Response Of Soil Microbe To Different Regulation Measures In Moderately Degraded Alpine Meadow In Qilian Mountain

To provide technical support for the rapid restoration of moderately degraded alpine meadows,the moderately degraded alpine meadows in Qilian Mountains were taken as the research object.By studying the effects of different short-term regulation measures（spring rest grazing,spring rest grazing-cutting turf,spring rest grazing-cutting turf-fertilization,spring rest grazing-cutting turf-sowing,spring rest grazing-cutting turf-fertilization-sowing）on vegetation characteristics,soil properties and microbial characteristics of moderately degraded alpine meadow.This work provides a technical support for the short-term restoration of moderately degraded alpine meadows.The main research results are as follows:1.The important values of miscellaneous grasses in moderately degraded alpine meadows decreased and the important values of Gramineae species increased under the different regulation measures,and the diversity index,richness index and evenness index of plant species were significantly higher than those of the control under the different regulation measures,while the dominance index was significantly lower than that of the control.However,the dominance index decreased significantly under each regulation measures.The aboveground and underground biomass of vegetation increased under the various regulation measures,and the aboveground and underground biomass of spring rest grazing-cutting turf-fertilization-sowing measures were significantly higher than those of other measures（P<0.05）.2.There were the highest that the contents of soil pH,bulk density and ammonium nitrogen in moderately degraded alpine meadow grassland.The content of soil available phosphorus was the highest under the measure of fallow-breaking turf in spring.Compared to moderately degraded alpine meadow,the content of soil nitrate nitrogen was the highest under the measure of spring rest grazing-cutting turf-fertilization.There was the highest that the content of soil organic phosphorus under the measure of spring resting grazing-cutting turf-sowing.There were the highest that soil water content,total organic carbon,total nitrogen,total potassium and available potassium under the measure of spring rest grazing-cutting turf-fertilization-sowing.3.Under the different regulation measures,the content of carbon,nitrogen,phosphorus of soil microbial biomass in 0-15 cm soil layer were 168.89-240.72 mg·kg^-1,41.88-104.98 mg·kg^-1 and 22.13-40.73 mg·kg^-1,respectively.Among them,the carbon content of soil microbial biomass was the highest under the spring rest grazing-cutting turf-fertilization measures,and the nitrogen and phosphorus content of microbial biomass were the highest under the spring rest grazing-cutting turf-fertilization-sowing measures.The differences was deteched in soil microbial biomass under different degrees and regulation measures.The results of high throughput sequencing showed that OTUs of microbial bacterial was higher than that of microbial fungi OTUs in alpine meadow soil under different regulation measures.The grassland soil under the different regulation measures,the dividion of Proteus,Actinomycetes,Actinomycetes,Planktonic microorganisms were the dominant bacteria,and the dividion of Ascomycetes,Mortierella,Basidiomycetes microorganisms were the dominant fungi.No significant difference was obtained in soil bacterial Chao1 index and Simpson index under the different regulation measures,but soil bacterial Shannon index under the moderately degraded alpine meadow,the spring rest grazing-cutting turf and spring rest grazing-cutting turf-fertilization measures was significantly higher than that of spring rest grazing-cutting turf-fertilization-sowing measures.The differences was acquired in Simpson index and Shannon index under different regulation measures,but differences were no significant differences.The Chao1 index of moderately degraded alpine meadow,spring grazing,spring rest grazing-cutting turf and spring rest grazing-cutting turf-fertilization measures were significantly higher than that of spring rest grazing-cutting turf-sowing and spring rest grazing-cutting turf-fertilization-sowing measures.The bacterial communities are mainly metabolic groups,genetic information processing groups and cellular processes under different regulation measures.The functional groups of soil fungi were pathological,saprophytic and symbiotic.The results of radar analysis demonstrated that the indexes of vegetation,soil and microorganisms were relative balance under the measures of spring rest grazing,cutting turf,fertilization and sowing,which was an ideal restoration measure for degraded grassland.The fitting results of piecewise structural equation model indicated that grassland vegetation diversity,soil physical properties and vegetation biomass directly affected soil chemical properties,and then affected the diversity and composition of soil microbial bacteria and fungi through soil chemical properties.