基于RS和GIS的土地生产力与人口承载量──以向家坝库区为例

A RS and GIS based study on land productivity and population supporting capacity: taking Xiangjiaba Reservoir area as an example

本文在分析土地生产力与承载力研究现状的基础上 ,以向家坝库区耕地为研究对象 ,根据库区经济地理现状 ,确定土地人口载量研究区域 ,并利用GIS和RS技术对研究区土地利用现状和地形地貌特点进行深入分析 ,建立“空间·属性一体化”数据库。本文还建立了土地资源人口承载量评价指标体系 ,利用潜力递减法 ,进行以村级为单位的耕地粮食综合村尺度的近期和远景 (2 0 12 )土地人口承载量研究 ,提出与当地农业发展相一致的整个研究区环境容量。结果表明 ,与其它耕作方式相比 ,复种耕种可获得更大的人口承载量 ;库区环境容量已趋饱和 ,而且未来库区土地承载力呈下降趋势 ;通过改良品种、扩大水稻播种面积可在一定程度上缓解地矛盾。

Man-land relationship has become one of the most sensitive problems in agricultural development, and study on land productivity and population supporting capacity opens up an effective way for quantifying regional man-land relationship. In this paper, we discuss present and future environmental capacity status and variation trend in Xiangjiaba reservoir area on village basis with land potential productivity degression method and bearing capacity evaluating model, regarding cultivated land as study object. According to geographic status, land bearing capacity evaluating region is confirmed, covering 23 832.91 ha and involving 21 towns or 174 villages. Coupling analysis of land use and physiognomic characters in the study is conducted with GIS and RS, and then the integrated spatial-attribute database is established. Supported by perennial sun light and temperature data, soil physio-chemical attributes on village scale, cultivated land spatial distribution and main crops (including paddy, wheat and corn) growing period in the reservoir area, the appraising index system of land productivity is set up, synthetical crop productivity of cultivated land on village scale is evaluated with land potential productivity degression model. Taking into consideration comparatively well-off standard of living for local people,including per capita grain and farmland availability,as capacity index of grain to support population, we establish land bearing capacity model based on reservoir construction planning and spatial pattern of land productivity to forecast per village farmland resource potential carrying capacity at present and in the near future(2012), and put forward environmental capacity of the whole study area coincided with local agricultural development. The result shows that multiple-cropping practice compared with other farming methods can gain even greater population supporting capacity; it is more reasonable to study land population supporting capacity based on output of grain rather than on farmland area, however, they should be combined with each other in practice; because the impact of fully implementation of land conversion from farmland to forest and grassland on land carrying capacity is greater than changes of unit area output of grain, hence under the same farming practices, the future land population supporting capacity does not increase but is smaller than the present environmental capacity, presenting an overall decreasing trend inevitably; environmental capacity of reservoir area is inclining to saturation, man-land conflict stands out;and population supporting capacity of cultivated land should be increased to some degree by means of increasing output of grain through expanding sown area of paddy and ameliorating breed.