Central South University of Forestry and Technology, Changsha, China.
Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou, China.
PeerJ. 2022 Mar 7;10:e12739. doi: 10.7717/peerj.12739. eCollection 2022.
The rapid growth and expansion of (Thunb. ex L. f.) D. Don in karst area strongly affects plant composition of native deciduous broad-leaved forest, which seriously threat ecosystem function and service. Given the importance of soil microorganisms in regulating nutrients cycling and plant species coexistence, understanding soil microbial attributes and their relationships with soil and vegetation features in forests harboring different abundance will help understanding the drivers of ecosystem function changes. Here we examined the diversity and composition of soil bacterial and fungal communities and their correlations with plant diversity as well as soil physicochemical properties in karst broad-leaved forests with different relative abundances of (i.e., a high, moderate, low and no proportion level with a stem density of 1,487, 538, 156 and 0 plant/hm, respectively) in Mid-Subtropical China. We found that soil pH decreased while soil water content (SWC), total nitrogen (TN), total phosphorus (TP) and total potassium (TK) tended to increase with the increase in abundance. In contrast, soil available nitrogen (AN), available phosphorus (AP) and available potassium (AK) content declined by 26.1%∼49.3% under the high level of abundance. A gradual decrease in relative abundance of Acidobacteria and Chloroflexi while a pronounced increase in relative abundance of Ascomycota and Basidiomycota were observed with increase of abundance. Alternations in bacterial composition were closely related to changes in AP and AK, while the change of fungal structure was mainly related to SWC, soil organic carbon (SOC) and pH, indicating that bacterial community was sensitive to declines in soil available nutrients and fungal structure was sensitive to changes in soil physicochemical properties (i.e., pH and SWC) and organic carbon resource. Understory plants had the highest -diversity in forest containing moderate abundance of , which might be related to the high bacterial diversity. Our findings suggest conservation of soil bacterial and fungal taxa that are responsible for nutrients availability and carbon sequestration is of great significance for improving the resistance of natural deciduous broad-leaved forests to the rapid spread of in karst areas. Moreover, Acidobacteria, Chloroflexi, Ascomycota and Basidiomycota are potential indicators for soil properties changes, which should be taken into consideration in karst forest managements.
（Thunb. ex L. f.）D. Don 在喀斯特地区的快速生长和扩张强烈影响了本地落叶阔叶林的植物组成，严重威胁着生态系统功能和服务。鉴于土壤微生物在调节养分循环和植物物种共存方面的重要性，了解森林中土壤微生物的属性及其与土壤和植被特征的关系，对于理解生态系统功能变化的驱动因素将有所帮助。本研究以中国中亚热带不同密度（高密度、中密度、低密度和无密度，分别对应 156、538、487 和 0 株/hm2） （Thunb. ex L. f.）D. Don 的喀斯特阔叶林为研究对象，分析了土壤细菌和真菌群落的多样性和组成及其与植物多样性以及土壤理化性质的关系。结果表明，土壤 pH 值随（Thunb. ex L. f.）D. Don 密度的增加而降低，而土壤含水量（SWC）、总氮（TN）、总磷（TP）和总钾（TK）则趋于增加。相反，在高密度下，土壤有效氮（AN）、有效磷（AP）和有效钾（AK）含量分别下降了 26.1%∼49.3%。随着（Thunb. ex L. f.）D. Don 密度的增加，酸杆菌和绿弯菌的相对丰度逐渐减少，而子囊菌和担子菌的相对丰度明显增加。细菌组成的变化与 AP 和 AK 的变化密切相关，而真菌结构的变化主要与 SWC、土壤有机碳（SOC）和 pH 值有关，这表明细菌群落对土壤有效养分的减少敏感，而真菌结构对土壤理化性质（即 pH 值和 SWC）和有机碳资源的变化敏感。在（Thunb. ex L. f.）D. Don 中密度的森林中，林下植物具有最高的多样性，这可能与较高的细菌多样性有关。本研究结果表明，保护负责养分供应和碳固存的土壤细菌和真菌类群，对于提高喀斯特地区天然落叶阔叶林对（Thunb. ex L. f.）D. Don 快速传播的抵抗力具有重要意义。此外，酸杆菌、绿弯菌、子囊菌和担子菌是土壤性质变化的潜在指标，在喀斯特森林管理中应予以考虑。
