Fundamental Studies on the Spatial Variation of Energy and Material Cycling in Agricultural Ecosystems.

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Detailed soil surveys were conducted to make clear the influence of micro-topographical condition on the spatial variation of soil properties, especially energy and water balance of soil plant system. To get a good grasp of spatial patterns several methods for image processing, including a thermal image processyr, were introduced and checked by detailed soil examinations in the field. The results can be summarized as follows.1. After the detailed terrain analysis several survey areas were selected in the hilly areas of Hokkaido and systematically sampled at sites fixed by a 20x20m grid in the field. Large scale maps of soil properties, especially of 137Cs, were prepared and compared with the results of terrain analysis. The spatial distribution of radioactive fallouts(137Cs) in the hilly areas was closely dependent upon the denudation-sedimentation processes of the solid soil materials that was controlled mainly by slope morphology and position at which sites were located.2. Methods for automatic quantitative photo-interpretation were studied to make a good grasp of the spatial distribution of soil condition. A sensor which measures the intensity of reflected red light were useful to measure the density of ordinary aerial photographs.3. A thermal image processor(INFRA-EYE5000) was effective for the purpose to grasp the energy balance of the soils and vegetated surfaces. Because of the soil surface temperature was controlled by the cooling due to evapolation from the surface under consideration, the energy and water flow across the surface and their spatial variation could be evaluated by using the physical models. Based on the results described above, routine procedures for the measurement by using the apparatus in the field and analytical methods for studies on the spatial variation of energy and water balance of soils were worked out.