摘 要 本研究目的在於瞭解颱風對海岸防風林及鳥類多樣性影響，研究區域為雲林縣麥寮鄉海岸防風林，探討2005年連續三次強烈颱風侵台事件，包括海棠強烈颱風（2005年07月16日至07月20日）、泰利強烈颱風（2005年08月30日至09月01日）與龍王強烈颱風（2005年09月30日至10月03日），運用衛星影像進行海岸防風林變遷分析，以鳥類調查及多元迴歸分析建構鳥類多樣性與環境因子之關係式，分析颱風對於海岸防風林之影響及對鳥類多樣性造成之衝擊，以及海岸防風林自我恢復過程對鳥類多樣性之效益。 研究結果說明如下： 連續三次颱風造成整個海岸防風林植生NDVI值持續性下降，顯示其對海岸防風林造成累積性影響。進一步分析颱風對不同寬度海岸防風林之累積性影響，結果發現寬度越窄海岸防風林颱風造成的累積性影響越明顯，此外，迎風面受到累積性影響最嚴重，其次是背風面。 海岸防風林遭受短期連續性三次颱風累積影響後，觀察往後五年海岸防風林植生NDVI值變化，發現具有逐年恢復的現象。整個海岸防風林生長變化過程呈現初期衝擊、逐漸恢復、趨於穩定的變化過程，符合景觀生態學中所提的區塊體遭受干擾後的自我恢復過程。 應用2010至2011年的鳥類調查及現地資料，以多元迴歸建構鳥類及棲地關係模式，結果發現海岸防風林的代表鳥類為白頭翁，模式分析結果得知全保留海岸防風林植生狀況較佳的區域（NDVI值大於0.3）面積增加，草地面積增加，草地與研究區域的土地利用期間相嵌情況提高，有助於白頭翁數量的增加；海岸防風林邊緣地帶的代表性鳥種為紅鳩，模式分析結果顯示農地面積增加及農地邊緣增加，紅鳩數量增加。 採用回推法方式，以2010-2011年鳥類與棲地關係為基礎，回推2005年三次連續性颱風對海岸防風林及周邊環境變化造成的影響，是否對於鳥類多樣性造成影響；以及海岸防風林自我恢復的過程。全保留研究結果，顯示連續遭受三次颱風侵襲，對海岸防風林及周邊環境造成影響，亦使得鳥類的多樣性產生變化，當連續遭受三次颱風侵襲後，鳥類多樣性大幅降低；之後隨著海岸防風林帶內部逐漸復原，有助於提升鳥類的多樣性。海岸防風林內部的代表鳥種白頭翁及邊緣的代表性鳥種紅鳩，推估結果顯示颱風後三年(2008年12月03日)數量可恢復颱風前水準。 關鍵字:累積性影響;海岸防風林; 鳥類;恢復力;颱風 Abstract The purpose of this study was to investigate typhoon effects on coastal windbreaks and bird diversity. This study focused on the coastal windbreaks located in Mailiao Township, Yunlin County and the three successive super typhoons that have hit Taiwan in 2005 including Typhoon Haitang from 16 to 20 July, Typhoon Talim from 30 August to 1 September and Typhoon Longwang from 30 September to 3 October. The change of windbreaks obtained from satellite image data and the formula for calculating bird diversity on environmental factors built from bird survey and multiple regression analysis were used to evaluate typhoon impacts on windbreaks and bird diversity, as well as the benefit to bird diversity from self-recovery process of windbreaks. Results and discussion The three successive typhoon events caused a continuous decline in the normalized difference vegetation index (NDVI) value of the coastal windbreaks, which indicated that the typhoon events had caused cumulative effects on coastal windbreaks. Further analysis of the cumulative effects on windbreaks with various widths showed that the narrower width of the windbreak, the stronger cumulative effects caused by the typhoons. In addition, the windward sides of windbreaks were the mostly affected followed by the leeward sides.
Five-year monitoring the NDVI value after the coastal windbreaks suffered from cumulative effects of the three typhoons showed a year-by-year gradual recovery. The windbreaks growth changing from initially damaged to gradually recovered then stabilized was consistent with the post-disturbance self-recovery process of landscape patches described in landscape ecology.
The Bird species and habitat relationship model was built from multiple regression analysis by using bird survey and field data from 2010 to 2011. Collected data revealed Pycnonotus sinensis was the dominant bird species in windbreaks and the analysis results showed that the increase in size of the well-conserved windbreaks area with better vegetation (NDVI value > 0.3) and the grassland area, and the increased temporal land mosaic of the grassland and study site favored an increase in the number of Pycnonotus sinensis. Data also revealed Streptopelia tranquebarica was the dominant species in the border area of windbreaks and the analysis results showed the number of Streptopelia tranquebarica grew as the size of farmland and its border area increased. Backward extrapolation based on the relationship between bird species and their habitat in 2010 and 2011 was applied to investigate whether the resulting effects on windbreaks and the change of surrounding environment caused by the three typhoons had an influence on bird diversity and also the self-recovery process of the windbreaks. Our results showed that the windbreaks and the surrounding environment were affected by the three typhoons as well as the bird diversity decreased significantly; and the following recovery of windbreaks helped to increase bird diversity. The backward extrapolation results showed that the number of the dominant bird species in windbreaks and the border area (Pycnonotus sinensis and Streptopelia tranquebarica respectively) retuned to pre-typhoon level three years after the typhoon events (3 December 2008).