Home | Sitemap | Login

   

Scientific Articles/Reports, Newsletters and Press Releases

Title: Modeling relationships between water table depth and peat soil carbon loss in Southeast Asian plantations
Date: 09-Jul-2015
Category: Article
Source/Author: IOP Science/Kimberly M Carlson, Lael K Goodman and Calen C May-Tobin
Description: Plantation-associated drainage of Southeast Asian peatlands has accelerated in recent years. Draining exposes the upper peat layer to oxygen, leading to elevated decomposition rates and net soil carbon losses. Empirical studies indicate positive relationships between long-term water table (WT) depth and soil carbon loss rate in peatlands.

Abstract
Plantation-associated drainage of Southeast Asian peatlands has accelerated in recent years. Draining exposes the upper peat layer to oxygen, leading to elevated decomposition rates and net soil carbon losses. Empirical studies indicate positive relationships between long-term water table (WT) depth and soil carbon loss rate in peatlands. These correlations potentially enable usingWTdepth as a proxy for soil carbon losses from peatland plantations. Here, we compile data from published research assessingWTdepth and carbon balance in tropical plantations on peat.Wemodel net carbon loss from subsidence studies, as well as soil respiration (heterotrophic and total) from closed chamber studies, as a function ofWTdepth.WTdepth across all 12 studies and 59 sites is 67 ± 20 cm (mean ± standard deviation). MeanWTdepth is positively related to net carbon loss, as well as soil respiration rate. Our models explain 45% of net carbon loss variation and 45–63% of soil respiration variation. At a 70 cmWT depth, the subsidence model suggests net carbon loss of 20 tC ha−1 yr−1 (95% confidence interval (CI) 18–22 tC ha−1 yr−1) for plantations drained for >2 yr. Closed chambermeasured total soil respiration at this depth is 20 tC-CO2 ha−1 yr−1 (CI 17–24 tC-CO2 ha−1 yr−1) while heterotrophic respiration is 17 tC-CO2 ha−1 yr−1 (CI 14–20 tC-CO2 ha−1 yr−1),∼82% of total respiration. While land use is not a significant predictor of soil respiration,WTdepths are greater at acacia (75 ± 16 cm) than oil palm (59 ± 15 cm) sample sites. Improved spatio-temporal sampling of the full suite of peat soil carbon fluxes—including fluvial carbon export and organic fertilizer inputs— will clarify multiple mechanisms leading to carbon loss and gain, supporting refined assessments of the global warming potential of peatland drainage.

Download file here.



[ Back ] [ Print Friendly ]