Presented by Kristell Hergoualc'h, CIFOR-ICRAF, at EGU general Assembly 2022, 23rd-27th May 2022 Vienna, Austria

1. Kristell Hergoualc’h, J van Lent, N Dezzeo, LV Verchot, J van Groeningen,
M Lopez, J Grandez
Major carbon losses from degradation of
Mauritia flexuosa peat
swamp forests in western Amazonia
EGU GA 2022, 23-27th May 2022

2. Peruvian peatlands
 Key contributor tropical peatlands
Gumbricht et al. (2017)
 Amazonian peatlands mainly Mauritia
flexuosa-dominated forests (Hastie et al. 2022)
 C-dense ecosystems (746 Mg C ha-1) (Honorio Coronado
et al. 2021)
 Recurrent degradation over 30 years: M. flexuosa
palms cut for fruit collection (Horn et al. 2018)
 73% M. flexuosa-dominated stands degraded in
pilot area (Hergoualc’h et al. 2017)

3. Experiment
Highly
deg.
Medium
deg.
Intact
 Iquitos, Northern Peruvian
Amazon
 Degradation gradient
I: Intact
mD: medium degradation
hD: high degradation
 Several years, monthly monitoring of soil heterotrophic respiration
(peat C output), litterfall, and root mortality (peat C inputs)
→ Peat C budget = (Sh + DOC) – (Litterfall + Root mortality) (IPCC)
Computed over 1 Y when all fluxes measured simultaneously at all sites
Dissolved organic C: Default value from Southeast Asia

4. Experiment and computations
 Biomass measurement 5 years after degradation started (according to
satellite imagery), 1 year before monitoring fluxes
 C loss from degradation
Intact site representative degraded sites before degradation
AGB C loss degraded site = (AGB C Intact – AGB C degraded site)
Peat C loss degraded site =
(Peat C stock gained / lost 5 Y degraded site
- Peat C stock gained 5Y Intact site)
-2
0
2
4
6
8
0 2 4 6
Peat
C
budget
(Mg
C
ha
-1
y
-1
)
Year
Intact
mDeg
hDeg
Biomass
measur.
Flux
measur.
Intact: Peat C budget steady state
Degraded: Linear change over
time peat C budget with initial
rate = rate at the Intact site

5. Peat C budget & C stock loss
 Peat C fluxes and budget
Degradation ↘ C inputs, ↗ C outputs
-1.8
± 1.8
-0.3
± 0.7
6.0 ±
0.6
-10.0
-6.0
-2.0
2.0
6.0
10.0
Intact mDeg hDeg
Mg
C
ha
-1
y
-1
Root Mort Litterfall Sh DOC
 Peat C built up / lost over 5 years
-9 ± 4
-7 ± 3
9 ± 3
-15
-10
-5
0
5
10
15
Intact mDeg hDeg
Peat
built-up
/
lost
(Mg
C
ha
-1
5
y
-1
)
Intact: C Sink
mDeg: C sink lessened
hDeg: Large source of C
⇒

6. Biomass & ecosystem C stock losses
 AGB biomass
↘ by 32% and 62% following medium and
high degradation
98 ± 15
67 ± 11
37 ± 11
0
30
60
90
120
Intact mDeg hDeg
AGB
(Mg
C
ha
-1
)
30 ± 19
61 ± 18
2 ± 6
18 ± 7
0
20
40
60
80
100
mDeg hDeg
Total
C
stock
loss
(Mg
C
ha
-1
5
y
-1
)
AGB Peat
79 ± 19
32 ± 20
 Ecosystem C losses
High degradation = 2.5 losses medium
degradation
Losses from AGB biomass = 94% and 77% for
medium and high degradation

7. Concluding remarks
 1st estimates of ecosystem C loss from degradation undrained
tropical peatlands, for peatlands of South America
1 location over a limited period ⇒ Need for replication along
degradation gradients in ≠ climate (precipitation, water table
fluctuation)
 Peat C budget (Mg C ha-1 y-1): Comparison Southeast Asia
Intact -1.8 ± 1.8 ≈ −1.4 ± 1.8 Intact peat swamp forests (Hergoualc’h &
Verchot 2014)
hDeg 6.0 ± 0.6 ≈ 5.3 ± 1.6 Drained degraded peat swamp forests
(Hergoualc’h & Verchot 2014; IPCC)
 Peat C budget estimates outside of Southeast Asia and for undrained
degraded peatlands very much needed for countries aiming at
including peatlands in their national climate change strategies

8. Thank you! Questions?