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During the past decade, Southeast Asian peat swamp forests have been deforested at double the rate of any other forest type. This deforestation is driven by wood production and demand for land on which to establish agriculture, including oil palm and timber plantations. In this presentation given in Vietnam on September 2011 at the annual REDD-ALERT meeting, CIFOR scientist Kristell Hergoualc'h shows how she and other CIFOR scientists assessed carbon losses from wildfires and land conversion in virgin peat swamp forests. They found that peat carbon loss contributes more than 63% to total carbon loss, demonstrating the urgent need to protect tropical peat swamp forests from land-use change and fires in the fight against climate change.
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THINKING beyond the canopy
Carbon loss associated with land-use change
in tropical peatlands: methods and estimates
Kristell Hergoualc’h 29 September 2011 – REDD-ALERT annual meeting, Da Lat, Vietnam
THINKING beyond the canopy
Stock change approach
Methodological approaches
C loss = CF - COP
C loss rate = C loss / life time
After
Before
Flux change approach
After
Before
C loss rate = ΔCF - ΔCOP
C loss = C loss rate × life time
Cout F
Cin F
Cin OP
Cout OP
ΔCF
= Cin F – Cout F
ΔCOP
= Cin OP – Cout OP
CF
COP
THINKING beyond the canopy
Literature review
Southeast Asian peatlands
C stocks, peat C fluxes
56 studies
Carbon loss estimates
Two publications Murdiyarso D, Hergoualc'h K & Verchot LV 2010, ‘Opportunities for
reducing greenhouse gas emissions in tropical peatlands’, PNAS, vol
107, no 46, pp. 19655-19660
Hergoualc’h K & Verchot LV 2011, ‘Stocks and fluxes of carbon
associated with land-use change in Southeast Asian tropical peatlands: a
review’, Global Biogeochemical Cycles, vol 25, GB2001.
THINKING beyond the canopy
Stock change approach
Carbon loss from wildfires
Land-use type
before fire
C stock loss (Mg C ha-1)
Burnt vegetation Burnt peat Total
Intact forest 152 ± 36 285 ± 67 436 ± 77
Logged forest 35 ± 36 285 ± 67 320 ± 77
Oil palm plantation 32 ± 9 285 ± 67 316 ± 67
Acacia plantation 28 ± 2 285 ± 67 313 ± 68
C loss: 65 – 90% from peat
THINKING beyond the canopy
Combination of the two methodological approaches
Stock change approach: Aboveground biomass C loss
Flux change approach: Peat C loss
Peat forest conversion to oil palm
Peat C stock changes: Difficulties and Limits
Peat depth (up to 20 m), compaction, limited number profiles
Presence logs, high water table level bulk density?
How to select the right ‘before land use change’ site?
How to address peat compaction, shrinkage and
decomposition caused by land-use change?
THINKING beyond the canopy
C fluxes into and out of the peat
Heterotrophic soil respiration = peat oxidation = peat decomposition
Heterotrophic soil respiration = Total soil respiration - root respiration
Litterfall
Root mortality
Heterotrophic soil
respiration
Land clearing
fire
CH4
Soluble & physical removal
THINKING beyond the canopy
Peat C balances in the forest and in the oil palm plantation
Cpeat F = Cin peat – Cout peat
= 1.0 Mg C ha-1 y-1
= 25 Mg C ha-1 25 y
After
Litterfall 1.5
Root mortality 3.6
Soil heterotrophic respiration 9.3
Land clearing fire 4.5
Soluble & Physical Removal 1
Cpeat OP = Cin peat – Cout peat
= - 9.8 Mg C ha-1 y-1
= - 245 Mg C ha-1 25 y
Before
Litterfall 7.4
Root mortality 1.5
Soil heterotrophic respiration 6.9
CH4 0.03
Soluble &
Physical
Removal 1 CH4 -0.0002
THINKING beyond the canopy
After
Cpeat OP = - 245 Mg C ha-1 25 y
CAbvgrnd biomass OP = 24 Mg C ha-1
Cpeat F = 25 Mg C ha-1 25 y
CAbvgrnd biomass F = 182 Mg C ha-1
Before
Peat forest conversion to oil palm plantation
C loss = 428 Mg C ha-1 over 25 years
C loss: 63 % from peat
- 270 Mg C ha-1 25 y
-158 Mg C ha-1 25 y
THINKING beyond the canopy
Conclusions
Very large carbon loss
C loss: 60-90% from the peat
REDD mechanism should prioritise peat swamp forests
Gaps knowledge on C cycle in tropical peatlands
Greenhouse gas accounting methods: heterotrophic soil respiration (N inputs), allometric models specific to peat swamp forests
General misunderstanding :
Peat heterotrophic soil respiration Peat C loss
N2O: Global warming potential 300
Increase in N2O emissions due to land-use change in tropical peatlands?
THINKING beyond the canopy
CIFOR advances human well-being, environmental conservation, and equity by conducting research to inform policies and practices that affect forests in developing countries.
www.cifor.org
Thank you
