- 學位論文
指定 Ellenberg-type 指標指數的新方法及其指定台灣指標指數的應用
New framework for assigning Ellenberg-type indicator values and its application to define Taiwan indicator values
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摘要
Ellenberg-type指標指數是一種序數值用來指示物種最可能被觀測到的環境。我們發展了一個以國家植群資料庫和大尺度環境網格資料來指定Ellenberg-type指標指數的新方法。該方法首先選取有效的環境因子來逼近感興趣的環境梯度，並運用前述資料及不同統計方式推算物種的最佳生態棲位及生態棲位寬度，最後再指定Ellenberg-type指標指數給物種。我們的方法可以應用於缺乏Ellenberg-type指標指數或對植物物種生態認識有限的新區域。本研究利用捷克共和國、奧地利和英國的資料評估該方法指定Ellenberg-type指標指數的表現、對樣本大小的穩固性，以及運用到其他國家的可轉移性。除此之外，台灣尚未有Ellenberg-type指標指數，因此我們更進一步將方法應用於台灣。我們指定了溫度、土壤濕度、雲霧和風速的台灣指標指數給502種木本植物，並使用國立台灣大學植群生態研究室收集的現地資料驗證台灣指標指數的生態意義。最後，本文討論該方法的優點、限制和可能的改進。該方法具有高度彈性，可以應用於擁有植物調查資料及大尺度環境資料的區域，且可以指定不同環境梯度的 Ellenberg-type指標指數。儘管對於使用的資料品質有限制，指定指標指數的過程亦可以做更多改善及嘗試，該方法仍能指定具生態意義的Ellenberg-type指標指數給物種。我們相信這些指標指數對於生態學研究具有極高的應用潛力，尤其是物種保育、生態復育、環境監測、植群動態相關領域。
並列摘要
Ellenberg-type indicator values are ordinal values assigned to plant species indicating the most likely environmental conditions where the species can be observed. In our study, we developed a framework to assign Ellenberg-type indicator values. Our framework first collects data from national vegetation databases and large-scale gridded environmental datasets and selects a valid environmental factor to approximate the environmental gradient of interest. It then applies statistical methods to the collected data and valid environmental factor to identify species’ niche optima and widths, based on which the framework assigns Ellenberg-type indicator values to species. Our framework can be applied to new regions lacking Ellenberg-type indicator values or having insufficient field experience with plant species. We evaluated the framework’s ecological performance, robustness to sampling effort, and transferability to other regions with distinct ecological contexts using data from the Czech Republic, Austria and Britain. We further applied our framework to Taiwan, where Ellenberg-type indicator values were not used so far, and assigned Taiwan indicator values to 502 woody species. In addition to temperature and soil moisture, we assigned also Taiwan indicator values for fog and wind, which are not considered in other Ellenberg-type indicator systems. The ecological performance of Taiwan indicator values was confirmed using data collected by the Vegetation Ecology Lab at the National Taiwan University. Finally, we discussed the advantages, limitations, and possible improvements of our framework. We conclude that our framework is highly flexible. It can be applied to regions with flora or vegetation data and large-scale gridded environmental data. It can also assign Ellenberg-type indicator values for different environmental gradients of interest. Although the ecological performance of our framework is confined by the data quality and more improvement or exploration on process to assign indicator values can be done in the future, our framework is still able to assign ecologically meaningful Ellenberg-type indicator values to species. We believe our framework and indicator values assigned by our framework show high potential for various ecological studies, especially in the fields related to conservation, monitoring of long-term environmental condition, and vegetation dynamics.
參考文獻
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