Effects of environmental change on terrestrial ecosystem from the point of calcium dynamics

This project aimed to analyze pattern and dynamic processes of biogeochemical cycles of calcium in terrestrial ecosystems. It was assumed that calcium was one of the key elements regulating dynamic ecological processes of terrestrial ecosystem. The project was initiated in the 1996 fiscal year and terminated in the 1998 fiscal year. Ten research scientists of different disciplines were participated in the project. The field analyses were conducted covering a wide geographical range from Hokkaido (Teshio Experimental Forest of Hokkaido university) to Kyushu (Yakushima Island). Major findings included ; 1. In Hokkaido, soils were generally poor in calcium and airborne particles were an important source of calcium, 2. It became apparent that analytical technique using Sr isotopes was effective to detect origin of calcium in terrestrial ecosystem. 3. Vegetation structure and soil characteristics were greatly influenced by topographical position and, in turn, vegetation and soils largely regulated chemical properties of water infiltrating through phytogeocoenoses. 4. Calcium was found to be a prime factor, synergistically with topographical position, regulating and determining ecological characteristics of cool temperate forest phytogeoceonoses. 6. Through decomposition experiments of leaf litter, it was found that calcium concentration of fallen litter tended to become converge to a certain level as the decomposition progressed, no matter how high or low the concentration was at the beginning of experiment due to litter species.