Study On Ecological Stoichiometry Characteristics Of Different Plant Community And Soil In Songnen Grassland

It is of great significance to investigate Songnen grassland plant components, soil nutrient elements and their distribution characteristics. The research is beneficial for revealing the demand of plant for nutrients conditions, the supply capacity of local soil nutrient, judging limiting nutrient elements, and knowing the feedback ability of plant to climate change and regional environments. By investigating 29 single optimal plant communities,we analyzed the stoichiometric characteristics of soil and different community plant components in this paper. The main results are as follows:The plants of gramineae, compositae and legumes can survive in Songnen grassland in the form of single optimal community, respectively. As a kind of miscellaneous grass, chenopodiaceae plants have strong salt resistance and tend to form a single community. The unique geographical environment in Songnen grassland is more suitable for the growth of plant which has strong saline resistance. The productivity of single communities is different because of plant species diversity. The average biomass of ground community is 0.666 and underground value is 3.155 kg/m2. Compositae, leguminous plant biomass is higher on the floor. Grasses, miscellaneous grass biomass is higher underground. The root-shoot ratios of different communities are 6.25( miscellaneous grass), 5.81(grass class), 4.36(compositae plants), and 3.40(leguminous plants), respectively.Total carbon content of plant components is reproductive components(53.2%) < leaf(53.3%) <stem(53.9%); Organic carbon content is reproductive components(37.9%) < leaf(41.9%) < stem(43.2%), accounting for 78.5%,80.3%, 71.4% of total carbon content respectively. Inorganic carbon content is stem(10.6%) < leaf(12.0%) < reproductive components(15.2%). Total nitrogen content of plant components is stem(9.0g/kg) < reproductive components(18.4g/kg) < leaf(18.5g/kg); Total phosphorus content is stem(1.48 g/kg) < leaf(2.23g/kg) < reproduction components(3.29g/kg); The N : P are leaf(9.09) > reproduction components(7.87) > stem(6.71). The N : P of all plant functional groups are less than 14, which suggests that the plants growth is limited by the phosphorus in Songnen grassland.Soil total carbon content presents a “down- up – down” trend; The content of organic carbon decreases with the soil depth; Inorganic carbon content is lower in surface layer(0-20cm), increases in the depth of 20-50 cm,but decreases slightly in the depth of 50-100 cm. Averaged in the depth of0-100 cm, the storages of soil total carbon and inorganic carbon decrease for C3 grasses, C4 grasses, compositae, leguminosae plants, miscellaneous grass in turn. The storage of soil organic carbon from high to low is the compositae,C3 grasses, C4 grasses, legumes, miscellaneous grass.Soil total nitrogen content has no obvious change with the increase of soil depth; The leguminous plants have higher nitrogen level than other functional group of plants in all the layers. Soil total phosphorus content has no obvious change with the increase of soil depth, with the largest content for C3 grasses.Averaged in the depth of 0-100 cm, the N : P of soil from large to small is leguminous plant(27.04) > compositae(11.54) > miscellaneous grass(10.56) > C4 grasses(9.71) > C3 grasses(8.45).