1980年以来5个时期洞庭湖区国际重要湿地景观动态研究

Landscape Dynamics of Wetlands of International Importance in Dongting Lake Area for 5 Periods since 1980

国际重要湿地是中国乃至全球湿地保护体系的重要组成部分,研究国际重要湿地景观动态对于湿地保护和管理具有重要意义。以洞庭湖区3处国际重要湿地为研究对象,利用1980年、1990年、2000年、2010年和2015年的Landsat MSS/TM/ETM+/OLI影像数据,采用面向对象的遥感影像分类方法,解译出5个时期洞庭湖区3处国际重要湿地的土地覆被信息,提取各处国际湿地的土地覆被类型分布信息;结合景观指数和人为干扰度指数,探讨5个时期洞庭湖区湿地面积动态及其景观格局动态特征。研究结果表明,从1980年到2015年,洞庭湖湿地总面积减少了232.60 km^2;南洞庭湖面积减少的最多,湿地面积减少了218.54 km^2,损失率高达20.30%;3处重要湿地中的湿地斑块数量增多,湿地趋于破碎化,景观间连通度降低;西洞庭湖景观破碎化程度最高,湿地景观连通度差,聚集度指数(CONTAG)相对最小;洞庭湖区湿地仍然受到强度较高的人类活动干扰,其中,耕地扩张是造成湿地损失的主要原因。

Wetlands of international importance(Ramsar site) are important component of wetland conservation system to China and to the world, and thus the investigation of landscape dynamics in Ramsar sites plays a critical role in wetland management. This study applied an object-oriented classification method to long-term series of Landsat MSS/TM/ETM+/OLI images in 1980, 1990, 2000, 2010 and 2015 to obtain the land covers in three Ramsar sites over the Dongting Lake. By integrating the landscape metrics and the quantitative analysis of natural and anthropogenic land covers, the results showed that wetland area over the Dongting Lake reduced totally by 232.60 km^2. Of which, the South Dongting Lake Ramsar site experienced the largest areal decline with aloss of 218.54 km^2. Wetlands tended to be fragmented particular in the West Dongting Lake Ramsar site, while landscape aggregation decreased remarkably in the West Dongting Lake Ramsar site.Moreover, threats from human activities was enhanced, of which agricultural cultivation is yet the major driving force to wetland loss and fragmentation.