Naturalistae, no. 9, 2004, 15-31 Vegetation and its changes on the Teshima Island in 20 years, Kagawa Prefecture, Japan Abstract:We drew a vegetation map of the Teshima Island (34 29ʼN, 134 50ʼE; highest point 339m a.s.l.; 15km 2 in area) in the Seto Inland Sea, Kagawa Prefecture, from phytosociologic fieldwork and aerial photographs. The map revealed that secondary forests (mostly dominated by Quercus serrata and Pinus densifl ora) cover most part of the area, and natural forest remains are localized only in small fragments. We compared our new map with a vegetation map of the island published 20 years ago, and revealed the following: (1) The area of pine forests (dominated by Pinus densifl ora) decreased about 30% in the two decades. (2) Deciduous broad-leaved forests increased to about 4 times in area. (3) About 60% of the pine forests in 1982 survived, but 30% were changed into deciduous broad-leaved forests in the 20 years. (4) Over 80% of deciduous broad-leaved forested areas survived in the same period. In sum, the forest vegetation succession on the Teshima Island is characterized by reduction of pine forests by pine wilt disease, and consequential expansion of deciduous broad-leaved forests. Key words: Seto Inland Sea, Teshima Island, secondary forests, vegetation map, succession Master s Program in Biosphere-Geosphere System Science, Graduate School of Informatics, Okayama University of Science (The present affiliation: Division of Environment Planning, WESCO Corporation) Department of Biosphere-Geosphere System Science, Faculty of Informatics, Okayama University of Science - 15 -
- 16 -
香川県豊島の植生 Fig.2.植生図(環境省,2002) Fig.3. 植生図(環境庁,1982) - 17 -
Pittosporo - Quercetum phillyraeoidis Juniperus rigida - Pinus densifl ora community C.Pinus densifl ora community - 18 -
Quercus serrata community E.Cinnamomum camphora community F.Photinio - Castanopiedis cuspidatae G.Mallotus japonicus - Celtis sinensis var. japonica community - 19 -
- 20 - H.Willow forest
- 21 -
- 22 -
- 23 -
- 24 -
- 25 -
- 26 -
- 27 -
- 28 -
- 29 -
- 30 -
- 31 -