應用性狀資料探討臺北地區都市化梯度上的鳥類群聚組成

Abstract

都市化發展與外來種引進正造成全球生物多樣性與群聚組成重大的影響。生物性狀反應物種在生態系中資源利用與功能表現的方式，能有效揭示環境特性與生物組成的關聯，並為生物友善都市規劃與保育策略提供科學依據。為探討臺北都會區都市化對鳥類群聚的影響，本研究分析棲地特性與鳥類組成、性狀、α及β多樣性之間的關係。透過建置臺灣鳥類性狀資料集，收集都市化梯度上的鳥類群聚，並量化地景覆蓋與植被高度等環境變數，以進行整體評估。在原生與外來鳥種多樣性分析中，結果顯示在農業覆蓋比例及地景組成異質度較高區域，原生與外來鳥種種類與數量均較多。然而，在植被高度較高的區域擁有較高的原生鳥種種類與數量，外來鳥種則相反。外來鳥種亦偏好不透水層覆蓋較高的區域及河濱草坪，可能與優勢外來種偏好地面覓食的生態習性相關。繁殖鳥類性狀方面，在不透水層覆蓋較高的區域，利用人為建築築巢、取食人類食物及廣食性的鳥種分布較多；相對的，植被高度較高的區域，則聚集較多樹冠層活動、果食性及不偏好地面覓食的鳥種。此外，本研究亦檢視都市地景覆蓋對分類、親緣與功能β多樣性的影響，並進一步探討轉換與嵌套對各β多樣性的貢獻。結果顯示，分類與親緣β多樣性在都市梯度上呈現顯著高度相關，反映雀形目與鴿形目鳥種在高度都市發展區域展現較強的適應力，進而驅動群聚組成變化。空間距離、地景組成異質度及不透水層覆蓋顯著影響鳥類β多樣性及轉換，加上都市梯度上，分類轉換較高而親緣與功能轉換較低，顯示在高度都市化區域中，部分親緣關係相近且功能相似的鳥種取代了其他不適應的鳥種。綜合而言，本研究建議保存臺北都會區內的森林、農田及草地覆蓋，並維持較高的地景組成異質度，有助於提升原生繁殖鳥種種類與數量，以及全年鳥種的親緣與功能β多樣性，減緩受都市化篩選導致的物種損失，以維持都市生態系的韌性與永續。此外，都市綠地中，高大且成熟的樹木可提升原生鳥種多樣性，可能與提供所需的食物與生態棲位相關，同時也限制偏好開闊地面覓食的優勢外來種。因此，強化綠地植被垂直結構，將有助於兼顧都市生態鳥類保育與外來種管理。

Urbanization and the alien invasive species have profoundly altered global biodiversity and community composition. Functional traits, which reflect how species utilize resources and contribute to ecosystem functioning, provide critical insight into the relationships between environmental features and species composition. Such knowledge is essential for developing biodiversity-friendly urban planning and conservation strategies. To assess the effects of urbanization on bird communities, this study examined the relationships between habitat characteristics, species composition, functional traits, and both α- and β-diversity along an urbanization gradient in the Taipei metropolitan area. I have established a comprehensive trait dataset including 454 bird species in Taiwan. Bird community data were collected across six urban habitats, and environmental variables such as landcover composition and vegetation height were quantified. The native and alien species richness and abundance presented significantly positive associations with agricultural cover and landscape compositional heterogeneity. Taller vegetation supported greater native bird richness and abundance, whereas alien species showed the opposite trend, favoring areas with higher impervious surface cover and riverside lawns—likely related to the dominance of ground-foraging alien species. The results of trait-based analyses further revealed that bird species nesting on buildings, feeding on human foods, and diet generalists were significantly more prevalent in areas with higher impervious surface cover. In contrast, the sites with taller vegetation supported more canopy-foraging, frugivorous species, but fewer ground-foraging ones. I also examined taxonomic, phylogenetic, and functional β-diversity, partitioning them into turnover and nestedness components. Taxonomic and phylogenetic β-diversity were significantly highly associated along the urbanization gradient, suggesting that adaptive tolerance among certain taxonomic groups drives community assembly in urban environments, including Passeriformes and Columbiformes. Spatial distance, landscape heterogeneity, and impervious surface cover significantly affected three β-diversity and their turnover components. Higher taxonomic turnover combined with lower phylogenetic and functional turnover indicated that phylogenetically closely related and functionally similar species tend to replace less tolerant species in highly urbanized areas. These findings highlight the importance of maintaining forest, agricultural land, and grassland cover, as well as promoting landscape heterogeneity within the Taipei metropolitan area, to enhance native bird α-diversity and maintain phylogenetic and functional β-diversity throughout the year. These landscapes with those features may mitigate biodiversity loss caused by urbanization and sustain the resilience and functionality of urban ecosystems. Moreover, tall and mature trees within urban green spaces promote native bird diversity by providing essential foods and ecological niches, while simultaneously limiting the dominance of ground-foraging alien species. Strengthening vegetation structure and vertical complexity in urban habitats can thus contribute to both biodiversity conservation and alien bird species management.