Assessing Habitat Suitability for Günther's Frog (Hylarana guentheri) in the Farm-Pond Landscape of Chiayi County, Taiwan.

The early and main functions of farm-ponds in Taiwan were agricultural irrigation and water supply for livelihood. As time goes by, the agricultural irrigation systems and technology of water supply got improved so the existing farm-ponds lost their original functions gradually. In response to the industrial development, most of the farm-ponds turn into breeding pools or are filled for construction. However, farm-pond is important habitat for aquatic organism and amphibians. Once the environment of farm-pond get damaged or significant change, it will cause serious impact on the ecosystem. In farm-pond, frog is highly sensitive to environmental changes so it can be described as indicator organism. Therefore, this study aims to assess habitat suitability for Günther's frog (Hylarana guentheri) in farm-pond landscape. Besides, we'll propose the policies for habitat improvement from a standpoint of vulnerability. With fuzzy Delphi method, we first established habitat assessment framework and indicators weights of Günther's frog in farm-ponds in Chiayi county, and the result determines 4 first-level items ('farm-pond water environment', 'farm-pond land environment', 'degree of link between farm-ponds' and 'residents' attitude'), 10 second-level indicators, in which 'the number of plant species within 100m of farm-pond land surrounding' is assessed as the most important, followed by 'if the farm-pond links the near another one'. We investigated frog species and amount in 69 farm-ponds in Chiayi county from 2013 winter to 2015 spring. Meanwhile, we scored and marked with the assessment indicators for Günther's frog in each farm-pond. The result shows that there are 17 farm-ponds (24.64%) with higher habitat suitability which are mainly located in Lucao township, Dalin township and Singang township. We also found that when the weighted assessment value greater than 2.645, the farm-pond is more likely to occur Günther's frog. This classification with overall accuracy of 81.16% indicates a high degree of confidence. Furthermore, comparing the weighted assessment value with the amount of Günther's frog, we found that there are 13 farm-ponnds (18.84%) as 'high habitat suitability and having more Günther's frogs' which should be given priority to be conserved, 3 farm-ponds (4.35%) as 'low habitat suitability but having more Günther's frogs', 43 farm-ponds (62.32%) as 'low habitat suitability and having less Günther's frogs', and 10 farm-ponds (14.49%) as 'high habitat suitability but having less Günther's frogs'. The follow-up action is to improve the habitat conditions to conserve and restore Günther's frog. In conclusion, with the method in this study, we can assess which farm-pond should be conserved, and judge the farm-pond habitat having Günther's frog or not. In addition, we propose constructing farm-pond as Günther's frog habitat through matrix analysis and case comparison.早期臺灣的農塘的功能主要為農業灌溉和民生供水，隨著時代推進，灌溉系統與供水技術改善，現存農塘原有功能逐漸喪失，部分農塘因應產業發展轉型為養殖池，或因都市或地方建設被填平。然而，農塘是水生及兩棲類生物的重要棲地，一旦農塘環境遭受重大的改變或破壞，將對生態系統造成嚴重影響。而蛙類對於農塘環境變化具有高度敏感性，可謂農塘生物棲地的指標生物。因此，本研究目的在於，評估貢德氏赤蛙的棲地適宜性，並以脆弱度的角度提出棲地改善策略。本研究首先透過模糊德菲法建立嘉義縣農塘貢德氏赤蛙的棲地評估架構和指標權重值，研究結果確立四個第一層級評估項目(農塘水域環境、農塘陸域環境、連結程度和居民態度)、十個第二層級評估指標，其中以「農塘陸域周邊 100 m內植物物種數」為最重要，其次是「鄰近農塘」是否與該農塘有所連結。本研究進行嘉義縣 69 個農塘地點之 2013 年冬季至 2015 年春季的蛙類物種和數量調查；同時採用貢德氏赤蛙的棲地評估指標於各農塘進行指標評分，調查結果顯示棲地環境適宜性較高的農塘地點共有 17 個 (24.64%)，主要分布於鹿草鄉、大林鎮、新港鄉；本研究亦發現當農塘棲地指標的加權評估值大於 2.645 分時，該農塘地點較可能出現貢德氏赤蛙，此分類方法總體精確度達 81.16 %，表示此分類法具高度可信度。 進一步透過農塘棲地指標的加權評估值與貢德氏赤蛙蛙況之比較，發現「棲地適宜性高且蛙況好」的農塘地點共有 13 口 (18.84%)，是最應優先保存的貢德氏赤蛙農塘棲地；「棲地適宜性低，但蛙況好」的農塘地點有 3 口 (4.35%)；「棲地適宜性低，且蛙況差」的農塘地點有 43 口(62.32%)；「棲地適宜性高，但蛙況差」的農塘地點共有 10 口 (14.49%)，後續應改善棲地環境條件以復育貢德氏赤蛙。綜合言之，本研究所建立之貢德氏赤蛙脆弱度與棲地適宜性的評估方法，可評估出貢德氏赤蛙農塘棲地保存地點，以及作為判斷農塘可能棲息貢德氏赤蛙與否的方法；而透過矩陣分析與案例比較法，可提出農塘營造為貢德氏赤蛙棲地之參考。第一章 緒論 1 第一節 研究動機與目的 1 第二節 研究設計 2 第三節 研究流程 3 第二章 文獻回顧 5 第一節 嘉義縣農塘發展及現況 5 第二節 兩生綱無尾目生物 9 第三節 脆弱度理論及應用 14 第三章 研究內容 19 第一節 農塘蛙類及棲地環境調查 19 第二節 民眾問卷調查 26 第三節 專家問卷調查 27 第四節 貢德氏赤蛙棲地環境評估架構 28 第四章 研究結果 44 第一節 農塘蛙類及棲地環境調查結果 44 第二節 專家問卷調查結果 101 第三節 貢德氏赤蛙棲地及脆弱度加權評估結果 109 第五章 結果討論 120 第一節 一致性檢定與矩陣分析 120 第二節 嘉義縣農塘貢德氏赤蛙之最適棲地 124 第六章 結論與建議 134 第一節 結論 134 第二節 研究建議 136 參考文獻 137 附錄1 『嘉義縣農塘貢德氏赤蛙之脆弱度評估』專家問卷 142 附錄2 氣象資料分析圖 15