Analysis of Environment and Ecosystem of Yakushima using Geographic Information Systems

主要研究结果如下。(1)利用FT和U-Pb测年方法估算了屋久岛岩体的冷却和隆升速率。通过基本填图和磁化率各向异性研究屋久岛岩体及其寄主岩石的结构格架的发展。提出了增生棱柱体中构造诱导构造与重力驱动构造的分离准则。(2)利用50 m格网DEM进行地貌分析，揭示了地形南北向收缩的特征。我们开发了计算机程序，利用数字化等高线对坡度、坡向、形状进行分类，并以1：25，000的比例尺应用于整个屋久岛。(3)我们调查了中马、小濑田、白谷温泉、淀川小屋和山顶的土壤剖面。宫之浦，显露出自己的特色。(4)本文测定了不同植被类型森林土壤CO_2和CH_4通量的季节变化。结果表明，森林具有CO_2汇的功能。森林土壤每年分解CH_4 9.5kg/ha。(5)从不同海拔和植被土壤中取样，并对土壤中的细菌进行DGGE分析。在细菌群中，几乎没有发现季节和植被的变化。(6)利用卫星遥感数据，分析了1994-2002年植被变化。植被指数在岛的西北部增加，而在中部和东南部减少。随后的地理信息系统分析表明，酸雨的可能影响。(7)通过地球化学分析，探讨了酸雨对土壤-植被生态系统的影响。(8)在社会经济方面，通过对长田村复兴的山崇拜的研究，分析了居民的环境认同。屋久岛最重要的产业之一屋久木的木材手工业也被调查。

The main results of research are as follows. (1) Cooling and uplift rate of the Yakushima pluton was estimated using FT and U-Pb dating method. Development of structural frameworks of the Yakushima pluton and its host rocks was studied through basic mappings and using anisotropy of magnetic susceptibility. We suggested criteria for separation of tectonic-induced structures from gravity-driven structures developed in accretionary prism. (2) Landform analysis was done by using 50-m grid DEM, thereby revealing north-south contract in characteristics of topography. We developed computer program with which to classify slope gradient, aspect, forms using digitized contours, which was applied to whole Yakushima at a scale of 1:25,000. (3) We investigated soils profiles at Nakama, Koseda, Shiratani-unnsuikyo, Yodogawa Hut and the top of Mt. Miyanoura, revealing their characteristics. (4) We measured the seasonal variation in soil CO_2 and CH_4 fluxes in forests with different vegetations. The results imply that the forest is functioning as CO_2 sink. Forest soil decomposes CH_4 9.5kg/ha annually. (5) Soils were sampled from different altitudes and vegetations, and bacteria in soils were subjected to the DGGE analysis. Among the groups of bacteria, little seasonal and vegetation variations were found out. (6) Using satellite remote sensing data, we analyzed vegetation changes 1994-2002. The vegetation index increased in the NW part of the island, whereas it decreased in the central and SE parts. The subsequent GIS analyzes suggest the possible influence of acid rain. (7) By geochemical analysis the influence of acid rain on the soil-vegetation ecosystem was investigated. (8) As to socio-economic aspect, environmental recognition of the inhabitants was analyzed through studying the revived Mountain worship of Nagata village. Wood handcraft of Yakusugi (ceder), one of the most important industry of Yakushima, was also investigated.