人穷还是地穷?空间贫困陷阱的地统计学检验

Poor people, or poor area? A geostatistical test for spatial poverty traps

引入地统计学的变异函数和交叉相关图方法,以甘肃省六盘山片区为案例区,通过分析村级贫困的空间格局及其与地理因子关系随空间尺度的变化,提供空间贫困陷阱检验关于尺度的深入理解。结果表明:地统计学方法兼具有效性和可靠性,可以反映地理因素—贫困状况关系随时空的变化,对"人地关系"视角下反贫困理论与实践研究具有积极意义。案例区空间贫困陷阱问题突出,村级贫困在一定空间范围内具有自相关性,空间总变异中自相关部分远高于随机性部分,这与不同尺度上地形、气候、区位等结构性因素的影响和控制有关,总体上到县城距离、海拔和总人口3个因子的影响范围和强度较大。

The test for spatial poverty traps（SPTs） is a hot issue in the field of the geography of rural poverty. However, the main existing approaches cannot provide spatial scale-related information, which may be a restriction on gaining a deeper understanding of the mechanism of SPTs. Therefore, we conducted a case study in the Liupan Mountain Region by introducing geostatistical methods. The semivariogram and cross-correlogram were employed to quantitatively describe the spatial pattern of village-level poverty and its relationship with the selected geographical factors respectively, so that the scale-dependent spatial form and underlying reasons for SPTs can be explored. The village-level poor population（PP） and poverty rate（PR） were used as the poverty indicators. The results show that the geostatistical methods can provide satisfactory and reliable performance in the test for SPTs：（1） The semivariogram models can indicate both the spatial structure and the autocorrelation range of the two indicators, which can describe the extent and the range of the spatial form of SPTs（i.e.the spatial aggregation of poverty）. The percentages of the random variance（nugget, C_0） in the total variance（sill, C_0＋ C） are 34.4% and 11.5% for PP and PR, respectively. The range of autocorrelation is 9.3 km for PR, and 5 and 48 km for PP.（2） The cross-correlograms further show that the two indicators are significantly（P〈0.05） correlated with the geographical factors within different spatial ranges. Generally, the poverty status of a village is mainly in response to three factors（i.e. the distance to the nearest county town, the elevation, and the total population） within a wide range. In conclusion, the evidence of SPTs from our work is consistent with the reality that the study area has suffered persistent poverty in the past three decades.