The Effects of Agricultural Lands Management Strategies for Biodiversity Recovery in Taroko National Park

27 Mar The Effects of Agricultural Lands Management Strategies for Biodiversity Recovery in Taroko National Park

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Abstract

太魯閣國家公園境內具有農業活動，為了減輕農業活動對保護區的環境衝擊，國家公園管理處採取兩種做法：1. 價購土地使其廢耕，讓植被重新演替，2. 輔導農民從慣行農法轉為有機農法。為了解此政策之效果，2017年本研究針對慣行農地、有機農地、廢耕地三種類型農地，以定點調查法、穿越線調查法、薛爾曼式陷阱、紅外線自動相機四種方法，分別調查鳥類、蝶類、小型哺乳類、中大型哺乳類之生物多樣性。結果顯示，鳥類多樣性在各類型農地間無顯著差異，但有機農地與廢耕地有助於形成不同的群聚結構，推測可能在較大之空間尺度上有益於生物多樣性。蝶類之物種數、夏農指數 (Shannon-Weiner index)、物種均勻度都以廢耕地最高，有機農地與慣行農地則相近。小型哺乳類僅在有機農地成功捕獲，但捕獲率很低 (2.19 隻/100 籠夜)。對於中大型哺乳類，僅分為現行農地與廢耕地兩種類型進行比較，發現廢耕地具有顯著較高的物種數，且山羌 (Muntiacus reevesi)與食蟹獴 (Herpestes urva)之活動頻度也顯著較高。整體而言，本研究結果支持廢耕地有助於生物多樣性之恢復，未來建議可持續推動。但目前尚無明確證據支持有機農法對生物多樣性恢復之效益。由於有機農地與慣行農地可能互相干擾，欲發揮有機農法之效益，需以社區為單位，從地景尺度進行較全面的規劃。

English Abstract

Agricultural activities have existed for decades in Taroko National Park before its establishment. To mitigate the environmental effects caused by agricultural activities, the managers of the national park adopted two strategies: 1. requitioning the agricultural lands and not allowing any further cultivation, and 2. encouraging a transformation from conventional farming to organic farming. To evaluate the effects of these two strategies, we compared biodiversities of conventional, organic, and uncultivated farms in Taroko National Park. We carried out point survey, line transect survey, Sherman’s trap survey, and camera trap survey to study the fauna of birds, butterflies, small-sized mammals, and medium-large-sized mammals, respectively, in 2017. The results suggested that bird diversity did not differ among the three farm types. However, the composition of bird guilds in the organic and uncultivated farms was different from that in the conventional farms, suggesting better support of bird diversity in a larger space scale. Species richness, Shannon-Weiner index, and species evenness of butterfly were highest in uncultivated farms but were similar between those in conventional and organic farms. Small mammals were only captured in the organic farms, with a very low capture rate (2.19 no./100 trap-night). Moreover, we compared the biodiversity of medium-large-sized mammals between cultivated and uncultivated farms. The uncultivated farms had significantly higher species richness and higher activity levels of Reeve’s muntjac (Muntiacus reevesi) and crab-eating mongoose (Herpestes urva). In conclusion, this study reveals the positive effects of uncultivated farms on biodiversity, and thus, supports the policy of land requition and not allowing any further cultivation of farms. However, there was no strong evidence supporting the benefits of organic farming on biodiversity. Because the organic and conventional farms are close in proximity and may influence each other, managers should involve all farmers in a community and propose a management plan on a landscape scale to promote the effect of organic farming.