Effects Of Different Enclosure Treatments On Vegetation Community Characteristics And Soil Enzyme Activities In Semi-arid Meadow Grassland

Human activities have become an important factor leading to grassland degradation,so it is an urgent problem to determine the best grassland treatment in Inner Mongolia grassland.In this thesis,Inner Mongolia semi-arid Meadow Grassland as the research object,the effects of different treatments,including enclosure（UNM）,enclosure+1-year mowing（M₁）,enclosure+multi-year mowing（M_L）,enclosure+burning（F）and grazing（G）,on vegetation community and soil characteristics were studied.The effects of different treatments on plant species composition,vegetation quantitative characteristics,community diversity,soil temperature,water content,electrical conductivity,organic carbon and soil enzyme activities were analyzed,and the correlation between vegetation and soil factors was discussed,the best treatment method of semi-arid meadow grassland in Inner Mongolia was preliminarily determined to provide scientific basis for sustainable utilization of meadow grassland.The results:Compared with UNM treatment,M₁,F and G treatments resulted in the disappearance of some species and the emergence of some new species.The important values of species of functional groups in different plots of typical steppe were significantly different,the important values of Gramineae,leguminosae and compositae decreased by 4%～6%,and the number of weeds increased by 24%,the important values of compositae species were sensitive to fire treatment,and increased by 24%.The important values of weeds and legumes were increased and the important values of compositae decreased by 34%under the treatment of enclosure plus one-year mowing（M₁）.The effects of different grassland treatments on the quantity of vegetation community（vegetation height,coverage and aboveground biomass）were the lowest in g treatment（36.51 cm,81%and 567.83 g/m²）,which were 39%,10%and 24%lower than those in UNM treatment,respectively,compared with UNM,seasonal G decreased the vegetation height and aboveground biomass by 13%and 6%,respectively,with no significant difference in vegetation coverage The effects of M₁on the quantitative characteristics of vegetation were different from those of UNM.M₁treatment promoted the growth of vegetation under certain conditions,but inhibited the growth of species under certain conditions Compared with M_Ltreatment,G treatment in different plots decreased the quantity of vegetation.Under different treatments,the species diversity of UNM treatment was the lowest.Compared with UNM treatment,G treatment increased theαdiversity of vegetation community,and increased the richness index,diversity index,and dominance index by46%～50%,14%～28%,and 4%～13%,respectively.There was no significant difference in evenness index Compared with UNM treatment,seasonal g treatment had no significant difference inαdiversity index,while F,M₁treatment had significant difference in abundance index and diversity index,but had no significant difference in dominance index and evenness index The species diversity was increased in M_Ltreatment compared with G treatment.With the increase of soil depth,soil electrical conductivity,organic carbon and the activities of three soil hydrolases all decreased,and showed“Surface aggregation”,the soil organic carbon and soil enzyme activities were decreased due to the decrease of nutrients entering the soil roots during the photosynthesis of vegetation.UNM treatment of soil surface layer was rich in litter and avoided the disturbance of livestock and human activities,soil organic carbon and enzyme activities increased.After treatment with F,litter and litter entered the soil in the form of Ash,soil fertility increased,vegetation roots were more sensitive to nutrient absorption,vegetation grew luxuriantly,root exudates increased,soil enzyme activity increased.The enzyme produced in the process of M_Lis more active than that in the process of G.Sucrase and alkaline Alkaline phosphatase are both increased.While trampling by livestock promotes the decomposition of litter and faeces,the faeces of cattle and sheep contain more urea,soil urease activity increased.Considering the above factors,enclosure+fire（F）is the best treatment method for meadow grassland.