Collaborative Research: Forest productivity and hydrological patterns regulate methane fluxes from peatlands in the Amazon basin

Project: Research project

Project Details


Project Summary Collaborative Research: Forest productivity and hydrological patterns regulate methane fluxes from peatlands in the Amazon basin Overview: The Amazon basin contains the largest wetland system ,~1,000,000 km2, emitting greenhouse gases (GHG) such as methane (CH4) on the order of 1.7 to 21 Tg CH4 y-1. Recent reports of hundreds of peatlands across basins in the West and Central Amazon (Pastaza-Maraon, Beni-Mamor and Negro River) suggest they play an important, previously not considered regional role in OC and GHG dynamics. Field measurements have shown these peatlands as major unreported OC repository (3-6 Gt), and in several Amazon peatlands we have recently recorded significant GHG emissions (CO2, N2O, CH4), and large variability in environmental and biological (plants and microbes) diversity. We propose to study a set of sites that are ecologically variable yet representative of the peatland types in the Pastaza-Maraon region. Evaluations of C stocks, primary productivity, GHG fluxes and response to water table manipulation are proposed to test hypotheses about the ecological drivers and sensitivity of CH4 flux to environmental change. Our team is comprised of scientists with complementary expertise and backgrounds including peat CH4 flux and geomicrobiology (Cadillo-Quiroz), tropical forest biogeochemistry (van Haren), biogeochemistry modeling (Zhuang) and forest productivity and conservation (Del Castillo). Intellectual Merit: The Pastaza-Maraon basin in the western Amazon contains the highest density of peatlands in the region, holding an estimated 3-6 Gt of soil OC in an area of 21,929 Km2. In our preliminary study of eight Amazon peatlands in this region, we found all sites emitted GHG at highly variable rates, likely caused by multiple biotic and abiotic factors. Our results support that a broad ecological and environmental diversity occur in Amazon peatlands, where GHG fluxes are highly variable within and among sites. With a preliminary total CH4 emission estimate of ~0.8 Gt y-1, peatlands in the Pastaza- Paraon basin can play a major role in regional GHG fluxes and the undocumented seasonal variation and ecosystem controls on OC stocks and CH4 fluxes needs to be systematically studied. We propose to test the following hypotheses by continuously studying a set of contrasting Amazon peatlands: (H1) Hydrology and vegetation dynamics are the main drivers of GHG flux dynamics in Amazon peatlands through control of soil redox potential and carbon inputs. (H2) The response of GHG flux to water table manipulation is modulated by peatland diversity. We propose to establish research plots in three representative peatlands for continuous monitoring of trees biomass, litter inputs, respiration rates, water table fluctuation, soil and air temperature, GHG (CO2, CH4, N2O) fluxes and soil water geochemistry. Water table manipulations will be done for two years across sites to of its influence on CH4 flux and to test whether peatland diversity has a modulating effect. To further evaluate peatland variability and its influences on GHG flux, we will also develop time discrete samplings at four additional sites. Finally, overall field observations and manipulations responses will be integrated through modeling efforts for these representative peatlands. Broader Impacts: The composite above and belowground OC content makes Amazon peatlands the densest sites in OC in the Amazon, and their C cycling can influence regional GHG emissions. Measuring OC stocks, fluxes and GHGs is of critical scientific and societal importance to predict their response and/or feedbacks to observed atmospheric change. We will provide the first comprehensive analysis of an overlooked pool of OC and source of GHGs in the Amazon. This will benefit the scientific community in general but in particular will provide data to quantify the uncertainty of CH4 emissions from the Amazon. of the project will collect data of C stocks and fluxes for future comparisons under climatic change and will provide evidence to monitor tropical peatlands for future conservation and policy-making efforts. This collaborative effort including three US and one Peruvian (IIAP) institutions, will train a postdoctoral researcher, two graduate and one undergraduate students, plus IIAP personnel. Field consultants will include Peruvian students independently developing a Professional Title research at IIAP. Our project will further contribute to the capacity building in the region by providing open training workshops at IIAP, and also by our work through a virtual classroom program connecting high school students in Arizona and Iquitos to discuss the impact of ecological research in Amazon peatlands, to track expeditions and execute independent sister science fair projects. Our educational activities at the high school level are targeted to generate an effective conservation-teaching tool to reach a broader public
Effective start/end date5/1/144/30/19


  • NSF: Directorate for Biological Sciences (BIO): $643,874.00


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