Unraveling the mechanisms underlying pulse dynamics of soil respiration in tropical dry forests

Tropical dry forests are already undergoing changes in the quantity and timing of rainfall, but there is great uncertainty over how these shifts will affect belowground carbon (C) cycling. While it has long been known that dry soils quickly release carbon dioxide (CO2) upon rewetting, the mechanisms...

Full description

Saved in:
Bibliographic Details
Published in:Environmental research letters 2016-10, Vol.11 (10), p.105005
Main Authors: Waring, Bonnie G, Powers, Jennifer S
Format: Article
Language:English
Subjects:
Biomass
Birch effect
Carbon cycle
Carbon dioxide
Decay
Decay rate
Dry forests
ENVIRONMENTAL SCIENCES
Enzymes
Forest ecosystems
Forests
Immobilization
Microorganisms
Organic matter
Organic soils
precipitation
Rainfall
Respiration
seasonality
soil carbon
Soil dynamics
Soil organic matter
Soils
tropical dry forest
Tropical forests
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Tropical dry forests are already undergoing changes in the quantity and timing of rainfall, but there is great uncertainty over how these shifts will affect belowground carbon (C) cycling. While it has long been known that dry soils quickly release carbon dioxide (CO2) upon rewetting, the mechanisms underlying the so-called 'Birch effect' are still debated. Here, we quantified soil respiration pulses and their biotic predictors in response to simulated precipitation events in a regenerating tropical dry forest in Costa Rica. We also simulated the observed rewetting CO2 pulses with two soil carbon models: a conventional model assuming first-order decay rates of soil organic matter, and an enzyme-catalyzed model with Michaelis-Menten kinetics. We found that rewetting of dry soils produced an immediate and dramatic pulse of CO2, accompanied by rapid immobilization of nitrogen into the microbial biomass. However, the magnitude of the rewetting CO2 pulse was highly variable at fine spatial scales, and was well correlated with the size of the dissolved organic C pool prior to rewetting. Both the enzyme-catalyzed and conventional models were able to reproduce the Birch effect when respiration was coupled directly to microbial C uptake, although models differed in their ability to yield realistic estimates of SOC and microbial biomass pool sizes and dynamics. Our results suggest that changes in the timing and intensity of rainfall events in tropical dry forests will exert strong influence on ecosystem C balance by affecting the dynamics of microbial biomass growth.
ISSN:1748-9326
1748-9326
DOI:10.1088/1748-9326/11/10/105005