内蒙古草原灌丛化对土壤有机碳的影响及其驱动机制

项目名称： 内蒙古草原灌丛化对土壤有机碳的影响及其驱动机制

项目编号： No.31470525

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 生物科学

项目作者： 沈海花

作者单位： 中国科学院植物研究所

项目金额： 86万元

中文摘要： 草原灌丛化在干旱半干旱地区普遍发生，给生态系统结构和功能产生深刻影响。然而，草原灌丛化如何改变土壤有机碳含量一直在争论之中，野外观测证据有限而且绝大多数仅仅局限于浅层土壤，对驱动机制的研究也十分缺乏。灌木的深根性不仅显著影响浅层土壤也会深刻改变深层土壤的有机碳，而且灌丛化对土壤有机碳的影响受灌木种类、灌丛化程度、土壤环境和气候条件等多种因素的控制。本项目拟以内蒙古典型灌丛化草原为研究对象，采用有机地球化学、生物标志物及微生物分子生态学等分析方法，研究不同种类灌木及不同程度的灌丛化对表层及深层土壤有机碳的影响，阐明土壤有机碳的垂直分布与土壤理化性质和微生物群落组成等的关系，揭示灌丛化对草原生态系统土壤有机碳分布、储量的影响以及驱动机制。本项目的研究结果为正确评估草原灌丛化的土壤碳源汇效应，保护干旱半干旱地区草原的生态功能提供必要的科学依据。

中文关键词： 土壤有机碳；深层土壤；草原灌丛化；草原生态系统；全球变化

英文摘要： Shrub encroachment in arid and semiarid grasslands has been widely reported, and could substantially affect ecosystem structure and function. However, the impacts of shrub encroachment on soil organic carbon (SOC) storage and its underlying mechanisms still remain unclear. There are only few studies from field observations, and most of the evidences are limited in shallow soil layers within 1m, and little evidence is available from deeper soil layers. Shrub plants usually have deep root than grass. Shrub encroachment into grassland are expected to not only change SOC in shallow soil, but also to affect the SOC in deep soil, which is controlled by several factors, such as shrub species, degree of shrub encroachment, soil environment and climate etc. In this proposal, we try to provide first attempt to examine the impacts of shrub encroachment on SOC in deep soil, and their driving mechanism in Inner-Mongolian grasslands. By using field observation, biogeochemical and molecular microbial ecological methods, we are to 1) investigate the SOC both in shallow and deep soil under conditions with different shrub species and different degree of shrub encroachment; 2) clarify the effect of shrub encroachment on soil physicochemical characteristics and microbial community structure, and the relationship between these changes and SOC storage and its vertical distribution; then 3) indicate the impacts of shrub encroachment on SOC distribution and storage, and their underlying mechanisms. This study will provide scientific insight and basic information for predicting the soil carbon effect of shrub encroachment, and conserving ecosystem function in arid and semiarid grasslands.

英文关键词： Soil organic carbon;deep soil;shrub encroachment;grassland;global change