基于ARCGIS的四川省分级退耕还林还草空间决策分析

Decision on Gradually Reforesting and Regrassing Some of the Dry Land Based on ARCGIS in Sichuan Province

首先,利用遥感和GIS技术建立土地利用、土壤侵蚀、数字高程模型、坡度、生态环境质量等级、植被指数、降雨、温度、植被分区、土壤类型和行政区、水体缓冲区、聚落缓冲区等栅格GIS数据库。其次,将旱地数据分别与坡度、土壤侵蚀、植被指数、生态环境质量等级、水体缓冲区和聚落缓冲区等栅格指标数据进行叠加分析。再次,利用各指标构建了基于ARCGIS的一、二级退耕决策模型及其空间复合模型,并得到一、二级退耕面积分别为724 495hm2和333 085hm2。然后,利用温度和降雨指标数据构建了基于ARCGIS的还林还草决策模型,并得到一、二级还林的面积分别为702 362hm2和331 357hm2,还草的面积分别为22 133hm2和1 728hm2。最后,将其分别与行政区、植被分区和土壤类型数据进行空间叠加统计分析,得到各行政区的退耕还林还草情况,以及每一个退耕栅格单元所处的植被分区和土壤类型情况。研究表明,该方法可以节约大量的人力、物力和财力。其研究结果对退耕还林还草工程的规划、实施和管理等具有较大的应用价值。

Decision on gradually reforesting and regrassing some of the dry land based on ARCGIS in Sichuan Province is discussed here,which is very important for the ecological restoration and sustainable development in Sichuan.Five steps are included.Firstly,the database platforms for making decisions are established including land use,soil erosion,DEM,slope,eco-environmental quality, normalization vegetation index （NDVI）,precipitation,temperature,vegetation subregion,soil type, administrative district,waterbody buffer and residential area buffer which are created by using ARCGIS.All data are referenced to the same projection and coordination,and interpolated as grid data with a resolution of 100 m.Secondly,the dry land from landuse database is overlain with slope database,soil erosion database,NDVI database,eco-environmental quality database,waterbody buffer data and residential buffer data.Thirdly,the expert knowledge about reforesting and regrassing some of the dry land is collected,and the models for finding a suitable place for being returned back to forestland and grassland are formulated based on ARCGIS by using the knowledge.There are 724495 and 333085 ha of dry land to be gradually converted into forestland and grassland on the basis of the models,which respectively account for 9.3% and 4.3% of the dry land.Fourthly,the suitable place is overlain with precipitation layer and temperature layer to find out the place respectively suitable for trees and grass by the model that is formulated by using the knowledge of forest distribution and ARCGIS.In the first order, there are 702362 and 22133 ha to be respectively converted into forestland and grassland,or 96.9% and 3.1% of the suitable place for firstly being returned back to forestland and grassland. In the second order,there are 331357 and 1728 ha to be respectively converted into forestland and grassland,which respectively account for 99.5% and 0.5% of the suitable place for secondly being returned back to forestland and grassland.Finally,the distributions of the place suitable for trees and the place suitable for grass in administrative district,vegetation subregion and soil type region were obtained by using the overlay and spatial statistic analysis,which are of benefit to the selection of suitable tree and grass species for reforesting and regrassing.The research shows that with this the method considerable manpower, material and financial resources can be used sparingly. The result can not only be presented in table form,but also in graphic form,which is very useful for planning,executing,and managing the program of reforesting and regrassing some of the dry land in Sichuan province.