楠溪林道臺灣水鹿對樹皮之啃食偏好與樹皮化學成分之關聯

The Debarking Preference for Tree Species by Formosan sambar(Rusa unicolor swinhoii)at the Nanshi Forestry Road and its Relationship with Bark Chemical Contents

葉川逢(Chuan-Feng Yeh)

指導教授 ： 翁國精

國立屏東科技大學/農學院/野生動物保育研究所/碩士(2015年)

https://doi.org/10.6346/NPUST.2015.00043

摘要

鹿科動物的啃食樹皮行為能造成樹木死亡，啃食情形嚴重的話會影響森林的演替與更新。生於臺灣本島的臺灣水鹿(Rusa unicolor swinhoii)近年來被發現有大量啃食樹皮的情形，本研究希望能了解其發生原因而設計實驗。本研究選擇楠溪林道作為實驗地，以水鹿對樹種的偏好習性做基礎，假設水鹿偏好的樹種含有高於食草的特定營養成分或幫助水鹿排除腸胃道寄生蟲的縮合單寧，接著檢驗(1)營養假說及(2)自我醫療假說兩個解釋啃食行為的假說。本研究在楠溪林道進行水鹿對樹種的偏好程度、樹皮厚度測量及樹皮採集，分析營養成分及縮合單寧的含量，再比較樹皮與食草在化學成分上的差異及以主成分分析篩選出最具代表性的因子，最後以迴歸分析來評估這些成分及樹皮厚度與啃食偏好係數的關係。結果顯示樹皮和食草所含的各種營養成分含量皆相當接近，而食草中缺乏縮合單寧。迴歸分析的結果顯示水鹿偏好的樹種樹皮厚度較薄且縮合單寧含量較低，因此推斷樹皮的物理性質及縮合單寧的含量會影響水鹿對樹種的選擇。由於最受水鹿偏好的樹種樹皮縮合單寧含量落在偶蹄目動物攝食的最合適含量範圍，且食草中缺乏縮合單寧，因此推測水鹿啃食樹皮與腸胃道寄生蟲的抵禦機制有關。

關鍵字

腸胃道寄生蟲 ； 自我醫療 ； 縮合單寧 ； 營養 ； 森林更新

並列摘要

Bark stripping behavior by cervid may kill trees, which further impacts forest regeneration when the animals are over abundant. The intensity of bark stripping by Formasan sambar deer (Rusa unicolor swinhoii) increased recently in Taiwan. The purpose of this study is to reveal why sambar debarks. The Nanshi forestry road is selected for this study. Formosan sambar deer debarks selectively, so this study hypothesizes that the preferred tree species contain higher nutritional contents (nutrition hypothesis) and/or anti-parasitic compounds (self-medication hypothesis), such as condenses tannin. This research measured the preference for tree species, damage level on individual trees and thickness of bark among the study site. Barks were analyzed for their chemical contents. Principal component analysis were used to reveal the major groups of chemicals and multiple regression was used to evaluated the correlation between these chemical groups and bark thickness with preference for tree species and damage level of individual trees. This research also compared the chemical contents of barks and two major forages. The results show that the chemical contents of barks and major forages for Formosan sambar are similar, but condensed tannin is absent in the major forages. Regression analysis shows that the preference for tree species and damage level of individual trees are negatively correlated with the amount of condensed tannin but are positively correlated with bark thickness, indicating that the physical properties of bark may affect the debarking preferred. Since the most preferred tree species by Formosan sambar have an amount of condenses tannin within the most suitable range for artiodactyls, this research suggests that Formosan sambar debark to mitigate the infection of gastrointestinal parasite.

並列關鍵字

gastrointestinal parasite ； self-medication ； condensed tannin ； nutrition ； forest renewal

參考文獻

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