筑坝蓄水过程对高原湿地拉市海湖滨植被的影响

EFFECTS OF DAM IMPOUNDMENT ON LAKESIDE VEGETATION SUCCESSION IN THE PLATEAU WETLANDS OF THE LASHI LAKE

选择滇西北高原湿地拉市海湿地湖滨作为研究区域,采用传统的野外植被调查和定位观测相结合的方法对该区域植被特征、分布格局及受筑坝蓄水过程的影响进行分析和研究。结果表明:研究区共有维管束植物97种,隶属于34科76属,可划分为2个植被类型,3个植被亚型,10个群落类型;拉市海筑坝蓄水过程对研究区植物群落分布格局和组成结构产生明显的影响,草甸植被、沼泽植被和湖泊水生植被占研究区面积比重分别从2009年的44.54%、18.69%和36.76%变为2011年的32.59%、13.68%和53.59%,草甸植被和沼泽植被的面积不断缩小,湖泊水生植被面积持续扩大,狗牙根(Cynodon dactylon)逐渐取代蒿属(Artemisia)植物在草甸植被中的优势地位,而李氏禾群落(Com.Leersia hexandra)成为了研究区湖滨带水生植物的主要成分;研究区植被在筑坝蓄水过程的胁迫下呈草甸植被(杂草群落、狗牙根群落Com.Cynodon dactylon),沼泽植被(葱状灯心草群落Com.Juncus al-lioides、菖蒲群落Com.Acorus calamus、刚毛荸荠群落Com.Eleocharis vallcculosa、水蓼群落Com.Polygonum hy-dropiper),湖泊水生植被(李氏禾群落Com.Leersia hexandra、两栖蓼群落Com.Polygonum amphibium、满江红群落Com.Azolla imbricata、鸭子草-穗状狐尾藻群落Com.Potamogeton distinctus-Myriophyllum spicatum)的演替格局;拉市海植物群落受筑坝蓄水过程影响发生的逆向演替,从理论上延长了湿地的服务年限,但蓄水过程对鱼类的生存和繁殖、越冬水禽的生境及整个湿地生态系统结构和功能的影响是长期的,还有待深入的研究。

The Lashi lake,a typical wetland in the upstream of the Yangtze River was selected to study the effects of dam impoundment on the characteristics and distribution patterns of vegetation by the methods of traditional field survey combining with locate study.The results showed that there were 97 species of vascular plants in the studying area belonging to 34 families and 76 genera.The vegetation could be divided into 2 types,3 subtypes and 10 communities.The vegetation distribution pattern and composition structure alternated obviously.The proportions of swamp,meadow and aquatic plants in the study area were changed from 44.54%,18.69% and 36.76%,respectively in 2009 to 32.59%,13.68% and 53.59%,respectively in 2011.The area of meadow and swamp shrank as dam impounding while the area of aquatic plant expanded gradually.The dominant species of Artemisia in the meadow was replaced by Cynodon dactylon gradually.And the community of Leersia hexandra became the main component in the study area.The vegetation succession model was meadow（weeds community,Cynodon dactylon community） to swamp（Juncus allioides community,Acorus calamus community,Eleocharis vallcculosa community,Polygonum hydropiper community） to aquatic vegetation（Leersia hexandra community,Polygonum amphibium community,Azolla imbricate community,Potamogeton distinctus-Myriophyllum spicatum community） following the dam impounding.The measure of dam impoundment made the Lashi lake vegetation succession reversely,which prolonged the life of the lake wetland but its effects on fish,waterfowl,and the wetland ecological structure and ecological service need further study.