澎湖群島早於日據時期即已積極建造海岸防風林，惟澎湖造林之五十年間尚難謂造林成功，除因自然條件不佳外，颱風及人為破壞為防風林造林之主要阻力。本研究自1999年起於澎湖島東南端劃設六個監測樣區，進行防風林植群生態長期環境監測，監測期間共記錄33科84種植物，造林樹種以木麻黃為主，部分防風林為木麻黃與苦楝或黃槿混植林，亦有少量景觀植栽之植物入侵防風林內。下層植物以三角葉西番蓮分布最廣，所有監測樣區皆有紀錄，且豐富度一般均達3級以上。木麻黃雖為防風林帶之優勢種，然由於林帶海岸綿延數公里，林緣接近村落、公路、遊憩區等之差異影響下層地被組成，因此相似度分析結果顯示：樣區間物種結構差異大，相似度指數約在12至47間，相似度最高之第一及第六樣區，皆位於林帶寬度50公尺以上之防風林內，外來干擾較少，物種結構較相似。監測期間發生奇比颱風橫掃澎湖，使得部分樣區損毀，然植物種類於颱風過後明顯增加，顯示清除木麻黃防風林下層枝葉層有助地被植物著生。人為干擾部分則以防風林撫育較為頻繁，影響較顯著者則為複層林之建造，使得喬木層結構改變。早期澎湖防風林造林樹種選擇以耐鹽抗旱之木麻黃為主要造林樹種，然其有衰退期早、不易天然更新及枝葉層影響地被植物生長等缺點，現今防風林逐漸轉為建造多層次混合林方式，未來植群生態可能趨於多樣化。
This paper presents results of a five-year (1999-2003) vegetation monitoring of windbreaks on Penhu Island, the main island of Pescadores. Six sampling plots were establishes. Species richness of vegetation, the important value index of trees, and the cover-abundance of groundcover were analyzed to evaluate the vegetation changing dynamics. A total of 33 families and 84 plant species were recorded. The main species of plantation are Casuarina equisetifolia, Hibiscus tiliaceus, and Melia azedarach. Passiflora suberosa is the most abundant species of groundcovers that was found in all monitoring plots. The similarities of species composition, calculated by Jaccard coefficient, among the sampling plots were from 12 to 47. The Jaccard coefficient between plot I and VI is 47, which means near half of vegetation in these two plots are the same. The species of groundcovers among the plots were diverse because the boundary of windbreaks access was different among landuse types. Species richness was recorded every season and the highest 44 species was recorded in the first monitoring season of 2002. The least record was taken in the summer of 2001 after Typhoon Chiby crossing Penghu Island. After the Typhoon destroyed the groundcover, more species were recorded in the coming season. In addition, human activities strongly affected the vegetation composition of plantation. Planting and nursing methods, such as selective cutting, cutting vines and grasses, and planting seedlings were applied from time to time during the monitoring period. The multiple layer sylviculture designed by the County Sylviculture Team may be one of the important activities that affected the vegetation composition. Different coastal tree species were planted on the selective cutting lines in the mature Casuarina windbreaks. In this way, it is possible to establish biologically diverse windbreaks in the near future.
