ARAI Tadashi TAISHO UNIVERSITY, EARTH ENVIRONMENTAL SCIENCE, PROFESSOR, 地球環境科学部, 教授 (10062811)
OHNO Masao TOYO UNIVERSITY, LITERATUR, PROFESSOR, 文学部, 教授 (80057992)
OKUDA Shigetosi YOKOHAMA NATIONAL UNIVERSITY, INSTITUTE OF ENVIRONMENT SCIENCE AND TECHNOLOGY, PROFESSOR, 環境科学研究センター, 教授 (00000141)
|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 2000 : ¥2,200,000 (Direct Cost : ¥2,200,000)
The main purpose of these studies is to carry out research into the ecosystem in the Institute for Nature Study. National Science Museum, which is surrounded by urban environment. This research includes the plant and animal association in the Institute, and also the inorganic environment like atmosphere, soil and water balance. Also these investigations intend to demonstrate the transition during the past 20 years comparing the surveys done in this period.
The results are as follows. The pollen analysis in mud develops the historical change of the forest from the ancient time to the present day. The climatic data gathered over a span of 120 years shows rise in air temperature and fall phenomenon of humidity. Especially it is important to point out that it is verified that under the influence of the heat island the invasion and ecesis of the species of warm district of Trachycarpus, Pteridophyta, Myxomycetes, Aves and butterflies have occurred.
Besides this, the exploration of the inorgan
ic environment bring out the facts below. Water balance makes sure the increase of an outflow of water as a consequence of rise of impermeability layer. Among the soil heavy metal, it is observed that there are no transformation in nickel and lead, but higher content in copper and zinc than before. According to the survey the dust fall is proved to be changeless.
The plant community investigation confirmed that there are more evergreen trees with the transition progress at forest in the Institute for Nature Study, on the other hand the wild grass of sun plant, ruderal plant and shrub tend to reduce. The remarkable decrease in Aucuba that have clumped in shrub layer make a interesting contrast with increase by 10 times in Acea palmatum.
In the Fauna and Flora, the new species of the fungi and oribatid mites are recorded, several species of lichens, spiders, and oribatid mites are newly recorded in Japan, Pteridophyta, Myxomycetes, spiders and moths of rare species were observed. Comparing the previous research, Pteridophyta, Myxomycetes, Aves, land snails, Coccoidae show the slight increase. On the other hand Bryophytes, Myriapoda, Oligochaeta, butterflies, moths diminish in numbers. The Orthoptera, dragon flies demonstrate remarkable decrease. The cause of this transition can be related to the accuracy of the survey, but the environmental transition caused by having more evergreen forest and the isolation of the Institute for Nature Study invited by urbanization are thought to be the major factor in these transitions. Less