不同水分条件下藏北盐化沼泽湿地土壤碳氮的分布

Distribution of Soil Carbon and Nitrogen under Different Water Conditionsin Alpine Salty Wetlands,Northern Tibet Plateau

目前,对于高寒湿地土壤碳氮的研究多集中于泥炭沼泽,盐化沼泽土壤的研究相对较少。为了全面认识湿地土壤碳氮的特征以及对未来气候变化的响应,以藏北高原腹地格仁错湖沼湿地为研究区,分析高寒盐化沼泽常年积水、季节性积水和无积水三种水分条件下土壤剖面(0~50 cm)内有机碳和全氮的垂直分布特征。研究结果表明:随水位梯度的升高,各土层碳氮含量逐渐减少。在无积水区和季节性积水区,有机碳(SOC)和全氮(TN)的分布均表现为表层(0~10 cm)含量最高,沿土壤剖面呈下降趋势;常年积水区各土层间的SOC和TN含量差异很小。其中,无积水区、季节性积水区和常年积水区0~50 cm土层的SOC储量分别为7.60 kg/m2,4.11 kg/m2和2.35 kg/m2,TN储量分别为0.56 kg/m2,0.28 kg/m2和0.19 kg/m2。相对于高寒草甸沼泽土和泥炭沼泽土壤来说,高寒盐化沼泽土是碳氮累积较少的土壤类型,高水位、高盐度和低气温成为盐化沼泽土壤碳氮累积的主要限制条件。

At present, studies on soil properties in alpine wetlands concentrated on those inalpine peat wetlands. However, less was known about soil carbon and nitrogen in alpine salty wetlands. To determine the vertical distri- butions of soil organic carbon（SOC） and total nitrogen （TN） in natural salty wetland to increase of soil water lev- els, soil samples （0 ~ 50 cm ）from three water levels were collected in a typical salty soil on Xainza County of Northern Tibet, which was no water area （NWA） , seasonal water area （SWA） , perennial water area （PWA）. We found that SOC and TN contents gradually reduced with the rise of water levels. In NWA and SWA, the highest SOC and TN contents appeared in surface soil layer （0 -10 cm） , and their contents show a decreasing trend with the deeper of the soil layer. In PWA, SOC and TN contentshad fewer differences in five soil layers. Compared with C and N in meadow soil and peat soil, SOC and TN storages were lowerin salty soil （0 -50 cm）. In detail, the val- ues of SOC storage were 7.60 kg/m2 in NWA, 4.11 kg/m2 in SWA and 2.35 kg/m2 in PWA, and the values of TN storages were 0.56 kg/m2 in NWA, 0. 28 kg/m2 in SWA and 0.19 kg/m2 in PWA. Generally, high soil mois- h^re, high salinity and low air temperature lead to less carbon and nitrogen accumulations in alpine salty wetland soil.