人為活動對臺灣中大型哺乳類空間分布影響評估

人為活動對野生動物的影響為生態保育的重要課題之一，近年有許多國外研究在探討人為活動對野生動物的影響；諸如分析夜晚光照、人類足跡、基地台分布等人為因子，對哺乳動物分布或活動週期的影響。臺灣的相關研究主要是針對特定區域的小尺度分析，較少有對全島的大尺度分析。本研究以臺灣基地台覆蓋範圍作為人為活動的指標，計算基地台密度和其它環境因子的相關性，確認基地台在臺灣能代表人為活動。後續整合1988 - 2020年臺灣13種中大型哺乳動物出現紀錄資料，配合環境因子資料建立各物種的分布預測模式；計算動物紀錄資料、預測資料在基地台覆蓋範圍內的出現的比例，評估各物種對人為活動的耐受程度。分布預測模式的結果進一步建構決策樹模型，以得知影響動物分布的主要環境因子及其決策過程。結果顯示臺灣基地台密度和人口密度的相關性最高，和NDVI相關性最低。臺灣中大型哺乳動物傾向出現於基地台覆蓋範圍外的區域，整體出現比例為 38%，出現區域中有88% 位於海拔1000公尺以下；保育類 (31%) 的出現比例低於一般類 (38%)。單一物種中只有白鼻心及石虎出現比例超過50%，保育類中的黃喉貂、山羊、黑熊、水鹿都低於20%，其餘物種約落在25% - 35% 之間。從各物種決策樹模型的前三層得知，平均海拔、離城市距離、寒季總降雨量及混合林面積4種因子共佔78% 的節點出現次數，為主要影響臺灣中大型哺乳動物出現的環境因子。本研究得知基地台在臺灣能一定程度代表人為活動，並整合臺灣近十幾年的中大型哺乳動物出現紀錄，配合基地台覆蓋範圍及其它多種環境因子，得知大尺度下人為活動對13種哺乳動物分布影響程度。建議可加強臺灣低海拔區域的監測，以應對日後人為活動的擴張。

關鍵字

哺乳動物；人為活動；基地台；物種分布預測模式；決策樹

並列摘要

The impact of human activities on wildlife is one of the important topics of ecological conservation. Over the years a number of research have studied the impact of human activities on wild animals. They analyze the effects of human factors such as night-time light, human footprints, and cellphone towers coverage on the distribution of mammals or the activity cycle. The relevant research in Taiwan is mainly for small-scale analysis of specific areas, little is known about the large-scale effect of the whole island. In this study, the coverage of cell towers in Taiwan was used as an indicator of human activities. The correlation between cell towers density and other environmental factors was calculated to confirm that cell towers in Taiwan can represent human activities. Subsequent integration of 13 species of medium- and large-sized mammals in Taiwan from 1988 to 2020 record data, combined with environmental factor data to establish a distribution prediction model for each species. Calculated the proportion of animal record data and predicted data in the coverage area of the cell towers, and evaluated each species tolerance to human activity. The results show that Taiwan cell towers density had the highest correlation with population density and the lowest correlation with NDVI. Medium- and large-sized mammals in Taiwan tend to appear in areas outside the coverage of cell towers. The overall occurrence rate was 38%, and 88% of the occurrence areas were located under an elevation of 1000 meters. The protected animals (31%) presented a lower proportion than the not threatened animals (38%). Among a single species, only Masked palm civet and Chinese leopard cat appeared more than 50%. The protected animals’ Yellow-throated marten, Formosan serow, Formosan black bear, and Formosan sambar were all less than 20%, and the other species were between about 25%-35%. From the first three levels of decision-making results of the decision tree model for each species, it was known that the average altitude, distance from the city, total rainfall in the cold season, and mixed forest area accounted for 78% of the node. These were environmental factors that mainly affect the occurrence of medium- and large-sized mammals in Taiwan. This study shows that cell towers can represent human activities to a certain extent in Taiwan. Integrating the occurrence records of medium- and large-sized mammals in Taiwan in the past ten years, combined with the coverage of the base station and other environmental factors, we can know the degree of human activities affecting the distribution of 13 mammals at a large scale. This study suggested that monitoring in low-altitude areas in Taiwan can be strengthened to respond to the expansion of human activities in the future.