Data for the responses of soil carbon and microbial community in forests

Global changes can alter plant inputs from both above- and below-ground, which thus may differently affect soil carbon and microbial communities. However, the general patterns of how detritus input changes affect them in forests remain unclear. By conducting a meta-analysis of 3193 observations from 165 experiments worldwide, we found that alterations in aboveground litter and/or root inputs had profound effects on soil carbon and microbial communities in forest ecosystems. Litter addition stimulated soil organic carbon (SOC) pools and microbial biomass, while removal of litter, root or both (no inputs) decreased them. The increased SOC under litter addition suggested that aboveground litter inputs benefit SOC sequestration despite accelerated decomposition. Unlike root removal, litter alterations and no inputs altered particulate organic carbon, while all detrital treatments had minor effects on mineral-associated organic carbon. In addition, detrital treatments contrastingly altered soil microbial community, with litter addition or removal shifting it towards fungi, while root removal shifting it towards bacteria. Furthermore, the responses of soil C and microbial biomass to litter alterations positively correlated with litter input rate and total litter input, suggesting that litter input quantity is a critical controller of belowground processes. Taken together, these findings provide critical insights into understanding how altered plant productivity and allocation affects soil carbon cycling, microbial communities and functioning of forest ecosystems under global changes. Future studies can take full advantage of the existing plant detritus experiments, and should focus on the relative roles of litter and roots in forming SOC and its fractions.

全球变化可改变地上与地下的植物输入物，进而对土壤碳库与微生物群落产生差异化影响。然而，森林生态系统中植物碎屑输入变化如何影响土壤碳库与微生物群落的普遍规律仍不明确。本研究通过整合全球165项实验的3193组观测数据开展荟萃分析（meta-analysis），发现地上枯落物和/或根系输入的改变，对森林生态系统的土壤碳库与微生物群落具有显著影响。枯落物添加可提升土壤有机碳（soil organic carbon, SOC）库与微生物生物量，而移除枯落物、根系或同时移除二者（无输入处理）则会降低其水平。枯落物添加下SOC的增加表明，尽管分解过程被加速，地上枯落物输入仍有助于SOC的固存。与根系移除处理不同，枯落物输入改变与无输入处理会影响颗粒有机碳（particulate organic carbon），而所有植物碎屑输入处理均对矿质结合态有机碳（mineral-associated organic carbon）影响微弱。此外，各类植物碎屑输入处理对土壤微生物群落的影响存在显著分化：枯落物添加或移除会使群落结构向真菌主导方向转变，而根系移除则使其向细菌主导方向转变。进一步分析发现，土壤碳与微生物生物量对枯落物输入改变的响应，与枯落物输入速率及总输入量呈正相关，这表明枯落物输入量是地下生态过程的关键调控因子。综上，本研究结果为理解全球变化背景下，植物生产力与分配模式的改变如何影响土壤碳循环、微生物群落及森林生态系统功能提供了关键认知。未来研究可充分利用已有的植物枯落物实验数据，并重点关注枯落物与根系在SOC形成及其组分分馏过程中的相对作用。