Effects Of Enclosure On Plants And Soil Properties Of Temperate Steppe In The Northern Slope Of Tianshan Mountains

Enclosing grazing is an important measure for the restoration and reconstruction of the grassland ecosystem.Studying the effects of enclosure on grassland vegetation characteristics,soil physical and chemical properties and soil microorganisms can provide a scientific basis for the sustainable use and management of grassland ecosystems.Tianshan is the cornerstone of Xinjiang’s grazing industry.This study takes the temperate steppe in the middle section of the northern slope of Tianshan Mountain in Xinjiang as the research area to analyze the effects of enclosure and its different years(2 years,10 years and 11 years)on the characteristics of grassland vegetation(community composition,Abundance,biomass,etc.),soil physical and chemical properties(p H,bulk density,electrical conductivity,carbon and nitrogen content,etc.)and soil microbial(diversity and community structure).The main findings are as follows:(1)The impact of enclosure and its different years on vegetation and soil properties:Compared with the grazing,the proportion of Legumes in total aboveground biomass increased by11.81% after 2 years;the soil total nitrogen content and density of 5-10 cm and 10-20 cm soil were significantly reduced.After 10 years of enclosure,Gramineae has been significantly reduced by 30.08%;soil bulk density,total nitrogen content and density,and organic carbon density of 10-20 cm are significantly reduced.After 11 years,the proportion of Gramineae has been significantly reduced by48.46%,and Forbs increased by 219.40%;plant species richness,aboveground living and litter biomass increased significantly;soil surface bulk density and p H have decreased significantly;The organic carbon content of 10-20 cm soil increased significantly.This study also found that the longer the enclosure period,the wider the impacts on vegetation characteristics and soil physical and chemical properties.(2)The impact of enclosure and its different years on microbial diversity and community structure:The change characteristics of soil microorganisms in enclosure and different years: Actinobacteria(21.71%-47.29%)is the most abundant in the dominant soil bacteria phylum,followed by Proteobacteria,The abundance proportion is 16.21%-30.86%,and Acidobacteria,the third most dominant bacteria,also accounts for 11.42%-33.19%;compared to outside the fence,the relative abundance of the Proteobacteria is after 10 years of enclosure Significant increase,while the acid bacteria phylum decreased significantly;at the level of classification,Actinobacteria accounted for the highest proportion,with an average abundance of 36.20%.Soil fungi are dominated by the Ascomycota,with abundance as high as 46.63%-72.19%,followed by Basidiomycota(8.68%-22.28%)and Mortierellomycota(0.74%-2.75%);The classified fungi are mainly Sordariomycetes,but the average abundance accounts for only 14.20%,and more fungi have not been classified at the class level;Agaricomycetes have been significantly increased in 11 years of enclosure abundance.The classification level of soil archaea is relatively simple.The phylum Thaumarchaeota(59.10%-92.61%)has an absolute advantage,followed by the phylum Euryarchaeota(2.40%-5.04%);the classification level of the class is Nitrososphaeria(59.10%-92.61%)and Thermoplasmata(1.74%-4.72%).Bacterial and fungal community structure(OTU)are clearly distinguished from enclosure for 2 years and enclosure for 10 and 11 years in time series,but there is no obvious difference between the inside and outside of the fence.At the same time,the diversity of bacteria,fungi or archaea is not significantly affected by the enclosure and its age.(3)Effects of soil and vegetation characteristics on microbial:Pearson correlation analysis indicated that microbial diversity and dominant microbial communities have no significant correlation with vegetation characteristics and soil physical and chemical properties.Combining soil microorganisms and main environmental factors for correlation analysis,it is concluded that soil organic carbon,nitrate nitrogen,ammonium nitrogen,and plant richness and coverage will affect the composition of bacterial(OTU)community,and fungal(OTU)community composition It is affected by soil organic carbon,nitrate nitrogen,ammonium nitrogen,plant richness,plant diversity and coverage;further analysis shows that specific bacterial flora is mainly influence of plant diversity,and the main The environmental factors are soil moisture content,and these environmental factors did not change the archaea.This study shows that enclosure will change the composition of plant communities,increase the aboveground biomass,and decrease soil bulk density,p H and electrical conductivity,indicating that enclosure is beneficial to the restoration of grassland vegetation and soil after grazing.And as the enclosing period increases,the wider the impact on vegetation characteristics and soil physical and chemical properties,the deeper the impact.Enclosure and its different years have no significant impact on soil microbial diversity,and the changes in the relative abundance of bacteria and fungi are the most extensive.Environmental factors such as soil organic carbon content and plant diversity will affect bacterial and fungal communities,while archaeal communities are relatively stable.A comprehensive analysis of the response of soil-plant-microbes to enclosure will help us find an entry point for the restoration of degraded grasslands.The research results can provide new ideas for the development and utilization of grassland resources in Xinjiang.