台灣外來種陸域脊椎動物風險評估系統

A Risk Assessment System of Exotic Terrestrial Vertebrates for Taiwan

相對於控制或滅除入侵種需投注的鉅額資源，預防外來種成功入侵的花費可謂相當低廉。風險評估系統具預警功能，可快速反應外來種的威脅性並協助決定後續研究與防治措施在資源支配上的優先性。本研究試圖建立一量化且適用於台灣的外來陸域脊椎動物風險評估系統。我們參考相關文獻，篩選出可能影響外來種在引入地點是否能成功建立族群的因子，及對入侵地的經濟、自然資源、社會健康造成危害的重要特性後，歸類出外來種的引入潛力、建立族群潛力和危害能力3項評估指標。經測試22種已引入台灣但尚未在野外建立族群和20種已入侵台灣的物種，發現二者的總分、建立族群潛力和危害能力皆有顯著差異，顯示此系統能界定外來種在台灣入侵能力和威脅程度的差異。對進口動物的申請審核方面，根據13種尚未引入台灣，但在其他入侵地點已造成危害的物種，其建立族群潛力和危害能力兩項指標分數都不低，此結果顯示本系統仍能定量顯示該物種的威脅性供管理單位參考。 Preventing invasion of exotic animals is far less costly than control of their post-establishment. Arisk assessment system plays an important role in prioritizing research and control efforts on exoticanimals, and reduces their potentials of establishing viable populations in wild and to cause damagingeffects. This study was intended to develop a quantitative system of risk assessment of exotic terrestrialvertebrates for Taiwan. We reviewed pertinent literature and identified traits of common exotic speciesthat had successfully established viable populations outside their natural ranges. We also identifiedattributes of those exotic species that had become pests to economic, natural resources, or public health.The three assessment criteria were used: the likelihood of being introduced, likelihood of establishingviable population, and likelihood of species to cause damages. We tested this system with 22 exoticspecies that had not established natural populations in the wild in Taiwan and 20 species that had becomeinvasive. Scores of the risk likelihood for the latter were significantly higher than those of the former,indicating that this system would provide a good predictor for assessing the threats of exotic speciesinvasion and their pest status. Furthermore, 13 species that had not been introduced to Taiwan but hadinvaded other countries were also assessed. Their risk scores were also high for potentials to establishviable populations and to cause damage effects. The results of this study indicated that this riskassessment system is a useful qualifier for placing exotic species of terrestrial vertebrates under differentthreat categories, that enables us to set import restrictions and to prioritize research and control efforts ofexotic species for Taiwan.