vegetation condition and water quality in great lakes ... · vegetation condition and water quality...

Vegetation Condition and Water Quality in Great

Lakes Coastal Wetlands

Carol A. Johnston, ProfessorSouth Dakota State University

Understanding the Vegetation and Hydrology of Upper Midwest WetlandsSeptember 22-24, 2010

Carlton, MN

Acknowledgments

Michael Bourdaghs

Tom Hollenhorst

This research has been supported by a grant from the US Environmental Protection Agency's Science to Achieve Results (STAR) Estuarine and Great Lakes (EaGLe) Coastal Initiative through funding to the Great Lakes Environmental Indicators (GLEI) Project, US EPA Agreement EPA/R-8286750

Bad River Band of the Lake Superior Tribe of Chippewa Indians for permission to sample

Many collaborators, including:

Great Lakes, Great Wetlands

Caro

l A

. Jo

hnst

on

“develop a suite of new, integrative indicators of ecological condition, integrity, and/or sustainability that can be incorporated into long-term monitoring programs”

ENVIRONMENTAL INDICATORS IN THE ESTUARINE ENVIRONMENT2000 Science To Achieve Results (STAR) Program

GLEI: Great Lakes Environmental Indicators

Research Questions What are the plant community types of

northern Great Lakes coastal wetlands? How are they related to water chemistry?


Caro

l A

. Jo

hnst

onMade 20,560 observations of cover class within 2051 sample plots in 90 wetlands

Photo: Lynn Vaccaro

Northern Great Lakes wetland vegetation sample sites

+3 sites on northern L. Huron →

Water chemistry measured on 26 northern sites (Trebitz et al. 2007, Morrice et al. 2008)


Caro

l A

. Jo

hnst

onA Unifying Approach

1. sample wetlands representing the entire range of anthropogenic stress

2. sample a range of water depths within wetlands

3. use non-metric multidimensional scaling to determine a condition gradient

4. use hierarchical clustering to interpret MDS results

5. use GIS to map results

1. sample wetlands representing the entire range of anthropogenic stress

2. sample a range of water depths within wetlands

3. use non-metric multidimensional scaling to determine a condition gradient

4. use hierarchical clustering to interpret MDS results

5. use GIS to map results

Step 1: Sample wetlands representing the entire range of anthropogenic stress

Wolter et al. 2006. Land use land cover change in the U.S. Great Lakes basin 1992 to 2001. J. Great Lakes Res. 32: 607-628.

Step 2: sample a range of water depths within wetlands


Caro

l A

. Jo

hnst

onStep 3: Use non-metric multidimensional scaling to determine a condition gradient

• MDS, NMS, NMDS• computed Bray-Curtis similarities among 90

wetlands• ordination based on ranked distances among

vegetation species assemblages• software packages PC-ORD, Primer

• MDS, NMS, NMDS• computed Bray-Curtis similarities among 90

wetlands• ordination based on ranked distances among

vegetation species assemblages• software packages PC-ORD, Primer

100806040200

easterncattail

westerncattail

burreed/ lake sedge

three-square

bluejoint/tussock

poor fens

Phragmites

Mere23% similarity

Step 4: Use hierarchical clustering to interpret MDS results


Caro

l A

. Jo

hnst

onStep 5: Use GIS to map results

• ArcMap 9.2• identify geographic clusters of similar

vegetation• identify geographic outliers

• ArcMap 9.2• identify geographic clusters of similar

vegetation• identify geographic outliers

Plant Communities of Northern Great Lake Wetlands

Pokegama RiverPokegama River

Burreed marsh

Photo: C. Johnston

burreed (Sparganium eurycarpum)arrowhead (Sagittaria latifolia)Northwest Territory sedge (Carex utriculata)bladderwort (Utricularia macrorhiza)bulrush (Schoenoplectus tabernaemontani)

Photo: M. Bourdaghs

Wild rice (Zizania aquatica)8 out of 90 sites, 7 on Lake SuperiorSilt soil indicator

Bayview BeachBayview Beach


Northern poor fen

Photo: C. Johnston

Sphagnum mossWooly-fruit sedge (Carex lasiocarpa)Myrica galeleatherleaf (Chamaedaphne calyculata)bog rosemary (Andromeda polifolia)pitcher plant (Sarracenia purpurea)bogbean (Menyanthes trifoliata)

Photo: M. Bourdaghs


Tahquamenon RiverTahquamenon River

Photos: M. Bourdaghs

Bluejoint / tussock sedge

Bluejoint (Calamagrostis canadensis)Tussock sedge (Carex stricta)Softstem bulrush (Schoenoplectus tabernaemontani)Jointed rush (Juncus nodosus)


Point au SablePoint au Sable

Cattail marshes

cattail (Typha angustifolia, Typha x glauca)bluejoint (Calamagrostis canadensis) jewelweed (Impatiens capensis)rice cutgrass (Leersia oryzoides)

Photos: C. Johnston

…what are plants telling us about wetland condition?So much diversity…

Non-metric multidimensional scaling – northern Great Lakes wetland vegetation


worst ← Condition → best

Chemical gradients among plant communities

a

bbc

c

poor fen cattailbluejointburreed

log [Chloride]

log conductivity

pH

Nutrient gradients among plant communities

a

b

b


log [TP]

log [TN]

log [Chlorophyll a]b

Turbidity gradients among plant communities

a

bb


log Ttube log [TSS]

b


b b

b

a

Plant communities have different chemistry

Parameter † Relationshipspecific conductance*** cattail & bluejoint > burreed & fenchloride***, pH** cattail > bluejoint ≥ burreed ≥ fentotal P***, total N***, chl_a***, turbidity***, TSS***

cattail > bluejoint & burreed & fen

NO3-N, NH4-N, DOC, DO not significant

** p < 0.01, *** p < 0.001


↑ Superior

↓ Michigan, Huron

175

176

177

178

179

180

181

182

183

184

1850 1870 1890 1910 1930 1950 1970 1990 2010Year

Elev

atio

n, m

eter

s

Superior lake levelMichigan/Huron lake level

Lake Superior fluctuates less than Lakes Michigan/Huron

Lakes have different chemistry

Parameter † Relationshipspecific conductance***, pH*** Huron & Michigan > Superiorchloride** Michigan ≥ Huron ≥ Superiortotal P**, total N*** Michigan > Superior & Huronchlorophyll_a* Michigan ≥ Superior ≥ HuronNO3-N* no Tukey differences

NH4-N, TSS, DOC, DO, turbidity not significant

* p < 0.05, ** p < 0.01, *** p < 0.001

Open-coast wetlands (Cw)

Riverine wetlands (Rw)

Protected wetlands (Pw)

3 Geomorphic Types

Geomorphology

conductivity: Pw < Cw*

Conclusions Plant species distinguish four major plant

communities in northern Great Lakes Water quality varies by plant community and

lake but not by geomorphology Based on chloride: cattail > bluejoint ≥ burreed ≥ fen Cattail wetlands (Lake Michigan) have poorest

water quality (more total P, total N, chl_a, turbidity, TSS)

Future threats: invasive wetland plants

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0 0.1 0.2Kilometers

´1999

Photos: M. Tulbure

2004: common reed (Phragmites australis)

Monthly Water Level (MWL) at Green Bay, Lake Michigan, WI from 1999-2004Source: NOAA

175.4

175.6

175.8

176

176.2

176.4

176.6

176.8

Mar-99

Jun-99

Sep-99

Dec-99

Mar-00

Jun-00

Sep-00

Dec-00

Mar-01

Jun-01

Sep-01

Dec-01

Mar-02

Jun-02

Sep-02

Dec-02

Mar-03

Jun-03

Sep-03

Dec-03

Mar-04

Jun-04

Sep-04

Wat

er le

vel (

Met

ers

abov

e IG

LD 1

985)

MWLMeanMinimum

6/19/017/9/044/10/99

Take home messages A one-time “snapshot” sampling of multiple

wetlands can advance understanding Take a GPS with you when you do the

sampling! Keep looking at the data – it has many stories

to tell

References

Johnston, C.A., et al. 2007. Plant species indicators of physical environment in Great Lakes coastal wetlands. J. Great Lakes Res. 33 (sp3):106-124.

Trebitz A.S., et al. 2007. Water quality in Great Lakes coastal wetlands: Basin-wide patterns and responses to an anthropogenic disturbance gradient. J. Great Lakes Res. 33 (sp3):67-85.

Morrice J.A., et al. 2008. Human influences on water quality in Great Lakes coastal wetlands. Environ. Manage. 41:347-357.

Johnston, C.A., et al. 2009. A unifying approach for evaluating the condition of wetland plant communities and identifying related stressors. Ecol. Appl. 19:1739-1757.

vegetation condition and water quality in great lakes ... · vegetation condition and water quality...

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