Seasonal Variation in Bird Species Richness along Elevational Gradients in Taiwan

台灣鳥類種豐富度分布與群聚組成之季節變異

許皓捷(Hau-Jie Shiu) ； 李培芬(Pei-Fen Lee)

《Acta Zoologica Taiwanica》 14卷1期 (2003/05) Pp. 1-21

https://doi.org/10.6576/AZT.2003.14.(1).1

摘要

本研究探討台灣鳥類種豐富度沿海拔梯度分布之型態，以及鳥類群聚組成與環境之關係。我們蒐集過去研究及資源調查報告，建立資料庫。依據鳥類出現情形，將季節區分爲全年、繁殖季與非繁殖季。使用主成分分析、群團分析與降趨對應分析探討這三種類型鳥類分布與環境之關係。結果顯示種豐富度沿海拔分布模式有季節變異，以全年資料來看，鳥種數從平地至海拔1500公尺均維持相似值，往高海拔則有下降情形。若僅以特定季節來看，繁殖季鳥種數在海拔1500公尺附近最高，呈鐘形分布曲線；非繁殖季種豐富度由平地至海拔1500公尺則維持一致的高峰，之後隨海拔遞升而遞減。將非繁殖季區分爲留鳥與候鳥，留鳥的模式與繁殖季類似，冬候鳥則呈現負指數曲線。主成分分析及群團分析結果發現，可將留鳥組成依海拔300及2300公尺爲界，劃分爲三個類群。降趨對應分析則顯示不論在繁殖季或非繁殖季，留鳥群聚變異與海拔及人爲干擾均有極顯著之關係。本研究認爲季節對鳥類種豐富度估算有顯著影響，進行鳥類群聚研究的取樣應考慮季節效應。

關鍵字

鳥類群聚 ； 海拔梯度 ； 季節變異 ； 種豐富度 ； 台灣

並列摘要

Seasonal variations in the distribution of bird species richness and community composition along elevational gradients in Taiwan were studied. We compiled bird species richness data through an extensive literature review, and classified the data into breeding season, non-breeding season, and year-round sets. We then examined the avifaunal-environmental relationships using presence/absence data by principle components analysis (PCA), cluster analysis, and detrended correspondence analysis (DCA). With the year-round dataset, species richness appeared roughly constant from sea level to about 1500 m, then declined with increasing elevation; while the richness during the breeding season was non-linearly related to elevation, with a hump-shaped curve which peaked at around 1500 m. By separating migratory landbirds from residents during the non-breeding season, however, we found that the two groups had different patterns along the gradient: residents showed a hump-shaped pattern similar to that of the breeding season, whereas migratory landbirds showed a negative exponential pattern. The results of PCA and cluster analysis demonstrated that the resident assemblages were classified into three major categories: lowlands, mid-elevation domain, and highlands, separated roughly by the elevations of 300 and 2300 m. DCAs indicated that elevation and human disturbance are the major environmental factors contributing to variations in the trend of resident assemblages. The seasonality of data collection strongly influences bird species richness distribution patterns and should be clearly defined to obtain a meaningful result in bird species richness studies.

並列關鍵字

bird community ； elevational gradient ； seasonal variation ； species richness ； Taiwan