城市湿地转变为不同土地利用类型后土壤碳氮分布特征

以安徽省蚌埠市龙子湖湿地为研究区,选择由湿地退化形成的林地、公园绿地、耕地、水产养殖地、防护林带5种土地利用类型为研究对象,分析土壤中总有机碳(TOC)、全氮(TN)含量,颗粒有机碳(POC)、颗粒有机氮(PON)含量与分配比例,以及土壤碳氮比(C/N)和颗粒组分碳氮比(POC/TOC),研究不同人为干扰强度和干扰形式下土壤碳氮的分布特征.结果表明: 林地、水产养殖地、耕地土壤中TOC呈现出表聚性,公园绿地和防护林带各土层间TOC含量无显著差异;5种土地利用类型土壤POC、TN、PON呈现出表聚性;受人为干扰程度较强的公园绿地和防护林带POC分配比例较高,耕地和水产养殖地受到的人为干扰也较强烈,但其POC分配比例与受人为干扰较弱的林地相当,说明除干扰强度外,干扰的形式也可能是影响POC分配比例的重要因素;林地C/N随土层深度增加而逐渐降低,公园绿地、耕地和防护林带C/N随土层深度增加变化不显著,除林地和耕地外,其他土地利用类型土层深度对POC/TOC的影响不显著.

Distribution characteristics of soil carbon and nitrogen in different land use types changed from urban wetlands.

Five land use types of Longzihu wetland in Bengbu City, Anhui Province of China, including woodland, greenbelt, aquaculture land, cultivated land, shelter forest, were chosen as the research object. Through analyzing the content and allocation proportion of total organic carbon (TOC), total nitrogen (TN), particulate organic carbon (POC), particulate organic nitrogen (PON), as well as soil carbon nitrogen ratio (C/N) and soil particles component carbon nitrogen ratio (POC/TOC), soil carbon and nitrogen distribution characteristics were discussed under dif-ferent human disturbance intensities and modes. Results showed that TOC showed surface accumulation in woodland, aquaculture land and cultivated land, while it did not show significant variation in each soil layer of greenbelt and shelter forest. POC, TN and PON showed surface accumulation in all land utilization types. Greenbelt and shelter forest, being disturbed strongly by human activities, had higher POC allocation proportions, while aquaculture land and cultivated land, heavily interfered by human activities, had relatively lower POC allocation proportions which were commensurate with that of woodland. Woodland received less interference by human activities, so in addition to disturbance intensity, disturbance mode might be another important factor affecting POC allocation proportion. C/N decreased with the increase of soil depth in woodland, but C/N of greenbelt, cultivated land and shelter forest had no obvious changes along the soil profile. Soil depth had no significant impact on POC/TOC in the land use types except woodland and cultivated land.