Response of soil organic matter dynamics to conversion from tropical forest to grassland as determined by long-term incubationReportar como inadecuado

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Biology and Fertility of Soils

, 44:1053

First Online: 28 May 2008Received: 15 December 2007Revised: 08 April 2008Accepted: 14 April 2008


Understanding soil organic carbon SOC responses to land-use changes requires knowledge of the sizes and mean residence times MRT of specific identifiable SOC pools over a range of decomposability. We examined pool sizes and kinetics of active and slow pool carbon C for tropical forest and grassland ecosystems on Barro Colorado Island, Panama, using long-term incubations 180 days of soil and stable C isotopes. Chemical fractionation acid hydrolysis was applied to assess the magnitude of non-hydrolysable pool C NHC. Incubation revealed that both grassland and forest soil contained a small proportion of active pool C <1%, with MRT of ~6 days. Forest and grassland soil apparently did not differ considerably with respect to their labile pool substrate quality. The MRT of slow pool C in the upper soil layer 0–10 cm did not differ between forest and grassland, and was approximately 15 years. In contrast, changes in vegetation cover resulted in significantly shorter MRT of slow pool C under grassland 29 years as compared to forest 53 years in the subsoil 30–40 cm. The faster slow pool turnover rate is probably associated with a loss of 30% total C in grassland subsoil compared to the forest. The NHC expressed as a percentage of total C varied between 54% and 64% in the surface soil and decreased with depth to ~30%. Grassland NHC had considerably longer MRTs 120 to 320 years as compared to slow pool C. However, the functional significance of the NHC pool is not clear, indicating that this approach must be applied cautiously.

KeywordsActive pool carbon Forest conversion Grassland Incubation Mean residence time Non-hydrolysable carbon Slow pool carbon Stable C isotopes Panama An erratum to this article can be found at

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Autor: Luitgard Schwendenmann - Elise Pendall


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