Evaluating a Microbial Functional Group-based Model to Explain Greenhouse Gas Productions and Consumptions from Puerto Rican Tropical Forest Soils
Abstract
Wet tropical forest soils contribute significantly to global emissions of carbon dioxide (CO2) and methane (CH4). However, landscape topography largely controls the proportions of CO2 over CH4 emissions, particularly in the tropical regions. Here we attempt to explain the dynamics of greenhouse gas emissions along a ridge-slope-valley topographic gradient in the El Yunque National Forest, Puerto Rico using a microbial functional group-based model. In general, CO2 fluxes follows the trend of ridge>>slope>valley, where average fluxes in ridge soils were approximately 4.5 times greater than corresponding values in the valley soil. In contrast, CH4 fluxes follow the trend of valley>>slope>=ridge. On average, we observed net emissions of CH4 from valley soil and marginal but net uptakes of CH4 from ridge soils. Soil temperature ranges were overlapping across topographic locations, however, soil water (and oxygen) ranges were contrasting between ridge vs. valley soils. Soil porewater chemistry (e.g. concentrations of organic acid, dominant electron acceptor, and pH) also varied as a function of topographic location. These changes are expected to alter the substrates for soil microbial respiration, methane production, and methane consumption as well as the dynamics of respective microbial functional groups (acetotrophic or hydrogenotrophic methanogens and methanotrophs), which in turn, can influence net fluxes of CO2 and CH4. Thus, contrasting patterns of soil water (and oxygen) and associated soil biogeochemistry between ridge vs. valley soils played an instrumental role in GHGs fluxes from the wet tropical soil of Puerto Rico, which can be mechanistically explained using a microbial functional group-based model. This study contributes to the ongoing development and improvements of the Earth System Models to better simulate the microbial roles on global carbon cycling.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B21F..06S
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 1631 Land/atmosphere interactions;
- GLOBAL CHANGEDE: 1655 Water cycles;
- GLOBAL CHANGE