不同農法施作對魚池鄉茶園蜘蛛多樣性及群聚組成之影響

The effects of different farming practices on the spider diversity and community in tea plantations of Yuchi Township, Taiwan

農業生產的過程中透過各種環境友善措施達到生物多樣性維護的需求，已是現今農業活動重要的課題。本研究於南投縣魚池鄉的茶園，以蜘蛛類為調查對象，欲瞭解不同農法是否影響茶園中的蜘蛛多樣性、群聚組成，以及重要的環境因子為何？我們選取有機茶園及慣行茶園各3個樣區，於2019年間分別以定點搖動法、目視搜尋加敲擊法及掉落式陷阱法共進行4次調查，比較不同農法施作下，茶園中的蜘蛛數量、科及物種豐富度、生物多樣性指數和群聚組成，並分析這些指數與環境因子的關聯。調查結果顯示地表游獵型的旋囊脈狼蛛（Venonia spirocysta）為茶園樣區中最優勢的物種，而有機茶園的蜘蛛數量顯著高於慣行茶園，物種豐富度亦有較高的趨勢，不過在群聚組成上，有機與慣行茶園間並未有明顯差異|此外，研究結果也顯示蜘蛛物種豐富度隨草生植被覆蓋度及平均高度提高而增加、夏儂歧異度指數亦隨草生植被覆蓋度提高而增加。故本研究說明有機農法施作及適當的田間底層植被管理，皆有助於提升茶園環境中的蜘蛛多樣性。

More agricultural activities in Taiwan have been dedicated to conserve biodiversity during the processes of production and various eco-friendly approaches are implemented. The study sites were located in tea plantation in central Taiwan, focusing on spiders to investigate whether different farming practices affect spider biodiversity and composition, and to assess related environmental factors. Spider surveys were conducted four times from June to November in 2019 using shrub-swaying, visual search with branch-beating, and pitfall traps at each of three organic and conventional farming sampling sites. We compared spider abundance, family and species richness, biodiversity indices and spider composition in organic fields with those in conventional fields, and examined the potential effects of environmental factors. The results showed that the ground-hunting Venonia spirocysta was the dominant species in the studied areas, and the spider abundance and species richness in organic farms were statistically greater than those in conventional farms. On the other hand, no significant difference was shown in species composition between different farming practices. In addition, the results presented that species richness increased with the increase of grass coverage and mean grass height, and Shannon- Wiener diversity index value increased with more grass coverage. Therefore, the result of this study suggests that organic farming and the suitable management on understory vegetation can improve and maintain spider biodiversity in tea plantations.