| Deforestation, one of the important problems in the tropical forest, can affect the accelerated land degradation that lead to decreased soil productivity and agricultural production. Geographical attributes in the landscape, such as land use types, topographic attributes, and soil information play important roles in determining the landscape structure and functions. This study used spatial analysis, such as GIS overlay and a non-parametric test of land use dynamics to provide a historic documents of deforestation and land use dynamics in the Wat Chan watershed, between 1974 and 1996. Soil-landscape relationships were used to express our understanding of the distribution of soil materials in relation to geomorphologic features.; The method of a non-parametric trend analysis for land use change permits extracting a probability of change in land use and helps illustrate that about 0.76% of the landscape can be identified as cycled land. Regressing the probability of land use change on physical attributes and topographic attributes indicated that increased land use change from forest to open lands were associated with short distances to villages, short distances to forest edge, high elevation and high CTI (R2 = 0.74).; Analysis of soil landscape indicated that elevation, slope, land use, and annual rainfall were the attributes most highly correlated with measured soil properties. CTI and profile curvature showed some influence on the variation of N and OM in this landscape. Coefficients of sand, silt, N, OM, extractable P, and bulk density variable were highly significant as indicated by t-test with R2 ranged from 0.40 to 0.55.; Multiple criteria analysis was used to characterize degradation of sub-watersheds based on landscape attributes that are influencing erosion. Only two sub-watersheds were characterized as extremely low degradation while five sub-watersheds were characterized as high degradation. The most of sub-watershed were classified as low and moderately degraded.; Results illustrate that spatial analysis and GIS can improve understanding of geographical distribution in the Wat Chan watershed in both spatial and temporal aspects. This knowledge of landscape attributes and their spatial and temporal variation are important components for efficient management of resources in the Wat Chan watershed, Northern Thailand. |
