The Stability Of Mixture Grassland Of Cultivated Perennial Grass And Its Regulation In Alpine Region Of Qinghai-Tibetan Plateau Of China

Mixture grassland of cultivated perennial grass is the best choice for improving the productivity of grassland and keeping the balance of man-interfered grassland ecosystem in the alpine region of Qinghai-Tibetan Plateau of China. Due to the severe ambient condition (especially the low temperature), the productive-ecological stability of the cultivated mixture grassland is not easily maintained. In order to tThd the ideal ways to maintain its stability, from May. 1998 to Octobr of 2000, this study was conducted at the Jingqianghe Alpine Grassland Station of Gansu Agricultural University, which is located in Tianzhu County, 3000m ASL of altitude (with -0.1 0C of annual temperature and 416mm of precipitin annually). The results indicate: 1. The stability of mixture grassland was the unified characteristic of production, composition and disturbance-resistance. The optimum choice and combination of grass species were the basis for achieving the high productivity of grassland, maintaining the stable compositions of community, and resisting the disturbance from outside. 2. The aboveground biomass of the mixture grassland of perennial grass was substantially accumulated in the late time of growing season. The temperature of soil within different depth was raised by the dense coverage of mixture grass, the micro environmental condition of grass community was therefore improved, and the production of grassland was increased subsequently. 3. The re-greening period of cultivated grassland was 15 days(around 20th of April) ahead of natural pasture, but their mature period was same. In the second year of establishment, the yeild of mixture grassland were 8.OtDM]hm2 for Bromus innermis(B)+Clinelymus nutans(C) community, 6.5 tDM/hm2 for Elymus nutans(E)+Agmpyron cristatum(A) community, 5.5 tDM/bm2 for B+C+A community, 8.1 tDM/hm2 for E+B+C community 7? tD~A/~2 for C+E+A community, 14.2 tDMlhm2 for B+E+C+A community, 9.6 tDM/hm2 for B-i-C+A+Poa crymophlla(P) community, 13.5 tDM/bm2 for B+E+A+P commwiit~ 9.5 tDM/hin2 E+C+A+P community. 4. After establishment, the production of the single grassland of perennial grass began to decrease in the third year, and those of the mixture grasslands were keeping high production continuously in the second and the third year. In the second year of establishment, the yield of mixture grassland was 2? times as high as natural pasture, equaling to the yield of annual oat land. Therefore , the mixture grassland of perennial grass can achieve the high production in alpine region. 5. In mixture community, the dominant species increased their net biomass by capturing more resources (light and nutrients)and living space, thus to compete with the neighbor plant, and the non-dominant species formed the defensive strategies, namely, improving the Root/Tiller rate to capture more nutrients in soil. The stability of community is kept eventually. 6. In the first year of establishment, the aggressivity of grass was relatively low, and they failed to compete with the weeds, the yield of grassland dramatically dropped down. It was veiy important to control weeds in the first year of establishment of mixture grassland in alpine region. 7. All the communities of grass in this stud3?can be assorted into 3 groups according to their...