School of Ecology and Environmental Sciences, Yunnan University, Kunming, 650500, China; Ministry of Education Key Laboratory for Transboundary Eco-Security of Southwest, Kuming, China.
Kunming Natural Resources Comprehensive Survey Center of China Geological Survey/Technology Innovation Center for Natural Ecosystem Carbon Sink, Ministry of Natural Resources, 650100: Kunming, China.
J Environ Manage. 2024 Jul;363:121395. doi: 10.1016/j.jenvman.2024.121395. Epub 2024 Jun 8.
Vegetation degradation caused by intense human disturbances poses a significant challenge to the preservation and improvement of ecosystem functions and services in the karst region of southwest China. Soil microorganisms are major regulators of ecosystem multifunctionality (EMF). Currently, there is a dearth of knowledge regarding the effects of vegetation degradation on soil microbial communities and their corresponding multiple ecosystem functions in karst regions. In this study, we selected the vegetation degradation sequences of second natural forest (NF), agroforestry (AS) and cropland (CL) to investigate the diversity of bacterial, fungal and protistan communities, and their hierarchical co-occurrence network, and EMF to explore the relationships between them. Compared to the NF, the carbon cycling index, nitrogen cycling index, soil water regulation power, and the EMF were significantly decreased by 8.2%-50.6%, 48.7%-86.8%, 19.8%-24.5%, and 31.4%-69.5% in the AS and CL, respectively. The development of EMF can be explained by the fungal, protistan and microbial hierarchical β-diversity, as well as the complexity (e.g. degree) of microbial hierarchical interactions during the process of vegetation degradation. Notably, correlations between the abundances of sensitive amplicon sequence variants (sASVs) for different karst vegetation types and EMF varied in distinct network modules, being positive in module 1 and negative in module 2. Moreover, the relative abundance of keystone taxa in fungal and protistan communities provided greater contributions to EMF than the bacterial communities. Additionally, random forest modeling showed that carbon and nitrogen sources, and soil water content, and trace elements (e.g. exchangeable magnesium, iron, manganese, and zinc) were identified as key driving factors of the EMF. Collectively, our findings demonstrate that vegetation degradation obviously alters soil microbial diversities and hierarchical interactions, emphasizing their key role in maintaining ecosystem functions and health in karst regions.
强烈的人为干扰导致的植被退化，对中国西南喀斯特地区生态系统功能和服务的保护和改善构成了重大挑战。土壤微生物是生态系统多功能性（EMF）的主要调节者。目前，对于植被退化对喀斯特地区土壤微生物群落及其相应的多种生态系统功能的影响，我们的了解还很匮乏。在本研究中，我们选择了次生天然林（NF）、农林复合（AS）和耕地（CL）的植被退化序列，以调查细菌、真菌和原生动物群落的多样性，及其层次共生网络，以及 EMF，以探索它们之间的关系。与 NF 相比，AS 和 CL 中的碳循环指数、氮循环指数、土壤水分调节能力和 EMF 分别显著降低了 8.2%-50.6%、48.7%-86.8%、19.8%-24.5%和 31.4%-69.5%。EMF 的发展可以通过真菌、原生动物和微生物层次β多样性，以及植被退化过程中微生物层次相互作用的复杂性（例如，度）来解释。值得注意的是，不同喀斯特植被类型敏感扩增子序列变异体（sASVs）丰度与 EMF 之间的相关性在不同的网络模块中表现出不同的特征，在模块 1 中为正相关，在模块 2 中为负相关。此外，真菌和原生动物群落中关键分类群的相对丰度对 EMF 的贡献大于细菌群落。此外，随机森林模型表明，碳和氮源、土壤水分含量以及痕量元素（例如可交换镁、铁、锰和锌）是 EMF 的关键驱动因素。总的来说，我们的研究结果表明，植被退化明显改变了土壤微生物的多样性和层次相互作用，强调了它们在维持喀斯特地区生态系统功能和健康方面的关键作用。
