鄱阳湖湿地烧荒遥感监测及其影响分析

鄱阳湖湿地属于我国生态功能区划重要区,兼有洪水调蓄和生物多样性保护的生态服务功能。该区域建有9个国家和省级自然保护区。近年来,全球变暖引发的区域性干旱气象灾害频发,造成鄱阳湖区水体和湿地水位下降、甚至干涸,大量薹草滋生,时有湖区烧荒现象,严重威胁到鄱阳湖湿地自然保护区安全及区域生态环境。2012年初,针对新出现的多起烧荒事件,研究结合遥感快速监测、植物地面调查和GIS缓冲区分析等方法,及时掌握第一手的烧荒区域面积、分布和地面火烧区域与非火烧区域植被生长状况,并经对比和分析获得一些初步认识:①此次春季烧荒区域总斑块95个,烧荒总面积10278.6196hm²,烧荒面积最大的斑块面积1293hm²,烧荒区主要分布在永修县吴城镇鄱阳湖国家级自然保护区和新建县南矶山湿地自然保护区;②火烧后薹草萌发与生长的数量要显著提高,前期地表生物量与盖度也高于未火烧区,但生长后期地表生物量与盖度要低于未火烧区;在萌发与生长的全过程,火烧后薹草的高度均显著低于未火烧区;在生长后期,火烧后薹草群落物种丰富度与生物多样性要明显低于未火烧区;③烧荒地缓冲区分析表明受烧荒影响最大的土地覆盖类型仍是干涸的湖底和邻近农田,随着缓冲区范围的扩大,受影响的森林和农村聚落类型比重加大,应引起足够重视。基于以上三个方面的分析,提出了相关的鄱阳湖区湿地资源保护和烧荒地管理的建议。

Study on Moorburn Remote Sensing Monitoring on Poyang Lake Wetland Area and Its Influence

Poyang Lake wetland is an important district of ecological function zoning in China, which has the functions of flood controlling and biodiversity conservation for ecological services. There are nine national and provincial nature reserves in Poyang Lake area. In recent years, the regional drought meteorological disasters frequently occurred caused by global warming, which made Poyang Lake area water body and water level of wetlands decline, even dry up. This resulted in the breeding of a large number of moss grassland in the region. Moorburn occurred frequently consequently. This is a big threat to Poyang Lake wetland nature reserve and regional ecological environment. In early 2012, the events of moorburn appeared in many places in Poyang Lake area. Facing to this urgent situation, this study, using the remote sensing quickly monitoring technology and vegetation ground investigation method, acquires the first-hand moorburn distribution area, location and vegetation growth state data. Serial knowledge are obtained based on the vegetation growth situation contrast analysis between moorburn area and non-moorburn area, and GIS buffer and overlay analysis. 1) The total patches of the moorburn region are 95, the total area of the burned is 10278.6196 ha, and the largest patch area is 1293 ha. Moorburn region mainly distributed in the Poyang Lake National Nature Reserve in Wucheng town, Yongxiu county, and the Nanjishan provincial wetland nature reserve in Xinjian county. 2) Moss grassland number was increased obviously in moorburn area, and its surface biomass and vegetation coverage are higher than that in non-moorburn area, but lower in the late period of growth. The vegetation height is lower in moorburn area than that in non-moorburn area in all the progress of bourgeon and growth stage. The moss grassland community species richness and biodiversity in moorburn area is lower than that in non-moorburn area obviously in the late period of growth. 3) GIS analysis indicates that the land cover types which were mostly influenced by the moorburn are still the dry lakebed and adjacent farmland. With the expansion of the buffer zone, the proportion of affected forests and rural settlement types increased, and more attention should be paid to this consequence. Related suggestions on wetland resources protection and moorburn management are proposed finally.