Zhou Hanchang, Ma Anzhou, Zhou Xiaorong, Chen Xianke, Zhang Jiejie, Zhang Qinwei, Qi Xiangning, Liu Guohua, Zhuang Guoqiang
Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
Front Plant Sci. 2022 Mar 23;13:848691. doi: 10.3389/fpls.2022.848691. eCollection 2022.
Alpine ecosystem stability and biodiversity of the Tibetan plateau are facing threat from dry valley vegetation uplift expansion, a process which is highly connected to variations in the soil microbial community and soil nutrients. However, the variation of microbial community properties and their relationship to soil nutrients have scarcely been explored in Tibetan dry valleys, which is a gap that hampers understanding the dry valley ecosystem's response to vegetation change. In this study, we sampled grasslands (G), a grass-shrub transition area (T), and shrublands (S) along an uplift expansion gradient and investigated the link between microbial community properties and soil nutrients. The results showed that shrub degradation by grass expansion in Tibetan dry valley was accompanied by increasing relative phosphorus (P) limitation, which was the main driver for bacterial and fungal composition variation as it offered highest total effect on PC1 (0.38 and 0.63, respectively). Total phosphorus (TP) was in the center module of bacterial and fungal network under shrub soil and even acted as key nodes in fungal networks. During the replacement by grass, TP was gradually marginalized from both bacterial and fungal center network module and finally disappeared in networks, with ammonia and nitrate gradually appearing in the bacterial network. However, TC and total nitrogen (TN) were always present in the center modules of both fungal and bacterial network. These support that a TP variation-induced compositional and network functional shift in the microbial community was a potential reason for vegetation uplift expansion in Tibetan dry valley. This study highlighted the effect of TP on microbial community properties during dry valley vegetation uplift expansion and offered basic information on Tibetan alpine dry valley ecosystem's response to climate change.
青藏高原的高山生态系统稳定性和生物多样性正面临着干谷植被隆起扩张的威胁，这一过程与土壤微生物群落和土壤养分的变化高度相关。然而，在藏区干谷中，微生物群落特性的变化及其与土壤养分的关系几乎未被探究，这一空白阻碍了我们对干谷生态系统对植被变化的响应的理解。在本研究中，我们沿着隆起扩张梯度对草原（G）、草灌过渡区（T）和灌丛（S）进行了采样，并调查了微生物群落特性与土壤养分之间的联系。结果表明，藏区干谷中草本植物扩张导致的灌丛退化伴随着相对磷（P）限制的增加，这是细菌和真菌组成变化的主要驱动因素，因为它对主成分1（PC1）的总效应最高（分别为0.38和0.63）。总磷（TP）在灌丛土壤下的细菌和真菌网络的中心模块中，甚至在真菌网络中充当关键节点。在被草本植物取代的过程中，TP逐渐从细菌和真菌中心网络模块中边缘化，最终在网络中消失，同时氨和硝酸盐逐渐出现在细菌网络中。然而，有机碳（TC）和总氮（TN）始终存在于真菌和细菌网络的中心模块中。这些结果支持了TP变化引起的微生物群落组成和网络功能转变是藏区干谷植被隆起扩张的潜在原因。本研究突出了TP在干谷植被隆起扩张过程中对微生物群落特性的影响，并提供了有关青藏高原高山干谷生态系统对气候变化响应的基础信息。
