Effects of Logged and Unlogged Forest Patches on Avifaunal Diversity
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Effects of Logged and Unlogged Forest Patches on Avifaunal Diversity Maryam Ghadiri Khanaposhtani • Mohammad Kaboli • Mahmoud Karami Vahid Etemad • Saeedeh Baniasadi
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Received: 21 April 2012 / Accepted: 26 October 2012 / Published online: 18 November 2012 Ó Springer Science+Business Media New York 2012
Abstract In the Hyrcanian forests of northern Iran, reduced-impact silviculture systems, (single-tree and group-tree selection) were applied over a large area, which generated different local habitat structures. The aim of this study was to assess the differences between treated and untreated areas of forest and their effect on avian richness, abundance and diversity (R.A.D). Birds were surveyed during the breeding season in 2009 by 100-point counts, equally distributed in the treated and untreated area. Avian R.A.D was significantly different and higher in the untreated area. Generally, forestry practices cause noticeable changes in canopy percentage, tree composition, snags and shrub number. Treated forest habitats in the area of study had a much more developed understory, fewer snags and fewer large diameter trees. The results highlighted the importance of forest maturity and showed that preventing silvicultural disturbances may not be the best solution for conserving and enhancing biodiversity. Rather, methods such as selective cutting seem an appropriate and sustainable way of forest management. It is suggested that forests should be managed to conserve structural elements which create favorable habitat for bird species, preventing future species losses due to logging practices. Keywords Forest structure Bird community Richness Abundance Diversity Silvicultural treatment
M. Ghadiri Khanaposhtani (&) M. Kaboli M. Karami V. Etemad S. Baniasadi Department of Environmental Sciences, Faculty of Natural Resources, University of Tehran, Daneshkadeh Street, PO Box 41111, Karaj, Iran e-mail: [email protected]
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Introduction Human exploitation of forest ecosystems has greatly affected forest structure and landscape in many regions of the world. Several studies have shown that changes in vegetation structure and composition following timber harvesting in forest habitats can result in dramatic changes in composition of avian communities and in the abundance of many bird species (Thompson and others 1999; Augenfeld and others 2008; Tozer and others 2010). The main effects of regular wood extraction include habitat fragmentation, stand-age gradients, changes in tree species composition, foliage height profile, decrease in large canopy trees, and changes in the amount of snags and downed woody debris. All the above factors can influence bird communities to a large extent (MacArthur and MacArthur 1961; Laiolo and others 2003). Thus, for the purpose of forest management and avian conservation, the identification of critical structural elements and their relationships to bird species richness and abundance is essential (Diaz and others 2005; Ghadiri and others 2012a). Hyrcanian deciduous forest (Caspian
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