Effects of Main Land-Use Types on Plant and Microbial Diversity and Ecosystem Multifunctionality in Degraded Alpine Grasslands

Grassland resources occupy an important place in the national economy. However, grasslands in alpine regions of China are severely degraded, and the effects of land-use types on species composition, soil nutrients, and ecosystem multifunctionality of degraded alpine grasslands are less certain. To ascertain the effects of main land-use types (no-tillage reseeding and fertilization) on species diversity and ecosystem multifunctionality in alpine grasslands, we investigated the changes in these factors by subjecting specified areas. Using a standardized field survey, we measured the cover, richness, and evenness of plants. At each site, we measured microbial diversity and twelve soil variables critical for maintaining ecosystem multifunctionality in alpine grasslands. The results showed that: (1) the Margalef, Shannon-Wiener, and Simpson indices of plant community, and fungal diversity indices increased significantly in no-tillage reseeding and fertilization; (2) at the phyla level, the relative abundances of Basidiomycota, Olpidiomycota, and Proteobacteria increased significantly in no-tillage reseeding and fertilization, as well as, at the genus level, those of Coniochaeta, Solirubrobacter, Pseudonocardia, and Microvirga; (3) the soil physicochemical properties (except the C:N of soil) increased significantly in no-tillage reseeding and fertilization; (4) correlation analysis showed that species diversity was mainly correlated with soil nutrients in control check, while it was mainly correlated with soil physical properties in no-tillage reseeding and fertilization; (5) linear regression analysis showed significant positive relationships between Margalef, Shannon-Wiener, and Simpson indices of plant community and ecosystem multifunctionality. In addition, ecosystem multifunctionality was positively related to Pielou, Shannon-Wiener, and Simpson indices of the fungal community and it was positively related to Pielou and Shannon-Wiener indices of bacterial community. These observations indicated that no-tillage reseeding and fertilization of degraded alpine grasslands had the potential to improve ecosystem functions in many ways.