洞庭湖湿地景观破碎与生物多样性保护

研究了洞庭湖湿地景观破碎化过程、特性、原因及其与生物多样性的关系.①现有洲滩湿地1 037块,破碎度2.00块/km2,其中环境资源斑块面积只占32.08%;水域1 337块,破碎度2.00块/km2;②在120多年间,由一个湖泊斑块变成2 374个斑块,中间经历了5个分割阶段,以近21年间的景观破碎速度最快;③被分割的321个洲滩斑块变成820块,破碎度增大了150.00%,破碎景观面积占98.5%,扁长状斑块消失,鸟足状和岛屿状斑块占总斑块数减少了6.77%和11.34%;原始资源斑块面积减少24.2%~81.56%,人工替代引进(杨树)增加100%,干扰斑块(荻)增加63.70%,从而引起生物多样性变化;④杨树入侵、沟河引入、荻、芦扩张、自然资源无价的错误认识是造成天然湿地景观破碎的原因.同时,提出了洞庭湖区自然保护区的最小面积和管理机构模式.

Wetland Landscape Fragmentation and Bio-diversity Protection of Dongting Lake

The authors studied the wetland landscape fragmentation process,characteristics and reasons of Dongting Lake and the relation between wetland landscape fragmentation and bio-diversity.The main results include:(1) The wetlands are 1 037 patches at present and the fragment indexes are 2 patches per km~2.Among these wetlands,the area of resource patches occupied 32.08 percent.The water areas are 1 337 patches and the fragment indexes are 2 patches per km~2.(2) Over the last one hundred and twenty years,this lake changed into 2 374 patches in five phrases and the speed was the highest in recent twenty-one years.(3) The separated wetlands changed from 321 patches into 820 patches.The fragment indexes increased 155.45 percent.The area of fragmentation landscape occupied 98.5 percent.The narrow patches have disappeared;the patches are like bird's feet and the island patches have reduced 6.77 percent and 11.34 percent respectively.The area of native resource has reduced 24.2 percent to 81.56 percent while the artificial patches such as poplars have increased 100 percent and the disturbed patches such as reeds increased 63.7 percent.All of the above are the reasons that cause the changing of biodiversity.(4) The authors indicate that the effect factors of the wetland landscape fragment include the invasion of polar,the introduction of the ditch river,the expansion of the reed and the mistaken understanding of the priceless natural resource.The authors also give some suggestions for the minimum area of nature reserve and management organization mode for Dongting Lake.