Study On The Productivity And Stability Of Perennial Cultivated Grassland In Qinghai-Tibetan Alpine Meadow

The experiment chooses three kinds of perennial grasses,Elymus nutans, Festuca.sinensis and Festuca ovina,which distributed widely in the east of Qinghai-Tibetan alpine meadow to study the productivity and stability of cultivated grassland.The experiment experience three years and the main conclusions as following:1.The re-growth period of cultivated grassland was 10 days ahead of natural pasture and the mature period was same.2.After establishment,the productivity of monoculture perennial grassland began to decrease in the third year(the F.ovina grassland was exceptional).Those of 2 species combined mixtures and 3 species combined mixture keep high production continuously in the second and third years and the change of weed biomass and weed abundance was unconspicuous.The stability of production and component in mixture grassland was better than in monoculture grassland and the 3 species combined mixture was the best. The mixture grassland of perennial grass can achieve the high production in alpine meadow.3.The initial competitive pattern was formed between E.nutans,F. sinensis and F.ovina in the seeding emergence stage and the pattern was not changed in the second year.E.nutans was dominant species and F. sinensis and F.ovina were inferior species in mixtures.In the third year, the highest adult survival increased F.ovina competitive ability in mixture.The adult survival ability of E.nutans,F.sinensis were second and third.4.In E.nutans/F.sinensis and E.nutans/F.ovina mixtures,the combined components utilized the same resource and showed competitive trend in higher seeding densities and the combined components in F.sinensis/F. ovina mixture utilized the same resource in the second year.The competition ability of E.nutans was the strongest,then F.sinensis, followed F.ovina based on Relative Yield Total and Competition Ratio.In the third year,the combined components competed the same resource and interfered each other in three mixtures.The competitive ability of E. nutans was the strongest,F.ovina was the second and F.sinensis was the third. 5.Fertilizer improved the horizontal competitive ability of dominant population(E.nutans)and improve the upright competitive ability of inferior population(F.sinensis and F.ovina).At the same time,it decreased weed biomass and weed abundance in mixture grassland.The production of grassland increased lineally due to fertilizer,the stability can be improved as well.6.Clipping decreased the production and increased the weed biomass and weed abundance in mixtures.The cultivated grassland must not be used by any way in the first year and can be utilized moderately in the second and third year.6cm stubble,2 clipping annually,the first clipping in the blooming stage of grass,the second clipping in the elongating stage of grass was the ideal clipping management for mixture grassland of perennial grass in the alpine region of Gannan area.7.The mezzo seeding density could increase the grassland production effectively and decreased the weed biomass and weed abundance in grassland in the second year.seeding density was effective way to maintain the stability of production and combined component in cultivated grassland. The seeding density effect on the grassland production was minished in the third year.8.In the first year of grassland establishment,the aggressivity of grass was relatively low,and they failed to compete with the weed.The annual weed were compete winners such as E.patrini Garcke,Artemisia tangutica and Chenopodium Album.The seeding grass re-growth early and became dominate population in grassland in the second and third year.The frequency of many weed were decreased and had no serious effect on grassland production.The production of grassland achieved fastigium in the second and third year but the work of weed removed was still a serious question.