模擬氣候變遷對臺灣受威脅藥用植物阿里山十大功勞適宜棲地之影響

Modeling the effect of climate change on suitable habitats for threatened medicinal plant, Mahonia oiwakensis Hayata in Taiwan

氣候變遷會影響生物的地理分布，特別是對於受到威脅的植物，將可能面臨滅絕的危機。阿里山十大功勞（Mahonia oiwakensis）為臺灣特有的藥用植物，在全球及臺灣區域尺度的保育評估系統，分別被列為易受害與瀕危等級。本研究應用最大熵（maximum entropy ;MaxEnt）預測了該物種現時和未來的適宜棲地，總計使用了85個出現點位與10個環境變項，模擬現時與2070年代表濃度途徑2.6（暖化減緩）和8.5（暖化加劇）兩種氣候情境下，物種適宜棲地的時空變化。研究結果顯示，年均溫為MaxEnt模型提供了重要的貢獻，從響應曲線可知，年均溫7~14°C範圍應為該物種最佳的生態棲位；而從模擬的結果發現，未來暖化減緩或加劇的情景，十大功勞的適宜棲地皆會縮減，尤其海拔2500 m以下的族群，將可能無法承受暖化的衝擊。因此，建議現有的植物保育策略與行動方案，應考量氣候變遷的衝擊，以避免該物種將來走向滅絕。

Climate change affects the geographical distribution of organisms significantly, particularly those of endangered plants. Mahonia oiwakensis is a medicinal plant endemic to Taiwan and is recognized as a vulnerable and endangered species by global and Taiwanese conservation assessment systems respectively. In this study, we applied maximum entropy (MaxEnt) to predict suitable habitats for this plant species both currently and in the future. The calculations used 85 occurrence points and ten environmental variables to simulate temporal and spatial changes in the species' suitable habitats in climate conditions under representative concentration pathways 2.6 (mitigated warming) and 8.5 (aggravated warming) now and in 2070. The results demonstrated that annual mean temperatures provide key contributions to the MaxEnt model, and the response curve indicated that annual mean temperatures 7–14 °C are the best ecological niche for this plant species. The simulations indicated that under conditions of mitigated or aggravated warming in the future, suitable habitats for M. oiwakensis will be reduced, especially for population at altitudes of 2,500 m and under, which will be unable to withstand the effects of global warming. We suggest that current plant conservation strategies and action plans should take into consideration the effects of climate change to avoid these plant species becoming extinct.