若尔盖县景观破碎化及湿地恢复优先性

Landscape fragmentation and wetland restoration priority in Zoige County of Sichuan Province of China

关键词:  湿地景观演变函数  熵值法  景观破碎化  湿地恢复

Key words:  wetland landscape evolution function  entropy method  landscape fragmentation  wetland restoration

摘要:

对四川省阿坝藏族羌族自治州若尔盖县1980-2015年湿地景观破碎化及恢复优先性进行研究，以1980、1990、1995、2000、2005、2010和2015年7期土地利用数据为数据源，在ArcGIS与Fragstats软件的支持下，获取景观破碎化及湿地变化信息，实现对若尔盖湿地景观破碎化及湿地动态演变过程的深度分析，在此基础上构建湿地景观演变函数，揭示若尔盖湿地多年变化类型分布，并给出该区域湿地恢复的优先性。结果表明：1）研究区湿地景观破碎化主要表现为斑块平均面积和蔓延度指数的萎缩，斑块密度的上升及香农多样性指数的增大。整个研究时段内，研究区湿地斑块平均面积减少了249.77 hm²，斑块密度上升0.013 hm^-2。2）根据土地利用动态变化的空间涵义，将研究区湿地划分为稳定型、退化型、恢复型和波动型4种类型，研究发现退化型湿地的面积与稳定型湿地相比，是其75.43%，与恢复型湿地相比，是其2.27倍，若尔盖湿地退化严重，亟需进行湿地恢复。3）采用熵值法，以行政乡镇为若尔盖湿地恢复单元，得出若尔盖8个受影响的乡镇中，有2个一级恢复区、3个二级恢复区、3个三级恢复区。三级恢复区（阿西乡、嫩哇乡、达扎寺镇）应当予以优先恢复。

Abstract:

Based on the data of land use in 1980,1990,1995,2000,2005,2010 and 2015,this paper studied the wetland landscape fragmentation and restoration priority in Zoige County.By using ArcGIS and Fragstats softwares,the spatial distribution information of landscape fragmentation and wetland transfer were obtained to realize the wetland landscape fragmentation and the fragmentation dynamic evolution in Zoige.A wetland landscape evolution function was built and the distribution of wetlands changes in Zoige County was revealed.The priority of wetland restoration in this study area was then given.The results showed that:1) The wetland landscape fragmentation in the study area was mainly manifested by the shrinkage of mean patch size and contagion index and the increase of patch density and Shannon diversity index.During the study period,the mean patch size of study area decreased by 249.77 hm² and the patch density increased by 0.013 hm^-2.2) According to the spatial meaning of land use dynamic change,the wetland in the study area was divided into four types which were stable type,degraded type,restored type and fluctuating type.It was found that compared with the stable wetland,the area of degraded wetland was 75.43%,which was 2.27 times larger than that of the restored wetland.The Zoige wetland was seriously degraded and needed to be restored urgently.3) By using the method of entropy and taking the administrative township as the restoration unit of Zoige wetland,it was concluded that there were two one-level restoration areas,three two-level restoration areas and three three-level restoration areas in eight affected towns of Zoige County.The three-level restoration areas (Axi,Nenwa and Dazhasi towns) should be given priority for restoration.This study provides a reference for the spatial and temporal sequence of wetland restoration in Zoige County and it also provides a rapid assessment method for wetland restoration assessment.