Xu Miaoping, Xi Jiazhen, Liu Yushu, Li Shiqing
College of Soil and Water Conservation Science and Engineering, Northwest A&F University, Yangling, 712100, Shaanxi, China.
College of Soil and Water Conservation Science and Engineering, Northwest A&F University, Yangling, 712100, Shaanxi, China.
J Environ Manage. 2024 Nov;370:122668. doi: 10.1016/j.jenvman.2024.122668. Epub 2024 Sep 26.
Sequestering farmland for secondary succession is an effective method of restoring ecosystem services to degraded farmland, but long-term secondary succession often alters ecosystem environments, resources, and substrate stoichiometry. Currently, it is not known how resource changes and stoichiometric imbalances due to secondary succession affect soil microbial community structure and function, hindering our understanding of the natural resilience for degraded ecosystems. Here, we assessed nutrient limitation elements, community structure, metabolic functions, co-occurrence network complexity, and community stability of soil microorganisms during secondary succession of abandoned farmlands on the Loess Plateau. Results showed that secondary succession significantly altered plant characteristics and soil properties, as well as causing stoichiometry imbalances in nutrient resources. Along the secondary succession chronosequence, microbial nutrient metabolism shifted from phosphorus (P) limitation to carbon (C) and nitrogen (N) co-limitation. Microbial diversity, eutrophic flora, plant growth-promoting bacteria, and metabolism functional groups increased significantly during the 20 years after the abandonment of the farmlands, but decreased significantly with long-term succession. However, oligotrophic flora and P-solubilizing bacteria became dominant after 30 years of secondary succession on abandoned farmlands. The topological features of microbial co-occurring networks, including nodes, degree, closeness, betweenness, and eigenvector complexity, natural connectivity, and community stability first increased and then decreased with secondary succession. Correlation and random forest analyses indicated that secondary succession-induced stoichiometry imbalances in C:N and N:P, as well as changes in soil organic C and lignin phenols, were the key factors influencing microbial community structure and function. Overall, these results enhance our understanding of the adaptation strategies of soil microbial communities in ecologically managed regions to changes in ecosystem resources and stoichiometric imbalances.
封存农田以进行次生演替是恢复退化农田生态系统服务的有效方法，但长期的次生演替往往会改变生态系统环境、资源和底物化学计量。目前，尚不清楚次生演替引起的资源变化和化学计量失衡如何影响土壤微生物群落结构和功能，这阻碍了我们对退化生态系统自然恢复力的理解。在此，我们评估了黄土高原弃耕农田次生演替过程中土壤微生物的养分限制元素、群落结构、代谢功能、共现网络复杂性和群落稳定性。结果表明，次生演替显著改变了植物特征和土壤性质，同时也导致了养分资源的化学计量失衡。沿着次生演替时间序列，微生物养分代谢从磷（P）限制转变为碳（C）和氮（N）共同限制。弃耕后的20年内，微生物多样性、富营养菌群、植物促生细菌和代谢功能群显著增加，但随着长期演替显著减少。然而，在弃耕农田次生演替30年后，贫营养菌群和溶磷细菌成为优势菌群。微生物共现网络的拓扑特征，包括节点、度、紧密性、中介性和特征向量复杂性、自然连通性以及群落稳定性，随着次生演替先增加后减少。相关性和随机森林分析表明，次生演替引起的C:N和N:P化学计量失衡以及土壤有机碳和木质素酚的变化是影响微生物群落结构和功能的关键因素。总体而言，这些结果加深了我们对生态管理区域土壤微生物群落对生态系统资源变化和化学计量失衡的适应策略的理解。
