Effect of rainfall seasonality on carbon storage in tropical dry ecosystems

While seasonally dry conditions are typical of large areas of the tropics, their biogeochemical responses to seasonal rainfall and soil carbon (C) sequestration potential are not well characterized. Seasonal moisture availability positively affects both productivity and soil respiration, resulting i...

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Bibliographic Details
Published in:Journal of geophysical research. Biogeosciences 2013-07, Vol.118 (3), p.1156-1167
Main Authors: Rohr, Tyler, Manzoni, Stefano, Feng, Xue, Menezes, Rômulo S. C., Porporato, Amilcare
Format: Article
Language:English
Subjects:
Annual rainfall
biogeochemical model
Carbon
Carbon capture and storage
Carbon cycle
Carbon sequestration
carbon storage
Drought
Drying
Ecosystems
Moisture availability
primary productivity
Productivity
Rainfall
Rainfall distribution
rainfall variability
Rainy season
Respiration
Seasonal variations
seasonally dry ecosystems
Soil (material)
Soil moisture
Tropical environments
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Summary:While seasonally dry conditions are typical of large areas of the tropics, their biogeochemical responses to seasonal rainfall and soil carbon (C) sequestration potential are not well characterized. Seasonal moisture availability positively affects both productivity and soil respiration, resulting in a delicate balance between C deposition as litterfall and C loss through heterotrophic respiration. To understand how rainfall seasonality (i.e., duration of the wet season and rainfall distribution) affects this balance and to provide estimates of long‐term C sequestration, we develop a minimal model linking the seasonal behavior of the ensemble soil moisture, plant productivity, related C inputs through litterfall, and soil C dynamics. A drought‐deciduous caatinga ecosystem in northeastern Brazil is used as a case study to parameterize the model. When extended to different patterns of rainfall seasonality, the results indicate that for fixed annual rainfall, both plant productivity and soil C sequestration potential are largely, and nonlinearly, dependent on wet season duration. Moreover, total annual rainfall is a critical driver of this relationship, leading at times to distinct optima in both production and C storage. These theoretical predictions are discussed in the context of parameter uncertainties and possible changes in rainfall regimes in tropical dry ecosystems. Key Points Seasonal rainfall drives unique optima in mean carbon storage and productivityDecomposition and litterfall compete to further complicate carbon cyclingFuture carbon storage becomes a function of current and projected climate trends
ISSN:2169-8953
2169-8961
DOI:10.1002/jgrg.20091