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

该项目旨在分析陆地生态系统中钙的生物地球化学循环的模式和动态过程。推测钙是调节陆地生态系统动态生态过程的关键元素之一。该项目于1996财政年度启动，1998财政年度终止。来自不同学科的10名研究科学家参与了这一项目。实地分析覆盖了从北海道(北海道大学的Teshio实验森林)到九州(八岛岛)的广泛地理范围。主要发现包括：1.在北海道，土壤普遍缺乏钙，空气中的颗粒物是钙的重要来源；2.利用锶同位素分析技术显然是探测陆地生态系统钙来源的有效方法。3.植被结构和土壤性质受地形位置的影响较大，反过来，植被和土壤在很大程度上调节着通过植物群落入渗的水的化学性质。4.钙是调节和决定寒温带森林植物群落生态特征的首要因子，与地形位置协同作用。6.通过对凋落物的分解实验发现，随着分解过程的进行，凋落物中的钙离子浓度趋于趋于某一水平，无论实验开始时由于凋落物种类的不同，钙的浓度有多高或多低。

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.