Download Ecology and biodiversity of tropical forests

Department of Plant Ecology and Ecosystems Research
Ecology and biodiversity of tropical forests
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Species-rich tropical montane rainforest in the southern Ecuadorian Andes.
The lower montane forests resemble the structurally rich lowland forests.
Spectacular species in tropical rainforests: (1) orchid
(Sulawesi), (2) longhorn beetle (Sulawesi), (3) 'Quetzal' Tropical moist forests in East Africa are the natural habitats of
coffee that grows in the understorey (Bale Mountains, Ethiopia).
trogon bird (Costa Rica).
Background
Tropical forests have fascinated many scientists for a long time because of their particular richness of plant and animal
species and their complex structure. At most tropical regions, the natural forests cover is dramatically reduced by gross
timber extraction and conversion into agricultural land. Accordingly, their is a strong need for research on the meaning of
biodiversity for ecological functioning in tropical forests, but also on the effects of land use intensification on ecosystem
processes in tropical countries.
Research
10
12
25
50
Tree height, r2 = 0.92, p < 0.01
30
r = 0.80 (p < 0.05)
25
r = 0.73
(p < 0.05)
20
40
20
30
15
20
10
5
10
r2
Tree genera, = 0.92, p < 0.01
0
1000 1500 2000 2500 3000
15
12
14
16
18
20
Norg (g kg-1)
0
3500
4000
200
160
120
80
40
Lapse rate: 6.45 g C 100 m-1
r2 = 1, p < 0.001
0
500 1000 1500 2000 2500 3000 3500
Elevation (m asl.)
Elevation (m asl.)
Respiratory activity of tree organs
in tropical forests is tightly related
to the elevational decrease of the
air temperature (South Ecuador).
C flux with leaf and root litter
(g m-2 yr-1)
Tree species diversity in tropical montane forests is found to
coinced with nutrient stocks in the soil (Ecuador, left). Other
parameters, however, such as elevation not only affect tree
height but also the diversity of tree genera (Bale Mts, Ethiopia).
1000
1.0
r = 0.95 p < 0.05
800
0.8
600
0.6
400
0.4
undisturbed forest
small disturbance
large disturbance
200
r = 0.72 p = 0.10
0.2
cacao + natural trees
cacao + planted trees
0
0.0
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70
75
80
85
90
The 'Estación Scientífica de San
Francisco' in the south-ecuadorian
Andes is an excellent facilitation for
studies on the ecology of tropical
mountain forests.
Root:leaf litter ratio of C flux
8
Number of tree genera (per 0.2 ha)
6
Tree height (m)
(Hurlbert-rarefied)
Tree species number
4
Stem and coarse root respiration
(g C m-2 yr-1)
Porg (g kg-1)
2
35
95
Canopy cover (%)
c
b
ab
ab
ab
ab
a
sun-lit leaves
800
600
400
200
shade leaves
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a
op
.c
f.
ul
ne
us
gl
A.
ab
cf
. c ra
at
ur
P.
us
ar
ge
nt
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T.
s
or
ie
nt
M
. b alis
ar
ba
tu
s
pi
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is
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M
H
M
.t
an
a
ri u
s
0
Secondary vegetation and agricultural systems frequently replace
natural tropical forest (e.g. Central
Sulawesi,
Indonesia).
Important
ecosystem functions e.g. carbon flux
via leaf and root litter to the soil are
altered via forest conversion (above).
Hence, knowledge about ecological
attributes of successional tree
species is important (left).
4000
Epiphyte biomass (kg ha-1)
c
.p
Max. stomatal conductance
(mmol m-2 s-1)
1000
Disturbance of old-growth forests in
tropical mountains has not only
major implications for the forest
structure and related carbon stocks,
but also for the abundance of
vascular
epiphytes
such
as
bromelias (Costa Rica).
3500
3000
2500
2000
1500
1000
500
0
c.12 years 40 years
successional
old-growth
Forest type
Major projects: "Nutrient limitation in tropical mountain forests" - DFG Research Unit 816 "A Mountain Ecosystem in South Ecuador"
"Stability of Rainforest margins in Indoensia STORMA" - former DFG Collaborative Research Centre 552
Key results
y Despite increasing efforts in the past years, ecologists are still at the beginning of an enhanced understanding of the
relationship between biodiversity and ecosystem functioning in tropical forests.
y Tropical montane forests appear in many ecological functions to be in particular sensitive to differences in nutrient
availability.
y Forest use intensity and forest conversion into agricultural systems have major implications for not only for plant and
animal species composition, but also for important ecosystem functions (such as the carbon cycle).