Effects Of Plant Species Diversity On Soil Microbial Communities: Insight From Tibetan Alpine Grassland

How soil microbial diversity assembly,maintaining and change is key topic of ecology.A large number of studies show that soil microbial biodiversity controls not only by soil environment but also by plant species diversity.The " diversity begets diversity " hypothesis of field research has become an almost universally accepted theory in ecological studies,although we still do not know the details of the mechanism.In the mechanism of plant diversity for microbiality,the diversity-promoting hypothesis holds that different plants provide different matrix resources for microorganisms.However,from investigating study in field it remains challenge to isolate and clarify the role of plant diversity per se in regulating soil microbial biodiversity due to strong covariation between plant diversity and soil environmental factors in nature.Hence,here,we aim to clarify how plant diversity affects soil microbial diversity in environment-consistent artificial communities.In this study,we examined difference in species diversity of soil bacteria and fungi among plots subjected single-and mixed-sowing of three grass species and fertilization treatments and different plant species excluding treatments after more than 10 years' experiment in the eastern Qingzang(Tibetan)Plateau.We also analyzed the relationships between soil microbial diversity and edaphic factors or plant community attributes.Important findings(1)the species richness and diversity of soil bacteria,but not of soil fungi,significantly consistently decreased in mixed-sowing plots relative to single-sowing plots,with higher relative abundances of proteobacteria and actinobacteria but lower that of acidobacteria,bacteroidetes and planctomycetes in the mixed-sowing plots.(2)Soil p H and total nitrogen content significantly decreased but soil total phosphorus content increased in mixed-sowing plots relative to single-sowing plots.Fertilization significantly increased soil available phosphorus while decreased soil p H and soil humidity.However,variations in these edaphic factors accounted little variation of soil microbial diversity.(3)Fertilization significantly increased plant aboveground biomass while declined richness of present plant species,which also negatively associated with soil bacterial diversity.(4)The species richness of both soil bacteria and fungi,and diversity of soil bacteria,significantly increased in weeds excluding plots relative to no excluding(CK)plots.(5)soil available nitrogen content and plant species richness significantly decreased in weeds excluding plots relative to no excluding(CK)plots.soil available phosphorus content significantly decreased but plant aboveground biomass significantly increased in kobresia excluding plots relative to no excluding(CK)plots.In the field conditions,the study found that the influence of plant species diversity on soil microbiota was much greater than that of soil biochemistry properties,and the mixing of grasses significantly reduced soil bacterial diversity and tended to reduce soil fungal diversity The loss of rare plant species also significantly affects the bacterial diversity and community structure of soil.The study shows that plants have complex effects on underground ecosystems.In a word,it presents a new challenge to the traditional hypothesis of “plant diversity begets micro-biodiversity” and provides reference for the sustainable development of Tibetan alpine grassland.