基于信息增益综合加权的山地生态质量评价

Evaluation on Ecological Quality of Mountainous Areas Based on Integrated Weighting of Information Gain

生态环境与经济发展密切相关,客观准确地评价生态质量对区域生态整治以及资源的合理开发利用具有重要意义。已有研究针对生态质量的相关评价多以主观赋权法和客观赋权法进行评价,忽略了生态环境因子主客观因素之间的内在关系,其结果具有局限性。本文以选取坡度、土壤侵蚀强度、地形湿度指数、归一化植被指数等6项生态指标因子,提出一种基于信息熵、信息增益理论和数据先验知识综合加权的生态质量评价方法,并以陕西省北部黄土高原地区进行了实例研究。结果表明:(1)研究区生态质量等级为一般的范围最大,主要集中在黄土高原北部地区,面积占比约为63.50%,该区域峁梁起伏、沟壑纵横、土壤侵蚀严重、植被分布较少。(2)研究区6项生态指标因子权重占比分别为土壤侵蚀强度24.65%、地形坡度20.37%、年日照总时数16.82%、地形湿度指数15.78%、植被净初级生产力14.89%、归一化植被指数7.49%。(3)本文提出的信息增益综合加权法,具有能够充分利用数据先验知识、适用于多种数据类型、算法稳定的特点。本研究可为山地生态质量评价和生态保护规划提供科学理论参考。

Eco-environment has close connection with economic development.An objective and accurate evaluation of environmental quality contributes to the improvement of the ecology on a regional scale and facilitates the rational development and utilization of local resources.Most assessments related to ecological quality were completed based on the subjective weight determination method and the objective weight determination method.However,the intrinsic links between the subjective and objective aspects of environmental factors are not included in the assessment,making their conclusions not comprehensive.In this study,six ecological factors,including slope,soil erosion intensity(SEI),topographic wetness index(TWI),and normalized difference vegetation index(NDVI)were selected for constituting an improved model to evaluate environmental quality on a region basis for the Loess Plateau in northern Shaanxi province,China.In the model,the weight of each index was properly determined by a combination of a priori knowledge and information gain theory.The following results are obtained:(1)The region with average ecological quality was mainly concentrated in the northern part of the Loess Plateau,with an area percentage of about 63.50%and the largest range.This region had undulating mountains and ravines,severe soil erosion and less vegetation distribution.(2)The weight coefficients for the six ecological factors of the study area were 24.65%for the soil erosion intensity(SEI),20.37%for the terrain slope,16.82%for the annual illuminate duration(AID),15.78%for the topographic wetness index(TWI),14.89%for the net primary productivity(NPP),and 7.49%for the normalized difference vegetation index(NDVI).(3)The improved model constructed based on the integrated information gain weighting method proposed in this paper was stable and feasible,which could make full use of the prior knowledge of the data,and be applied to multiple data types.This research can provide a scientific and theoretical reference for ecological quality evaluation and ecological conservation planning in mountainous areas.