daniel metcalfe oxford university centre for the environment daniel.metcalfe@ouce.ox.ac.uk...
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Daniel MetcalfeOxford University Centre for the Environment
daniel.metcalfe@ouce.ox.ac.uk
Comprehensive monitoring of carbon allocation and cycling
across the Amazon basin
Objectives
1) Establish baseline of current forest carbon storage and allocation
2) Monitor ongoing changes in forest carbon cycling
Increasing COIncreasing CO22 “fertilizer” in the “fertilizer” in the
atmosphereatmosphere
0 0.1 0.2 0.3 0.4 0.5 0.6
NW Amazonia
NE Amazonia
N Congo
E Indonesia
SW India
W Africa
C Amazonia
SW Amazonia
Cameroon
W Indones
S Congo
C America
SE Amazonia
Rate of Temperature Change (oC/decade)
SENSITIVITY: TEMPERATURESENSITIVITY: TEMPERATURE
Malhi and Wright (2004), Philosophical Transactions of the Royal Society
↓ precipitation ↑ atmospheric CO2 levels
↓ photosynthesis & ↑ soil respiration
↑ temperature
↑ terrestrial CO2 emissions↑ replacement of forest with savannah
IPPC 2007 working group 1 report
Dry seasonlength
+-
Current trends: spatial variation
Field Sites
Caxiuana
Tanguro
Noel Kempff
Kosnipata
Iquitos
Tambopata
Comparisons • Drought• Soil type• Fire• Altitude
Ecosystem respiration Net primary production
Rstem
Rleaf
Rsoil
Pcanopy
Pstem
ProotRcwd
Mleaf
Mroot
Mstem
Constructing bottom-up carbon budgets
Rsoil
Rroots
Rmycorrhizae
Rsom
Rlitter
Soil CO2 efflux partitioning
Constructing bottom-up carbon budgetsGPPflux tower = 30.4; Predicted GPP = 29.9 � 4.8Manaus, Brazil
R leaf = 10.0 � 4.0
R stem = 4.2 � 1.0
R CWD = 2.5� 0.3
R total = 29.3 � 4.7
R aut = 19.8 � 4.6
R het = 9.6 � 1.2
NPPtotal = 10.1 � 1.4
NPPAG = 7.3 � 1.3
NPPBG = 2.8 � 0.7
Fdoc = 0.19 � 0.07
DFine litterfall = 3.6 � 0.7
DCWD= 3.4� 1.0
R roots = 5.6 � 2.0
Predicted R soil = 12.6±2.3
Measured R soil = 12.1 � 1.7
DRoot = 2.8 � 0.7
R soil het.=7.1 � 1.1
NPP coarse roots = 0.8 � 0.2
NPP fine roots = 2.1 � 0.7
NPP stem = 2.58 � 0.06
NPP VOC = 0.13 � 0.06NPP leaves,flowers,fruit = 3.6 � 0.7
NPP branch turnover = 1.0 � 1.0
Equipment contruction & installation
Ecosystem respiration Net primary production
Rstem
Rleaf
Rsoil
Pcanopy
Pstem
ProotRcwd
Mleaf
Mroot
Mstem
Pcanopy
Pstem
Mleaf
Mstem
Foliage densityFoliage density
ClassificationClassification
OutputsOutputs
Specific leaf areaSpecific leaf area
Threshold image to calculate area
Fill in eaten leaf area to quantify herbivory
Leaf morphology
Variation with canopy height
Leaf dark respiration
Leaf light respiration
Ecosystem respiration Net primary production
Rstem
Rleaf
Rsoil
Pcanopy
Pstem
ProotRcwd
Mleaf
Mroot
Mstem
Stem Dynamics
Measurements1)Below and above 10cm DBH2) Basic data (species, DBH, height wood density)3) Mode of death4) Respiration......basal vs contruction respiration
Res
pira
tion
Growth
Biomass change / Mg ha-1 yr-1
0
2
4
6
8
10
12
14
16
18
-4 -3 -2 -1 0 1 2 3 4 5 6
No
. plo
ts
1.22 ± 0.42 Mg ha-1 yr-1
Histogram of rate of biomass change over the 1980s and 1990s as observed in 59 RAINFOR plots. The mean change is 1.22±0.42 Mg biomass ha-1 year-1. From Baker et al (2004), Philosophical Transactions of the Royal Society of London.
Current trends: Increasing biomass
Changes in tree recruitment (green) and mortality as observed in RAINFORold-growth forest plots in recent decades. Forests appear to be becoming Increasingly dynamic. From Phillips et al (2004)
An
nu
al r
ate
of
stem
m
ort
alit
y/re
cru
itm
ent
(%)
Year
Current trends: Increasing dynamism
Ecosystem respiration Net primary production
Rstem
Rleaf
Rsoil
Pcanopy
Pstem
ProotRcwd
Mleaf
Mroot
Mstem
Ecosystem respiration Net primary production
Rstem
Rleaf
Rsoil
Pcanopy
Pstem
ProotRcwd
Mleaf
Mroot
Mstem
TECHNIQUES: RHIZOTRONSTECHNIQUES: RHIZOTRONS
1.1. In situIn situ measurement measurement2.2. High temporal frequencyHigh temporal frequency3.3. Record root growth, Record root growth,
mortality, longevitymortality, longevity
RHIZOTRONS: CONVERTING LENGTH TO MASS RHIZOTRONS: CONVERTING LENGTH TO MASS
Calculate cross-sectional root area
Multiply area by length/width of plot to derive volume
Multiply volume by root density
Frequent root mass production (t ha-1)rhizotron screenrhizotron screen
rootsroots
Source: Bernier & Robitaille. (2004), Plant and Soil.
TECHNIQUES: INFRA-RED GAS ANALYZERTECHNIQUES: INFRA-RED GAS ANALYZER
CO2
IRGAIRGA
1.1. Record soil respirationRecord soil respiration
2.2. Remove litter, measure respiration againRemove litter, measure respiration again
3.3. Remove soil core, roots from core. Measure Remove soil core, roots from core. Measure root respiration.root respiration.
4.4. Subtract root and litter respiration from total Subtract root and litter respiration from total soil respirationsoil respiration
isolate litter isolate litter contributioncontribution
estimate root estimate root contributioncontribution
estimate residual estimate residual respiration (i.e.: from respiration (i.e.: from soil organic matter)soil organic matter)
Soil CO2 efflux partitioning
No litterControl 2 × litter
Control
No roots or mycorrhizae
No roots
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 Metcalfedaniel.metalfe@ouce.ox.ac.ukdaniel.metalfe@ouce.ox.ac.uk
Caxiuana
Tanguro
Noel KempffAndesTransect
Iquitos
Lloyd (1999), Functional Ecology.
The The current effect of CO effect of CO22 fertilizer on fertilizer on
terrestrial ecosystemsterrestrial ecosystems
Synthesis of results
1.1. Good evidence for drought-induced decline in Good evidence for drought-induced decline in photosynthesis, photosynthesis, but this is balanced out by a decline in soil this is balanced out by a decline in soil COCO22 efflux. efflux. What accounts for inter-annual patterns?
2.2. Some evidence for drought-induced changes in mortality Some evidence for drought-induced changes in mortality and reproduction, and reproduction, but massive variability. massive variability.
3.3. Overall, the forest appeared suprisingly resilient to droughtOverall, the forest appeared suprisingly resilient to drought
BUT
Other poorly quantified components of the carbon cycleOther poorly quantified components of the carbon cycle
Robustness of the modelled “Amazon Robustness of the modelled “Amazon drought”drought”
Short-term model predictions:Short-term model predictions: Climate & Carbon Climate & Carbon
Differences amongst regionsDifferences amongst regions
Long-term model predictions:Long-term model predictions: Vegetation Vegetation
Long-term model predictions:Long-term model predictions: vegetation vegetation
↑ atmospheric CO2 levels↓ precipitation
↓ photosynthesis & ↑ soil respiration
↑ temperature
↑ terrestrial CO2 emissions
e.g.: see Cox et al. (2000), Nature.
↑ replacement of forest with savannah
Results from the first two years: soil moisture
Results from the first two years: canopy properties
Results from the fifth year: canopy properties
Results: tree dynamics
Mortality over 3 yearsMortality over 3 years
Control: 2.4% of pop.Control: 2.4% of pop.
TFE: 1.5% of pop.TFE: 1.5% of pop.
BUT
Control: 1.3 t C haControl: 1.3 t C ha-1-1
TFE: 2.1 t C haTFE: 2.1 t C ha-1-1
↑ atmospheric CO2 levels↓ precipitation
↓ photosynthesis & ↑ soil respiration
↑ temperature
↑ terrestrial CO2 emissions
e.g.: see Cox et al. (2000), Nature.
↑ replacement of forest with savannah
Overlooked components of the C cycle
Leaf dark respiration
TEMPORAL TRENDS: RESPIRATIONTEMPORAL TRENDS: RESPIRATION
Model uncertainty caused mainly by lack Model uncertainty caused mainly by lack of information about below-ground of information about below-ground processesprocesses
Source: Lloyd & Prentice (1998), Nature.
RHIZOTRONS: RESULTS RHIZOTRONS: RESULTS
surge in both growth surge in both growth and mortality during and mortality during
the wet seasonthe wet season
Additional surge on Additional surge on the Drought plot the Drought plot
coinciding with the coinciding with the first big rain eventsfirst big rain events
? ? ?
SYNTHESIS: ABOVE- & SYNTHESIS: ABOVE- & BELOW-GROUND DATABELOW-GROUND DATA
0
1
2
3
4
5
6
7
control drought
tC h
a-1
yr-1
litter- rep.
litter- leaveslitter- wood
stemroot
Treatment differences in stem wood Treatment differences in stem wood production are relatively small compared production are relatively small compared
to root and litter fall productionto root and litter fall production
The drought treatment alters ecosystem The drought treatment alters ecosystem carbon cycling, e.g.: the balance between carbon cycling, e.g.: the balance between carbon entering the soil via litter fall, and carbon entering the soil via litter fall, and
leaving via microbial respirationleaving via microbial respiration
Accounts for 45% of the worlds tropical forestAccounts for 45% of the worlds tropical forest
Stores 40% of carbon residing in terrestrial vegetationStores 40% of carbon residing in terrestrial vegetation
Hosts a large proportion of global biodiversityHosts a large proportion of global biodiversity
Malhi & Grace (2000), TREE.
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