三江平原湿地生态风险评价及空间阈值分析

湿地生态风险评价对区域自然资源保护及规划管理具有重要意义。以三江平原湿地为研究区域，基于2000年、2005年、2010年、2015年4期土地利用数据，以城市扩张导致的土地利用变化、道路建设等人类活动为风险源，景观生态格局、生态系统服务价值为风险受体构建了三江平原湿地生态风险综合评价体系，分析三江平原湿地生态风险时空变化特征。进而，利用距离阈值确定空间距离权重，采用双变量空间自相关模型揭示了不同时间尺度下生态风险的空间集聚分布特征。结果显示：从风险源角度，人类活动风险源强度呈增加趋势，松花江、穆棱河、倭肯河地区一直处于中高风险水平；从风险受体角度，景观生态风险的中高风险地区重点集中在湿地与水体分布区，生态系统服务低价值区主要分布在中部水田、旱田、建设用地以及东北部与东南小范围的湿地区域。综合生态风险结果显示，三江平原生态风险在时间上呈增加趋势，空间上由松花江河滩型湿地区与穆棱河地区逐渐向四周蔓延。此外，生态风险的强弱受到空间距离的影响显著，选取5km为自相关分析的距离阈值，土地利用与综合生态风险的空间格局存在显著的空间正相关关系，高-高地区集中分布在研究区内的松花江流域及周围滩地地区，随着土地利用变化及转移，空间关联逐渐增强且区域分布不断扩大。研究结果可从人类活动控制、景观格局优化、生态服务价值提升等方面为三江平原生态风险防控分区管理提供理论依据。

Ecological risk assessment and spatial threshold analysis of wetlands in the Sanjiang Plain

Ecological risk assessment of wetlands is of great significance to protect natural resource and promote regional planning. Based on four phases of land use data in 2000, 2005, 2010, and 2015 in Sanjiang Plain, this study intends to construct an ecological risk assessment model of wetlands from the aspects of risk sources considering various human activities such as land use change and road construction caused by urban expansion, and risk receptors including landscape ecological pattern and ecosystem services value. To analyze the spatial agglomeration pattern of ecological risks, the distance threshold was used to determine the spatial distance weight, and the bivariate spatial autocorrelation model was applied to evaluate the spatial agglomeration and distribution characteristics of ecological risks at different time scales. Results show that from the perspective of risk sources, there is an increasing trend in the Sanjiang Plain. The Songhua River, Muling River, and Woken River areas have always been at a medium-to-high risk level. From the perspective of risk receptors, the medium to high risk areas of landscape ecological risk are concentrating on wetlands and water body areas. Low-value areas of ecosystem services are mainly distributed in the central paddy fields, dry fields, construction land, and small-scale wetland areas in the northeast and southeast. A trend of centralization in areas with medium to high risk levels resulting from wetlands, water bodies and other high-value areas of ecosystem services are occupied. The ecological risks of wetlands exist an obvious increasing trend on the time scale. The results of comprehensive ecological risk show that high-risk areas increased from 2000 to 2015, spatially scattered from the Songhua River to the Muling River. The intense of the ecological risk is affected by the spatial distance. The larger the distance threshold, the larger the relevant area centered on a certain grid, while the overall correlation index decreases. Through the comparison analysis of the adjacency matrix and the distance matrix, 5 km was selected as the distance threshold for local autocorrelation analysis. It is significant to represent a positive correlation spatial pattern of land use and ecological risk. The areas with high-to-high land use and ecological risks are mainly concentrated in the Songhua River Basin and surrounding beach areas in the study area. With the change and transfer of land use, the spatial correlation gradually strengthens and the regional distribution continues to expand. From the aspects of human activities, landscape pattern and ecosystem service value, this study provides a theoretical basis for ecological risk management in the Sanjiang Plain.