Quantifying human impacts on tropical forest biodiversitySapotaceae: Pouteria spp. and others Work...
Transcript of Quantifying human impacts on tropical forest biodiversitySapotaceae: Pouteria spp. and others Work...
Quantifying human impacts on tropical forest biodiversity
Jos BarlowLancaster Environment Centre, Lancaster University
INPE,agosto 2009
1975
Rio Teles Pires
1984
1990
1996
2004
My research aims to answer two questions about TF biodiversity
1) What are the consequences of deforestation and land-use change?
2) What are the consequences of degradation within the remaining forests?
1) What are the biodiversity consequences of deforestation?
Intensification DegradationRegeneration
Predictions based on forest loss are inadequate for biodiversity
“Thirty-five primate species lose 60–100% of their Amazonian range….”.
Soares-Filho et al. 2006 Nature
Mico spp. Callicebus spp. Ateles spp.
Most abundant in degraded and secondary forests Absent from degraded forests
2050: Business as usual
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1) Lack of consistency in conclusions: e.g. Birds & SFs
Study Location Ages sampled
Change in richness
Community overlap
Blake & Loiselle 2001 Costa Rica 4-13; 25-35 Increase High
Johns 1991 Brazil 1-2 Increase Low
Borges 2004 Brazil 4-35 No change High
Sodhi et al. 2005a Sulawesi 40 No change High
Schulze et al 2004 Sulawesi Young No change High
Lawton et al. 1998 Cameroon >40 No change -
Andrade & Rubio-Torgler 1994
Colombia 1-17 No change High
Raman et al. 1998/Raman 2001
India 1, 5, 10, 25 and 100
Decrease High
Bowman et al 1990 PNG 0-25+ Decrease High
Terborgh & Weske 1969 Peru Young Decrease -
Barlow et al. in press Brazil 13-19 Decrease Low
2) Many studies have flawed methodologies; e.g. Of 11 studies on birds in SFs
• Lack of spatial replication– 4 had no within treatment replication; 7 had less
than 3 replicates
• Edge effects– Nine of 11 studies on birds in SFs were in plots
“adjacent” to primary forest
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3) Lack of seasonal replication: Butterflies
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Rainfall
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Observed richness
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4) Lack of congruency between taxa (which taxa to believe???)
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“No-one group serves as a good indicator taxon for changes...of other groups”
Lawton et al. 1998, Nature
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Jari – a unique Amazonian landscape• >1M ha of primary forest
• 53,000ha of Eucalyptus plantations on 5-7 yr rotations
• 50,000ha of fallow lands (secondary forests)
Field sampling
Outline of results
1. Response types: Species richness
2. Response types: Community structure
3. Examine congruence using different
response metrics
4. Which taxa are outliers?
5. Assess the unique conservation value of
primary forest
1) Response types:Species richness
• Hypothesis: Faunal richness would reflect richness in vegetation
Tree genera
0 500 1000 1500 2000 25000
50
100
150
200
250
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2) Response types: Species composition
Taxonomic group Community structure comparison
PF-SF PF-EUC SF-EUC
Trees and Lianas 0.99** 1.0** 1.0**
Birds 1.0** 1.0** 0.98**
Fruit-feeding butterflies 0.88** 1.0** 0.96**
Leaf-litter amphibians 0.26* 0.51** 0.88**
Large mammals 0.80** 1.0** 0.96**
Bats 0.77** 0.49** 0.45**
Lizards 0.56** 1.0** 0.83**
Dung beetles 0.67** 0.60** 0.48*
Epigeic arachnids 0.39* 0.83** 0.53*
Grasshoppers 0.64** 0.94** 0.31*
Scavenger flies 0.40* 0.79** 0.42*
Fruit flies 0.46* 0.79** 0.06
Small mammals 0.25* 0.43** 0.03
Orchid bees 0.31* 0.35* -0.02
Moths 0.51** 0.95** 0.52**
3) Congruency between taxa with different response metrics
Based on pairwise correlations of 15 taxa across 15 sites (105 possible pairwise correlations),
• Community structure (CS)
• Community composition (CC)
• Observed richness (OR)
• Estimated richness (ER)
• Abundance (AB)
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4) Are some taxa outliers? MDS ordination based on response similarity
Composition
MDS Axis 1
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
MD
S a
xis
2
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
AM
OBAR
CF
DBLM
SM
FF
GH
BA
MO
BI
LZ
BU
TL
Small Mammals
Low sample representation
Orchid Bees
Highly vagile & feed on
ephemeral resources
Amphibians – Unique resource reqirements?
BatsHighly
vagile & feed on
ephemeral resources
Taxa with similar
responses
%of species unique to primary forest
0 10 20 30 40 50 60
Orchid beesLarge mammalsScavenger flies
Fruit fliesEpigeic arachnids
GrasshoppersFruit-feeding butterflies
BatsMoths
Dung beetlesSmall mammals
LizardsLeaf-litter amphibians
BirdsTrees and Lianas
Barlow et al. 2007 PNAS
5. Conservation value of primary forests
Conclusions – Quantifying the biodiversity value of forests
• Assesments of habitat quality should focus on species composition rather than richness
• Secondary forests and plantations both have some complementary conservation value
• BUT: 25% of species were only ever recorded in primary forest
• AND: These figures are likely to be conservative…– 50% of species were unique to primary forest when
singletons were excluded from the analysis– the difficulties of sampling the full range of diversity found
within primary habitats
2) What are the consequences of forest degradation for biodiversity?
Forest wildfires: 20M ha burned during the 1997-1998 ENSO event
Increasing threat? Interact with ongoing threats to the Amazon
Positive feedback: low-intensity fires lead to recurrent fires
Very high tree mortality following fire in central Amazonia (Tapajos-Arapiuns)
Mean char height
0.0 0.5 1.0 1.5 2.0 2.5
No.
of l
ivin
g tre
es
0
20
40
60
80
100
120
140
160
Unburnt
Once-burnt
Twice-burnt
Barlow and Peres 2004 Phil. Trans. Roy. Soc.
Similarity between
BF2-BF2
UF-UF
BF-BF
UF-BF
BF-BF2
UF-BF2
Mea
n (+
/-SD
) M-H
inde
x0.0
0.2
0.4
0.6
0.8
1.0
Short-term effects of fires on understorey avifauna
Barlow et al. 2002Biological Conservation
Loss of understorey specialists in once-burned forest
Complete species turnover following recurrent fiires
Barlow and Peres 2004Ecological Applications
Recurrent fires affect ecosystem functioning (litter decomposition)
Silveira, Barlow et al. 2009 Journal of Tropical Ecology
Recurrent fires lead to a cascade in species composition and possible ecosystem phase-shift
Barlow and Peres 2008 Phil. Trans. Roy. Soc.
Bombacaceae: Bombax sp.
Cecropiaceae: Cecropia spp.
Boraginaceae: Cordia sp.
UF BF1 BF2 BF3
Burseraceae: Protium and Tetragastris Spp.
Bignoniaceae: Jacaranda copaia
Forest treatment
Fabaceae: Sclerolobium spp.
Sapotaceae: Pouteria spp. and others
Work in progress…
1) Examining the longer-term consequences of wildfires across Amazonia
RESEX Tapajos-Arapiuns, Pará
Querencia, Mato Grosso
RESEX Chico Mendes, Acre
Ilha de Maracá, Roraima
2) Quantify the temporal basis of biodiversity responses
Time after most recent burn event
Cha
nge
from
und
istu
rbed
Prim
ary
fore
st
Understorey fires
Recurrent fires
3) Link biodiversity responses with spatial mapping of forest degradation
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C. Souza and M. Cochrane
Conclusions
• The consequences of land-use change and degradation for tropical forest biodiversity are complex, and can be highly context dependent
• Landscape processes such as deforestation and degradation are highly linked, and we need to take a whole landscape approach to understand their effects on biodiversity
• A better understanding of the spatial and temporal consequences (extrapolating local processes through RS) could help develop effective management strategies
Obrigado!