清代西南地区耕地空间格局网格化重建

Gridding Reconstruction of Cropland Spatial Patterns in Southwest China in the Qing Dynasty

本文以现代耕地分布格局为基础，通过量化地形（海拔、坡度）、气候生产潜力（光照、温度、水分）和人口密度等因子与耕地空间分布的关系，重建了清代西南地区6个时点分辨率为10km×10km的耕地数据。结果表明：①就整体而言，清代西南地区耕地空间格局的变化表现在两个方面：一是垦殖范围的扩张，1661-1911年土地垦殖率在O-10％的网格占比减少了约24％，主要分布在四川盆地和云贵高原；二是垦殖强度的提高，1661-1911年垦殖率大于30％的网格占比提高了10.3％，最为显著的是四川盆地和云南中东部地区。②就清代西南地区耕地数量增减来看，整个时段可划分为3个阶段：前期（1661-1724年）“复原性”垦殖，60多年间土地垦殖率在0-10％的网格占比减少了11．4％；中期（1724-1820年）缓慢“拓展性”垦殖，全区垦殖率在0-10％的网格占比下降约7％，在30％以上的网格占比提高约7％；后期（1820-1911年）局部抛荒与再垦，垦殖率在0-10％的网格占比从75．0％降至72．2％，在30％以上的网格占比从9．1％提高至10．9％。相关分析表明，本文网格化重建的清代西南地区的耕地空间格局具有一定的合理性。

On the basis of modem cropland spatial pattern, we designed a method to quantify the relationship among topography （including altitude and slope）, production potential of climate （including light, temperature and water）, population density and cropland spatial pattern. Then the method was used to reconstruct cropland spatial pattem with a resolution of 10 km by 10 km in Southwest China for 6 periods between 1661 and 1784 in the Qing Dynasty. The results are shown as follows. （1） As a whole, the changes of cropland spatial pattern in Southwest China can be described in two respects. One is the expansion of cultivated area, which are mainly distributed in the Sichuan Basin and the Yunnan-Guizhou Plateau. The grid cells with small cropland fractions （0-10%） decreased by 24.0% during the past 250 years. The other is enhancement of cultivation intensity, which are obvious in the Sichuan Basin and the central-eastern parts of Yurman Province. The grid cells whose cropland fractions are relatively large （〉30%） increased by 10.3% during the past 250 years. （2） The process of cropland change in Southwest China in the Qing Dynasty can be divided into three periods. The cultivation recovery period （1661-1724）--the grid cells whose cropland fractions are small （0-10%） decreased by 11.4%; the slow cultivation expansion period （1724-1820）-the grid cells whose cropland fractions are small （0-10%） decreased by 7% while the grid cells with relatively large cropland fractions （〉30%） increased by 7%. The postwar abandonment of cropland in some parts of the study area and recovery period （1820-1911）-the grid cells whose cropland fractions are small （0-10%） decreased from 75.0% to 72.2% while the grid cells whose cropland fractions are relatively large （〉30%） increased from 9.1% to 10.9%. The results of correlation analysis indicate that the reconstruction is reasonable to some degree.