EGU21-831
https://doi.org/10.5194/egusphere-egu21-831
EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Spatial and temporal variability of soil N2O and CH4 fluxes along a degradation gradient in a palm swamp peat forest in the Peruvian Amazon

Kristell Hergoualc’h1, Nelda Dezzeo1,2, Louis Verchot3, Christopher Martius1, Jeffrey van Lent1, Jhon Del Aguila Pasquel4, and Mariela Lopez1
Kristell Hergoualc’h et al.
  • 1CIFOR, Lima, Peru (k.hergoualch@cgiar.org)
  • 2IVIC, Caracas, Venezuela (ndezzeo@gmail.com)
  • 3CIAT, Bogota, Colombia (l.verchot@cgiar.org)
  • 4IAAP, Iquitos, Peru (jdelaguilap@iiap.gob.pe)

Mauritia flexuosa palm swamp, the prevailing Peruvian Amazon peatland ecosystem, is

extensively threatened by degradation. The unsustainable practice of cutting whole

palms for fruit extraction modifies forest's structure and composition and eventually

alters peat-derived greenhouse gas (GHG) emissions. We evaluated the spatio-temporal

variability of soil N2O and CH4 fluxes and environmental controls along a palm swamp

degradation gradient formed by one undegraded site (Intact), one moderately degraded

site (mDeg) and one heavily degraded site (hDeg). Microscale variability differentiated

hummocks supporting live or cut palms from surrounding hollows. Macroscale analysis

considered structural changes in vegetation and soil microtopography as impacted

by degradation. Variables were monitored monthly over 3 years to evaluate intra- and

inter-annual variability. Degradation induced microscale changes in N2O and CH4 emission

trends and controls. Site-scale average annual CH4 emissions were similar along the

degradation gradient (225.6 ± 50.7, 160.5 ± 65.9 and 169.4 ± 20.7 kg C ha−1 year−1 at

the Intact, mDeg and hDeg sites, respectively). Site-scale average annual N2O emissions

(kg N ha−1 year−1) were lower at the mDeg site (0.5 ± 0.1) than at the Intact (1.3 ± 0.6) and

hDeg sites (1.1 ± 0.4), but the difference seemed linked to heterogeneous fluctuations

in soil water-filled pore space (WFPS) along the forest complex rather than to degradation.

Monthly and annual emissions were mainly controlled by variations in WFPS, water

table level (WT) and net nitrification for N2O; WT, air temperature and net nitrification

for CH4. Site-scale N2O emissions remained steady over years, whereas CH4 emissions

rose exponentially with increased precipitation. While the minor impact of degradation

on palm swamp peatland N2O and CH4 fluxes should be tested elsewhere, the evidenced

large and variable CH4 emissions and significant N2O emissions call for improved modeling

of GHG dynamics in tropical peatlands to test their response to climate changes.

How to cite: Hergoualc’h, K., Dezzeo, N., Verchot, L., Martius, C., van Lent, J., Del Aguila Pasquel, J., and Lopez, M.: Spatial and temporal variability of soil N2O and CH4 fluxes along a degradation gradient in a palm swamp peat forest in the Peruvian Amazon, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-831, https://doi.org/10.5194/egusphere-egu21-831, 2021.

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