向海沼泽湿地土壤氮素的空间分布格局

本文运用地统计学方法探讨了吉林省通榆县向海沼泽湿地土壤氮素在植物生长初期的空间分布格局 ,结果表明除铵态氮外 ,其他各形态氮素主要集中分布在表层土壤 ,呈现出由表层向下逐渐减少的趋势。各形态氮素和全氮都具有高度的变异特征 ,其中表层土壤碱解氮的变异最大 ,铵态氮最小 ,变异系数分别为 6 5 6 4%和 4 9 5 1% ;其他各层土壤有机氮、全氮和硝态氮含量的统计变异较大 ,而碱解氮和铵态氮较小 ;有机氮和全氮的空间分布格局具有显著的相似性 ;表层土壤全氮、有机氮和碱解氮的高值区和低值区具有高度的一致性 ;除碱解氮主要集中在土壤表层外 ,其他形态氮素和全氮在土壤较深层次均出现累积峰。

Spatial distribution pattern of nitrogen in marsh soils in Xianghai wetlands

Wetlands serve as source, sink or transfer of nitrogen(N), and spatial distribution of N in wetlands also significantly influences most ecological processes of wetlands. Some researchers have testified that soil nutrients in wetlands had higher spatial heterogeneity. Geostatistics have been successfully used in soil science and become an efficient tool to research spatial heterogeneity of soils since the 1970s. Xianghai wetland is a one of international importance, which is located at the downstream of Huolin river catchment of semi-arid area and is a typical agriculture/pastoral ecotone and ecological fragibility zone in the west of Jilin province. Xianghai wetland has been the important factor keeping ecological balance and one of the natural barriers for eastern ecological environment in this region. At present, Xianghai wetlands are potentially threatened as a result of such human activities as overgrazing, building large-scale irrigation works and unreasonable reclamation. Spatial distribution pattern of total N and N forms in marsh soils during plant budding were studied using geostatistics of Xianghai wetlands in May, 2001. The results showed that, with the exception of ammonium N, other forms of N and total N were mainly distributed on surface soils, appearing a decreasing tendency gradually with the increase of soil depth; the total N and all forms of N contents had higher statistical variations; on surface soils, the statistical variation of the available N was the highest, but ammonium N the lowest, with variation coefficients of 65.64%and 49.51%, respectively. For other soil layers, soil organic N, total N and nitrate N had higher statistical variations, but available N and ammonium N had lower statistical variations. The spatial distribution pattern of total N was similar to that of organic N; it was highly consistent in distribution areas with higher or lower contents of N forms; with the except of the fact that available N concentrated on top soils, other forms of N appeared accumulation peaks in deeper layers of soil profiles. Both N behavioral processes and environmental factors controlled spatial distribution pattern of N, but quantifying their influences on spatial distribution pattern needed further studies.