鄱阳湖湿地植被退化原因分析及其预警

2003年以来,鄱阳湖长期处于低枯水位状态,湖盆植被面积减少600km2;洲滩土壤含水量降低,旱生植物物种入侵,占据高程15m以上洲滩,湿地植被演变成中生性草甸,使物种大幅度增加;湿生和水生植物向湖中心下移,生长空间缩减;对水深、污染物敏感的植物群落的物种、生物量减少,生物多样性退化;对水深适应性强和耐污染的植物迅速扩张。无序采砂、防火烧荒、牲畜放牧加剧了这一局面。在气候变化和人类活动影响下,鄱阳湖湿地植被正在逐步退化。为了遏制这一退化现象,正在建立鄱阳湖健康评价体系与标准,加强植物群落固定断面和针对稀有物种、对水深和污染物敏感物种、危害湖泊健康物种进行专项监测,针对发现的问题,用遥感影像辨识、实地勘测研究分析全湖变化状况,判断其危害程度,提出防治对策,向相关部门和地区提出预警建议。

CAUSE ANALYSIS AND EARLY WARNING FOR WETLAND VEGETATION DEGRADATION IN POYANG LAKE

The wetland vegetation is gradually degrading in Poyang Lake due to the influence of climate change and human activities, the area of wetland vegetation have reduced 600 km2 since 2003 when state of low water level remain in the Poyang Lake. Since the soil water content decrease, the xerophytes invade and the plant species increase significantly occupying the lake beach above the elevation of 15 m. The wetland plants and aquatic plants down to the lake center resulting in reduced growth space. The plants which are sensitive to water depth and pollutants are disappearing leading to the reduction of the plant biomass and biological diversity. The plants which are resistant to water pollution rapidly expand because the water in the lake is shallow. The disorder of sand mining, vegetation incineration and animals grazing aggravate this situation. In order to curb the phenomenon of wetland vegetation degradation in the Poyang Lake, the evaluation system and evaluation standard of wetland ecosystem health in the Poyang Lake are establishing. Changes of plant community in the existing cross section will be monitored. The rare species, the species sensitive to water depth and pollutant will be monitored. The vegetation change situation in the lake will be determined using remote sensing image recognition and field survey. Finally, the prevention and control countermeasures are putting forward