Chinensis Grassland Decomposers Sub-system Energy Flow

This paper was focused on typical Aneurolepidium chinense community and Puccinellia tenuiflora community in Songnen Grassland and the research work about energy flow of decomposer subsystem of Aneurolepidium chinense grassland was completed through field and laboratory experiments during the period from 2000 to 2001. The work on seasonal dynamics of litter input and decomposition and the relationship between them and environmental factors was studied through the method of harvest and weight loss. Soil respiration rate was measured by alkali-absorption method and the contribution from soil microorganism respiration and from root respiration was determined through trendline method of linear regression between soil respiration rate and belowground biomass. Mathematical models were established between the seasonal dynamics of main components of soil total respiration including soil respiration, root respiration, soil microorganism respiration, litter respiration and environmental factors. Grey-analysis was used to compare the difference of seasonal dynamics of soil respiration between Aneurolepidium chinense community and Puccinellia tenuiflora community. Dry-weight conversion method was used to measure the seasonal dynamics of energy accumulation of soil microorganism and mathematical models between energy accumulation and environmental factors were established. Compartment model was applied to describe the energy flow between litter and soil microorganism and stabilization analysis was conducted.1. The annual input of litter was 124.8g.m-2 and 99.8g.m-2 in Aneurolepidium chinense community and Puccinellia tenuiflora community respectively. The litter input amount in the two communities was negatively correlated with soil surface temperature, precipitation and green biomass of plants. The maximum values of decomposition rate of Aneurolepidium chinense community and Puccinellia tenuifloracommunity were 4.285 mg-g^.d"1 and 8.109 mg.g^.d"1 respectively in August and was positively correlated with soil temperature, soil water content and negatively correlated with soil organic matter content and ratio between carbon and nitrogen of soil.2. The diurnal release rate of CO2 was 0.3908gC.m"2.hr~1 in Aneurolepidium chinense community and O.83gC.m-2.hr-1 in Puccinellia tenuiflora community with the maximum value in 11-13:00 and the minimum value in 1:00. The release rate of the two communities were positively correlated with soil surface temperature. The two communities had obvious seasonal dynamics of soil respiration. Soil respiration rate of Aneurolepidium chinense community reached the maximum value of 12.66gC.m-2.d-1 in August and that of Puccinellia tenuiflora community reached the maximum value of 11.4 gC.m-2.d-1 in July. The soil respiration rate of the two communities was positively correlated with soil surface temperature, precipitation, soil water content, relative humidity, green biomass and litter decomposition rate and was negatively correlated with ratio between carbon and nitrogen of soil and litter biomass of soil surface. The gray correlation order in Aneurolepidium chinense community was: pH (0.4702) > wind velocity (0.4194) > soil water content at 0-10cm depth (0.397)> soil water content at 10-20 depth (0.3932)> soil water content at 20-30cm depth (0.3764)> porosity(0.3705)> relative humidity (0.3576) > organic matter content of soil(0.306)> C/N (0.2776) > soil temperature at 0-10cm depth (0.2422)> precipitation amount (0.1716)and the gray correlation order in Puccinellia tenuiflora community was: soil water content at 0-10cm depth (0.4835)> pH(0.3999)> wind velocity (0.3877)> porosity (0.3559)> organic matter of soil (0.3473) >soil temperature at 0-1 Ocm depth (0.3386)> soil water content at 10-20cm depth (0.3287)> C/N(0.2915)> relative humidity (0.2661)> soil water content at 20-30cm(0.256)> precipitation amount(0.1892).3. The percentage of root respiration to soil respiration during growth period was 52% with the variation range of 38%-71% in...