Analysis of the plant N and P sequestration from common reed and common reed+ cattail communities in wetland soil in Qinhu Lake of northern Jiangsu, China

Abstract

湿地土壤是湿地生态系统固持氮（N）、磷（P）的重要库，水生高等植物在湿地土壤固持N、P过程中起到了非常重要的作用.本研究采用室外取样与室内实验结合的方法，对溱湖湿地两种主要湿地类型（芦苇（Phragmites australis）群落和芦苇＋香蒲（Typha latifolia）群落）影响湿地土壤N、P固持过程的规律展开研究.分析了芦苇、香蒲各器官生物量和总氮（TN）、总磷（TP）含量及储量对于土壤各土层TN和TP含量的影响.结果显示：（1）溱湖湿地对于水体TN和TP有一定的削减作用，且对TN的削减作用更大；（2）芦苇可以增强湿地土壤（30 cm以下的土层）富集N的效率，并且芦苇＋香蒲群落中土壤固N效率更高，芦苇植株内TN和TP储量都是根 > 茎 > 叶 > 穗，而香蒲则是根 > 穗 > 茎 > 叶；（3）芦苇和香蒲茎、叶器官的TN和TP含量在夏季均显著高于其他几个季节，尤其是芦苇茎的TN含量在夏季高出其他几个季节70%~84%，而TP含量甚至高出其他几个季节81%~92%；（4）芦苇、香蒲对于P贫瘠的响应机制不同，导致芦苇会消耗土壤P，而香蒲的介入可以抵消这一消耗过程.因此，芦苇＋香蒲的植物配置模式可以提高湿地土壤固持N、P的综合效率.;Wetland soil is a significant pool of nitrogen (N) and phosphorus (P) sequestration in the wetland ecosystem in which the aquatic higher plants plays an important role. Field sampling and indoor analysis were conducted by two communities of the common reed (Phragmites australis) & the common reed + cattail (Typha latifolia) from Qinhu Lake wetland to enhance our understanding of the immobilization of N & P in the soil. Organs biomass of common reed & cattail, contents of total nitrogen (TN) & total phosphorus (TP) and their impacts on soil TN & TP contents were analyzed. Results showed that (1) consumption effect of Qinhu Lake wetland on soluble TN and TP was observed, especially a bigger effect on TN. (2) Common reed could enhance the efficiency of N enrichment in wetland soil (below 30 cm soil layer) and the effect is much higher than that in common reed + cattail community. Order of the TN and TP storage from high to low in the organs of common reed was root>stem>leaf>spike, while the order in cattail was root>spike>stem>leaf. (3) TN and TP contents in the stem and leaf of the common reed and cattail in the summer were higher than other seasons significantly, while TN content of common reed stems in the summer was 70%-84% higher and TP content was 81%-92% higher than other seasons. (4) The common reed would consume soil P when cattail would offset P because of the different mechanism response to P limitation. Therefore, the configuration mode of common reed + cattail could improve the efficiency of N and P sequestration of the wetland soil.