淮河流域湿地变化的特征、热点及其影响因素

利用Landsat遥感数据定量研究了淮河流域1995—2007年间各湿地类型的规模变化,分析了其变化特征,辨识了湿地消长的热点区域,并研究湿地变化热点空间分异的影响因子。结果表明,研究期间流域内水田、库塘等人工湿地大幅增加(净增量分别占1995年湿地总面积的16.81%、4.57%);湖泊、沼泽等自然湿地则明显减少(净减少量分别占1995年湿地总面积的1.06%、2.79%),且多转为人工湿地。湿地变化热点多分布于流域东部及南部;人工湿地变化热点分布连续而集中,自然湿地变化热点则稀少而分散。高程和气温对人工湿地增长热点及自然湿地减少热点的发生影响强度相对较高;社会经济与可达性因素对热点的发生具有显著作用,但其影响强度相对较弱。整个淮河流域,湿地变化热点的发生受多种要素的耦合作用,但湿地变化热点空间分异的首要因素是流域自然地理等背景条件的约束作用。

Characteristics,Hotspots and Influencing Factors of Wetland Change in Huaihe River Basin

Using Landsat remote sensing data, we study the size change of each wetland type in Huaihe River Basin from 1995 to 2007 quantitatively and analyze the characteristics of wetland change. Then we identify the hotspots of wetland change using neighborhood analysis and study the influencing factors of spatial differentiation of wetland change hotspots by constructing Logistic regression model. Results show a remarkable increase in artificial wetlands (including paddy fields, reservoir and ponds), but a distinct decrease of natural wetlands (mainly referring to swamps and lakes) during the research period. Increase amount of paddy fields and reservoir ponds are 10296.05 km² and 2796.45 km², which account for 16.81% and 4.57% of the total wetland area of the Huaihe River Basin and 3.82% and 1.04% of the whole basin area in 1995 respectively. Decrease amount of lakes and swamps are 648.22km² and 1705.97 km², which account for 1.06% and 2.79% of the total wetland area of the Huaihe River Basin and 0.24% and 0.63% of the whole basin area in 1995 respectively. The decreased swamps and lakes are principally converted to artificial wetlands. Hotspots of wetland change are mostly distributed in the eastern and southern part of Huaihe River Basin. And hotspots of artificial wetlands change exhibit a more concentrated and continuous distribution, but that of natural wetlands are sparser and more disperse. Among all natural and geographical influencing factors, elevation and temperature have relatively higher impacts on the occurrence of artificial wetlands increase hotspots and natural wetlands decrease hotspots. And there is a high incidence of wetland change hotspots in areas which have relatively higher temperature and are lower lying. Moreover, wetland change hotspots are also inclined to occur in areas having relatively lower precipitation. Socio-economic factors and transport accessibility play a significant but less important role in hotspots occurrence. For the socio-economic influencing factors, artificial wetland increase hotspots are prone to occur in areas which have higher economic output value, while natural wetland decrease hotspots are apt to distribute in areas which have lower economic output value. As for transport accessibility, artificial wetland increase hotspots mostly occur in the area far from the high grade road and close to residential area, and natural wetland change hotspots mainly occur in the area far from the residential area. In Huaihe River Basin, the hotspots occurrence of wetland change is affected by the coupling effect of multiple factors, but the restriction effect of physicographica background is the primary factor leading to spatial differentiation of wetland change hotspots.