关键词: 水生植被;演替过程;演替驱动力;富营养化;水位变化;水污染综合治理措施;洱海;

Abstract: Erhai is the mother lake and centralized drinking water source of Bai people in Dali City. Driven by natural conditions and human activities, the succession of aquatic macrophyte in Erhai Lake has been obvious in recent 60 years, and the macrophyte resources show significant recession characteristics. Based on the relevant data of water level, water quality, species and area of aquatic macrophyte and the number of phytoplankton in Erhai Lake over the years, the change process of water level and water quality in Erhai Lake, and its correlation with the succession process of aquatic macrophyte were systematically studied. The driving factors for the succession of aquatic macrophyte in Erhai Lake were discussed. The results showed that: ① Over the 60 years, the succession of aquatic macrophyte community in Erhai Lake had experienced a process of expansion, prosperity, decline and stability. The population structure of aquatic vegetation had become simple, and its distribution in water depth and area had shrunk greatly, and the dominant population had gradually changed from clear water type to pollution resistant type, such as Vallisneria natans, Ceratophyllum amphibium and Potamogeton maackianus. ② The succession of aquatic macrophyte was significantly affected by the change of water level in Erhai Lake. The key to drive and maintain the good growth and maximum area distribution of aquatic macrophyte in Erhai Lake was to maintain the low water level from May to August and the large fluctuation of water level in the year. ③ The water pollution changed the lake from grass type to algae type and caused a sharp decline of water transparency, which was the key environmental driving factor for the rapid degradation of aquatic macrophyte in Erhai Lake from 1990s to 2003. Therefore, measures such as controlling and reducing the content of nitrogen, phosphorus and other nutrients in the water entering the lake, formulating the low water level operation plan from May to August, and implementing a ecological water level regulation scheme with large water level variation within a year, can effectively promote the natural restoration of aquatic macrophyte in Erhai Lake and the sustainable improvement of water environment quality.

Key words: aquatic macrophyte; succession process; driving force of plant succession; eutrophication; water level variation; comprehensive measures to control water pollution; Erhai Lake