桂西北石漠化空间分布及尺度差异

运用研究区TM影像,结合GIS&RS技术等手段建立桂西北石漠化基础数据,通过多元逐步回归、冗余分析(RDA)研究了不同尺度上桂西北石漠化与相关因子的关系,探索石漠化的空间分布规律及尺度差异性.结果表明,自然因素对石漠化分布的影响大于人为因素,人为作用的影响随着石漠化等级的提高而增大.石漠化空间分布的控制因子存在尺度转移.在县级尺度上,土壤类型起决定性作用,石质土对石漠化的贡献率最大;在乡镇尺度上,地形与土地利用类型的影响更重要,石漠化因子的重要性排序为山地比例>平均高程>裸岩地>石灰土>未利用地>石质土.两个尺度上,极强度石漠化均表现为人为活动的结果.由于石漠化空间分布的控制因子存在尺度差异,部署石漠化恢复治理任务时,需遵从其空间分布的规律.

Spatial distribution of rocky desertification and its difference between scales in northwest Guangxi

On the basis of TM images and GIS, RS technology, basic database on rocky desertification in the northwest Guangxi was built. The relationship between rocky desertification and related factors at different scales was analyzed, and the spatial distribution pattern of rocky desertification and its difference between scales were explored by using multiple stepwise regression analysis and redundancy analysis (RDA). The results showed that the influence of natural factors on the distribution of rocky desertification was greater than that of the social factors, and the influence of human activity gradually increased with increasing grade of rocky desertification. Decisive factor changed with scale in determining the spatial distribution of rocky desertification. At the county scale soil types played a decisive role, for example, stony soil had most contribution on rocky desertification. At the town scale, both landform and land use pattern were the most important factors. The importance of impact factors in decreasing order was: montanic proportion＞average elevation＞bare rock land＞limestone soil＞unutilized land＞rocky soil. Extremely strong rocky desertification was caused by human activity at both scales. Due to the scale difference of decisive factor in regulating the distribution of rocky desertification, it was necessary to abide by the distribution pattern when deploying the tasks on recovery and control of rocky desertification.