鄱阳湖湿地现状问题与未来趋势

近年来鄱阳湖秋冬季水文呈干枯态势,湿地生态系统及其关键因子也发生了变化。如何合理保护和利用鄱阳湖湿地引起各方关注。系统综述了鄱阳湖湿地生态系统在水文、江湖关系、水质、水鸟栖息地、渔业资源等方面存在的问题,梳理了引起这些问题的外部和内部因素。针对"一切照常"和"水位调控"两种情景,预测了湿地未来的变化趋势,并指出了当前研究中的不确定性问题。研究认为:鄱阳湖秋冬季的低枯水位,对水质、湿地植被、水鸟栖息地以及鱼类食物资源和"三场"(即:产卵场、洄游通道、索饵场)产生了一定不利影响。建议通过模型模拟和情景预测来分析不同调控方案的影响效果,优化调控方案、将生态系统的负面影响降到最低。

CURRENT ISSUES AND FUTURE TRENDS OF POYANG LAKE WETLAND

Poyang Lake is the largest freshwater lake of China and also one of the only two large-scale water-carrying lakes that takes in and sends out water in the Yangtze area. Extreme droughts and low water levels have frequently occurred in dry seasons of Poyang Lake in the last decade which affected the function of wetland ecosystems and their important factors. How to get balance between relieving the drought situation so as to use the wetlands wisely and protecting biodiversity is a major concern both domestically and internationally. This research analyzed the existing problems of Poyang Lake wetland ecosystem regarding hydrology, river-lake relationship, water quality, waterbird habitat and fishery resources, and systematically reviewed the external and internal factors causing these problems. Our results suggest that the lower water levels in dry seasons of Poyang Lake have negative effects on wetland ecosystems of Poyang Lake. In the area, the hydrological regime changed, as dry seasons arrived earlier and the duration extended as well as water levels in dry season lowered than that before 2003. The interaction between Poyang Lake and Yangtze river was altered; Wetland ecosystem degraded such as water quality declined, wetland vegetation degraded, threats to habitat of waterbirds increased and recession of fishery resources. Changes of Poyang Lake wetland both were affected by external drivers, composed by upstream reservoir group (including Three Gorge Dam), controlling reservoirs within the watershed, climate change, water consumption, pollutant emissions, overfishing, sand mining and water-control activities et al., but also by the constraints of internal drivers, including changes of water flow, velocity of flow, flooding duration, and water depth. Based on the scenarios of "business as usual" and "water level regulation", future trends of wetlands were predicted, and the uncertainties in the current study were pointed out. Predicted impacts on local ecosystem of different regulatory schemes through model simulation and scenario analysis were suggested in case to optimize the regulatory schemes and minimize their adverse impacts.