长江河口九段沙互花米草湿地生态系统N、P、K的循环特征

Characteristics of N,P and K cycling in Spartina alterniflora wetland ecosystem in Jiuduansha shoal of Yangtze River estuary

研究了九段沙外来入侵种互花米草(Spartina alterniflora)湿地生态系统的营养元素含量、分布规律与循环特征。结果表明,九段沙的上沙、中沙和下沙互花米草湿地土壤全量养分含量差异相对较小,而速效性养分含量差异相对较大。土壤剖面中TK含量大大高于TN和TP含量,排序为:TK>TN>TP。各沙洲速效性养分含量排序为:速效K>速效N>速效P。土壤速效性养分与全量养分的空间分布规律并不一致,土壤剖面营养元素的垂直分布差异比较明显,速效性养分土壤剖面垂直分异比全量养分显著。各深度土壤营养元素含量均存在差异,不同沙洲同一深度土壤营养元素含量也存在差异。各沙洲不同深度土壤TN含量的差异明显大于TP和TK含量差异。植物中3种营养元素含量以K最高,N其次,P最低。湿地生态系统营养元素归还量远大于存留量。吸收系数排序为:N>P>K。不同沙洲营养元素的利用系数和循环系数存在明显差异,上沙P元素、中沙与下沙K元素利用系数最大,上沙K元素、中沙P元素与下沙N元素循环系数最大。

In the upper, middle, and lower shoals of Jiuduanshashoal at Y angztse River estuary, an investigation was made on the content, distribution pattern, and cycling characteristics of nutrient elements N, P and K in invading species Spartina alterniflora wetland ecosystem. The results showed that among the S. alterniflora wetland ecosystems in the three shoals, the contents of soil total N, P, and K had relatively small differences, but those of soil available N, P, and K had larger differences. The total K content in soil profile was far higher than the contents of total N and P, with the order of total K 〉 total N 〉 total P. Soil available nutrient contents in the three shoals were in the order of available K 〉 available N 〉 available P. Soil available N, P, and K had different spatial distribution patterns from soil total N, P, and K, and their vertical differentiation in the profile was more obvious than that of soil total N, P, and K. The contents of N, P, and K at different soil depths in the same shoals or at the same soil depths in different shoals were different, and the difference of total N was obviously larger than that of total P and K. The plant K content was the highest, followed by N, and P. The return of nutrient elements in the wetland ecosystem was far greater than their reserve, and the absorption coefficient was in the order of N 〉 P 〉 K. There existed obvious differences in the utilization coefficient and cycling coefficient of N, P, and K among the three shoals of Jiuduansha shoal. The P in the upper shoal and the K in the middle and lower shoals had the highest utilization coefficient; while the K in the upper shoal, P in the middle shoal, and N in the lower shoal had the highest cycling coefficient.