Liu Guofu, Bai Zhenjian, Cui Guowen, He Wenhua, Kongling Zelai, Ji Guoxu, Gong Hao, Li Dandan
Department of Animal Science and Technology, Northeast Agricultural University, Harbin, China.
Qiqihar Grassland Station, Qiqihar, China.
Front Microbiol. 2022 Jul 8;13:865184. doi: 10.3389/fmicb.2022.865184. eCollection 2022.
Land use change obviously changes the plant community composition and soil properties of grasslands and thus affects multiple functions and services of grassland ecosystems. However, the response mechanisms of soil microorganisms, key drivers of the nutrient cycle and other soil functions during changes in grassland use type and associated vegetation are not well understood. In this study, Illumina high-throughput sequencing was used to analyze the changes in the soil microbial community structure of four grassland use types: exclosure (EL), mowed land (ML), grazed land (GL), and farmland (FL) in the Songnen Plain of Northeast China. The results showed that the FL and EL had significantly higher soil total nitrogen (TN) and lower soil electrical conductivity (EC) and pH than GL and ML. In contrast, the GL and ML had higher soil bulk density (BD) and organic matter, respectively, than the other land use types. In addition, the values of the Shannon diversity and Pielou's evenness indexes were highest in the EL of all the land use types. Based on the high-throughput sequencing results, we observed high levels of α diversity in the FL for both bacteria and fungi. A structural equation model (SEM) revealed that pH and EC had a direct and positive effect on the bacterial community structure and composition. In addition, plant taxonomic diversity (according to the Shannon diversity and Pielou's evenness indexes) indirectly affected the bacterial community composition via soil pH and EC. Notably, fungal composition was directly and positively correlated with soil nutrients and the value of Pielou's evenness index changed with land use type. In conclusion, soil properties and/or plant diversity might drive the changes in the soil microbial community structure and composition in different grassland use types.
土地利用变化明显改变了草原的植物群落组成和土壤性质，从而影响了草原生态系统的多种功能和服务。然而，在草原利用类型及其相关植被变化过程中，作为养分循环和其他土壤功能关键驱动因素的土壤微生物的响应机制尚未得到充分了解。在本研究中，利用Illumina高通量测序技术分析了中国东北松嫩平原四种草地利用类型：围栏封育草地（EL）、割草地（ML）、放牧草地（GL）和农田（FL）的土壤微生物群落结构变化。结果表明，与GL和ML相比，FL和EL的土壤全氮（TN）含量显著更高，土壤电导率（EC）和pH值更低。相反，GL和ML的土壤容重（BD）和有机质含量分别高于其他土地利用类型。此外，在所有土地利用类型中，EL的香农多样性指数和皮洛均匀度指数值最高。基于高通量测序结果，我们观察到FL中细菌和真菌的α多样性水平都很高。结构方程模型（SEM）显示，pH值和EC对细菌群落结构和组成有直接的正向影响。此外，植物分类多样性（根据香农多样性指数和皮洛均匀度指数）通过土壤pH值和EC间接影响细菌群落组成。值得注意的是，真菌组成与土壤养分直接正相关，且皮洛均匀度指数值随土地利用类型而变化。总之，土壤性质和/或植物多样性可能驱动不同草地利用类型中土壤微生物群落结构和组成的变化。
