Study On The Variation Of N,P,K Nutrients Pool Of Different Type Of Alpine Meadow In Eastern Qilian Mountains

Based on the investigation of different types of alpine grassland in Jinqiang River valley of Tianzhu Country, Gansu Province, seven representative grassland types according to the different vegetation type were selected to study the nutrients pool in vegetation, soil and microorganism. The aims of the research were to study alpine meadow ecosystem nutrients circulation and interaction between vegetation, soil and microorganism biomass nutrient pool. The nutrient pools were investigated at May, July, September and November in 2006. To provide the necessary data for futher study alpine meadow ecosystem nutrients storage and circulation, and analysis the ecological value of alpine meadow in global climate change.1. Different type of alpine aboveground biomass charactersticsThe alpine brushland aboveground biomass significantly increased at May and July, decreased at November. Rhododendrons brushland aboveground biomass seasonly mean were largest 889.6g/m~2DM, Salix cupularis brushland lower 550g/m~2DM, Dasiphoru fruticosa shrubs lowest 200.6g/m~2DM. There were significant different (p<0.01) between this three plot and the underground biomass(0 to 20cm) showed similar changes to the aboveground biomass. Except Salix other plots A/U were all less than 1. The alpine grassland aboveground biomass ranged from 89.2 to 146 g/m~2DM, where grass steppe were lowest and Kobresia meadow highest, and those four plots A/U were more than1.2. Different type of alpine vegetation N, P, K nutrients pool storageThe annual mean N storage of seven different types of alpine grassland ranged from 55.48 to 157 kg/hm~2, where Dasiphoru fruticosa shrubs were the lowest and Kobresia meadow highest and there were significant differences between those plots (p<0.05). The seasonal mean P storage ranged from 3.83 to 11.21kg/hm~2, where Dasiphoru fruticosa shrubs were the lowest and the swamp meadow the highest and there were significant different between those plots (p<0.05). The seasonal mean K storage ranged from 13.76 to 38.75 kg/hm~2, where grass steppe were the lowest and Rhododendron brushland the highest and there were significant different between those plots (p<0.05).3. Different type of alpine soil N, P, K nutrients pool storageSoil N nutrient pool (0 to 20cm) ranged from 6.17 to 12.83t/hm~2, and it decreased slightly in July, increased in September and then decresed again in November. The N storage change was opposite with vegetation biomass and the vegetation N pool. Soil P nutrient pool (0 to 20cm) ranged from 0.54 to 1.24t/hm~2. It was obvious in the 0～10cm soil layer P pool spatial distribution characteristic significantly, and the result of significant difference analysis showed that between the plot had extremely significant difference. However, the spatial distribution characteristic of P pool within 0 to 10cm soil layer was not as obvious as upper layer. Soil K nutrient pool (0 to 20cm) ranged from 28.97 to 53.25t/hm~2, it decreased in July, and slightly increased in September and November, which was consistent whith N pool variation.4. Different type of alpine microbial biomass N, P, K nutrients pool storageDifferent alpine meadow microbial biomass N pool (0 to 20cm) ranged from 52.74 to 183.66 kg/hm~2, accounting for 0.62% to 2.9% of total nitrogen pool storage. The soil microbial biomass N pool of different alpine meadow ecosystem was different. The herbaceous alpine meadow microbial biomass N pool was far more than brushland. Microbial biomass P pool (0 to 20cm) ranged from 28.38 to 49.54kg/hm~2, accounting for 3.19% to 8.08% of total phosphor pool storage.5. The total nutrient storage in different alpine meadowIn East Qilian Mountain, total N, P, K nutrients pool storage of different types of alpine grassland ranged from 36.1 to 65 t/hm~2, in which, soil was the main nutrient pool and its nitrogen storage accounted for 13.73% to 20.93% of the total nutrient, the phosphorus accounted for 1.5% to 2.07%, and the K accounted for 77.08% to 86.11%.