南洞庭湖湿地鱼类生境景观变化及其人为驱动

通过实地调查和制图分析,研究1983~2013年南洞庭湖区万子湖湿地和鱼类生境景观变化及其人为驱动,结果表明:湿地洲滩面积由1.410×104 hm2增加到2.135×104 hm2,敞水面面积由1.363×104 hm2减少到0.631×104 hm2;芦苇洲减少,但林地由0.056×104 hm2增加到0.728×104 hm2并扩展到保护区核心区;新增泥围21个、网围10个,引淤、沥水排水设施长度增加了201.71km。人为干扰对景观变化有极大影响,其中引种意大利杨及芦苇改变了地形和群落结构,挤占了自然演替条件下应有的草洲景观空间,使鱼类产卵、索饵的适宜生境减少;泥围作为有害渔法,与网围都处于建设发展阶段,占据了草洲、洼地等鱼类产卵、索饵的适宜生境;引淤渠建设使大面积湖泊快速淤积成洲,将水生生态景观转变为大多数时间干露的以陆相生态景观为主的水陆相生态景观,鱼类生境被压缩,并对南洞庭自然保护区核心区继续发挥促淤作用。

LANDSCAPE CHANGE AND HUMAN DRIVE IN SOUTH DONGTING LAKE WETLAND AS A FISH HABITAT

Through field investigation and map analysis, this research studied the changes of landscape pattern and human drive of Wanzi Lake Wetland, a part of South Dongting Lake, as a fish habitat during 1983 to 2013.The results showed that the beach area increased from 1.410×10⁴ hm² to 2.135×10⁴ hm², water area decreased from 1.363×10⁴ hm² to 0.631×10⁴ hm², reed land decreased, while woodland increased from 0.056×10⁴ hm² to 0.728×10⁴ hm² and extended into the core protection area, and there is a large increase in the number of fishery facilities and channels.Human disturbance have a great influence on landscape.Plantation of Italian Poplar and reed changed the terrain and pattern of community and seized the original natural grassland, which reduces fish spawning and baiting' s suitable habitat.Mud enclosure, as one of the harmful fishing facilities, now remains in developing stage, just like the enclosure fishery facility.These fishing facilities occupied the good position on grassland and low beach, harmful to fish spawning and baiting.The construction of silt diverting canal caused the lake silt up rapidly, turn aquatic landscape to amphibious landscape and exposure to terrestrial landscape.As a result, fish habitat is compressed.However, in the meantime, the silt diverting canals keep diverting mud out of the core area of South Dongting Lake nature reserve.