碩士 / 國立中興大學 / 植物學系 / 89 / Vegetation cover and subsidence at southwestern coastal wetlands of Taiwan were investigated. The SPOT images were applied for interpreting vegetation changes in these wetlands. The rate of subsidence increased from inland to coast. It subsided more at Tongshi and Putai than at Peimun. The maximum subsidence at Tongshi Harbor and Wanliao during 1987-1998 was 1.17 m and that at Peimun during 1988-1995 was 0.29 m. In Tongshi and Putai, subsidence rate was higher (7.50-17.90 cm/yr) during 1988-1993 and lower (3.46-9.21 cm/yr) during 1993-1998.
1986, 1990 and 1998 SPOT images were analyzed with normalized differential vegetation index (NDVI) and vegetated areas were calculated. During 1990-1998, the Avicennia marina forest at Lonkon estuary and Puz estuary decreased. It decreased at the rate 3 ha/yr at Lonkon estuary. During 1986-1998, Avicennia forest increased at the rate 1.48 ha/yr at Pachang estuary. Subsidence affected the vegetation changes of coastal wetlands. Based on NDVI analysis, serious subsidence caused rapid vegetation decline at Puz and Lonkon estuaries, and also caused the invasion of Avicennia into Casuarina forest at the eastern part of Haumeiliao sandbar as well as the formation of marshes in the Haumeiliao Casuarina windbreak. Vegetation types at Haumeiliao sandbar and windbreak can’t be interpreted by NDVI images.
Greenbelt vegetation at Haumeiliao wetland was investigated. The cover of Sesuvium portulacastrum at sandbar increased from May to August and then decreased in September. The marsh formed at the windbreak was dominated by the flood-resistant Paspalum vaginatum and Panicum repens in the summer. However, the cover of Alternanthera sessilis, Solanum alatum and Lycopersicon esculeutum increased in the Autumn. Seasonal cover change was affected by rainfall and water level. Avicennia marina population at Pachang and Chishui estuaries and Toukang drainage have developed into close stand ; those at Haumeiliao has well regenerated ; those at Lonkon estuary has degraded and probably will be disappeared if subsidence sustains.
| Identifer | oai:union.ndltd.org:TW/089NCHU0366016 |
| Date | January 2001 |
| Creators | HsiaoShun Wu, 吳孝順 |
| Contributors | Chen, Ming-Yih, 陳明義 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 60 |
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