南四湖流域1980-2015年土地利用变化及其对流域生境质量的影响

生境质量在一定程度上决定了区域生物多样性维持能力的高低，评估区域生境质量对土地利用/覆被变化的响应，可以间接衡量区域生物多样性维持功能的时空变化，为生物多样性保护提供定量参考.本文以南四湖流域为例，运用InVEST-Habitat Quality模型模拟评价1980-2015年流域生境质量的时空变化，定量评估湖区退耕还湿还林和丘陵地区退耕还林2种政策情景对区域生境质量改善的效果.结果表明：35 a间流域耕地、林地和草地大量转化为建设用地，城市建设用地增长40.23%，湖泊面积减少35.56%，主要转化为渔业坑塘；南四湖流域整体生境质量处于较低水平，近35 a来快速发展的工农业生产和不断扩张的城市用地使得流域生境质量呈现降低趋势，当前平均生境质量为历年最低（0.20）.环境保护力度和人类活动剧烈程度的差异导致生境质量在空间上呈现出西部平原区（0.19） < 东部丘陵山区（0.44） < 南四湖湖区（0.81）的分布特征.近35 a来生境稀有度（即生境保存完整性指数）较高的区域主要是湖区主体和流域东部丘陵山区，但部分边缘湖区生境稀有度指数却极低，受人类活动干扰剧烈，主要原因在于沿湖渔业养殖和农业活动.定量评估湖区退耕还林还湿和流域丘陵旱地退耕还林2种政策情景对生境质量的改善效果，结果表明湖区退耕还湿还林能使湖区生境质量上升9.21%，而丘陵旱地退耕还林可使流域平均生境质量提高16.75%.

Land use change and its impact on habitat quality in Lake Nansi Basin from 1980 to 2015

Habitat quality determines the capacity of regional biodiversity conservation. Assessing the response of regional habitat quality to land use changes can indirectly measure the temporal and spatial changes of regional biodiversity maintenance function and provide a quantitative reference for biodiversity conservation. In this paper, the InVEST-Habitat Quality model was used to simulate the temporal and spatial changes of habitat quality in Lake Nansi Basin from 1980 to 2015. Quantitative assessment the effect of two policy scenarios of returning farmland to forest in hilly areas and returning farmland to forest and wetland in the lake area on the improvement of regional habitat quality. The results showed that the cultivated land, forest land and grassland were transformed into a large number of construction land during 35 years, urban land increased by 40.23% as well as lake area decreased by 35.56% which were mainly converted into reservoir pond. The overall habitat quality of the Lake Nansi Basin is at a low level due to the rapidly development of the industrial and agricultural production as well as the expanding urban land use in the past 35 years, and the current habitat quality is the lowest (0.20). The difference of the intensity of the environmental protection and the intensity of human activities led to the spatial distribution of habitat quality showed the trend of western plain area (0.19) < eastern hilly and mountainou area (0.44) < Lake Nansi area (0.81). In the past 35 years, the area of highly habitat rarity (ie, Habitat Conservation Integrity Index) is mainly in the lake area and the eastern hilly area of the basin. However, the Habitat Rarity Index in some marginal lakes is very low, which is disturbed by human activities. The main reason is that Lake fisheries farming and agricultural activities Scenario analysis showed that returning farmland to forest and wetland in the lake area could increase the average habitat quality by 9.21% while that returning farmland to forest in the hilly area could increase the average habitat quality by 16.75%.