云南高原湖泊杞麓湖动态演变及景观生态风险评价

  目的  探究气候变化背景下杞麓湖动态演变过程及其流域景观生态风险。  方法  基于1975-2015年8期时序Landsat数据，提取湖泊边界，并解译得到3期流域景观类型分类数据。从湖泊面积、轮廓和质心3个方面对杞麓湖动态演变进行研究，通过划分生态风险采样小区，建立生态风险评价模型，定量分析杞麓湖流域的景观生态风险。  结果  ① 近30 a来，杞麓湖流域景观结构变化特征明显，建设用地和滩涂湿地面积显著增加，农地、林地和水体面积持续减少，未利用地面积变化不大；②近40 a来，杞麓湖处于持续萎缩状态，2015年水体面积仅为面积最大年（1985年）的56.05%；杞麓湖形状体现为连续的复杂变化，以西部和南部的河流入湖口处变化最为明显，东部变化最小；杞麓湖质心主要向东北方向迁移，1975和2015年湖泊质心相距1 242 m；③生态风险评价结果表明:流域以较低生态风险为主，所占比为26.75%~35.09%，1985-2015年生态风险均值由0.957 8增加至1.013 9，流域生态风险趋于恶化。  结论  杞麓湖流域生态风险空间分布具有明显的区位性和异质性，高生态风险主要分布于杞麓湖水体部分，低生态风险主要分布于流域的湖盆之中，其余生态风险主要沿湖盆和湖泊呈块状或带状分布。

Dynamic evolution and landscape ecological risks assessment of Qilu Lake in Yunnan Plateau

  Objective  The research aim is to study the dynamic evolution process of Qilu Lake and its watershed landscape ecological risks under the background of climate change.  Method  The lake boundary was extracted based on eight time series Landsat images from 1975 to 2015, and three watershed landscape classification data were interpreted. The dynamic evolution of Qilu Lake was studied from the change of lake area, lake shape and the lake centroid. The ecological risk assessment model was established by dividing ecological risk sampling plots, and the landscape ecological risk of Qilu Lake Basin was quantitatively analyzed.  Result  (1) Over the last 30 years, the landscape structure of Qilu Lake Basin has changed obviously; the area of construction land and beach wetland has increased significantly; the area of farmland, forest land and water area has decreased continuously, and the area of unused land has not changed much; (2) Over the last 40 years, Qilu Lake has been in a continuous shrinking state, and the water area in 2015 is only 56.05% of that in the largest year (1985); Qilu Lake is characterized by continuous and complex changes in shape, the most obvious change is at the entrance of rivers to lake in the west and south part, and the smallest change in the east part; The centroid of Qilu Lake mainly migrates to the northeast, and there is a 1 242 m gap between the centroid in 1975 and that in 2015. The results of ecological risk assessment indicates that the main ecological risk is in lower grade, accounting for 26.75%-35.09% between 1985-2015; The average ecological risk has increased from 0.957 8 to 1.013 9 between 1985-2015, indicating increasing ecological risks.  Conclusion  The spatial distribution of ecological risk in Qilu Lake Basin has obvious aggregation and spatial heterogeneity. The high ecological risk mainly lies in the Qilu Lake, the low ecological risk mainly in the lake basin, and the other ecological risks mainly in block or band along the lake basin and lake.