关键词: 九段沙湿地, 芦苇收割, 生长特征, 生物量, 全氮含量

Abstract: To explore effects of continuous harvesting on Phragmites australis-dominated wetland, growth and biomass of P. australis and variation of content of soil total nitrogen were monitored in two plots of reed wetland, one subjected to continuous harvesting for 10 years and one left intact, in Jiuduansha, Shanghai for comparison. Results show that reed harvesting significantly promoted density of P. australis (P＜0.05), but had no much effect on shoot height and basal shoot diameter of the plants. The above-ground biomass of P. australis was significantly higher in the harvested plot than in the intact plot（P＜0.05）. However, a reverse trend in below-ground biomass was observed. Reed harvesting not only significantly reduced the content of total nitrogen in the surface soil (0-5 cm), but also affected the vertical distribution of soil nitrogen. The total nitrogen content was generally lower in the harvested plot than in the intact plot in all the soil layers (0-50 cm), and the difference was especially significant in soil layers of 0-10 cm and ＞10-20 cm. In addition, in the intact plot, soil total nitrogen content tended to decrease with increasing soil depth, while in harvested plots, it was found lower in superficial and middle soil layers (0-20 cm) than in the other layers. Therefore, the practice of long-term continuous harvesting may affect the allocation of biomass between the above- and below-ground parts of P. australis, and reduce the content of soil total nitrogen in P. australis-dominated wetland. It is advisable to develop a more reasonable strategy for harvesting reeds in the wetland.

Key words: Jiuduansha Wetland, Phragmites australis harvesting, growing characteristics, biomass, total nitrogen content