土地整理的生态风险评价

On the ecological risks assessment of the land-use rectification and reconstruction

土地整理对生态环境存在水土流失、生态演变、环境容量变化及环境脆弱性变化4类潜在风险。结合国家投资基本农田土地整理项目,在土地整理风险识别的基础上建立了土地整理生态风险识别指标体系,该体系包含水、土、生物3个要素与14个指标。结合土地整理实践与生态学知识,拟定指标分级标准;采用层次分析法计算出各指标在评价体系中的权重并建构综合生态风险评价指数(ER)。计算结果表明:1)土地整理后,ER总分减少28.94,生态风险级别由Ⅲ级降为Ⅳ级,项目区生态风险显著减小;2)就单要素来看,水的ER总分由21.53降为6.16,降幅达15.37,对整个项目区生态风险减小的贡献率达53%;而土和生物要素两者的贡献率仅共占47%;土和生物要素的生态风险综合指数也较整理前有了降低,降幅分别为12.79和0.78,没有水要素明显。研究表明,土地整理生态风险识别指标体系能有效识别土地整理前后生态风险的变化,可为以后的土地整理工作提供参考依据。

The present paper is aimed at introducing its authors＇ work on the establishment of index system for identifying land-use rectification risks characterized with 14 indexes and 3 factors. As is known, the problem of land-use rectification and integration has become an urgent problem with the fast development of our multi-linear economy. So far as we can see, the land-use rectification and reconstruction involves 4 types of projects, i.e. the project of farmland leveling, that of fanning irrigation system renovation, the project of roadway transformation, as well as that of wind-break forest perfection. Theoretically speaking, the proper plan of such projects and its implementation of the functional reformation should be done in favor of sustainable positive recycling of the eco-environmental benefits. But in practice, it actually involves risks and hazards with regard to the rectification of soil erosion, ecological evolution, environmental durability and environmental vulnerability. To solve such problems, we have established an index system for identifying such risks which is characterized with 14 indexes and 3 factors, including water, soil and biological structure. In addition, an index standard has also been worked of by weighting the proper allocation of the index system members by means of AHP. Thus, the integrated index system for the ecological evaluation （ER） has been confirmed in a detailed way. The results of the trial use of the suggested index system indicate that, 1 ） The ER can be reduced to 28.94 when the land rectification project is finished, and the ecological risk can drop down from level Ⅲ to level Ⅳ; 2） The element analysis also indicates that the water ER decrease from 21.53 to 6.16 with its contribution to the ecological risk reduction being 53 ℃ ; At the same time, the ERs of soil and bi- ological factors also drop respectively to 12.79 and 0.78, with their contribution of ecological risk lower than that of water. Thus, the above results show that the index system suggested in this paper is available and applicable for the identification and assessment of the ecological risks in land-use rectification with the ecological risks reduced considerably.