本研究在綠島進行植物資源與植群調查，加上前人研究之樣區共計有155個樣區及三項環境因子，初步的調查共記錄339種植物，包含31種稀有植物。使用降趨對應分析和典型對應分析，並參考雙向指標種進行植群分類，區分植物社會為A.安旱草－水芫花群叢、B.濱大戟－馬鞍藤群叢、C.茅毛珍珠菜－馬鞍藤群叢、D.林投群叢、E.文珠蘭－草海桐群叢、F.黃槿群叢、G.山豬枷－台灣蘆竹群叢、H.卵形飄拂草－馬尼拉芝群叢、I.山林投群叢、J.蘭嶼新木薑子－樹杞群叢、K.貝木－鵝掌柴群叢、L.紅頭咬人狗－大葉樹蘭群叢、M.稜果榕群叢、N.木麻黃群叢及O.紫背草－黃鵪菜群叢共15個群叢。結果顯示植群型與干擾、海拔高度、離海距離、坡向等環境因子有顯著相關，並建議山林投群叢、蘭嶼新木薑子－樹杞群叢、貝木－鵝掌柴群叢、紅頭咬人狗－大葉樹蘭群叢及安旱草－水芫花群叢等為綠島特有或稀有之植群型應加以保護。

The purpose of this study was to investigate the vegetation ecology of Green Island, one of major offshore islands of Taiwan. A total of 155 plots, including established plots from former studies, were surveyed. Results showed that 339 plant species were found, of which 31 were considered rare species. The community was classified into 15 associations using detrended correspondence analysis (DCA), canonical correspondence analysis, and two-way indicator analysis. These associations were: 1. Philoxerus wrightii - Pemphis acidula association; 2. Lysimachia mauritiana - Ipomoea pescaprae association; 3. Chamaesyce atoto - Ipomoea pescaprae association; 4. Pandanus odoratissimus association; 5.Crinum asiaticum - Scaevola taccada association; 6. Hibiscus tiliaceus association; 7. Ficus tinctoria - Arundo formosana association; 8. Fimbristylis ovata - Zoysia matrella association; 9. Freycinetia formosana association; 10.Neolitsea villosa - Ardisia sieboldii association; 11. Timonius arboreus - Schefflera octophylla association; 12. Dendrocnide kotoensis - Aglaia elliptifolia association; 13. Ficus septica association; 14. Casuarina equisetifolia association; and 15. Emilia sonchifolia var. javanica - Youngia japonica association. DCA showed that vegetation type was most significantly affected by environmental variables, namely disturbance regime, altitude, distance to coast, and aspect. By comparing community similarity on Green Island with those on Hengchun Peninsula and Lanyu Island, it was suggested that Freycinetia formosana association, Neolitsea villosa - Ardisia sieboldii association, Timonius arboreus - Schefflera octophylla association, and Dendrocnide kotoensis - Aglaia elliptifolia association on Green Island were considered rare vegetation associations and should be protected.