Title
Spatial and temporal variability of soil N<inf>2</inf>O and CH<inf>4</inf> fluxes along a degradation gradient in a palm swamp peat forest in the Peruvian Amazon
Date Issued
01 December 2020
Access level
open access
Resource Type
journal article
Author(s)
Hergoualc’h K.
Dezzeo N.
Verchot L.V.
Martius C.
van Lent J.
López Gonzales M.
Publisher(s)
Blackwell Publishing Ltd
Abstract
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 spatiotemporal 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.
Start page
7198
End page
7216
Volume
26
Issue
12
Language
English
OCDE Knowledge area
Ciencias del medio ambiente
Scopus EID
2-s2.0-85090406265
PubMed ID
Source
Global Change Biology
ISSN of the container
13541013
Source funding
Centre for International Forestry Research
Sponsor(s)
This research was conducted under the Sustainable Wetlands Adaptation and Mitigation Program (SWAMP) and CIFOR's Global Comparative Study on REDD+. It was generously supported by the Government of the United States of America (Grant MTO‐069018) and Government of the Norway (Grant agreement # QZA‐12/0882). It was undertaken as part of the CGIAR research program on Forests, Trees and Agroforestry (CRP‐FTA) with financial support from the CGIAR Fund Donors. We are extremely thankful to Julio Grandez Rios for his long‐term commitment and dedication to collecting field data; this work would have not been possible without his support. We would further like to thank Nicole Mitidieri Rivera for her hard work in the field at the beginning of this experiment. The authors are grateful to the staff of the Quistococha reserve for facilitating the study and to the inhabitants of the villages San Julian and Las Brisas (the degraded sites), especially to Ulises Mozombite Murayari for his endless efforts and hard work as a field assistant. We would like to extend our gratitude toward our partner—the Instituto de Investigaciones de la Amazonía Peruana (IIAP) in Iquitos, and we would especially like to thank Dr. Dennis del Castillo Torres and his team for their support. Finally, four referees and the editor of the journal did their utmost to improve this manuscript; their contribution is very much appreciated.
Sources of information: Directorio de Producción Científica Scopus