典型岩溶区域主要土壤类型分布特征与表层土壤保有量估算

在我国西南岩溶区域,土壤受地质和地形条件的影响程度较深,表现出强烈的非均一性;且在不同地质地形条件下,缺乏具体的量化参照系数,致使对土壤元素库容等方面的估算存在较大偏差。据此,本研究基于对贵阳市乌当区实地考察结果,归纳确立土壤在不同地质与地形下的分布特征,修正了现有的土壤图。利用地形图提取区域的坡度信息,再与土壤图和地质图进行叠加,乘以相应类型条件下土壤的经验系数,估算区域主要土壤类型表层(≤1m)土壤的保有量。结果表明,乌当区境内坡度>35°的碳酸盐岩地区无黄壤分布;石灰土的覆盖率和土壤剖面深度随坡度的增加,呈下降趋势,但连续性石灰岩分布区的石灰土变异程度较大;该区表层土壤(≤1m)保有量约为65656万t,主要集中分布在0°～15°碳酸盐岩分布区,且黄壤占50%以上。

Distribution characteristics and surface soil-retaining amount of main soil types in typical Karst region

Due to the great effects of geology and topography, the soils in Karst region of Southwest China present a distinct spatial heterogeneity, and under the conditions of different geology and topography, the soil nutrient pools were over- or underestimated because of the lack of quantitative parameters. Based on the field investigations in Wudang district of Guiyang City of Guizhou Province, the distribution characteristics of the soils in the district under different geologic and topographic conditions were summed up, the present soil maps were emended, and, by the spatial overlapping of soil maps, geological maps, and topographical maps and by multiplying the empirical coefficients of the soils under corresponding conditions, the surface soil (≤1 m) retaining amount of the main soil types in the district was estimated. Within the Wudang district, no yellow soil was distributed on the slopes > 35°. The coverage rate and profile depth of limestone soil presented a decreasing trend with the increase of slope degree, but the variance of the limestone soil in limestone region was very high. In the district, the surface soil-remaining amount was about 656.56 million ton, mainly distributed on the 0°-15° slopes, and yellow soil occupied over half.