Post-logging recovery of amphibian assemblages and habitat preferences of the endangered giant squeaker frog (Arthroleptis krokosua) in Ghana’s moist semi-deciduous forests

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2015-02-20
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Logging intensity and the area size continue to increase rapidly each year. As a result, there are indications that by the year 2050 nearly all tropical forests will be logged. However, to date there is a lack of quantitative information on the effectiveness of selective-logging practices in ameliorating impacts of logging on faunal communities. To assess post-logging effects on amphibian assemblages, we conducted a large-scale replicated field study in three Ghanaian selectively logged moist semi-deciduous forests at varying times after timber extraction. Specifically, we assessed whether the diversity, abundance, and assemblage composition of amphibians changed over time for forest-dependent species and those tolerant of forest disturbance. We sampled amphibians in Suhuma, Krokosua Hills and Sui River forest reserves in southwestern Ghana (total of 48 study plots, each 2 ha). We also investigated and herein we provide further data on the species' variability and habitat preferences of one of the world’s rarest frogs, the Giant West African Squeaker Frog, Arthroleptis krokosua. In each forest, we established plots in undisturbed forest, recently logged forest, and forest logged 10 and 20 years previously. Logging intensity was constant across sites with 3 trees/ha removed. A total of 24 species, 8, 267 amphibians were collected including 14 specimens of A. krokosua, its highest abundance since discovery. Recently logged forests supported substantially more species than unlogged forests. Simultaneously Simpson’s index decreased, with increased in dominance of a few species. Over time following logging, increased richness of disturbance-tolerant species decreased until 10 years after logging when their composition was indistinguishable from unlogged forests. Simpson’s index increased with time since logging and was indistinguishable from unlogged forest 20 years after logging. Forest specialists decreased after logging and recovered slowly. However, after 20 years amphibian assemblages had returned to a state indistinguishable from that of undisturbed forest in both abundance and composition. These results demonstrate that even with low-intensity logging (≤3 trees/ha) a minimum 20-year rotation of logging is required for effective conservation of amphibian assemblages in moist semi-deciduous forests. Furthermore, remnant patches of intact forests retained in the landscape and the presence of permanent brooks may aid in the effective recovery of amphibian assemblages. Further data on the breeding habitats and detailed population estimates of A. krokosua are also recommended in order to set up plans for the long-term conservation of the peculiar Ghanaian forest frog.
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A Thesis submitted to the Department of Wildlife and Range Management, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the degree of Master of Philosophy, 2014
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