科研之友
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摘要
The typical dishing wetlands in Sanjiang Plain, Northeast China are dominated consecutively - from the center to the edge - by Carex pseudocuraica, Carex lasiocarpa, Carex meyeriana, Calamagrostis angustifolia, and Calamagrostis angustifolia-Shrub. The consecutiveness of the vegetation is related to the depth of standing water. Using a compartments model, the researchers examined the nitrogen (N) distribution and cycling in plant-soil systems in three different freshwater wetland types - Calamagrostis angustifolia wetland (CAW), Carex meyeriana wetland (CMW) and Carex lasiocarpa wetland (CLW) - located along a water level gradient in the Sanjiang Plain. The objective was to provide insight into the mechanism of water level changes constraining the process of nutrient circulation by quantifying and comparing the N cycling of three freshwater wetland types along a water level gradient in the Sanjiang Plain, Northeast China. In the three wetland types, N storages, N distributions, N fluxes and cycle coefficient in the plant-soil systems were measured. Soil proved to be the main N storage of plant-soil systems in the three wetland types. N storages in soil among the three wetland types showed a significant decrease: CAW>CMW>CLW. A large percentage of annual N uptake from the soil is detained in roots, and just a small percentage of annual N uptake is used in the plant-soil system internal circulation also showing a noteworthy decrease: CMW>CAW>CLW. Moreover, a large percentage of the annual N uptake by aboveground plants is returned through litter-fall. N released from litter decomposition among the three wetland types shows a decrease line as well: CAW>CMVV>CLW. With water level increasing, annual N uptake and annual N retention increased, but annual N return and cycle coefficient decreased. The research results indicate that in case the water levels in wetlands decrease, the rates of biological cycling significantly increase.
- 出版日期2010
- 单位西南林业大学; 中国科学院东北地理与农业生态研究所
