Butler, Andre, Meir, Patrick, Saiz, Gustavo, Maracahipes, Leandro, Marimon, Beatriz Schwantes, and Grace, John (2012) Annual variation in soil respiration and its component parts in two structurally contrasting woody savannas in Central Brazil. Plant and Soil, 352 (1-2). pp. 129-142.

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Abstract

Background and aims: Due to the high spatial and temporal variation in soil CO₂ efflux, terrestrial carbon budgets rely on a detailed understanding of the drivers of soil respiration from a diverse range of ecosystems and climate zones. In this study we aim to evaluate the independent influence of vegetation structure and climate on soil CO₂ efflux within cerrado ecosystems.

Methods: We examine the seasonal and diel variation of soil CO₂ efflux, including its autotrophic and heterotrophic components, within two adjacent and structurally contrasting woody savannas in central Brazil.

Principle results: We found no significant difference in the annual soil CO₂ efflux between the two stands (p=0.53) despite a clear disparity in both LAI (p<0.01) and leaf litterfall (p<0.01). The mean annual loss of carbon from the soil was 17.32(± 1.48) Mg Cha⁻¹ of which approximately 63% was accounted for by autotrophic respiration. The relative contribution of autotrophic respiration varied seasonally between 55% in the wet season to 79% of the total soil CO₂ efflux in the dry season. Furthermore, seasonal fluctuations of all the soil respiration components were strongly correlated with soil moisture (R²=0.79-0.90, p<0.01).

Conclusions: Across these two structurally distinct cerrado stands, seasonal variations in rainfall, was the main driver of soil CO₂ efflux and its components. Consequently, soil respiration within these ecosystems is likely to be highly sensitive to any changes in seasonal precipitation patterns.

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