The Conversion Efficiency And Phytomass Of Alpine Grassland With Different Degraded Degree In Qinghai Lake Area

Alpine steppe, Alpine meadow, desert steppe, Wetland meadow is mostly grassland types in Qinghai lake area , the area of Alpine steppe and Alpine meadow is the largest, they is important in economy of animal husbandry and ecological protection. Stipa purpurea and Kobresia capillifolia grassland was used as material to quantitatively study community characteristics, seasonal dynamics of phytomass and energy storage, conversion efficiency of solar radiation of two grasslands types under moderate and heavy degraded state, which was in order to find out season dynamic of energy storage in alpine grasslands and provide basal data of matter cycle and energy flow of ecological system of alpine grassland. The experimental results showed:1. The species diversity (a diversity index) of plant community decreased and important value increased with the aggravation of degraded degree. The diversity indexes of Stipa purpurea community with moderate and heavy degradation were 2.50, 2.26 respectively, the important value of dominant species were 19.09, 23.8 respectively. The diversity indexes of Kobresia capillifolia community with moderate and heavy degradation were 2.6069,2.4167 respectively, the important value of dominant species were 13.31, 22.81 respectively.2. Season dynamic of abovegroung population phytomass of Stipa purpurea and Kobresia capillifolia grassland types take on single apex curve, the value of apex appeared in the last ten day of August, the phytomass of aboveground population of two grassland types have clear difference. the equation y=e^a+bx simulate season dynamic curve of aboveground phytomass of Stipa purpurea and Kobresia capillifolia grassland type well.3. The dry weight ratio of the grasses of Stipa purpurea type to community decreased but that of forbs increased with the aggravation of degradation. The rate of dry matter accumulation decreased, which finally lead to decreasing net primary production. The net production of above-ground phytomass of moderate-degraded plot of Kobresia capillifolia type was more than heavy-degraded plot, because of grazing in germination, the grasses percentage of moderate degraded plot of Kobresia capillifolia type was less than heavy-degraed plot. The net production of above-ground phytomass of Stipa purpurea community with moderate and heavy degradation were 104.99g/m2.a, 48.38 g/m2.a respectively. The net producion of above-ground phytomass of Kobresia capillifolia community with moderate and heavy degradation were 144.82g/m .a > 87.96g/m2.a respectively.4. The more than 80% belowground phytomass distributed at 0²0cm soil layer, the equation y=axb simulate mean phytomass and its percentage of individually soil layer at growing period. Under the 40 centimeter deep soil layer, the net production and turnover value of belowground-ground phytomass of Stipa purpurea community with moderate and heavy degeneration were 849.6g/m2^ 32.45'%^ 1346.05g/m2.a> 51.93% respectively. Those of below-ground phytomass of Kobresia capillifolia with moderate and heavy degradation were 787.13 g/m2.a^ 26.08%> 1190.6 g/m2^ 51.33% respectively.5. The ratio of below-ground phytomass to above-ground phytomass increased with the aggravation of degradation. The ratios of below-ground phytomass to above-ground phytomass of Stipa purpurea community with moderate and heavy degradation were 16.86 > 51.51 respectively. The ratios of below-ground phytomass to above-ground phytomass of Kobresia capillifolia community with moderate and heavy degradation were 24.61 > 27.22 respectively.6. The measures of caloric value of every plot showed that: The caloric value of above-ground more than that of owlow-ground, the caloric value of above-ground was the highest on the forage flourishing stage, the lowest on green up period, on the withering stage in the second level, the caloric value of above-ground more than that of the terraneous. The energy storage of above-ground, under-ground and total community were linear positive significance to the biomass .7 The net production or spatial distribution decreased with the aggravation of degraded degree. The net production of spatial distribution of Stipa purpurea community with moderate and heavy degradation were 0.1667n 0.0439 respectively, that of Kobresia capillifolia community with moderate and heavy degradation were 0.2257 > 0.1049 respectively.8. The conversion efficiency of solar radiation of above-ground decreased with the aggravation of degradation. The conversion efficiency of solar radiation of above-ground oi Stipa purpurea community with moderate and heavy degradation were 0.03% ^ 0.013% respectively, that of below-ground were 0.178% > 0.303% respectively, that of total community were 0.208% -. 0.317% respectively. The conversion efficiency of solar radiation of above-ground of Kobresia setchwaneusis community with moderate and heavy degeneration were 0.04% > 0.024%, that of below-ground were 0.177% > 0.234% respectively, that of total community were 0.216%> 0.259%.