近百余年(1900-2020年)洞庭湖湿地演化驱动因素分析

Driving factors of wetland evolution in Lake Dongting during 1900-2020

自20世纪以来,在自然以及人类活动共同作用下,洞庭湖湿地面积与格局发生显著变化。本文在综合大量历史资料、相关文献以及数据的基础上,采用分段线性回归方法将近百余年(1900—2020年)洞庭湖湿地面积与格局变化划分为4个阶段,并重点分析了各阶段影响湿地演化的驱动因子及相互作用关系。1900年以来,洞庭湖湿地面积变化可分为1900—1949年的明显下降期、1950—1978年的快速萎缩期、1979—1998年的稳定期以及1999年至今的略微回升期,湿地景观格局变化经历了新中国成立前的相对稳定阶段、1950s—1990s的水域向洲滩转化阶段以及21世纪以来的洲滩向水域转化阶段。不同时期,由于社会经济与生产力水平的差异,湿地演变的驱动因素存在差异,导致湿地演变的速率与方向有所不同。围湖垦殖与退田还湖是导致湿地面积发生改变的主要因素,气象波动、水库建设、湖区采砂以及河道整治等则通过改变入湖水文泥沙情势影响湿地格局变化,并影响围湖垦殖与退田还湖等活动。为满足经济发展要求,政府在湿地演变中的参与度逐渐增加,对围湖垦殖的态度发生了“鼓励—参与—禁止—还湖”的转变,为近百余年洞庭湖湿地演化的核心驱动要素。近百余年洞庭湖湿地的演化过程是区域社会经济发展过程的综合呈现,是人力与自然力的角力过程,也是人地关系矛盾协调演化并趋向缓和的过程。

Since the 20th century,the area and pattern of Lake Dongting wetland have changed significantly under the combined effect of natural and human activities.Based on a lot of historical materials,related literatures and data,this paper identified 4 evolutionary regimes of Lake Dongting wetland area and landscape pattern in the past 120 years(1900-2020)using the piecewise linear regression method,and analysed the driving factors and their interactions of each regime.The evolution of Lake Dongting wetland area could be divided into the obvious decline period(1900-1949),the rapid decline period(1950-1978),the stable period(1979-1998),and the slight recovery period(1999-present).The evolution of the landscape pattern experienced the relatively stable period(before 1949),water transformation to floodplain stage(1960s-1990s)and floodplain transformation to water stage(2000s-present).Due to differences in socio-economic and productivity levels,the drivers of wetland evolution were different between regimes,resulting in different rates and directions of wetland evolution.Lake reclamation and the return of agricultural land to the lake were the main drivers of wetland change.Meteorological fluctuations,reservoir construction,sand mining and channel regulation affected the wetland pattern by changing the water-sediment situation in the lake.They had also influenced the reclamation of lake embankments and the return of farmland to the lake.In order to meet the demands of economic development,the government's participation in wetland development had gradually increased,and the government's attitude towards lake reclamation had gone through stages,including“encourage-participate-prohibit-return lakes”,which was the core driving factor for the development of Lake Dongting Wetland over the past 120 years.The development process of Lake Dongting Wetland over the past one hundred years is the comprehensive representation of regional socio-economic development,the wrestling process of human and natural forces,and the harmonious development and tendency to gradually reduce the contradiction between man and land.