Lakeside Zone Of Soil Respiration And Microbial Biomass Carbon Dynamics

Riparian area/zone is an important type of ecotone and of wetlands. Wetlands is a huge reservoir/storage of carbon in terrestrial ecosystems. As a"switch"in the emission and fixation processes of CO2-the primary greenhouse gase (GHG),the shift of its function between a carbon "source" and "sink" has a significant effect on global warming. Soil respiration and microbial biomass carbon are directly bound up with the production of CO2. In this thesis, the riparian zone of Taihu Lake in Yuyang Mountain was chosen as study site, for the study on both temporal and spatial variations and their influencing factors of soil respiration and microbial biomass carbon, in order to explore the specific processes concerning soil carbon cycle in wetlands, and lay a theoretical foundation for future study, by understanding its contribution and response to global climate change. The results showed that:(1)The soil respiration rate in the Seasonally Flooded Zone was significantly higher than the other three experimental zones. Soil moisture is the main influencing factor in determining spatial variation of soil respiration in the riparian zone; In addition to that, soil temperature is also likely to play a significant role on the control of soil respiration, in cooperation with soil moisture.(2) There is a significant exponential function relation between the seasonal variation of soil respiration and that of temperature in the riparian zone, which accorded with the most common model discovered in wetland soils; the seasonal variations of both soil and atmospheric temperatures may explain the majority of that of soil respiration rate, which indicates that they are the dominant factors influencing seasonal variations of soil respiration.(3) Within a certain range of soil moisture, the sensitivity of soil respiration to temperature increased along with increasing soil moisture, but in water saturation area the role of temperature playing on soil respiration was restrained, showing the sensitivity of its response was significantly reduced.(4) The horizontal distribution of microbial biomass carbon is significantly affected by soil moisture and soil nutrients such as total C,P-the highest microbial biomass occurred in the area with optimum water and nutrient content-but uncorrelated with the soil nitrogen.(5) Soil microbial biomass declined sharply along with increasing soil depth, and its vertical distribution is greatly affected by the soil moisture and total C, N, P, S, indicating that microbial biomass is vulnerable to soil moisture and nutrient constraints.