| Summary: | 碩士 === 靜宜大學 === 生態學研究所 === 94 === This study investigated 65 islands in Peng-Hu archipelagoes. Based on various sizes of island, three different investigating path were designed. The aim of this study: 1) knowing the plant composition of all islands. 2) pursuing the structure of plant sociality in Peng-Hu archipelagoes. 3) understanding what kind of plant species in each habitat. 4) understanding floristic relationship between Taiwan island and Peng-Hu archipelagoes.
There are 55 plant-covered islands in Peng-Hu archipelagoes. A total of 260 species were recorded, belonging to 68 families and 190 genera. Among them 170 species are native, 52 are naturalized and 38 are introduced. Because precipitation less than evaporation and strong winter gale, the environment is very arid. The mainly covered is herbaceous vegetation. Ferns and aquatic plants of archipelagoes as the humidity indicators are in low diversity. habitat to reflect the drought. After linear regression analysis, area (log scale) is good predictor for species per island and habitat diversity. Habitat diversity also predicted species per island very well.
From average landwash to shoreline is back-shore zone. Fore-land means from shoreline to the empty of substance salt contained. Native species is major composition form back-shore zone to fore-land. This area keep primary status of plants composition consisted in Peng-Hu archipelagoes. From fore-land to interior is called back-land. This area consists intermingled native and introduced species.
The plot setting is based on homogenous sampling. Totally, there are 2,131 plots established. By the TWINSPAN, the vegetation could be classified to 11 types. The characters of each habitat is describing as following:
1.Type Ⅰ Sesuvium portulacastrum vegetation type : mainly distributed in nearby landwash.
2.Type Ⅱ Spinifex littoreus vegetation type : largely distributed in sand beach.
3.Type Ⅲ Ipomoea imperati vegetation type: only found in sand beach.
4.Type Ⅳ Vigna marina vegetation type: an element of sand beach vegetation and also distributed in grassland of fore-land zone.
5.Type ⅤChloris formosana vegetation type is dominate vegetation in rocky seashore and cliff.
6.Type Ⅵ Zoysia matrella-Ipomoea pes-caprae vegetation type: distributed in back-shore zone to fore-land zone.
7.Type Ⅶ Zoysia matrella-Setaria viridis vegetation type: distributed in fore-land zone to back-land.
8.Type Ⅷ Panicum repens vegetation type: mostly dominate in open flat land of back-land zone.
9.Type Ⅸ Imperata cylindrica vegetation type : mostly dominate in open flat land of back-land zone.
10.Type Ⅹ Leucaena leucocephala vegetation type: at southern slope or indented abandon farming areas.
11.Type XI Casuarina equisetfolia vegetation type: all in afforestation.
By the TWINSPAN, the plant of Peng-Hu archipelagoes could be classified to several types such as: 1. widespread distribution type, 2. large-island distribution type, and 3.south-island distribution type. All species of south-island distribution type can found in south Taiwan and 82.4% species distributed in north Taiwan. There are 95.2% of widespread distribution type distributed in south Taiwan and 73.2% species can found in north Taiwan. Species of large-island distribution type that distributed in south Taiwan and north Taiwan is almost the same. In geographical distribution outside Taiwan show that tropical type have 93 species(54.7%), eastern Asiatic type have 24 species(14.1%), cosmopolitan type have 23 species(13.5), tropical Asia to eastern Asia have 14 species(8.2%), endemic of Taiwan have 11 species(6.5%), Taiwan & Japan type have 5 species(2.9%). There are none north temperate and subboreal species in Peng-Hu archipelagoes. A comparison of geographical distribution composition and the species common to Taiwan. They are closest floristic relationship between Peng-Hu archipelagoes and south Taiwan.
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