Diversity and distribution of polypores in the wet evergreen and shola forests of silent valley national park, Kerala
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Date
2015
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Department of Forest Management and Utilisation, College of Forestry, Vellanikkara
Abstract
The study was carried out with the objectives to assess the diversity and distribution of polypores in the wet evergreen and shola forests in Silent Valley National Park during three different seasons during 2014-15. An attempt has also been made to find out the effect of substrate features like diameter, type and decay class on the diversity and abundance of polypores. Three fixed size permanent sample plots of 100 m×100 m with subplots of 10 x 10 m were established in three different locations in each ecosystem and these sample plots were enumerated during three different seasons to collect information on influence of seasonal fluctuation in fruitbody production and details on substrate characteristics. Apart from the plot based sampling, opportunistic sampling method was also adopted to maximize the documentation of polypore fungal diversity and distribution.
A total of fifty seven species were recorded from the National Park and among this Inonotus pachyphloeus, Phylloporia pectinata, Trametes menziesii, Trametes ochracea and Trametes pubescens were the first report from Kerala. Three species (Inonotus sp. nov., Microporus sp. nov. and Polypores sp. nov.) were found to be new to science and these species have been described based on the macro and micro-morphology.
The wet evergreen forest showed relatively high polypore diversity and richness than that of shola forest with higher Simpson’s index of diversity (0.92) and Margalef richness index (3.15). Similarity between polypore communities in two ecosystems was found to be low during all the seasons. The peak fruitbody production of the polypores was observed during the monsoon. The altitudinal variation analysis of polypores revealed a monotonic decrease pattern in species richness from lower altitude wet evergreen forests to higher altitude shola forests. The density of many of the polypore species was also found decrease drastically along the altitudinal gradient. The degree of dominance and evenness also showed a trend of increase and decrease respectively, along the altitudinal gradient.
Polypore-host association revealed that, of the 91 tree species under 32 families, 29 tree species (31.87 %) belonging 16 families were hosts to polypores.Among them, Mesua ferrea harboured maximum polypores belonging 13 species followed by Elaeocarpus tuberculatus with 12 species and Cullenia exarillata with 8 species. Most of the polypore were found to be host generalist and only five species showed possible preference for a particular tree species.
Among the substrate types, maximum polypore occurrence was observed on logs followed by branch/twig and snag while, living trees supported only very few polypores. The maximum species richness, density and occurrence has been recorded on substrates under 31- < 40 cm diameter class followed by 21- < 30 cm and 11- < 20 cm. Decay class association of polypores showed that the intermediate decay stages harboured the maximum both in terms of number of species, density and frequency of occurrence. The conceptual framework on primary ecological strategy revealed that polypores exhibits ruderal, combative and stress tolerant behaviours. The present study concluded that the diversity and distribution of polypores are determined by seasonal fluctuations, arborescent floral diversity and substrate features.
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