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

Autor: Christopher Martius, Mariela López Gonzales, Nelda Dezzeo, Jeffrey van Lent, Jhon del Aguila-Pasquel, Louis V. Verchot, Kristell Hergoualc'h
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Global Change Biology 26 (2020) 10
Global Change Biology, 26(10), 7198-7216
ISSN: 1354-1013
DOI: 10.1111/gcb.15354
Popis: Mauritia flexuosa palm swamp, the prevailing Peruvian Amazon peatland ecosystem, isextensively threatened by degradation. The unsustainable practice of cutting wholepalms for fruit extraction modifies forest's structure and composition and eventuallyalters peat-derived greenhouse gas (GHG) emissions. We evaluated the spatio-temporalvariability of soil N2O and CH4 fluxes and environmental controls along a palm swampdegradation gradient formed by one undegraded site (Intact), one moderately degradedsite (mDeg) and one heavily degraded site (hDeg). Microscale variability differentiatedhummocks supporting live or cut palms from surrounding hollows. Macroscale analysisconsidered structural changes in vegetation and soil microtopography as impactedby degradation. Variables were monitored monthly over 3 years to evaluate intra- andinter-annual variability. Degradation induced microscale changes in N2O and CH4 emissiontrends and controls. Site-scale average annual CH4 emissions were similar along thedegradation gradient (225.6 ± 50.7, 160.5 ± 65.9 and 169.4 ± 20.7 kg C ha−1 year−1 atthe 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) andhDeg sites (1.1 ± 0.4), but the difference seemed linked to heterogeneous fluctuationsin 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, watertable level (WT) and net nitrification for N2O; WT, air temperature and net nitrificationfor CH4. Site-scale N2O emissions remained steady over years, whereas CH4 emissionsrose exponentially with increased precipitation. While the minor impact of degradationon palm swamp peatland N2O and CH4 fluxes should be tested elsewhere, the evidencedlarge and variable CH4 emissions and significant N2O emissions call for improved modelingof GHG dynamics in tropical peatlands to test their response to climate changes.
Databáze: OpenAIRE
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