2010年1月5日 星期二

雖有穩定的植物資源,非洲雨林中鱗翅目昆蟲的組成仍具頗高的季節性差異

大戟科木本植物 Neoboutonia macrocalyx Pax 圖片來源:Prelude Medicinal Plants Database
文獻來源:Sini Skippari, Timo Olavi Veteli, John Kasenene, Pekka Niemela and Heikki Roininen. 2009. High temporal variation in the assemblage of Lepidopteran larvae on a constant resource. African Journal of Ecology 47: 537–545

本文作者在非洲烏干達的吉貝利(Kibale)國家公園的中海拔熱帶雨林中,研究不同樹木植株之間的鱗翅目幼蟲物種多樣性與物種組成之時間變化。調查方式為在1995年1月~1996年12月間,每個月對大戟科樹木 Neoboutonia macrocalyx Pax 葉片上的鱗翅目幼蟲進行採樣。在研究其間總計採得1961個樣本,共有76個形態種的鱗翅目昆蟲。各個物種的標本數量差異非常大,範圍少至一種只有1個樣本、多至一種有707個樣本。不同植株上採得的物種組成非常相似且以尺蛾科幼蟲為主。植食者豐度的時間性變化很高,其個體量的高峰在1995年主要發生於雨季,但此現象在1996年並未出現,且在這兩年當中、豐度均未和降雨量有顯著的相關性。相反地,在這兩年中的觀察資料顯示:鱗翅目多樣性與降雨量反而呈現負相關,且似乎因此造成一個半年為期的循環,使得每年會出現一至二個物種多樣性的高峰。此外,物種組成的相似程度亦具有季節性,而且同一物種會在一年之中的特定時段出現在該組成當中。此研究顯示:短期的生物多樣性評估會對熱帶雨林中生物多樣性做出偏頗的結論。

Abstract
We studied variation in the assemblage of lepidopteran larvae between individual trees, and temporal variation in the diversity and species composition of the assemblage in a medium-altitude rainforest in Kibale National Park, Uganda. Monthly samples of lepidopteran larvae were collected from the leaves of Neoboutonia macrocalyx Pax. between January 1995 and December 1996. During this period, a total of 1961 specimens representing 76 lepi- dopteran morphospecies were found. The numbers of individuals within species varied enormously, ranging from one to 707 individuals. Assemblages of individual trees were highly similar and dominated by geometrid larvae. Temporal variation in herbivore abundance was high. The number of individuals peaked during the major rainy season in 1995 but not in 1996 and was not cor- related significantly with rainfall within these 2 years. In contrast, a negative correlation was found between lepi- dopteran diversity and rainfall that seems to cause a semi- annual trend in diversity with one or two peaks per year. Furthermore, there was seasonality in the similarity of the assemblage. Consequently, the same species were found in the assemblage during certain times of the year. Our study shows that short-term biodiversity assessments can give a skewed picture of the diversity of tropical forests.

Key words: diversity, herbivory, insects, resource avail- ability, seasonality, species richness

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