基于景观生态风险评价的涪江流域景观格局优化

Abstract

以流域为尺度进行景观生态风险评价以及景观格局优化，有利于为流域生态系统服务的提高和人类活动管控提供科学依据。以涪江流域为研究区域，从"自然-社会-景观格局"3个维度选取10个评价因子建立评价指标体系，采取空间主成分分析法（SPCA）对流域景观生态风险进行综合评价，再基于生态风险评价的结果和生态源地利用最小累积阻力模型（MCR）和网络分析等方法实现流域景观格局优化。研究结果表明：①涪江流域景观生态风险等级在空间分布上呈西北部高于东南部地区，主要是受自然和景观格局因子影响较大。②涪江流域所面临的生态风险问题较为严重，生态风险等级为中度及以上的区域面积总和为25596.51 km²，占研究区总面积比例的65.35%。③生态源地以林地和水域为主，面积为11194.28 km²，占流域总面积比例为25.58%。④构建生态廊道共41条，总长度为5229.04 km，其中原有廊道29条，新添廊道12条，提取生态节点53个；利用网络分析形成了以主廊道为"中轴"，构建的生态廊道为"辅助"，提取的生态节点为"枢纽"的较为完整的网络生态结构。对研究区景观格局优化前后的连通度进行对比，优化后的整体景观格局连通度得到较大幅度提升。;Taking the watershed as the scale to conduct landscape ecological risk assessment and landscape pattern optimization is conducive to providing a scientific basis for the improvement of watershed ecosystem services and the management of human activities. The ecological risks faced by the Fujiang River Basin are affected by multiple factors, and the optimization of landscape pattern is an effective method to deal with ecological risks. In this research, 10 factors from three aspects (e.g. natural, society, and landscape pattern) were selected to establish the index system. The Spatial principal component analysis (SPCA) was used to evaluate the ecological risk of watershed landscape, and then based on the results of ecological risk assessment and ecological sources, the minimum cumulative resistance model (MCR) and network analysis were used to optimize the landscape pattern of the watershed. The results show that ①The spatial principal component analysis method can effectively evaluate the spatial distribution of landscape ecological risks. The level of ecological risk in the northwest was higher than in the southeast, which was mainly affected by the two dimensions of natural and landscape pattern factors. ②The ecological risks problem faced by the Fujiang River basin are severe. The area of ecological risk grads of moderate and above is 25596.51 km², accounting for 65.35% of the total area of the study area. ③The ecological sources are mainly forests and water areas, with a total area of 11194.28km², accounting for 25.58% of the total area basin of the basin. ④The network ecological structure is composed of 15 ecological sources, 53 ecological nodes, 41 auxiliary ecological corridors with a total length of 5229.04 km and 1 main central axis corridor, which can effectively reduce the ecological risk in the study area and promote the flow of material and energy in the study area. By comparing the connectivity of the landscape pattern before and after optimization in the study area, it can be found that the connectivity after optimization has been significantly increased. The research results are helpful to improve the ecological stability of the study area, and provide a scientific basis for the landscape ecological risk assessment and landscape pattern optimization research.