崇明东滩围垦堤内植被快速次生演替特征

崇明东滩湿地98大堤内的生态示范区由于人工排水而干涸,芦苇塘成为次生裸地,土壤条件发生变化,呈明显的旱化和盐渍化,植被群落结构呈典型的次生演替,适宜旱地的耐盐植物獐茅和碱蓬等先锋植物出现.文中分别于2003年秋季、冬季和2004年春季沿植被带对塘内各种植物的生物量、高度、密度等指标进行取样分析.结果表明,堤内植被群落已形成明显的带状獐茅草-獐茅草/碱蓬-碱蓬/芦苇-芦苇旱生植被群落.碱蓬在裸地中2003年秋季平均生物量达到415.4 g·m^-2、2004年春季为391.53 g·m^-2,成为裸地的优势种,并向芦苇中扩散,生物量和高度逐渐增加,密度逐渐稳定,表现出良好的生长趋势.

Secondary succession characteristics of vegetations on reclaimed land inside Chongming wetland seawall

National reserve Chongming Dongtan wetland was designated as an important international wetland (ramsar site) in 2002. The area outside 98 seawalls is the core area of the reserve, while their inside is the experimental area. A wetland restoration project was started in June 2003, and a large pond behind the seawall was unwatered, which changed the soil condition and appeared drought and salinization. The vegetations presented typical secondary succession, and Aeluropus littoralis and Suaeda glauca invaded the area originally dominated by reed. From July 2003 to April 2004, the soil moisture content and salinity of 15 samples were determined, with the biomass, height, density, and coverage of each kind of vegetations measured. The results showed that the vegetation layout had become an obviously zonary distribution of Aeluropus littoralis-Aeluropus littoralis/Suaeda glauca-Suaeda glauca/Phragmites communis-Phragmites communis community. Suaeda glauca gradually extended to the reed area, and became the dominant species of the area, with an average biomass of 2003 415.4 g x m(-2) in autumn, and of 2004 391.53 g x m(-2) in spring. The biomass and height of Suaeda glauca increased, and its density was getting stable, suggesting that the plant had strong growth ability in drought area.