| Dynamics of nitrogen, phosphor and carbon in decomposer subsystem in Leymus chinensis grassland was studied in this paper. Dynamic models of N, P and C were established through statistical and systematical analysis by SPSS software which quantitatively described the input, transfer and output of the three elements.The dynamic of litter input showed power function with the time and the maximum was 213.39g m-2 The dynamic of the output of litter had the same trend with the input, and the maximum was 203.00g m-2. So the annual loss was 28.52g m-2. Litter was mostly decomposed in the period from April to October in one year, during which litter was lost by about 30% and the amount of decomposition could hit 90% of that of one year. The dynamic of dead roots existed showed double-hump curve with the season. The first hump happened in May which was 403.74gm-2 and the lowest happened in July which was 190.36gm-2. Till the end of growing season, there was the second hump. Biomass of microorganism in soil increased from May, till August it could hit the maximum which was 24.97mg g-1soil, then decreased in the end of growing season.N content of litter increased with the season. The minimum and maximum happened in May and October which were 2.29mgm-2 and 892.04mg m-2 respectively. The dynamic of N content in dead roots showed double-hump curve with the season. The first and hump happened in June and the second happened in September which werel414mgm-2 and 1171mgm-2 respectively. The scope of N content changed with season was from 704mg m-2 to 1414mg m-2. The dynamics of N content of microorganism in soil showed single-hump curve. The maximum and minimum were 27.81mgT00g-1 soil and 14.36mg 100g-1 soil which happened in August and end of October respectively. The dynamic of total N in soil showed single-hump curve by and large. The maximum and minimum were 445.8g m-2 and 333.7 g m-2 which happened in July and September respectively.Dynamics of input and accumulation of P in litter had the same trend with the season. Annual input of P was 125.3lmg m-2 and annual accumulation was 119.77mgm-2. So the annual loss was 18.37mg m-2. The dynamic of P content in dead roots showed double-hump curve. The first and the second hump happened in May and September respectively. The scope of P content changed with season was from 268.45mg m-2 to 133.25mg m-2. The dynamic of P content of microorganism in soil showed single-hump curve. The maximum and minimum were 1.53mg 100g-1 soil and 10.262mg 100g~ soil which happened in August and October respectively. The total P in soil decreased with the season on the whole. The maximum and minimum were 0.661mg m-2-soil and 0.479mg m -2 soil which happened in May and July respectively. The dispersion was only 0.182 mg m-2 soil. The dynamic of available P in soil was related to P needed by plants in different growth phases, which was logarithmically related to the total P. The maximum and minimum were 10.9ug g-1 soil and 5.21 ug g-1 soil which happened in May and July respectively.C content of litter increased with the season. Input of C from May to July was low and increased gradually from August, till October it could hit the maximum (101.1g m" ). C content in dead roots changed sharply with the season, which was similar to the dynamic of dead roots existed. The dynamic of C content of microorganism in soil showed single-hump curve. The maximum and minimum were 3.16 mg 100g-1 soil and 1.63 mg 100g-1 soil which happened in August and October respectively. Dynamic of total C in soil showed "L" curve. The total C hit the maximum in May (6.29kg m-2), then decreased gradually, till August hit the minimum (3.98 kg m-2) and then increased from September.N, P and C contents were extremely positively related to the energy involved in litter and dead roots, which illuminated that dead and withered plants supplied materials and energy simultaneously to microorganisms. Energy in dead and withered plants was extremely negatively related to N, P and C contents of microorganism, which showed energy was needed when microor... |
