ;!. -CoI_

te 10 .-• .. ·-L ...... _ .-.-

140- 0 " " A

\10

100 !!!!: Il. 1.

20 eo sa

110 •• ... J

4Q ..., A 40

10 10

Q 0

TIME TIME

J\cure ).12 a.npa 10 the <taant.1ty ot phoaphorua in the ten Uttar tnea durtn« th. tlrat yar ot decOIIlpol1 tion

/

liII" __ 4

/ P " , 9

/ A 1 , 1

./ /

,A,' ):. , 1 ~ 6' 1

4 A

fil' --~----.~'W""--- - ---.. ~ "

91.

the original phosphorus. remains after one year. About one-half these

losses oeeur during the nnter. Other leaf tissues show overall phosphorua

lasses of 20 to 40% over one year, while Carex 1imesa shows a graduaI

inerease in phosphorus over Ume. The pat tern of phosphorua change in

Sphagnum lit ter is highly variable, with inerease& of 5 ta 217% over one

year in all but one sample.

The trends in nitrogen alteration are somewhat les& erra tic than

those of phosphorua, and illustrate the importance of n1trogen as a struc­

tur~~ound (Figure 3.12). Sedge litters show the greatest relea.e. of

n~rOgen, both over the winter (5 to 45%) and one year (5 to 53%). B.tula

and SaUx appear ta ratain lIO.t of the1r nitrolen over the winter. and

generally show. 10 ta 45% iner.... in nitro,en content over the • __ r.

Sphapum show •• sim1l.r p.ttem. vitb aomevbat hi,h.r iner ••••• over th.

IIIOnths (22 to 82%). which .. y he due to nitro,.n fixation by livin, Sphapua

gronng up throuah the .ab ba, ••

The .tandard d.viat1ona encountered for tbe nutrient alterationa ar.

aa.eti.me. hiJh, but th.re do., not appear to be any specifie re1ationahip

with alte or tissue type. Potu8it.a .enerally .hows the ... l1 •• t vari.tion II'

betw.en r.plic:ate .aaple. vhieh, alain, .upporta tbe consistent 10 •• of th1.

element frOlR a1l tia.ue. at all .1t ....

Tbe ob.erved •• quence of nutrient 10 ••••• then, 1. ,ener.Uy 1> Ma>

Ca>N.P for •• d,e litter, lC>Ma>P>Ca>N for Betula and !!!!!,.leaves, and

K> Ha > Ca> P >N for SpbaID_ tb.ue

p -

(

- - - .• -_ .... - --- ... - .,.

92.

110 '.0

-Co ....... 140 -_·.Co ...... • --,. ....... M c..., ........

1- ...... • 0 ---............ 100 -L......- ,.

...... ..-.- zao

HO

• .. oS CIl • • .. ~ • 1: ~ c .,.

.., • 1&0

• J AI

--c."- 40

----" .,- 10

0 AI

.- -~-1 ,. . !!II: ~ - -

.e - -B 1 ..

•• • .- J

• -- AI • 0

• 0

TIIE TI"!

l

n~ ).1) Chan«" in the quantlt1 ot nitres_ ln the ten l1tter types 4ur1nc the tint 1e&r ot 4ecoapoal t,iOft..

~

, "

(

--- - .- T

9'3.

3.6 Influence of litter quality on decomposition.

Examinat:4on of mass losses in relation to the chemical quali ty of

tissues was concentrated on the first year deèay rates. Table 3.11. presents

the correlation coefficients and regression equations for the relationship

between!.. and the chemical composition of the original tissues.

Mass losses were positively correlated with N, P, and K, and nega­

tive1y re1ated to Ca and Mg. The correlations were significant for N, P,

and K on1y (p < 0.05). Of the organic compounds, lignin and cellulose show

a negative linear relationship with mass loss, which was statistically

signlflcant (p < 0.05) in both cases. The trend for cellulose, ~. slower

decay with increasing cellulose content of the original tissues, is the

reverse of what might be expectéd. This relationship rnay be effected by

the Sphagnum tissues, vhich have high cellulose concentrations and lov

values of k.

'.

.... ,~

Conatl tuent r Equation

Phoaphorua 0.645. y .. 0.08 .. 1 .09x

Hi troget'l 0.526· y. 0.10 + 0.05x

Pot&aalua 0 • .511 * y=:O .10 .. 0 • O?X

Ca lei ua -0.1)4 y= 0.17 - O.OJx

Magne.lu. -0.076 y. 0.17 - o.06x

Lignin -0.517· y - 0.20 - O.Ob

Cellulose -0.,564. y - 0.24 - O.OO)x

• .1gn1ficant a t ~ level

'DI.ble 3.11 Correlation eoef'fic1enta and ragre •• ion eq_Uon. for the relatlonah1p bat_en decay ra tu C4') and the original ch.lI1eal cOIIpO.l tien of the 11 t ter U .. ue ••

95.

Chapter 4. DISCUSSION

4.1 Peatlands in the Schefferville area

The three peatlands described in this study appear to fit the

characteriscics proposed for boreal and subarctic mires in North America

and Eurasia. There is some evidence to Buggest that these deposits are in

early stages of development. First, the depth of peat in the Schefferville

area i8 generally le98 than 2 metres, whereas pest depths Along the lower

shore of the St. Lawrence River range from 4 to 10 metres (84). Wickware et

al. (244) also found inereasing peat depths (1 to 4 metres) ~ith distance

from the coast in the Hudson Bay Lowlands. Although the type of peat depoait

(raised bog or fen) mU8t be recognized as a potential mediator of contemporary

pest accumulation rate., shallower mires are probably tha rasult of more

recent initiation and a harsher climate. Furthermore. numerous corings in

the 8ubaretie indicate that peatlanda originate as fens, and may later change

to boga (250). Ba.ed on the predominance of graminoid vegetation. and

generallyaineral enriehed watera. th. mires .xamined are fens.

G1ven th. surface and profile t .. perature. from the preaent study, and

tho •• of blanket peata in northern England (226) and shrub-sedge-moss tundra

in tb. subarctic belt of tha U.S .S.R. (228). the period of biological acUviey

in tb. peatland. of subarctic: Quebec 18 probably sOIIlewhat shorter than for

t .. perata peatland., but .tailar to tbat of'othar subarctic: systems. Differ-

encas in soil t .. perature. are t.portant indic. tors of the potential for

organ1 ... 1 act1v1ty. Thar. ia .0.. que.tion a. to the ca.patability of the

1 re&di1'1 •• , a. the tille of the observation. i. IlOt indicaud, and may not be

COD81atent batwaa rudi1'1 •• , withi1'1 stucli ••. Diurnal fluctuations in soil

t.aperature .. y be .1p1ficant. partic:ularly where plant cover la sparae (228).

96.

The mire vegetation of this area contains a relatively high ntunber of

species, and mixtures of plants with bath bareal and Dceanic affiliations.

Based on qualitative observations, the relative ecological positions of

various communities are not far different from those presented in Table 1.3.

Sorne plants typical of maritime peats, such as Carex 1imosa, ~. exi1is. and

Scirpus eespitosus, May occur quite commonly in this region. Carex 1imosa

also exists in weI:, waterlogged fen peat of the Hudson Bay Lowlands (250),

and in Minnesota (85).

The vegetation of aIl three peatlands differs somewhat, both with respect

ta species diversity, and concentration of dominance. Although no quantitative

comparisons can be made, the f10ra of more mine~trophic sites appears to

be richer, especially with regard ta cyperaceous species. .. . Just as there are marked floristic resemblances in these and Dther peat-

lands, there are a1so various chemical similarities. In the absence of careful

hydrologie determinations, aIl sites are probably influenced ta sorne degree

bY,minerotrophic waters. The ranges of pH (4.6 ta 7.9) and conductivity (20

ta 240 ~S'cm-l) are within those reported for weakly minerotraphic (paor fen)

ta rich fen waters (91, lIS, 140, 198), Mueh of the difference in these values

is attributable ta calcium and magnesium ions. The range of water quality

also appears to be more restricted for oligotrophic than eutrophie sites,

similar ta the findings of Claus en et al. (45),

Although ptoblems exis~ when comparing elemental concentrations in these

mires w1th those of previous studies, due ta the different extractants and

various units used ta express results, the paucity of available nutrients in

the peat substrate'and waters ia weIl documented. and rarely disputed. In peat,

•

Il

mineraI mater!al may average 1 to 6% of the dry weight (95), while the

same fraction in mineraI soils approaches 75% of the dry we~ht. The question

of whether fens provide a greater quantity of essential plant e1ements than

boga (particu1arly nitrogen and phosphorus, which are of predominant impor-

tance, Lnsofar as nutrlent deficiency is concerned) 19 oEten addresseJ. Stanek

and Jeglum (210) suggest that fens are richer in bath macronutr lents, while

the results of the present research and a study by Waughman (237) indicate

that the supply of r:J.trogen and phosphorus 1G lnrger in oligotrophic

chan eutrophie siles. •

l t muy no t be possible to assess the relative influence 0 f ionic concen-

trations in differentiating the plant canununities of bogs and fens, nor can

the average elemental composition for an individual species, or ecological

group1ng of species. be a re1iable indicator of site quality. Al though the

nutrient content of mires may in~eed increase from bog to fen, chis does not

presuppose tha t the plants growing in fen environments will have a greater

capacity for nutrient uptake. Low nutrient concentrations in plants may be a

consequence of; low soil contents; or, paor root growth (4). A1though 1itt1e

is known about the nutrient dynam1cs of wetland vegetation, variations 1n the

chemical composition of wetland plants have bean found to increase from within

'site intraspecific variation, between site intraspecific variation, and.

interspecific variation (24). Several factors, other than the nutrient supply

of the medium, may mediate the ionic levels within plant tissues, among which 4>

are e1emental changes· as the spec1es mature, and chemical variability between

different plant struc tures. (25) .

~onetheless, researchers have suggested that differences in the nutrient

J

l

98.

supply of the medium often show up as differences in the nutrient levels of

the plants it supports. Significant correlations between peatwater chemistry

and tissue concentrations have been found for phosphorus, potassium, and

sodium (25), and Lir phosphorus, nitrogcn, potassium, calcium, magnesiura,

sod1um, and manganese (237). This may Le less ~pplicable for SphagnuM ~osses,

which appear to adsorb atmospheric nutrients (46). In the present study, the

total nutrient concentration of the vegetation (both vascular and bryophyte),

ranged trom 1.3 to 4.0% of the dry weight of plant tissues, which i5 not

greatly different from the values of 0.7 to 4.2: recorded in Scapdinavia (140).

Concentrations of individual clements were also similar to those reported by

Halmer and Sjors (140) and Srnall (200) for vascular tissues, and Damman (58),

Malmer and ~ihlgard (141), and Pakarinen and Tolonen (166) for ~hagnum

mosses.

The nutrient concentrations of the vegetation are, at best, weakly

related to environmental nutrient levels, but this association is neither

clear cut nor consistent, and appears to differ with both species and individua1

~ elements. The lack of correlation between environmental and plant nutrient

levels 19 not necessarily conclusive, and May reflect, in part, the period at

which the plant tissues ware collected, Le. late August. At this time, impor-

tant elements may have bean translocated to perenn1ating organs for storage

during dormant periods (39, 43, 58, 180,201). Thus, the potentia! quantities

of nitrogen, phosphorus, and possibly potassium, may be underestimated. Tissue -analysis at the time of peak nutrlent uptake might provide a more satisfactory

answer to this question.

1

1

99.

4.2 Production by mire vegetation

One definit±ve characteristic of northern biocenoses i9 that, relative

to temperate systems, the vegetation exhibits a low amount of annual pro­

duction. In peatlands, this i8 compounded by low nutrient supplies, and

waterlogged conditions. When comparative data are available, and cover a

range of geographically distant sites and environmental conditions, the

standing crop and productivlty of a plant species may be taken as a reflection

of its suitability, adaptability, and utilization of the enviranment (213).

Several problems may exist in estimating productivity based on biomas8

clippings and allometric equations (27):

1. The rates depend on the sampling frequency.

2. Unaccounted losses of organic production occur between sampling periods.

3. AlI plant parts are seldom accounted for, particularly roots.

4. Respiratory lasses are not included.

5. Translocation of organic matter occurs wlthin the plant, particularly

between above- and below-ground co.ponents.

6. Productivity rates are assumed to be zero between the end and beginning of

the 'growing' season.

7. Productivity of other ecosystem camponents, such as a1gae and lover plants,

is ae1da. me •• ured or included in the estimatea.

Given thase numeroue reservations, thus, large potential for error, in

accurately eatimating true population or community productivity, the individual

and collective values obtained in the prelent atudy should be con.idered

minimum estimates of the gross primary production in these mire systems.

The aerial biomass of sedge species was variable and generally lov

...

t

100.

-2 (7 ta 327 g·m ). The predicted above-ground biomasa WBS calculated us1ng:

c:: 0.057T + 1.80

where c 18 the 10glOstanding crop, and T i8 the highest monthly mean temper­

sture (96). Glven T::l2.7 oC, the predicted biomass was 331 g.m-2, which i8

somewhat higher than the observed values. This prediction, however, accounts

for but a single env1ronm.ntal parameter, and so, probably ov.restlmates

actual figur.s, which are subject ta several controls. Desp1te the constraints

in interpr.ting material from the lit~rature, due to the array of differing

assumptions, methods of collection. and computation of results, the data from

this study ia within th. range of 248 g.m-2 (168) and 200 g.m-2 (96) proposed

for subarctic aite ••

The terminal standing crop give. a rel.tively accurate estimate of

production 1n thi. ca.e, .inee above-ground phytomaa. was rapresented by dead

11tter at the beginoing of the growing •••• on. Coaparative data for three

of th •• peci .. .anitored 1n thi. atudy (Cares aquat&lia, f. chordorrhiza, and

C. roatrata) i. av.ilable in the literature. Rate. of 340 g .• -2.yr-l for Cares

aquat.1i. (99), 738, 515, and 116 g •• -2.yr-l for f. rostrat. (16, 99, 176),

and 120 g •• -2.yr-1 for ~. chordorrhiza (191) have been report~. Th.se values

comp.re vith trutr.ta. of 69 to 327 g •• -2.yr-1 (f. aquata11s), 39 to 164

g •• -2.yr-l (~. roatrata), and 170 to 271 g •• -2.yr-l (C. cbordorrhiza) o~.rv.d

in thia .tudy. # -

Saveral factora .igbt account for the diacrapanci •• oba.rved between this

and otber tDve.tigat10na. Altbough lat1tudina1 difference ... y be aomewhat

axagg.ratad wben v~u .. of b1a.a.a production are aspr •••• d on an anoual basis

(b.c.ua. thi. u.ua11y reter. to the growing .... on rath.r than • 365 day year

... 1

r

101.

(27», the more souther1y location of some study sites explains, in part,

the greater production by ~ rostrata and~. aquatalis. Furthermore, the

degree of homogeneity of the areas sampled may differ. Consequently, lower

production May result when competition is increased, as in the case of Carex

chordorrhiza, which had lower values (1Z0 g:m- Z• yr-l ) in mossy-sedge tundra

with mixed vegetation, than in a homogeneous stand of fen vegetation. Dther

influences, however. cannot be overruled in this case.

Fina11y, variability in production rates. bath inter- and intra-specific.

has been attributed ta differences in plant density (163. 213). and individua1

shoot weights (25, 133). Densities of 300, 400, and 1476 shoots-m-2 have been

reported for ~. rostrata, ~. aquatalis, and ~. chordorrhlza respectlvely

(3, 99). Based sole1y on these figures. it would appear that lncreasing density

reduces productivity, although this ls an obvious oversimplification. Shoot

weights and denaities were not recordad in the preaent atudy, therefore, an

abso1ute comparisan cannat be made between thia and ather investigations.

Nonetheless. this type of variabillty might explain the relatively hlgh degree

of heterogèneity encountered in some of the standa (particularly ln sites l

anù 4).

,; Although decreases in standing crop with latltude and altitude are weIl

-2 -1 documented, Tie.zen (221) auua.ts that production value. of 3 to 242 g- m • yr

in tundra vegetatlon are not greatly different from thoae of t .. pera~ grass-•

lands of slmilar helght. Thi. range ls .tailar to th. 7 to 327 g.m-~yr-l

obtained for .&dge .pecle. in the pre.ent atudy. Forr.at (80) al.o conclud.a

that while bio.a .... y be lover in .ore extr ... environaents, production 1.

analogou8 to that of tempera te regious. Thua, the 8urvival of plants in this

. , ,

,

102.

zone de~ends on rapid growth during a restricted growing season. The

comparatively high productivity in peatlands. relative to other marginal

habitats, has been attrihuted to three features of wetlands (6):

1. Few environmental factors are limiting.

- there are cOllsistent and ample supplies of water

- nutrients are flushed from the surrounding upland soils

- red,ucing conditions attending submergence increase the solubil1ty of

(some) cations, as does increased acidity due to orgJnic decomposition

2. The majority of consumera are detri'vores.

3. Plants are adapted ta wetland environments.

- rhizOIIIes provide en.rgy and nutrient storage for rapid growth and a

means of vegetative propagation

- vertical leavas avoid heating stress, and ~m1ze leaf area indice •.

Betula 8landuloea and ~ ped1cellaris are bath 1011, single or clumped

shrubs, in th ..... y.te., •• ldoa raaching a height of mor. than one _tre.

This specie. of Salb: i8 known ta spnad by underaround st .... , which have

not be.n acco\a1ted for in the pr •• ent study., Previous studies suggest that )

teavas fora over 90% of th. annually reaenerated part. of shrubs and c1warf

.hrub~, 87).

Due to the liaited a.o\a1t of data available for production by ahrubs,

froa bath thi. and previoua in"..t1aat100a, an .xtensive diacussion of this 1)

co.poaent of aire productivity i. not poesible. B.cauae .hrub. are ganerally

a'lIinor f.ature of the a1re'veaetatlon in thia relion t the1r COIltribut1oa ta

the total productiCXl of the peaU_da ia probably quite ... 11. The production

value. obt&1nad for htul. _d saUx vere aoMVhat variable _d 1011 (43 to

"

..

•

,

10).

71 g •• -2. yr-I), although withln th. range Of 2 to 219 g.m-2.yr-1 obtained

for .hrub. of the .... ganus in other northern peat1ande (175, 240).

Th. di.tribution of B.tula and Sa1ix shrub., which, for the most part,

1. re.trlct.d to th. drler marginal and other el.vated (hummock and string)

ar,aa of peatland. in thia ragion, auggasts that this elemant .ay become

more important if and whan tha p .. t builds up to such an axtant that the

cantral portion of tha mir .. ia no 10ngar undar tha influance of flowing

watar. Thi. would tend to create le •• waterlogged conditions, and a more

consolidat.d peat .. terial. which app.ar to favour the eetablishment of

woody perannial planta.

The ta~ .-ploy" in d18cua.iona of va.cular plant production, such

.. ataDdtna crop and bio.aa., have no uaetul .. &llin. when applied ta Sphagnum

110..... .. thera ui.u DO clear divi.ion b.tvaen live and dead portion. of

tb ... oraani ... (48). la .pit. of thi., the rat .. of Sph!l!ua productivity

.. y be ~ra ... ily and pr.c1aely .... ur.d than thoaa of hi,har plant., becauae

lrovch 18 preclolli.aaAtly apical, ad no rooea oiat.

The .. tboda utl1iaed to ,aUle Sebelpua Irovth are au..arized by Clymo

(48). Brlaf1y, tbe .. inclucie: .. tbocla vbic:b ..... uaa of an iaaata tille aerker

(auch .. radioacUv. laballinl); ..... ur...at of arowth relative to .. run

plac.d outaide the pl.aAu; the use of planta eut CO kAovn initial lanltha;

and, duaet .... ur-.tU of cbanae in va1aht ov.r a liv_ tt.. intarval. lt

would appear that no ODe approach ia idaal, altbouah dir.ct (capitulua corrac-

tlon aDd vaisht uad.r v.t.r) .ad 1Ddir.ct (craaked vir.) .. thada provide

eo.patibla &Dd &ceurat. aattaet ...

-2 -1 The rate. of Spbllmw- production in thi. stucly (8 to 112 1'. • yr ) ara

..-

- -,

(

..

( -

•

~ --~- .... - ... ~ - ,- ~ --J-

104.

-2 -1 generally consistent with those of other studies (viz. 8 to 130 g.m .yr ).

shawn in Table 1.8. The growth by individual species. however, was sometimes

an order of magnitude or more lower than that obaerved by other investigators.

Comparative data ia available for Sphagnum lindbergii and Sphagnum riparium

(206). When balanced on a similar temporal scale, the difference is 300

-2 -1 -2-1 g-m 'yr ta 15 g'm ·yr (this study), and 2.7 to 9.1 cm ta 0.18 cm (this

study) for Sphagnum lindbergii and Sphagnum riparium respectively.

The higher growth rate by plants growing on hun:mocks is in direct

contradiction to the trend noted in the literature. ~. that growth decreases

from pools ta lawns ta hummoeks. Bath this and other interpretations should

be taken with some reserVation, if the fo11owing points are taken inta accoWlt.

1. Due to severai constraints airtady discussed (particularly methodological), 'J

it is perhaps inappropriate to compare results between studies.

2. Frequently, changes cao be deteeted only from one month to the next, so

aecurate estimates require data colleeted over several years, at several

iDtervals each year (36).

3. The growth (length incrernent u weIl as production) by SphagnWll observed

in thia study ... y be a.rioualy underestimated, as _&surementa ceued in ldd

August. Sphaanua growth has ~een reported weIl into the fall (206), and the

... jority of the extenaion .. y oecur at thia ti .. (48).

4. The lDU.ua! reault. for th. h~clt and lawn Sphapa _y be sOD!what a1a-

leading, and reflect phyaical proca •••• rath.r than actual biologieal differ-

énce •• Thet h, the crank.ed vira .thod -&ht b •• uspect for wet habitata. -

where the Sphapua carpet ia .or. li.,lA to .ove (48), and th. wire acre liltely

to be diaplacad by fRe •• th .. cycle •• In this c.e, the gr.atest error in

\

(

•

/ ,

105.

e.timating the position of the surface would occur for wet hollow8, and

would be least for closely packed capitula on hummocks. This might a180

.splain tbe high standard deviations observed within la~SPhagna communities,

relative ta tho.e of hummocka.

4.3 Factors influ.ncing species productivity in subarctic peatlands

Temp.r.ture, nu trient lev.l., latitude (which integrate. the effects of

in.ol.tion. d.y l.nsth. and l.ngth of th. growing •• a.on). drought and water-

logging have .11 b.an .hawn to h •• e an influ.nce on plant productivity in

individuel c ••••• Whan all otb.r conditions r ... in constant. any factor that

chansa ... y bacome tha driving forca of • p.rticul.r proca •• (27).

Althouah production by sedia .pacia. ..y siva • ral.tiva indic.tion of

product1v1ty in th .. a .y.t .... 1t .. y not b. poaalble, or real1atlc. to aacribe

diffareDt1al .rowth r.t .. betveeD a1t •• to aavlroaaeatal factor •• Sa.. part

of tha var1at1oD a1&ht Da due to ap.c1fie diff.rence. batweao .1t •• , and th.

1Aber_t diffaraacea :Ln arovtb hablt r ,ad lUa hJ.atory Chia aot.U •• In th.aa

cu .. , charactariatica .uch .. a 1_, .pread1na Irovth fora, aad ralativ.ly

early b1oM .. ad productioa peaU, ha .... lMIea kaova co raault Ua r.duead

uaad1Da ero, val .. (167). CU!! !J ..... ftta tlM tomer d .. criptiOl1, and

alao bu tba l.,.,..t ,rawth rate (7 to 49 ••• -2. yr-l ) of tha .pecie. atud1ad •

Purthar..r., the proclueeioD ..... of tha varioua apec1 .. auaiaecl .. ra ...... d

.ad Cana phlDrden!t+p lIna _t ..... uni"", ..... tha dat .. at vhlch cara

!ft!ta11a ... .Si5!!. merata anwtba ara optt.. an ~ GIlly tor lcRnIr

•

f \

106.

lati~udes, thua, may not be applicable here. 1

The roI. of tamp.r.ture and nutrients in promoting or lim1ting productivity

in northern and mire ecosy.tama ha. been widely investigated. Because the

major sit.s in th. pr ••• nt study vere s.turated at aIl time. during the growing

•••• on, th. direct .nd indirect effects of waterlogged conditions on plant

production are also of importance.

Of the pl.nt macronutrients, nitrogen and phosphorus are most often

sugg •• ted to be timiting ~o plant growth (40, 88, 201), although either may \

or may not b. restrictive in so •• organie soil., as fertilization doe. not

n.c •••• rily 10er •••• production (105). The ,.ucity of nitrog.n and phosphorua

supply le tb. re.ult of • numb.r of physical and chamlcal factors acting within

th •• eo.y.tam, vhicb .. y .erv. to Interfere vitb tbe ability of plants ta t.ke

up the.e .l...at ••

Baal (lOS) suu"c. chat ta.per.tur. pl.y. an i1aportant role in reinforcing

llucri_c daf1elaciu. III th. eue of Ditroa8ll, lov 1011 teaper.ture (3 OC)

deer_ ... both a,itrOl- uptalta by plaa.ta, as wall .s nitro •• n .. taboliS1ll (in

the fOrll of clae.y r.c .. , and llierobtal traaaforaation of organie nitrogen).

Tbua, produccioD i. ltaitad by • low cyellaa r.ce, racher chan nltrogen

.... a1labllity !!!..!!.. a-u (117) alao cOIlclude. chat nicrolsa. .. y not be •

U.it1na. facc.r la pl:OClucCioa, as fre. sad axchaftaed or ad.orbad __ niua la

DOC clepletad clur1q the arow1q HUOIl. Âa nitro._ cycl1q ia coupl.d. througb

r'" nactioDa. vith th. cycliq of var:1oua el_ta, lov production llight

ba .ttd,batecl co other cham.ca1 faccor(.) vb1ch lDhibit cl\e upUka of nitro.sa.

by .... tatioa (117).

(

\.

.~~------

107.

by chemical than phyaical or, biological factors. Phosphorus supply has

been shawn ta vary in organic so11s in relation to pH and soi1 molsture

levels. Even when the nutrient concentration of the .ubstrat~ is low, it

stands ta reason that the rate at which nutrients are supplied ta the root

surface will be greater in the presence of moving water than where diffusion

18 the principal mean8 of nutrient 8upply ta the roots (42). As the range of

pH ls g.nerally small within sites, and the number of potential influences

on pH relativ.ly great (including d.cay rate, other cations, and species

composition), no simple Interpretation of a phosphorus-pH re1ationship can

he made (6). Under reducing conditions, phosphorus supply is subject ta several

conaid.r a tion ••

1. The higbly soluble lron .. lt. located in and around plant roots may upset

tbe mineral nutrition of c.rtain plant. (4).

2. The greater salubility of phoapborua und.r waterlogged conditions i5 not

n.c .... rily ... ociated with enbanced uptake by planta (4).

3. Higher soil .ai.tur. content ... , sa diluts the sail solution that it

decrea ... tbe nutrient a •• ilabillty ta planta (105).

Tbe •• facton _1 ha of laportaoc. not only for phoaphorus. but for 1IIOst

_cronutriant auppli.s under waterlo .. ed condition ••

In tbe pre.ent study, the relat:Lonahip betyean taperature and production.

&ad cODductivity and production (by aed.e speci.s) vas positive but weak. Bath

t..,arature aod coaductivity appeared to ba of aqua! iaportance in influencing

procluc:tivity, such that 80M corralation beC:Ween t..,er.ature and conductivlty

_y aist. Tbeae r .. uita -y IlOt he cOllc1uai"e. bov."er .... pacifie differ­

enea ... y ... k tba affacts of t.-perature and nutrient. on grovth. In the only

(

lOB.

instance where a comparison can be made. because the growth form and life

cycle of the species are similar (~. that of Carex rostrata at site 3 and

Carex aquatslis at site 4). the mean production rate was approximately twice

as great ln the warmer. more eutrophie ~ite. Due to the low soil temperatures,

and waterlogged conditions of these mires, Any combination of the factors

diseussed above may play a role in modifylng plant production.

Although moss communitles may overlap in the field. they have dist1nctly

differant interactions with the physical environment (36). Water, however. Is

a fundamenGal factor. controlling both the growth and distribution of most

bryophytes. In Sphagna. water 19 absorbed directly through the weakly cutin-

ized leaves and stems of the plant, and retained within its structures by

matrie forces (122). The rate at which water i8 lost, and the frequency of

wetting and drylng. are crltical, and mediated by; physical factors, such as

temperature and wind. and. the growth form of Sphagnum indivlduals and

communities (carpets).

The rate of water loss from Sphagna has been estimated at 6 mm.day-l

(49), which ls siml1ar ta the maximum dally value of 6.? mm.day-l in a sedge-

grass marsh (172). Thus. despite the laek of physiologlcal machanisms ta

prevent des.lcation, the dense surface layer of capitula (whieh also impart

a relatively high water atorage capacity to tbese tissues. due ta the presence

of ribbed hyaline cells) mey present a physical barrier ta water 10s8. Tbe

abillty to transport water to tbe cap~tulum dur1ng periods of rapid evapor-

ation might alac be of soma importance ln dessieation tolerance (49).

The metabolie activity of mosses i8 closaly linked ta the water regime.

Bath metabollsm and evaporation are augm~nted as temperature lncreases. to

..

j~-- --

109.

some upper 11mit. This will tend to increase stress on the plants, resulting

in lowered production. Higher growth rates have been noted in habitats

protected from evaporative stress (i.e. shaded), although reduced length

increments have been attributed to low incident radiative fluxes (49).

Relationships between growth and the supply of inorgan1c ions have also

been recorded (49, 206). Nitrogen might present sorne exception, due to

nitrogen fixation by algae believed to be associated with mosses, particularly

those inhablting pools. Although little Is known about the physiology of

these plants, differences in growth might be related to the cation exchange

capacity of the cell walls. The amount of galacturonie aeid ~ound within a

speeies might confer a specifie range of exchange ability to the taxon,

enabling it to oceupy a particular habitat within the mire (208) • .

The slow growth of bryophytes makes it di(ficult to evaluate correlations

between production and environmental factors. The hydrologie regime is

probably of greatest importance, although the relationship between water

and MOSS growth is complicated by shrinking and swelling of the moss-peat ~

system with variations in water status, and relative evaporation and decom-

position rates (36).

The growth differenees between lawn and hummock Sphagna observed in the

pr.sent study were unusual in some respects. Even if growth i8 generally

found to be greater in wet (lawn and pool) than more terres trial habitats,

net assimilation at higher water levaIs may be inhibited (36). This could

explain, in part, the greater production by hummock species in this investi-

gation. Crowth also appeaY~ to be related to mineraI supply in sorne cases,

although separation of this variable fram conditions of moisture and/or

,;. ,

..

r,

110 •

temperature is not possible. Elevated areas (Eriophorum tussocks) were

found to have higher temperatures, as weIl as a greater depth of peat to

exploit (42). If Eriophorum tussocks are assumed to be analogous to Sphagnum

hummoeks. st least in a~hysiéal sense, higher production might be attributed

to the more favourable thermal and nutritional regime of this microenvironment.

lt would appear that Sphagnum species must make sorne trade-off in order

to occupy a particular habitat within the mire, and that this ls achieved

at the expense of optimizing growth. Based on the results of the present

study (specifie differences notwithstanding), the best conditions for Sphagnum

growth are offered by somewhat éhaded, relatively dry, and weakly eutrophie

habitats.

4.4 Litter decomposition in subaretic peatlands

A major emphasis in research programmes has been on the flow of dry

matter or carbon through the decomposer-consumer complex. into a relatively

large and constant pool of carbon dioxide (70). The aims of these investi­

gations are identieal to those of the present study, that is; (1) to define

the rates of decay of organic matter for individual components and for the

system; and, (2) to identify and characterize the main factors influencing

decay. Thus, a large body of material exists for comparison of decomposition

rates be~een this and other northern ecosystems.

The methods used to de termine tissue decomposition include:

1. ArP-aasay for the total numbers and biomass of organisme

2. enzyme assay Methode

"

, 1

111.

{ 3. thermal me.surements

4. gas exchange or respiration mesurements

5. rates of substrate disappearanee from meah enclo.ure ••

The first three techniques, although better me.surements, May not be 8uitable

for waterlogged soils, while the fourth measures only eatabolie proeesses,

whieh constitute but a portion of the total decay dynamics of wetland soils

(37). Despite the drawbacks of the litter bag methad, particularly, alteration

of the microclimate around decaying material, exclusion of detrivares, or

partieulate (tissue) comminution, this technique i8 commonly uaed in de cam-

position studies.

The 108s in mass, over time, of a lit ter sample integrates decrements

due ta respiration, leaching of soluble organic and inorganie materi~ü. and

the removal of ~articulate matter by soil fauna or by physieal factors (111). "

The contribud.on by each of these companents is likely ta change on a temporal

basis. During the early stages of decomposition. the majority of lasses are

probably due ta leaching and handling losses, and microbial respiration of

readl1y degradable compounds.

The mass losses observed in the present study ranged from 12.4 to 17.6%.

13.9 ta 21.4%, and 6.4 to 10.8% for sadge, shrub, and Sphagnum tissues respec-

UveIy. Previous studies of similar lit ter noted first year losses of 18 to

29% and 17.6 to 22% for sedge leaves (37, 111), 26 ta 41% for shrub leaves

(37), and 12.2 to 13.6% for Sphagna (47). Hence, the losses reported in this

study are comparable to those of other mire systems, as weli as to the first

y.ar 108s8s of 15 ta 50% observed for lichen woodland in this vicinity (151).

The losses of 1itter appear ta f0110w a linear pattern (Figure 3.8). In

• -----~ .. ••

112.

1

this case, as in most short term studies, lasses probably reflect the (

disappearance of labile constituents from the litter. The generally high

releases of potassium, calcium, and magnesium from the decomposing tissue

suggest that leaching may account for a large percentage of the observed

losses. Increases in nitrogen and phosphorus in some lit ter tissues indi cate

accumulation from the environment (192). The elemental mobility series,

K>Mg>Ca>N,P , is similar to that reported in many studies (137), and

reflects both the degree to which these elements are incorporated into

organic molecules, as weIl as the rate at which they are returned to the

system. This component of the out rien t cycle Is 1mportan t, as mire organisms

may be largely dependent on nutrient releases from decomposing organic mat ter

(both 11 t ter and peat) (70. Ill).

The magnitude of winter losses will affect the nutrient status of t.he

eeosystem, thus, the availabi li ty of ions to plants. 81801 ficant Wl.ntf' r-t ime

lasses have been observed in other are as (20, 145), and are remarkably con~

sistent between mire (65%) and lichen woodland (60 to 90% (151» systems i~'

this region. High tissue and nutrient losses during the period of minimal

biologieal acti vit y contribut.e to the nutrient defieiency of the system.

Given the present data, it i8 not possible to determine whether the major

losses oecur prior to significant snow accumulation (September ta November),

under the snowpack (NoveIli>er to May), or during spring snowmelt. Nonetheless,

decomposition is possible throughout the year, sinee micJ:'o-organisms and

o microfauna can be active st t~mperatures as low as -5 C (77); subnivean

o temperatures at Schefferville did not: fall below -3 C (Moore, unpublished

data) •

1

" ~-.- .. ~ - T ~-- ----- J ~

1! J.

Although longer term studies might reveal an exponential trenù ta decay, \

following the initially high lasses of easily removed compounds, this is not

allo/ays the case, and should not be a foregone conclusion. Furthermore, in

this and other one year studJes whieh report both the instantaneous (~') and

constant <'!t) fractional loss rates (37, 192), the value of ~ is invariably

an over-estimate of aetual decomposition rates. Values of ~.' however. are

generally reported in the literature. despite the caution which should be

exercised in assuming 'exponental' decay. An average deeomposition coefficient

of 0.3 has been suggested for northern peatlands (27). whJch, in aU but one

case. is higher than those ealculated for the present study. In most instances.

individuill constants deternined by other investigators (Table 1.10) for

comparative lu::.ter, are higher than tho'ie of 0.13 ta 0.31 and 0.15 to 0.22,

for sedge and shrub lit ter respectively, in pea tlands of subare tic Quebee.

This diversity may reflect aetual differences in the environmental constraints

on decomposition.

In decomposition studies, attention has been directed to establishing

the biotic and abiotic parameters which mediate decay, such that. predictive

models can be eonstructed. Variations in decay rates have been attributed to

variation in (110):

1. site factors; climatic and edaphic conditions

2. 1itter quality

3. position ln the so11 profile

4. changes in quality and environment with litter age

5. structure of the decomposer population

6. method01ogy.

) j

The microenvironmental cons craints on decomposition are perhaps moat

validly asaessed by looking at the mas. 109ses of the standard substrate,

cellulose, which, unlike plant litter, serves only as a carbon and energy

source. The decomposition of cellulose placed on the sail surface might vary

greatly, depending on microclimatic conditions (186). Alternat1vely, high

within site variation may m8sk between aite variation, and a large number

of replie.tes would be required in arder ta reduee standard errora. In the

present study. intr •• ite heteroganeity in cellulose decomposition i8 grester

than for plant litter., and there Is 1ittle difference between sites. This

May be a reflection of the high proportion of w1nter losses, hence, relative

absence of microcliaatie variability. Also. the lack of specifie temperature

and moitture data trom the decomposition plots makes it difficult to separa te

the effects of microclimate on decay.

In this study, firat year losses for cellulose ranged from 5.6 ta 6.6%.

Theae values compare with thoae of 15 to 41% in more tamperate pestlands

(Ill), l to 30% ln tundra (186), and 12 to 20% ln lichen woodland (151). The

/' combination of colder t .. peratures and anaerobic conditions probably accounts

for the 8lover rate. not.d in this inv.atigation relative to those of similar

habitat or location.

In addition to the general tendency for decomposition rat •• to increaae

with incr.a.ing t.-perature and aeration (moi8ture and oxygen availability),

Coulson and Butterfield (55) found high corr.lations betw •• n nitrogen and

phosphoru8 and th. rat •• of .icrobiai d.coapoaition of plant substrates. The

evidenc. pr •• ented in thi. study doe. Qot n.c •••• rily support either stat ... nt,

the former becaua. the differ.nce becw.en d.compo.ition of Sphagna in lawn

•

, --~

115.

and hummock (presumably varmer and drier) positions i. signiflcant only 17%

of the time (Table 3.7). Furth.r, based on the trend in~' valu.a, there May

be 80me relatioDship betveen decomposition and environmental nutr1ent status,

although the loteraction(s) betveen physical and chemical proparties cannot

be datarmined or separated.

I~-.nvironmental factors cannot be satisfactor1ly utilized to explain

the variability in litter br.akdovn betveen sites or tissue types, substrate

quality might be suggest.d as a rate-limiting mechanism. Meent.meyer (146)

states that the climat. may exert a greater control on decay rates on a global

seale, but that lignin concentration of the substrate i8 signlfieant in Any

particular region possesaing a reasonably uniform terrain and maeroclimate.

If this as.umption i8 correct, then littera of varylng lignln content vould

decay at slmi1ar rate. during the vinter, diverging ta some degree durlng the

high actual evapotranspiration (AEr) season. This Is more or less consistent

with the findings of this 8tudy, de.pite the narfov range of lignin concen­

trations ln the litter tis.ues.

When the lignin to nitrol.n ratio of the ti.sue is used a8 an index of

substrat. quality (192), lover decay rate. vou1d b. exp.cted vith a higher

ratio of 1igolo relative to oitrogen. The biab •• t ratios exist for Sphagoum

tis.ue. (up to 52:1), vhich al.o have tb. law •• t decay rate •• This. hovever.

say not b. an .ntirely .atisfactory axplanation for tbe apparent re.istance

of SphagaU8 to decay. a. a pbenolic coapound (vhich say inhibit microbial

activity) has b •• n found in these .a .... (67).

Ba •• d on a i~.ra1iz.d model coabinina AET and ligain concentration of

litter tissue. (146). the predicted annual decay ~ate. in the Schefferville

1

--------- -- -~--,- ... J -

116.

area sbould 11. betw •• n 25 and 30% for soft vascular matatial, and 20 to

25% for Sphagna. Actuel mean valu •• are 13.5 to 21%, and 9% for leaf and

mo •• tis.ues r.spectiv.ly (Table 3.6). lt 18 evidant, then~ that othar

factors, .uch a. tha nutrient ragime of the mire system, and the limited

decomposer population. ara of eqUal importance.

.

l

." -

,

t

--~~.-. - .. .- ,

117.

CONCLUS IONS

The Interpretation of biogeoc.noses requires a comprehension o.f natural

proc ..... Inherent in the system. The results obtained in this study indicate

that production and decay proce.d at relatively slow rates ln subarctic peat-

lands, but that the differences in the.e proce.s.s betw.en this and other

systems are pedietable, given that factors such as temperature, moistuTe,

and nutrient availabillty are both temporally and spatially heterogenous.

More ex.cting m .. sur.ments of the se variables are requlred if the interactions

between, and the effects of, these parameters are to be determlned vith

greater precision.

Ra.ad on the observations of the pre.ant investigation, the following

conclusions are reachad.

1. The four mira. supled fit into the range encounterad in other 8ubarctic

ar ... , in terms of flora, trophlc status, depth. tamperature, and hydrology.

The pauclty of avaU.ble nutrients in the peatwaters la espedally .vident

for n1tros_ and pbo.pboru ••

2. Eatillate. of aean abova-ground priJaary productivity ranse from 114 ta 335

g.1I-2. yr-l • ba.ed on. harv •• ting Il .... uraaent. for sedg's, l •• f biOtllu. for

.hrub., and lenath iner_ant. for Sphagn.a.

3. Ther. i. a geD.ral eonelati01l becv.en. lite productivity and trophic scattUl,

but thi. 11 coaplicaced by otber factors, particul.arly teaperature.

4. Fint Y"I" la •••• of ti •• ue, due to decQIIPO.itlon, ransed trOll 6.4 ta 21.4%,

.iailer ta th. low value. reportsd for oeher northem. eeo.y.e.... A large

proporU.on. of ~he la •••• (6S%) occurred froa Sept_ber to June. Decœpo.ition

rata. vere .oet .trocaly eorr.lated vitb ti ..... typ.. in. ehe .equence 1

•

r

(

----~-.-W"---- ~ T

shrub le.aves) sedges > masses, although site ditferences did have

aecandary effects.

118.

5. ExaD\ination of the nutrient quantities retained by decomposing lit ter show

that potassium ia rapidly lost frOID all tissues, folloved by calcium and

magnesium. but many tissues show an Increase ln nitrogen and phosphoruR

levels.

6. Clearly, spadea productivity and organie matter decay are complex proeesse8.

The absence of consistently signifieant eorrelationa between envlroIUllental

factors and plant growth and tissue decomposition indicates that a nurnber

of factors influence these proeessu. The interaction(s) between these

constituents i5 more likely to be mul tiplicative and divisive than additive

or subtrae tive.

7. Finally, al~hou8h temperature, mol.ture, and nutrient levela may weIl be

used ta eat:iJute general trends in growth and daeay in theae and other

sya tema. these procesaes are probably variable from year to year in any

given location. tlenee, care .hould be exereiaed in extrapolating the

r •• ults of short tem, ama11 aeale .cudie. sueh as this, to longer tem

or larger acale t>rediction ••

t

.. - ..... -

119.

1. Âa't11'. B., and H. Tauber. 19'1'. Ratee of peat forutlon ln relation to degree o~ huJd.f1catton and local env1ronIIIent, as shown by etudles of a 'raiaed bas in Denark. Borea. 4.1-1?

2. All1Dgtœ, K.R. 1961. The belge o~ central IAbrador-Ungava, an examination of thelr phyalcal eharacter1etlca. Geog. Anal. 4J.404-417.

J. AnctreeY, V.JI., T.F. Ga l&ktlonova, V.I. Zakharova, and A.I. Heu.trueva. 19'12. Methoda of eathatian of sea..onal changea ln above-ground phytoMS' o~ herba. In IBP Tundra Bio .. Proceed1ng., 1V. International Meetin« on the Blological Productlvlty o~ Tundra, Leningrad, October 1971, ed. ,. .K. Vlelgol&lJtl and T. ROIS_ll, pp.l0l-UO, Tundra Biou Steerin« Coaa1 t t .. , Stockhola, Sveden.

4. Arutrq, V., and D.J. Boatlllln. 1967. SOIle field observaUons relating the grovth of bo8 pl.&nta to condition. of so11 aeration. J. Ecol. 551101-UO •.

5. Auclair, A.H.D., A. Bouchard, and J. Pajaczkowaki. 1976&. Productivity relations ln a ~-dolÙnated eeo.yete •• Oecologia 26.9-)1. -

6. Aucl.air, A.H.D., A. Bouchard, and J. Paj&czkow.k1. 1976b. Plant standing crop and productiv1 ty relations in a Sclrpua-f.gulsetUJI wetland. Ecology 5'.941-952.

7. Avni_lech, Y. 1971. If! trate tranafol'1ll&tlon ln peat. Sol1 Science 111. 11)-118.

B. Baden. V., and FI. Fccela-.n. 1968. The hydrologie bldget of the highbogs ;n the Atlantic Reglœ. ln ProcHCl1Dca o~ the 'nl1rd International Peat Cqreaa, ~.bec, C&ftada, Aucuat 1968. pp.206-211.

9. Barr, D.R., and R.I. ~. 1981. Seleeted. cll_tolO«1cal data 1955-1980 for the Sebef't'ervllle (A) atation. McGill Subaretlc R •• ürch Paper )2.117-1)4.

10. Bartl.e7. D.D •• Nl<l B. Mattbna. 1969. Rat •• ot peat &ccuaulatlon in the UDp.". Ba, arM. R ... Paleobot. Palynol. 9.45-61.

11. Baa1l1er, 1., U. GJ:'&IlMU, Md. T.A. Staat.ria. 19'18. 11trocen nxaUOI1 in vet. Jd.nerotropb1c .,.. 00-.1 ti .. of a aubarctlc Jd.r.. Olkoa )112)6-2116.

12. Ba" ft.R. 1968. 'the h,JclrolGcJ of ..... 1 peat depoa1ta in nortbem JI1rmnota, USA. la Procee41JIca 01' t.be 'nl1rd. Int.ernaticaal P_t Conç •••• ~bee, Canada, Aupat 1968, ".212-218.

1

/

\

t

• -- ~---- - - -= ... - ~

120.

13. Bay. R.R. 1969. Runo!f ho. a_lI peatl&nd watersheda. J. Hydr01. 9. 90-102. f

14. Bella..,. D.J. 1972. Te.plates of peat fo~t1on. In Proceed1ngs of the ,ourth International Pe&t Congress. <À'ltanleai. Finland. June 1972. pp.1-17.

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.... -

121.

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J'I.. Burp, V.D., ancl r.E. Broac:lbmt. 1961. Fixation of aaon!a by organic 8OU ... So11 Sei. Soc. A •• Proe. 2.5.199-204.

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1

t

-------------y • - VI , ~-- - ---- ) ~ -.~ ./

122.

37. Chaille, J.P.M., and C.J. RIchardson. 1978. Deco.position ln northern wetlanda. In heah-.ter W.tlanda. Ecologlcal Proceases and Man.a«ellent Potentlal, ed. R.E. Cood, D.F. Whlghaa, and R.L. Si~son, pp.115-1JO. Acade.lc Press, New York. San Francisco, London.

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• .- .... )

12).

50. Clyao, R .S. 1978. A modf!! of peat bog ~ovth. In Production Ecology of So .. Br1. t1Sh Koora and Montane Grass lands , ed. O.W. Heal and D.F. Perk1ns, pp.18?-223, Springer-Verlag, Berlin, Heidelberg, New York. ç.

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>

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, 1

· - -- -----~.- .. ~ -

64. Dennis, J .G. lm. Distribution patterns of below-ground standing erop in arctie tundra at Barrow. Alaska. Aret. Alp. ~e •• 9.11J-127.

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"..- --- ----

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•

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91. Gorhaa, E. 19.56&. The ionic cf)mposl tion of some bog and fen wa tera in the Engl1sh Lake district. J. Ecol. 441142-152.

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~---------~-~

(

127.

104. Crtf'f'1n, K.O. lm. Palaeoecologioal aspectl!l of' the Red Lake peatland. Can. J. Bot. 551172-192.

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