Effects of Removing Chamaecyparis Sp. Snags and Logs on Bird Communities in Chilan Mt.

27 Mar Effects of Removing Chamaecyparis Sp. Snags and Logs on Bird Communities in Chilan Mt.

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Abstract

我們於榮民森林保育事業管理處位於棲蘭山之大溪事業區94林班地，針對160線未整理過及整理過枯立倒木的林地進行鳥類相調查，比較兩地鳥種及其生態同功群之差異，探討過去枯立倒木的整理作業對鳥類群聚所產生的影響。此區鳥類相除了大赤啄木（Dendrocopos leucotos）屬於珍貴稀有保育類外，另有13種鳥類屬於其他應予保育類，且有8種為台灣特有種。在未整理之樣區紀錄有28種374隻次，在整理之樣區有25種257隻次。以出現鳥類種數來看，兩樣區之間無明顯的差異。而在出現鳥種之組成上則有差異，其中較偏好未整理樣區的鳥種有屬於地面蟲食者的小翼鶇（Brachypteryx montana）和白尾鴝（Cinclidium leucurum），及灌叢蟲食者的灰頭花翼（Alcippe cinereiceps）、繡眼畫眉（Alcippe morrisonia）和深山鶯（Cettia acanthizoides）；較偏好整理樣區的鳥種有屬於樹幹啄木者的大赤啄木和綠啄木（Picus canus）。造成鳥類群聚差異的可能原因是在移除枯立倒木、整地、補植、除草等撫育過程中，造成森林中下層植被破壞及食物組成改變。枯立倒木的整理移除作業改變了棲地上的鳥種組成，然而未整理和不同年份整理的林地如能以鑲嵌式的方式交錯配置，在大尺度地景的多樣化之下，或可增加整體野生動物之生物歧異度。

English Abstract

We studied the effects of removing Chamaecyparis sp. snags and logs on bird communities in ChiLan Mt. Besides the White-backed Woodpecker (Dendrocopos leucotos) on the endangered species list, there are other 13 species on the protected species list including 8 endemic species in this area. We recorded 374 individuals belonging to 28 species at the control site and 257 individuals belonging to 25 species at the experimental site (removing snags and logs site). There was no significant difference in species number between the control and experimental sites. However, the bird community composition between these two sites was significantly different. The ground insectivores including the Blue Shortwing (Brachypteryx Montana) and White-tailed Blue Robin (Cinclidium leucurum), and the bush insectivores including the Streak-throated Fulvetta (Alcippe cinereiceps), Gray-cheeked Fulvetta (Alcippe morrisonia) and Verreaux’s Bush Warbler (Cettia acanthizoides) were more abundant at the control site. While the bole peckers including the White-backed Woodpecker and Gray-headed Green Woodpecker (Picus canus) were more abundant at the experimental site. A possible reason might be because the removing process and later on cleaning practices caused the damage to understory vegetation, which affected the birds ac-tive there. Removing the snags and logs changed the bird community composition. However, if the con-trol sites and removing sites from different years could be planned with a mosaic landscape layout, the wildlife biodiversity might be increased due to a more diversed landscape pattern