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Daniel Metcalfe and numerous othersOxford University Centre for the Environment
Drought impacts on leaf morphology and respiration
↑ atmospheric CO2 levels↓ precipitation
↓ photosynthesis & ↑ soil respiration
↑ temperature
↑ terrestrial CO2 production
Future drought in the Amazon
Model uncertainty
Justification & Objectives
Possible future drought.Possible future drought. What are the drivers of short and longer-term forest carbon What are the drivers of short and longer-term forest carbon
dioxide exchangedioxide exchange Neglected but important components of the forest carbon Neglected but important components of the forest carbon
cyclecycle
1)1) Characterize canopy characteristics over five years in an Characterize canopy characteristics over five years in an artificially droughted forest.artificially droughted forest.
2)2) Get a first approximation of drought impacts on a key Get a first approximation of drought impacts on a key component of the ecosystem carbon cycle- leaf dark component of the ecosystem carbon cycle- leaf dark respirationrespiration
Dry seasonlength
+-
Drought experiment1) Matched Drought and Control plots2) Panels exclude approx 50% rainfall3) Perimeter trenching to minimize lateral water transport
Rai
nfa
ll(m
m d
ay-1
)
30
60
90
2002 2003 2004 2005 2006 2007
Pcanopy
Pstem
Mleaf
Mstem
Rstem
Rleaf
Rsoil ProotRcwd
Mroot
Canopy morphology & densityCanopy morphology & densityL
eaf a
rea
inde
x (m
2 m-2
)
4
5
6
2002 2003 2004 2005 2006 2007
Sp
ecif
ic le
af a
rea
(cm
2 g-1
)
80
100
120
140
160
180
ControlTFE
2002 2003 2004 2005 2006 2007
Two contrasting ways of quantifying Two contrasting ways of quantifying canopy densitycanopy density
2002 2003 2004 2005 2006 2007
Can
opy
mas
s (t
ha-1
)
0
1
2
3
4
5
6
7
8
9
Lea
f are
a in
dex
(m2 m
-2)
4
5
6
2002 2003 2004 2005 2006 2007
Leaf dark respiration Leaf dark respiration
Lea
f d
ark
res
pir
atio
n(n
mol
g-1
s-1
)
2
4
6
8
Lea
f da
rk r
espi
rati
on(µ
mol
m-2
s-1
)
0.2
0.4
0.6
2002 2003 2004 2005 2006 2007 2002 2003 2004 2005 2006 2007
Variation with canopy heightVariation with canopy height
0-10m 11-20 m >21 m
Global trends in leaf respirationGlobal trends in leaf respiration
0 100 200 300 400Specific leaf area
Poorly quantified components of the ecosystemimproving infrastructure and equipments, applying techniques from other disciplines
Inferring long-term responses from short-term observationsIncreasing length of observations, improve mechanistic understanding of forest responses
Multiple interactionsMultivariate statistical analysis, increasing model complexity: requires more field data
Spatial HeterogeneityIncreasing measurement plots, intra-plot sample sizeEvidence accumulating for Evidence accumulating for
profound changes in the profound changes in the structure and function of the structure and function of the
Amazon ecosystemAmazon ecosystem
What will be the human and environmental impacts of these
changes?
Key websites- The Amazon Forest Inventory Network:
http://www.geog.leeds.ac.uk/projects/rainfor/- Project for the Advancement of Networked Science in Amazonia:
http://www.eci.ox.ac.uk/projects/panamazonia/- Large Scale Atmosphere-Biosphere Experiment in Amazonia:
http://www.lbaeco.org/lbaeco/
Daniel MetcalfeDaniel [email protected]@ouce.ox.ac.uk
