基于多风险源胁迫的西南地区生态风险评价

西南地区生态环境复杂、人地矛盾突出,生态系统面临着多种风险胁迫,进行生态风险评价对区域生态风险的预警和防控具有重要的意义。基于西南地区的生态环境特征,将生态风险分为自然灾害风险与人类活动风险,从风险源危险性、生态系统潜在损失度、生态系统易损性3个方面构建单一风险评价模型,将单一风险评价结果进行综合分析得到西南地区综合生态风险结果。研究表明,西南高生态风险区面积为17.02万km2,占研究区总面积7.4%,主要分布在念青唐古拉山、邛崃山、哀牢山、无量山、金沙江、怒江、澜沧江、大渡河流域等地,以及成都、重庆、贵阳等人地作用强烈的大城市周边。这些地区环境复杂,灾害易发,应加强防控与监测,优化产业结构,继续推进生态保护工程,降低生态风险。

Ecological risk assessment in Southwest China based on multiple risk sources

Ecological risk refers to the possibility that various stress factors arising from natural disasters and human activities in a given region affect a complex ecosystem, including reductions in health, productivity, genetic structure, and economic and esthetic values of certain elements or the entire ecosystem. In the complex environment of Southwest China, conflicts between people and land are prominent, and the ecosystem faces various risk stressors. Therefore, it is of great significance to carry out ecological risk assessments for the early warning and prevention of regional ecological risks. Considering the characteristics of Southwest China, we divided ecological risks into natural disaster risks, namely, drought, flood, earthquake, landslide, debris flow, soil erosion, and rock desertification, and human activity risks, namely, population pressure, economic pressure, water pollution, and soil pollution. Seven ecosystem types were used as risk receptors-forest, shrub, grassland, wetland, farmland, bare land, and urban. A single risk assessment model was constructed using three components:danger of risk source, potential ecosystem loss, and ecosystem vulnerability. The model spatially superimposed the results of a single risk assessment to obtain the comprehensive ecological risk value of the Southwest. Moreover, the dangerousness of risk sources was quantitatively analyzed using relevant environmental impact factors, and the degree of potential ecosystem loss was characterized by ecosystem quality. Ecosystem vulnerability was analyzed based on two aspects:environmental vulnerability and landscape structure vulnerability. The results showed that the area of high ecological risk in Southwest China measured 170200 km², accounting for 7.4% of the study area. High risk areas were mainly distributed along the mountains and hydrographic net, such as the Nianqingtanggula, Qionglai, Ailao, and Wuliang mountains and the Jinsha, Nu, Lancang, and Dadu rivers. These areas are geographically complex and prone to natural disasters. Therefore, geological readjustment, prevention, and monitoring should be strengthened to minimize the losses caused by natural disasters. The National Natural Forest Protection Project and Sloping Land Conversion Program should be continued to reduce the vulnerability of ecosystems and to improve ecosystem ability to resist risks. Ecological risks to Chengdu, Chongqing, Guiyang, and other cities (and their surrounding areas) are also relatively high because of their dense populations and strong human interactions. Therefore, to reduce the economic and population effects on ecosystems, efficiency of land use should be improved, human over-exploitation should be controlled, and industrial structure should be optimized. Although ecological risk is low in Northern Qinghai and Tibet, the ecological environment is highly vulnerable. Hence, ecological environmental construction should be enhanced to prevent the destruction of original fragile ecological environment.