| This dissertation examines specific aspects of the land use history of Nang Rong (1972 to 1997), Buriram Province, northeast Thailand, emphasizing the relationship between patterns of land use/land cover (LULC) and soils.; The potential for land degradation—a reduction in the capability of soil to support plant growth (including crops) due to human actions—was assessed by comparison of multi-temporal LULC data to soil surveys, using the situational indicator approach. Resulting patterns of land degradation potential were then used to infer agro-ecological sustainability (the ability to obtain and maintain socio-economically viable crop yields given the prevailing biophysical milieu of a place) on the basis of likely changes to soil attributes associated with land use practices. Digital and analogue geographical analysis techniques were used to manipulate and process the image, map, and field data collected and compiled to represent the phenomena of interest. Geographical information science, earth systems science, landscape ecology, and political ecology form the theoretical context influencing the research design and the interpretation of results.; The research was conducted in three distinct phases. First, Landsat imagery, cartographic, and field data were processed to produce LULC change trajectories (1972–1985–1997) for agriculturally-relevant classes (rice paddy, field crop, forest, savanna). Second, a composite soil crop suitability variable was created and compared to the LULC change trajectories to derive a map based on a qualitative Land Degradation Potential Index. Third, spatial pattern metric analysis was performed using the LULC data, stratified by composite soil suitability classes over time.; The LULC change trajectories indicate that cropland was extended between 1972 and 1997 (net increase in area of 17.9%), through conversion of forest and savanna (net decreases of 9.8% and 8.1%, respectively). Rice paddy was the dominant LULC type in all periods, expanding from 41.5% to 51.5% of the landscape, and largely representing a sustainable practice. Field crops increased in area from 2.1% to 10.1%, resulting in a relatively extensive, though spatially clustered, pattern of potential ecological un-sustainability. Pattern metrics derived for crop suitability zones provided additional insight, allowing the development of more refined, detailed, and complex conceptual models of agricultural systems for Nang Rong. |
