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Effects of Urban Sprawl and Habitat Management on Avian Diversity and Habitat Preferences in Fallow Rice Paddies of Yilan
urban sprawl,distance to the nearest building,rice paddy bird diversity,water depth,habitat preference,
|Publication Year :||2019|
第一部份結果顯示，離建物最近距離對鳥種豐富度與豐度呈顯著正相關，道路相鄰程度呈負相關。路徑分析結果顯示，離建物最近距離與建物分散程度對鳥類多樣性有直接影響，而離都市邊緣距離、道路密度與建物面積比例則為間接影響。田外植被對草生性水鳥之物種豐度呈正相關，水體面積比例與雁鴨科之物種豐富度及豐度呈正相關。田內尺度下，雁鴨科偏好深水環境，草生性水鳥偏好較高植被覆蓋度，中小型鷸鴴科則偏好淺水且植被稀疏的環境。第二部分的結果說明低水位（0–5 cm）水田之鳥類多樣性顯著高於中（6–10 cm）、高水位（>10 cm），而植被覆蓋度與田埂雜草有無則無顯著效果。因此，建物擴張嚴重衝擊了宜蘭農田之鳥類多樣性，且建議未來宜採聚居模式發展，以降低建物擴張的衝擊。在地景尺度下，保留或增加田間植被、水體亦有助於提高水田鳥類多樣性，田內尺度則建議在休耕期水田維持低水位(0–5 cm)，並保留少量雜草與再生稻提供敏感鳥種棲息，亦有助於提高宜蘭水田鳥類多樣性。
Under decreasing trend of natural wetlands, rice paddies have been regarded as compensative habitats for natural wetlands. However, agricultural intensification and landscape fragmentation have threatened farmland biodiversity worldwide. Fallow rice paddies of Yilan County are important habitats for waterbirds, but have been seriously encroached by urban sprawl. To examine effects of urban sprawl on bird species diversity and habitat preferences of birds, this study was divided into two section. In section 1, I conducted bird surveys in 42 and 51 sampling paddies in 2016/17 and 2017/18 winter respectively on Lanyang Plain, and measured field conditions (water depth, vegetation coverage, mudflat coverage, and sampling paddy area) and landscape structures within 500 m buffer zone (road adjacency, road density, distance to the nearest building, nearest neighbor index of building, sum of shape index, water area ratio, built area ratio, vegetated area ratio, and distance to urban area) to examine effects of environmental variables. In section 2, field experiments were conducted in 2017/18 winter in Xinnan Village to examine effects of water depth, vegetation coverage, and presence/absence of ridge grass on bird species diversity.
Results of section 1 revealed that distance to the nearest building and road adjacency were positively and negatively correlated with bird species richness and abundance respectively. Distance to the nearest building and nearest neighbor index of buildings had direct effects, while distance to urban area, road density and built area ratio had indirect effects. Vegetated area ratio was positively correlated with species richness of vegetation-dependent species, and water area ratio was positively correlated with species richness and abundance of waterfowls. At within-filed scale, waterfowls preferred deep water, vegetation-dependent species preferred high vegetation coverage, and medium-size and small-size waterbirds preferred low water depth and low vegetation coverage. In section 2, both species richness and abundance in low water depth (0–5 cm) sampling sites were significantly higher than in medium (5–10 cm) and high water depth (>10 cm), and vegetation coverage and presence/absence of ridge grass had non-significant effect on bird species richness and abundance. In conclusion, urban sprawl would seriously impact on bird species diversity in rice paddies of Yilan, and collecting housing is strongly suggested to mitigate the impacts by concentrate disturbances from buildings. At landscape scale, preserving or generating waterbody and vegetated area would increase bird species diversity. At within-field scale, maintaining low water depth (0–5 cm) and less vegetation coverage for sensitive species were also suggested to increase bird species diversity in fallow rice paddies of Yilan.
|Appears in Collections:||森林環境暨資源學系|
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