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NITROGEN CYCLING IN PLANT-SOIL SYSTEMS IN THREE FRESHWATER WETLAND TYPES ALONG A WATER LEVEL GRADIENT IN THE SANJIANG PLAIN, NORTHEAST CHINA

发布时间:2010-09-10点击数:2474

论文题目:NITROGEN CYCLING IN PLANT-SOIL SYSTEMS IN THREE FRESHWATER WETLAND TYPES ALONG A WATER LEVEL GRADIENT IN THE SANJIANG PLAIN, NORTHEAST CHINA

作者:Xuelian Guo1, Xianguo Lu2* and Kun Tian1*

关键词: China; Sanjiang Plain; nitrogen cycling; plant-soil systems; freshwater dishing wetlands; water level changes

刊物名称:Fresenius Environmental Bulletin

卷期:Vol.19 (4), 2010

页: 1-8

摘要:The typical dishing wetlands in Sanjiang Plain, North-east 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 compart-ments model, the researchers examined the nitrogen (N) distribution and cycling in plant-soil systems in three dif-ferent freshwater wetland types - Calamagrostis angustifo-lia 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 quanti-fying and comparing the N cycling of three freshwater wet-land 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 stor-age of plant-soil systems in the three wetland types. N stor-ages in soil among the three wetland types showed a signifi-cant 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 note-worthy decrease: CMW>CAW>CLW. Moreover, a large percentage of the annual N uptake by aboveground plants is re-turned through litter-fall. N released from litter decomposition among the three wetland types shows a decrease line as well: CAW>CMW>CLW. With water level increasing, annual N uptake and annual N retention increased, but annual N return and cycle coefficient de-creased. The research results indicate that in case the water levels in wetlands decrease, the rates of biological cycling significantly increase.

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