台灣蝴蝶分布的時空變遷

Abstract

台灣蝶類資源豐富，過去雖有學者針對單一地區探討蝶類群聚的變化，但長時間、較大尺度的蝶類研究卻付之闕如。本研究藉由地理資訊系統（Geographic Information System, GIS）、台灣蝴蝶分布資料庫與台灣生態與環境因子地理資料庫，探討台灣蝴蝶分布的時、空變遷情形。本研究之蝴蝶分布資料自1840至2006年為止，共計有144, 545筆分布資料、389種蝶種，資料分布佔3, 735個網格(約占總網格數的10 %)；使用的環境因子包含年均溫、年總降雨量、植生指數(NDVI)、森林密度、海拔高度、道路密度、建物面積、距主要城市最近距離以及距主要道路最近距離。在時間變遷分析上，將蝴蝶分布資料分為三時期：一、1840年至1945年，二、1946年至1984年，三、1985年至2006年。本研究發現，森林密度、距主要城市最近距離與蝴蝶種豐度的分布無明顯的關係趨勢；第二、第三時期的蝴蝶種豐度在低海拔有一高峰的趨勢；蝴蝶種豐度與道路密度、建物面積以及距主要道路最近距離呈現負相關的趨勢。在蝴蝶的空間分布上，有122種（占研究物種的31.8 %）改變其海拔平均分布狀態；所有蝶種在海拔分布範圍改變上無統一的變化趨勢。此外，台灣蝶類生物多樣性熱點多分布在低海拔區域，消失熱點內的都市化程度較現今熱點分布高出許多，然而台灣自然保護區的設立對於蝶類熱點的保育不盡理想，僅有0.8 %的蝶類分布熱點落於保護區的範圍內。影響蝴蝶分布變遷為多重因子的交互作用，人為干擾導致寄主、蜜源植物分布改變、土地利用型態改變、都市化程度增加或是氣候變遷可能導致的加乘影響，都有可能是造就目前台灣蝶種分布的原因。

This study investigates the spatial and temporal distribution pattern of the butterflies in Taiwan. I compiled literatures to establish Taiwan Butterfly Distribution Database using a 1×1 km grid system. This distribution pattern was analyzed by the Ecological and Environmental GIS Database. A total of 144, 454 records including 389 butterfly species span between 1840 and 2006. Data scattered among 3, 735 grids, about 10 % of the total. The environmental layers include annual temperate, annual precipitation, NDVI, forest density, elevation, road density, building area, nearest distance to major cities, and nearest distance to roads. The data was separated into three time periods: I= 1840- 1945, II= 1946- 1984, and III= 1985- 2006. Results show forest density and nearest distance to major cities had no obvious relationship trends with butterfly species richness (BFSR). Road density, building area, and nearest distance to roads showed inverse relationship trends with BFSR. BFSR peaked at low-elevation in Period II and III. There is no evidence for a systematic shift in distribution range (expands or contracts) or in average altitude (uphill or downhill) across all species, even though 122 species, 31.8 % of the research species, show significant distribution shifts in average altitude. Besides, results indicated 93 % of butterfly biodiversity hotspots (BFBH) are distributed over low-elevation. BFBH lost in Period III were located in high urbanized areas. However, there is only 0.8 % of BFBH situating in Taiwan Protected Areas. The butterflies’ distribution patterns in Taiwan are affected by host and nectar plants distribution, land use changes, and climate changes. Further studies are necessary.