Primary discussion on the relationship between spatial distributions of fuzzy slope positions and soil types

Abstract

As one of key factors which control the spatial soil variation in soil-landscape model, terrain information includes not only topographic attributes (such as slope gradient, curvature, etc.) but also information of slope positions. But the spatial gradation of slope positions is still not quantitatively considered in current predictive soil mapping and other related application areas. The issue of this paper is to make a primary discussion on the potential role of spatial gradation of slope positions in soil-landscape model. Taking a study area in Northeast China and a detailed taxonomy of slope position, this paper firstly utilized a fuzzy inference approach based on similarity to the typical locations to quantify the spatial gradation between slope positions. Secondly, we took use of the soil-subgroup map in study area to analyze whether there is an evident relationship between soil distribution and spatial gradation of slope positions or not, by means of the statistics on the percentage of slope positions on where each soil subgroup in study area is distributed. The results show that the distributions between slope positions and soil subgroups are clearly correlative in the areas where fuzziness as one certain slope position is little. And the soil distribution shows obvious intergradation and uncertainty in areas where the slope position is identified with much ambiguity. The evident relationship between soil distribution and spatial gradation of slope positions indicates that the quantitative information of spatial gradation of slope positions should be included into both soil-landscape model and its applications (e.g., digital soil mapping, etc.), for a better depiction on the co-variation between slope positions and soil type.