黄河三角洲新生湿地土壤碳氮磷分布及其生态化学计量学意义

河口湿地是连接陆地生态系统和海洋生态系统的纽带。土壤碳(C)、氮(N)、磷(P)元素是湿地生态系统营养水平的重要指示物,显著影响湿地生态系统的生产力。本文研究了黄河三角洲新生湿地不同植被下土壤C、N、P的分布特征和生态化学计量特征。结果表明,1)黄河三角洲新生湿地C、N、P含量分别为1.2~8.4、0.2~0.8、0.4~0.6g/kg,平均值分别为3.5、0.4、0.5g/kg;土壤表层的C、N、P含量显著高于亚表层。2)黄河三角洲新生湿地C/N、C/P、N/P比值分别为4.62~12.67、2.02~16.39、0.22~1.53,平均值分别为8.77、6.81、0.77。土壤C/N、C/P、N/P比值随土壤剖面深度向下递减,不同植被土壤之间的C/N、C/P、N/P比值有所不同。土壤生态化学计量比值显示黄河三角洲新生湿地土壤有机质分解快,氮的矿化度高。因此,提高该地区土壤有机质的归还,同时适当增加氮肥使用成为湿地生态恢复的优先选项。

Distribution Characteristics of Soil C, N and P in Newly-formed Wetlands of the Yellow River Delta, China and Their Stoichiometry Implications

Estuarine land is a link between terrestrial and marine ecosystems. The existence of C, N, and P elements in soil can greatly influence the primary productivity of wetlands ecosystems and they are also the referent for nutrient level of these ecosystems. The present study measured the distribution characteristics of C, N, and P elements and explored ecological stoichiometric implications in the newly-formed wetland of the Yellow River delta with different vegetation. Results show that 1) C, N and P concentrations in newly-formed wetland of the Yellow River delta range 1.2-8.4, 0.2-0.8, and 0.4-0.6 g/kg with average contents of 3.5, 0.4 and 0.5 mg/kg, respectively. Contents of C, N and P decrease significantly with increasing soil depth; 2) ratios of C/N, C/P and N/P in this wetland are 4.62-12.67,2.02-16.39 and 0.22-1.53 with average values of 8.77, 6.81, and 0.77, respectively. These ratios vary greatly in different soil vegetation and decrease gradually with increasing soil depth. In addition the ratio analysis indicates that in this newly-formed wetland the decomposition rate of soil organic matter is faster and the degree of nitrogen mineralization is higher. Therefore, increasing the return of soil organic carbon and the utilization of nitrogen fertilizer should be given preferential treatment for the restoration of newly-formed wetlands in the Yellow River Delta.