关键词: 土地利用总体规划, 生态风险评价, RRM, 乐山市

Abstract: Due to strong human interference, the implementation of land-use master planning (LUMP) will produce a profound impact on the structure and functions of ecosystems. Therefore, in order to avoid the potential threat from the initial decision-making phase, it is essential to introduce and establish an assessment mechanism in the planning to analyze the negative ecological effects on ecosystems and its acceptability. The combination of LUMP and ecological risk is a new research field that present interdisciplinary and challenging characteristics. In view of current development, although its importance has been recognized, quantitative analysis has not yet been conducted, and the depth of the research is actually inadequate. In China, LUMP is characterized by hierarchy. According to the range of administrative districts and decision-making effect, it can be classified into five levels, i.e., national-level, provincial-level, municipal-level, county-level, and town-level. The property, scope, and degree of ecological impact will vary with LUMP at the different levels. Therefore, a corresponding ERA system with planning levels needs to be established to improve the pertinence and operability of evaluation. The aim of this paper is to discuss how to carry out relative risk model (RRM) for the municipal LUMP. By applying the RRM, a relationship of relative risks can be obtained, which is applicable to comparing ecological risk degree among the assessment subdivisions in the study area. With an example, LUMP of Leshan City, which has been completed by the local land department, is investigated for its ecological risk. The city is divided into three units in terms of the topography (southwest mountains area, central valley plain area and northeast hilly area), eight types of habitats (cultivated land, garden land, forested land, grassland, other agricultural land, construction land, water area and natural reserved area), five risk sources (crop planting, livestock breeding, industrial production, transportation construction and population load) and three assessment endpoints (biological species, ecological system and landscape pattern). The evaluation results showed that the general ecological risk of Leshan City is on a downward trend in the planning period. The spatial difference in ecological risk is significant while the basic pattern of ecological risk has not changed after the planning implementation. In some places, the ecological environment will fluctuate and even deteriorate. There are three major sources of ecological risk, including crop planting, transportation construction and population load. The ecological pressure on the forested land and grassland is the most acute among all habitat types. And the damage of structure and function of ecological system is the major forms of risk effect. According to the research achievements, the emphasis of ecological risk prevention and control can be identified, and it can provide references to the practice. In addition, this method is helpful to regional ecological risk analysis. It should be noted that the assessment model presented still has a rise space for promotion, mainly through refining quantitative methods to improve the accuracy. And more research needs to be explored further in the follow-up work to other scale LUMP.

Key words: land-use master planning, ecological risk assessment, RRM, Leshan City