Study On Seed Production Techniquues Of Tibetan Wild Elymus Nutans In Lhasa Valley

Grassland enclosure and grazing ban is an important tool for restoration and rehabilitation of ecosystems.Investigating the relationship between fencing and the characteristics of grassland vegetation,the physicochemical properties of soil,and the physicochemical properties of vegetation and soil can provide methods and basis for effective restoration of degraded grasslands in grassland ecosystems..In this study,the alpine grassland of Bangor County,Nagqu City,Tibet Autonomous Region was used as the research area to analyze the response of long-term fencing(10 years)to grassland vegetation characteristics(species diversity,uniformity,richness,important values,aboveground biomass,cover),soil physical and chemical properties(weight capacity,organic matter,total nitrogen,full phosphorus,fact-acting phosphorus,fact-acting potassium,nitrate nitrogen,ammonium nitrogen,p H),species diversity and vegetation aboveground biomass to soil physicochemical properties.The main findings are as follows:(1)Differences between vegetation communities inside and outside the fence:the aboveground biomass of vegetation increased by 16.90 %(P<0.05),and the vegetation cover increased by 34.19 %.(P<0.01)。The above-ground biomass of the grass family increased extremely significantly by 179.83 %(P<0.01)and the cover of the grass family increased significantly by 62.13 %(P < 0.05)after fencing.The above-ground biomass of the grass family increased by an extremely significant 179.83 %(P < 0.01)and the cover of the grass family increased by 62.13 %(P < 0.05)after fencing and sealing.(2)Difference between the physicochemical properties of the soil inside and outside the fence:After fence sealing,soil bulk density decreased by 6.29 %(P<0.05),soil nitrogen content increased by 20.30 %(P<0.05),soil organic content increased by 23.48 %(P<0.05),soil p H decreased by 2.13 %(P<0.05).(3)Response of species diversity and aboveground biomass to soil physicochemical properties:Simpson’s diversity index of vegetation in fenced areas is significantly and negatively correlated with soil organic matter and fast-acting phosphorus(P<0.05),and an extremely significant negative correlation with soil total nitrogen and available potassium(P<0.01),the Simpson diversity index of species in free-grazing area had a significant negative correlation with soil organic matter(P<0.05)。This shows the importance of fencing for the ecological restoration of alpine grassland vegetation.