uhl et al 1982
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Successional Patterns Associated with Slash-and-Burn Agriculture in the Upper Rio NegroRegion of the Amazon BasinAuthor(s): Christopher Uhl, Howard Clark, Kathleen Clark and Pedro MaquirinoSource: Biotropica, Vol. 14, No. 4 (Dec., 1982), pp. 249-254Published by: The Association for Tropical Biology and ConservationStable URL: http://www.jstor.org/stable/2388082 .
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Successional PatternsAssociated with
Slash-and-BurnAgriculturen the
Upper Rio
Negro Region of the Amazon Basin
Christopher Uhl,' Howard Clark, and Kathleen
Clark
Institute f Ecology, University f Georgia,
Athens, Georgia 30602, U.S.A.
and
Pedro
Maquirino
San Carlos de Rio
Negro, TerritorioFederal de
Amazonas, Venezuela
ABSTRACT
In a
study of plant successionduring and
following lash-and-burngriculture earthe town of San
Carlos
de Rio
Negro
in
southernVenezuela
we found
that: 1.
Weeds established ust as readily n plots with Manihot
esculenta (the principal
crop plant
of
the region) present s
in
plots with
M.
esculen:a
removed.
2.
Repeated farm-plotweedings caused
woody
plants to decline
in
numbers nd biomassand
herbaceousplants
to
increase. 3. Forbs and grasses dominated
mmediately
followingfarm
ite abandonment, ut by one year
these had
begun to senesce and
fast-growinguccessionalwoody species
(particularlyVismia spp.) were common.
Standing crop biomass at one year was 773 grams dry weight
m-2.
4.
Several
microhabitat ypeswere presenton abandoned farm
ites. Grasses and forbs showed no microhabitat reference,
whereas
successionalwoodyindividualshad theirbest establishment ear slash and underfruit rees.
RESUMEN
En un
estudio de
sucesion, realizado
durante
y
luego
del
abandono
de
una
parcela
de
agricultura
e corte
y
quema,
en
los
alrededoresde
la
problacion
de San
Carlos de Rio Negro (Venezuela), encontramos
ue:
1.
Las
malezas
se establecieron
con la misma
rapidezen
las
parcelasde
Manihot
esculenta
que
es
el
principal
cultivo en
la
region), que
en las
parcelas
donde
se habian
eliminado
las
plantas
de
M. esculenta.2. El
desmalezado
repetido
de
las
parcelas
cultivadas
produjo
una
disminucion
n el
nuimero
biomasa de plantas leiiosas, y un
aumento n
las
plantas
herbaceas.
.
Inmediatamente
espues
de
ser
abandonada
la
parcela
cultivada
fue dominada por plantas herbaceas,pero
al
anio siguiente
stas
ya
habian
comen-
zado
a
senescer, ya
eran
comunes
as
especies
eniosas
e
crecimiento
apido (particulamente
Vismia
spp.).
La
biomasa
de esta parcela era de 773 gramos de peso seco
in-2
al
primer anio.
4.
En
las
parcelas
abandonadas
despues
de ser culti-
vadas se
encontraban
muchos
tipos diferentes e microhabitats. as plantas herbaceas
no
mostraban
ninguna preferencia
por
determinado
microhabitat,mientras ue
los
individuos
de
especies leniosas
e
establecian
mejor
cerca de
los
troncos
cortados
y
debajo
de
arboles frutales.
SLASH-AND-BURN
AGRICULTURE is thepredominant
farmingmethod n roughly 0 percent f
the
ex-
ploitable oils of the world nd supports
ver 250
million
eople Hauck 1974).
In
the
Amazon
Basin
an estimated
6,000
km2
f non-floodedorest ere
cleared y
slash-and-burngriculturistsrom 966to
1975, making his the mostcommon orm f land
use
in this
region
Meyers 1979).
This
paper
de-
scribes
uccession
uring
he
period
f
farm-plotse
and for the first
year following bandonmentn
theupperRio
Negro region.
THE
STUDY
SITE
The
studywas conductedn a 0.25 ha
tierra irme
(i.e., non-flooded)
lot ocated km east of thevil-
lage
of San
Carlosde
Rio Negro, lose to the con-
fluence f the Guainia
and Casiquiarerivers
10
56' N, 670 03' W, 119
m
elevation).
A
species-rich
evergreenorest
with a canopyheight f 25-35
m
was initially
resent n thisplot.This
forest as cut
and burned
n late 1976.The plot was
thenfarmed
for hreeyears sing traditional
racticesUhl and
Murphy
981)
and
then
bandoned
o natural uc-
cession. 30
x
50
m
plot
n
the center f
the farm
plot was designated
s the study lot.
The climate f the
region s relatively
seasonal
with mean nnual emperature
f 26?C
and
mean
annual ainfall f 3500mm.The months rom cto-
ber
through
arch
re less
rainy,
ut
monthly
ain-
fall
tillgenerally
xceeds 00 mm.
The
terrain
onsists f rolling
hills,
with
only
the
higher
ierra irme reas
being
used
for
farming.
Soils on thehigher reas
ontain n A horizon om-
posed mostly
f
fine sand that overlies
kaolinite
clay
nd
abundant erric
oncretionsHerrera 979).
These soils
are
very ow
in
nutrientsecauseof
in-
BIOTROPICA 14(4): 249-254
1982 249
IContribution
f
the InternationalAmazon
Project coordin-
ated by the Ecology Center of
the InstitutoVenezolano de
Investigaciones
ientificas IVIC),
Caracas,
Venezuela. This
work was funded
by the U.S. National Science
Foundation
in
cooperationwith IVIC.
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tensive
eaching nder
humid
ropical
onditionsor
millions
f
years
nd
the
absence
of
unweathered
parentmaterial
hich
ould serve s a fresh
ource
of nutrients
Fittkau
t al.
1975).
METHODS
PRE-ABANDONMENTUCCESSION.-Farm
plotsnthe
San
Carlos
region re
planted
rimarilyo
Manihot
esulenta
rantz.
known
ocallys
yuca),
with
pine-
apple
plants
nd
fruitrees
resentt low densities.
We
studied he
ffect f
yuca n weed
establishment
by
comparing
he
number
f
weeds nder
uca
lants
with
the
number
resent
n
plots
whereyuca
had
been
artificially
emoved.
ll
weeds were
removed
from
oth
reatments
t
the
beginning
fthe
xperi-
ment.
reatments
ere
paired,
x 2
m in
size,
nd
replicated
ight imes. 2
m
buffertripwas
cleared
around he
non-yucalots.
San Carlos farm lots are usuallyweeded once
in
the
first ear
ndtwo
times year
hereafterntil
plot
abandonment.ll
weeds are pulled
out of the
soil
except or
prouts
r
an
occasionalarge
ndivid-
ual which
must
e cut.The effect f
repeated
arm-
plot
weedingson
density,
iomass, nd
life-form
composition f
recolonizingegetation
as studied
by
pulling
all
non-crop lants
from
27
randomly
located
1
x
1.5
m
permanent
lots t
10, 16, 21,
26,
and
31
months.
While
thismimicked
ocal
practices,
it
resulted
n an
underestimatef
root
tanding rop
because
portion
f
the roots
was left
n
the
soil.
The harvestedlants n eachplot weregrouped s
forbs,
rasses, uccessional
oody
tems,
orest
rees,
and
vines.
Plants n
each
groupwere
divided nto
root, tem, nd
eaf
fractions,
ven-driednd
weighed.
The
effect f
farming
n
the
soil
seed
bank
was
studied y
comparing
he
number
nd
species om-
position
f
seeds
germinating
n
soil
samples
aken
from
he
farm ite
at
the timeof
abandonment
nd
from n
adjacent
ndisturbedorest
lot. Each
soil
samplewas
20
x
20
x
5 cm
deep. All
samples
were
spread
n
trays nd set
1.7 m
above
the ground n a
sunny ocation
on
large
tables.
Contamination
y
wind-
or
animal-borneeeds was
checked
hrough
surveysffive dditionalrays,ontainingoilwhich
had
beenoven-dried
t
250? C for
ive
hours, laced
among
he
ample rays
nder
tudy. rayswere
ur-
veyed
for new
germinations
wo
times week
for
two
months,
fter
which
ime the soil
in
each
tray
was
turned
ver nd
mixed.
urveys
ontinued ntil
no
further
erminations
erefound.
POST-ABANDONMENT
SUCCESSION.-Slash-and-burn
farm
ites
n
the
San
Carlos
rea
areactively
sedfor
two to threeyears.
armersmaycontinue o visit
their
plots for several dditional
years to harvest
fruits r an occasional atchof
mature uca.How-
ever,
ecause ittle r no weeding
ccurs, uch sites
wereregardeds
abandoned or hepurposes f this
study.
We recorded
he
height
nd
identity
f all in-
dividuals
:
5 cm tall n the
permanent
x 1.5m
plots
at 4, 10, and 16 months
ollowing he final
farm-site eeding.
Biomass f all plants
2
m tallwas estimated
one
year fter bandonmenty
harvestingll plants
presentincluding
ineapple lants) in 25 plotsof
1 M2.
Harvested lantswere
separated y life form
and
plant part, ven-dried,nd
weighed.
The
bio-
mass
(in grams) of
all
plants >
2 m
tall
in the
study
plot was estimated y the
regression f
di-
ameter2X height
both in cm) on stem weight
[y
=
(0.49x) -29.5;
n=
111 and
leaf weight y-
(0.17x) +76.4; n
111.
Diametermeasurements
weremade t
10
cm
height.Valuesofr2were
> 0.90
in
both ases.Rootbiomasswas estimated
y eparat-
ing all rootsfrom
oil to a depth f 50 cm in five
0.25 m2randomly
ocated lots.
At the
time f farm-site
bandonment,here
re
severaldistinct
microhabitatsresent.
Much of the
area
contains are
soil, but large,partially
ecom-
posed
ogs
still over he oil n some
places.Clumps
of
vegetatively
eproducingineapple lants
nd so-
latedfruit
rees 4-10
m
tall)
are
also
present.
inal-
ly,
soil
is
mounded nd
planted
o
yuca
n
patches
where t appears hat final ropis possible. he
effect
f
these
microhabitatypes n
the establish-
mentof successional
egetation ollowing arm-site
abandonment
as tested
n
a
25
x
25 plot
ocated
n
a
recentlybandoned
arm ite
ocated bout
150
m
from
he
main
tudy
ite.The
plot
was cleared f all
vegetation
nd slash
xcept
for
five ashew
rees.A
3
x
3
m
plot
was
formed round ach
cashew
ree.
The
remaining
our
reatmentsere
andomlylaced
in
3
x
3
m
plots
with m
border
trips
etween
lots.
The
bare
soil
plots
were
simply
marked
ff.
Pine-
apple plants
were
transplanted
nto their
ssigned
plots. oil was moundedn theyucaplots ndyuca
stem tocksnsertednto hemounds.
arge ogs
were
piled
in the
slash
plots.
All
herbaceous
nd
woody
plants
hathad
become
stablished
n
each
of
these
plots
were
ounted nd dentified
fter ne
year.
ix-
teen oil cores
6
cm diameter
5
cm
deep)
were
taken
rom ach
of
the
bare
oil, lash,
nd
fruit ree
plots
t
the
conclusion f the
experiment.
he cores
from
ach
plot
were
pooled
nd
set
n a
sunny pot
to
allow
germination
f
soil seeds s
described
bove.
250
Uhl,
Clark,
Clark, and
Maquirino
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RESULTS AND DISCUSSION
PRE-ABANDONMENT SUCCESSION.-The actual pres-
ence of yuca plantshad no apparent
ffect n the
ability fweedsto
reestablish
fter
arm-plot
eed-
ing, lthough he
yuca canopy
did
reduce ight
nd
soil-surface
emperaturetable 1). More than80
percent f
all
establishments
n
both
reatment
ypes
were the forbspecies,
Borreria latifolia
(Aubl.)
Schum. nd
Eupatorium erasifoliumSch.
Bip.)
Baker.Grasses omprisedn additional 0 percent r
moreof
all
establishments
n
both treatments
ith
Paspalum ecumbens w. the most ommon pecies.
The process f succession
egan
nd was
curtailed
through eeding
ive
imes
efore
he farm itewas
finally bandoned.
hese repeatedweedings ad no
clear effect n the
number
f
reestablishinglants
(table 2).
Plant
density
as low at the
first,econd,
and
fourthweedings
nd
relatively igh after
he
third nd fifth
weedings.Weedings hree
nd
five
occurred oward he end of the wet season,while
weedings wo and four ccurred t
the
end
of the
relativelyry eason.
Uhl et al. (1981) have shown
that reduced ainfall t San Carlos
owers he rate
of seed germinationnd seedling
stablishmentn
disturbedites.
The repeatedweedings
id
appear
to affect he
life-formompositionf the reestablishingegeta-
tion table 2).
Forest-treeensityt the first eed-
ingwas0.65individualslot-' all of sprout rigin),
butby
he
final
weeding ensity
ad declined o
0.11.
Hence, the
repeatedweedingshad apparently
x-
hausted
he
sprouting
eserves f manycut forest
trees. uccessional
oody pecies omprised 4 per-
cent i.e., 12.1 individuals lot-')
of the total tems
present t thefirstweeding, ut
by the fifth eed-
ing they
lso
had
declined n numbersccountingor
only
2
percent
f the total ndividuals resent. n
contrast,he density f forbs nd
grasseswas low at
thefirst
wo
weedings, uthigh hereafteri.e.,more
than25 individuals lot-'
forweedings , 4,
and
5).
Weed biomass measurements aralleled density
values.
Havel
(1960)
in
New Guinea,
Snedaker
(1970)
in
Guatemala,
nd
Kellman
1970)
in
the
Philippines eported
imilar rends.
High forb
nd
grass stablishment
n the
aban-
doned
arm
lot
mayhaveresultedrom
n
abundance
of favorable ermination
urfaces here. n
the San
Carlos
region,
oot mat
(a
surface
mat of forest
treeroots
5-30
cm
thick),
charred
wood,
and
bare
soil surfaces re the main seed-bed
ypespresent
following
orest
utting
nd
burning.
he
bare
soil-
surface ype ncreases
with timebecausethe root
mat decomposes nd the charredwood is washed
away
n
heavy
ains.
or
example,
1
percent
f
the
farm-siteurface rea was bare
soil one year after
forest learing, ut by
the
time
of abandonment9
percent
'f
his
ite
had
exposed
oil. n
separate
ur-
face olonizationxperimentsUhl
et al. 1981), forb
and
grass pecies
howed
ood establishment
n these
bare-soil urfaces
s
compared
o
successional
oody
species.
The results
f
the
seed-bank
urvey table 3)
TABLE
1. A
summaryof differences
etween
plots
with
yuca present nd adjacent plots where
yuca was
removed.
Yuca present Yuca removed
Number
of
species present 9
7
Number
of
woody
establishmentsa 0.7 + 0.8b 0.0
Number
of
herbaceous
establishments 15.6? 8.53 12.3?+
9.6
Total numberof
establishments 16.3
?
8.42
12.3
?
9.6
Midday light
at soil
surface
on
overcast ay (lux) 7,500?+9,500 22,750?+ 9,700
Midday temperature
t
soil
surface n sunnyday
(0C) 40.5?0.9
46.8?4.4
Soil
percentagemoisture
after three days
without ain 6.4?0.93
6.9?+1.16
aOnly plants
?
5
cm tall
were
considered s
established.
bNumber
of
plants presentper
2
x
2
m plot
?
95 % con-
fidence nterval.
TABLE 2. The mean number
of plants and grams dry-weight
iomass
in 27 1 x 1.5 m permanent
lots at each of
five
weedings.a
Forbs
and grasses
Woody plants
Total individuals
Weeding
Density Biomass
Density
Biomass
Density Biomass
1 6.1?
2.7b
7.1?
5.4 12.7?6.0
16.6+6.5
18.8? 7.4 23.7?
9.1
2
9.7? 5.6 55.2?24.9
2.2?0.9
8.5?4.7
11.9?
5.7
63.7?24.9
3
72.6?30.8 41.7?16.3
3.4.2.3
76.0?30.8
45.1?16.7
4
28.2+16.2
24.2?12.5
2.2?1.2
5.0+4.1 30.4?16.2
29.2?13.0
5
53.1?22.6 27.5?16.7
1.8?0.8
3.2?2.5
54.9?22.7 30.7?16.6
aIndividuals
<
3 cm
tall not
considered
n
density stimates.
"95 % confidence
nterval.
Slash-and-Burn Agriculture
n
Amazon
Basin 251
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also help to explain he
observed hift rom
woody
toherbaceous
ife-formominance
uring he
period
of
farm-plotse. The estimated
umber
f germin-
able
seeds
m-2
was 581 in the
farm ite at the time
of
abandonmentnd177 in
the djacent,ndisturbed
forest ite.
Another orest
ite, several
kilometers
away,was
also ampled t this ime
nd
had
a germin-
able seedbankof 752 seeds
m-2
(Uhl et al. 1981)
suggestinghat
eed-bank ize varies
with ocation.
Successionalwoodyspecies
dominatedhe germin-
able seed bank in
both the forest
ites;however,
most f
the dentified
erminationsn the farm
ite
were
forbs r grasses. orb
and grass eeds
ncrease
in
abundance n
farm-siteeed banks
becausetheir
life ycles re
shorterhan he nterval
etweetweed-
ings. n contrast,
uccessional oody
pecies reweed-
ed out before
heycan produce eed
locally,
nd
after everalweedings he
seed bankthatgives rise
to
thisgroup
s
greatly
educed.
POST-ABANDONMENT
SUCCESSION.-Four
months
after he last
farm-ploteeding,
rasses nd forbs
accountedor
3
percent
f the
ndividuals
?
5
cm
tall
n
the27
permanent X 1.5
m
study lots table
4).
The
most bundant
orb pecies
t this imewere
Eupatoriumerasifolium
nd Phyllanthusp. with .2
and
4.1 individuals
lot-',respectively.he most
common rass species n
the plotswere
Paspalum
decumbens nd
Panicum pilosum Sw.
Total plant
density eclined t the
10-
and
16-month urveys
because
many rasses
nd
forbs
ad died.
Mostdeath
resulted ither
rom hading y taller lants
r
from
senescence ollowing
ruiting. ll other ife forms
either ncreased
r remained hesame
between he
four-
nd
16-month
urveys. orest rees
had
very
low
densitieshroughouthe
study eriod nd
were
onlypresent s sprouts.
At
16 months,
uccessional oodyplantsdomi-
nated he site
withthe tallestndividuals
-4 m
in
height.
f
199
individuals
2
m tall
present
n
the
30 X 50
m
study lot
t
16 months,
1
percent
ere
Vismia
auriformis
Lam.) Choisy, 19 percent
Vismia
apurensis
eich,
and
9 percentwereCecropia
ficifolia
nethlage.
n additional
ight uccessional
woody pecies
had
from ne
to seven ndividuals
-
2
m
tall
present. hese
successional oody
pecies
presumably
riginated rom seeds
dispersed nto
the
site from ndividuals
inging he margin f
the
clearing.The margins f farmsites are seldom
farmed
because these areas
burnpoorlyand are
quickly vergrown ith uccessional
egetation.We
TABLE 3.
The
number
of germinable
eeds
in soil
samples
taken from the
farm plot at the time
of aban-
donment and from
an adjacent
matureforest
plot.
Farmedsite
Forest ite
Number of
samples
15
13
Mean
number f
germinations er
sample 23.3
12.88a
7.08?2.29
Number of
germinations
-2
581
177
Percentage f total
germinations
growing to
an
identifiable
tage 74
69
Forest rees,
ercentage f total
identified
erminations 0 1
Successional
rees,
ercentage
of total
identified
erminations 8
95
Forbs and grasses,
percentage
of total
identified
erminations 92 1
'95% confidence nterval.
TABLE
4.
Changes
n
density
nd
species
number n
27
permanent
x
1.5
m
plots during
the
first
6
months
f
succes-
sion
following
he
final farm-plotweeding.
Months following
final weeding
4
10 16
Mean number
of individuals plot-1:
forbs
7.8
+
3.9b
7.8?+ 4.2 3.1 ?+3.2
grasses
19.8?10.6
6.3 ?3.3
1.7+2.3
successional
woodye 1.8+ 0.8
3.1? 1.0
3.2?+1.0
primary orestwoody 0.04?+0.08 0.04?+0.08 0.07?+ 0.15
Total
29.4+13.4
17.2?6.0 8.1?5.4
Number of species,
all
plots:
forbsa
5
6
4
grasses
8 6 6
successionalwoodyc 6
10
9
primary
orestwoody
1 1
3
Total
20
23
22
:Includes
herbaceous reepers.
h95
% confidence
nterval.
'Includes woody vines.
252 Uhl, Clark, Clark, and
Maquirino
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have
observed ther
newly
abandoned
farm
plots
in
the environs
f SanCarlos
nd
found hem
o
be
similar
to the
studyplot
in
vegetation
ife-form
composition
nd
structural
evelopment.
Standing
rop
biomass n the
abandoned
arm
siteone
year fter
he final
yuca
harvest
i.e., 16
months
fter he
final
weeding)was
773 grams
ry
weight
m-2,
a value imilaro otheriteratureeports
for
bandoned
eotropical
arm
ites
(table 5).
Of
this
total,
30 grams
were
aboveground
uccessional
species
biomass nd
278
gramswere
biomass
from
crop
plants till
present n
the site.
Leaf
biomass f
the
successional
egetation
as 234
g
m-2
and
stem
biomass
was
196
g
m-2
while oots ccounted
or
nly
about
10
percent
f the
total
non-cropiomass. he
low
root
biomassvalue
may
be
an
artifact f
the
small
ample
ize. n
excavations
f
entire oot
ys-
tems
of several
ommon
uccessionalree
species,
root
biomass
has
generally
een
15-20
percent f
total iomassUhl,pers. bs.).
The
woody
speciespresent n the
abandoned
farm ite
ppeared o
have
greater
ensities
earde-
cayingogsand
under
ruit
rees.
Grasses nd
forbs,
by
contrast,
ere
ble
to
establish
n
open,bare
soil
areas
s
well s
near
ogs
nd
under
ruit
rees. hese
establishment
referencesere
demonstratedy the
results f
the
microhabitat
xperiment
table 6).
The
cashew
and
slash
treatmentsad
significantly
more
woody stablishments
p
<
0.01,DuncanMul-
tiple
Range
Test) than did
the
other
treatments,
while
no
significant
ifferencesn
the
numbers
f
forb
and
grass colonizers
were
detectable
mong
treatments.ecausepineapple ndyucagrewpoorly,
these
treatments
ere
probably
imilar o
the bare
soil
plots n terms
f
ight nd
soil
temperature.
TABLE
5.
The
standingrop
biomass
f
a
farm
ite
one
year
fter
bandonmentt
San
Carlosde
Rio
Negro
nd
at sites
lsewhere.
Mass
drywt, g m-2
Aboveground
biomass:
Grasses
127
Forbs
9
Successional rees
272
Primary orest rees 0
Vines
22
Cashew trees
39
Pineappleplants
239
Belowground
biomass:
All
groups combined
65
San
Carlos,
Total
773
Guatemala,
Total
aboveground
(Snedaker
1970)
836
Costa
Rica,
Total
aboveground
(Ewel
1971)
1067
TABLE
6.
The
mean numberof grass and forb and woody
colonizers
n
five treatmentsfter ne year. Only
individuals more than 10 cm tall were consid-
ered as established.
Mean number f colonizers/plot
Treatment Grasses and forbs Woody plants
Bare Soil 184+ 65.7 0.0
Yuca 130+ 62.3 0.2?0.6
Pineapple 137? 130.3 0.6?1.1
Cashew
146+108.0
10.2?8.0
Slash
185+115.5
10.2?4.2
'95 % confidence nterval.
Treatment ifferences
n
woodyplant establish-
ment ouldoccur
because
f differential
ispersal
o
certain
microhabitats.ndeed, soil-germinableeed
checks t the conclusion f the experimentevealed
that
oils under he cashew reeshad an estimated
932 germinable oody eeds
m-2
(all successional
species) as compared o 126 in the slash nd 74 in
thebare
soil
plots.Fruit rees, uch s cashew,may
supply ood s well as perch itesforbirds.Differ-
entialgerminationf seeds once in a microhabitat
and/or
differential
ortalityf seedlings ollowing
germination ay also be importantn explaining
higher stablishmentn fruit reeand slash micro-
habitats.
lash
presence esultsn lower oilevapora-
tion and lower
oil-surface
emperaturesUhl
et
al.
1981), therebyrovidingavorableoil-moistureon-
ditions
or erminationnd seedling rotectionrom
midday
eat.
The presence f fruit
rees
lso protects
seedlingsrom irect eating,ndsteadyitternputs
from
hese rees
may
ikewise
avor stablishment.
CONCLUSIONS
The
early
uccession
ollowing lash-and-burngri-
culture
t San
Carlos
s similar
n
life-form
ompo-
sition nd
structureo other iteratureeports rom
both
New
and
Old
World
tropical
arm
ites.
ym-
ington 1933) reportedhat bandoned
arm
lots
n
Malaysia
were dominated
y grasses (particularly
Imperata ylindrica), orbs, nd successional rees
and
shrubs.
ellman
1970)
found hat
early
uc-
cessional ites in the Philippineswere coveredby
stands
f
herbs, ut after ne year, oftwood
rees
began
to
overtop
he
herb
ayer
nd soon
formed
complete
over.
Clayton (1958) reported
hat
a
thicket f close-growingrees nd shrubs s formed
soon
after arm-sitebandonmentn Nigeria. n the
neotropics,
udowski
1961) and Ewel (1971) de-
scribed
early-fallowegetation
n
Costa
Rica as
tanglesdominated y a mixture f grasses, erbs,
vines,
nd
woody ioneers;
nedaker
1970) report-
Slash-and-Burn
griculture
n Amazon Basin 253
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ed that
ne-year-oldallowsn
Guatemalawere
dom-
inated y woody
hrubswhich
ormed more-or-less
uniform
anopy
t 2
m;
and
Blum
(1968) reported
a
similar egetation
tructurefter ne
year
n
Pan-
ama.
The time
required o
regrow forest n a
de-
forested
ite t San
Carlos
depends
n how the
forest
is removed nd on the manner f land use follow-
ingremoval. or
example, hen
heforests cut
for
timber, ecoverys
rapid
because manyforest
ree
species
have the ability
o sprout rom
ut stumps
(Uhl
et al.
1981).
If
sites re
cut and
burned
nd
then
immediatelybandoned,
uccession
proceeds
more
lowly ecause
burning educes
prouting o-
tential nd
reduces he
woodyspecies
seed bank
(Uhl
et
al.
1981).
If sites re
cut
and
burned
nd
and
thenfarmed
or several
yearsbefore
bandon-
ment
this
study), ecoverys
even slower. he re-
peated
weedings
uring arming
sually xhaust
he
sproutingeserves f thosestems hatsurvive he
burn.
orbs,
rasses,
nd
successional
rees
ominate
on
newly
bandoned arm
ites
becausethey
have
many
eeds
present
n
the
seed bank
and/or
ecause
they have
easily
dispersed
eeds. Forest
trees,
by
contrast, ave
few, f
any, seeds in
farm-site
eed
banks
nd often
have
large,
orly
dispersed
eeds.
Therefore,
rimary orest
mustbe
closeto
thefarm
clearing or forestrees o colonize. n caseswhere
clearings re
very
arge i.e.,
seed
sourcesmany
km
away) and
land
use
prolongedi.e.,
sprouting
o-
tentialost),
it seems
afe o
predict hat
he return
to
primary
orestwill
takemany
hundreds
r per-
haps even
thousandsf
years.
ACKNOWLEDGEMENTS
Thanks re
extended o Getulio
Gomez and
Paulo Livino
for
many ours f
help n the
field;
rs.
Carl
Jordan, ruce
Haines,
Martin
Kellman,
nd an
anonymous
eviewer or
their
ritical
eading
f
the
manuscript;
nd
Saundra
Green
forhelp n preparationf themanuscript.
LITERATURE CITED
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owlands of Panama.
Ph.D.
diss. Florida State Univ., Tallahassee, Florida, U.S.A.
BUDOWSKI,G. 1961. Studies on forest uccession n Costa Rica and Panama. Ph.D. diss. Yale
University, onnecticut,
U.S.A.
CLAYTON,W. D.
1958.
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217-238.
EWEL,J. 1971. Experiments n arresting uccessionwith cutting nd herbicides n five tropical environments. h.D. diss.
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Carolina, Chapel Hill,
North
Carolina, U.S.A.
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E.
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KLINGE, AND H.
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HERRERA, . 1979. Nutrient istribution nd cycling n an Amazonian caatinga forest n Spodosols in
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KELLMAN, M. C. 1970. Secondaryplant succession n tropical montane Mindanao. Publication BG/2, Aust.
Nat.
Univ.,
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MEYERS, N. 1979. The sinking rk. Pergamon Press, Oxford. 308 pp.
SNEDAKER, . 1970. Ecological studies on tropicalmoist forest uccession n eastern
owland
Guatemala.
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Univ.
Florida, Gainesville, Florida, U.S.A. 131 pp.
SYMINGTON, . F. 1933. The study f secondary rowth n rain forest ites n Malaya. Malay. Forest
2:
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UHL, C., K. CLARK,H. CLARK,AND P. MURPHY. 1981. Earlyplant succession
fter
orest utting
nd
burning
n the
Upper
Rio Negro region of the Amazon Basin. J. Ecol. 69: 631-649.
, AND P.
MURPHY. 1981. A comparison f productivitiesnd energy alues between lash
and
burn
agriculture
nd
secondary uccession
n
theUpper Rio Negro region of the Amazon
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Agro-Ecosystems
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63-83.
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Uhl, Clark, Clark,
and Maquirino
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