Creating a Landscape-Scale Model of Soil Evolution on the Pacific Coast of Costa Rica, Poster 20

Geographic soil models are essential for understanding geomorphic processes, environmental concerns, and security of food, water, and energy. In tropical regions, soil data frequently defaults to the often inaccurate... [ view full abstract ]

Geographic soil models are essential for understanding geomorphic processes, environmental concerns, and security of food, water, and energy. In tropical regions, soil data frequently defaults to the often inaccurate “kaolinite-dominated, nutrient-depleted” paradigm. This study synthesizes research conducted in three sub-regions of Costa Rica’s Pacific coast and analyzes soil properties from a fourth sub-region to create a soil model along the entire coast (spanning 400 km and 2° latitude). Each sub-region was characterized using X-ray diffraction, bulk soil geochemistry by ICP-AES and ICP-MS, and soil pH and CEC. These data were used to create soil weathering classifications applicable across climatic sub-regions. Ranging from dry (1500 mm/yr) to wet (4800mm/yr) environments, the sub-regions differ appreciably in weathering rates. Previous studies conclude that soils in tropical wet forest environments (4800mm/yr) evolve to a nutrient-depleted, kaolinite-rich Oxisol mineral assemblage in half the time of soils in a tropical dry forest (1500 to 2200 mm/yr). To model the spatial variability of soil weathering, this study compares a cokriged interpolation model and a class pedotransfer function weighing climatic, temporal and topographic data with above mentioned measurements. This spatial model can be address terrace correlation in interpreting landscape evolution over Holocene and Pleistocene time scales.