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首页> 外文期刊>Soil Biology & Biochemistry >Loss of labile organic carbon from subsoil due to land-use changes in subtropical China
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Loss of labile organic carbon from subsoil due to land-use changes in subtropical China

机译：亚热带中国土地利用变化导致土壤中不稳定有机碳的流失

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Topsoil carbon (C) stocks are known to decrease as a consequence of the conversion of natural ecosystems to plantations or croplands; however, the effect of land use change on subsoil C remains unknown. Here, we hypothesized that the effect of land use change on labile subsoil organic C may be even stronger than for topsoil due to upward concentration of plantations and crops root systems. We evaluated soil labile organic C fractions, including particulate organic carbon (POC) and its components [coarse POC and fine POC], light fraction organic carbon (LFOC), readily oxidizable organic carbon, dissolved organic carbon (DOC) and microbial biomass down to 100 cm soil depth from four typical land use systems in subtropical China. Decrease in fine root biomass was more pronounced below 20 cm than in the overlying topsoil (70% vs. 56% for plantation and 62% vs. 37% for orchard. respectively) driving a reduction in subsoil labile organic C stocks. Land use changes from natural forest to Chinese fir plantation, Chinese chestnut orchard, or sloping tillage reduced soil organic C stocks and that of its labile fractions both in top and subsoil (20-100 cm). POC reduction was mainly driven by a decrease in fine POC in topsoil, while DOC was mainly reduced in subsoil. Fine POC, LFOC and microbial biomass can be useful early indicators of changes in topsoil organic C. In contrast, LFOC and DOC are useful indicators for subsoil. Reduced proportions of fine POC, LFOC, DOC and microbial biomass to soil organic C reflected the decline in soil organic C quality caused by land use changes. We conclude that land use changes decrease C sequestration both in topsoil and subsoil, which is initially indicated by the labile soil organic C fractions. (C) 2015 Elsevier Ltd. All rights reserved.
机译：已知由于自然生态系统向人工林或农田的转化，表土碳（C）储量减少了;然而，土地利用变化对土壤C的影响仍然未知。在这里，我们假设由于种植园和农作物根系的高度集中，土地利用变化对不稳定的底土有机碳的影响甚至可能比表土更强。我们评估了土壤不稳定的有机碳组分，包括颗粒有机碳（POC）及其成分[粗POC和细POC]，轻组分有机碳（LFOC），易氧化有机碳，溶解有机碳（DOC）和微生物生物量，直至来自亚热带的四种典型土地利用系统的土壤深度为100厘米。在20 cm以下，细根生物量的减少比上层表土的减少更为明显（分别为人工林的70％和56％，果园的62％和37％），这导致了土壤中不稳定的有机碳库的减少。从天然林到杉木人工林，板栗果园或倾斜耕作的土地利用减少了土壤有机碳储量及其在上层和下层土壤（20-100厘米）中不稳定部分的存量。 POC的减少主要是由表层土壤中细小POC的减少引起的，而DOC主要在表层土壤中的减少。精细的POC，LFOC和微生物生物量可以作为表土有机碳变化的有用早期指标。相反，LFOC和DOC是下层土壤的有用指标。精细POC，LFOC，DOC和微生物生物量在土壤有机碳中的比例降低反映了土地利用变化导致土壤有机碳质量下降。我们得出的结论是，土地利用变化减少了表层土壤和下层土壤中的C固存，这最初由不稳定的土壤有机C组分表明。 （C）2015 Elsevier Ltd.保留所有权利。

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