A missing sink in forest ecosystems, the effect of dwarf bamboo understory on soil carbon sequestration

为了评价矮秆竹林下植被对森林生态系统土壤固碳的影响，比较了两个相邻落叶阔叶林立地间表层矿物层土壤碳含量和溶解有机碳(DOC)通量。由于SASA凋落物的存在，SASA站点有机土层的DOC通量比非SASA站点高出20%。我们还应用Rothamsted Carbon(Roth C)模型估算了SASA林下土壤有机质的固碳量。一项为期15年的模拟是在三个情景下进行的：A(树木地上和地下凋落物生产)、B(树木和SASA地上和地下凋落物生产)、C(树木和SASA地上和地下凋落物生产)。土壤有机碳年累积量(约0.7tC ha~(-1)yr~(-1))高于土壤有机碳年累积量(约0.7tC ha~(-1)yr~(-1))。这些结果表明，SASA通过增加土壤对DOC的吸附量而对土壤固碳起到正启动作用，并且SASA的凋落物产量(尤其是地下)对落叶阔叶林生态系统的SOC固持具有重要意义。

To evaluate the effect of dwarf bamboo (Sasa senanensis) understory on soil carbon sequestration in forest ecosystems, we compared the soil carbon content and the dissolved organic carbon (DOC) flux for a surface mineral horizon between two adjacent deciduous broad-leaved forest sites. The DOC flux of the organic horizon at the Sasa site was 20% higher than that at the non-Sasa site because of a presence of Sasa litterfall. We also estimated the carbon sequestration of organic matter in forested soil with understory Sasa by applying the Rothamsted carbon (Roth C) model. A 15-year simulation was run three scenarios: A (aboveground tree litter production), B (aboveground tree and Sasa litter production), C (above- and belowground litter production of trees and Sasa). The annual SOC accumulation in case C (ca. 0.7tC ha-1 yr-1) was higher than that of case A and B. These results suggest that Sasa exerts a positive priming effect on soil carbon sequestration by increasing the amount of DOC sorption, and that litter production (especially for belowground) of Sasa are important to SOC sequestration in deciduous broad-leaved forestecosystems.