CULTIVABLE FUNGAL DIVERSITY IN THE FOREST SOIL DURING LITTER DEGRADATION: MICROCOSM STUDY AT DIFFERENT TEMPERATURE REGIMES
Abstract
In the soils of the forest ecosystems litter decomposition is an important part of the carbon cycle. Soil fungi play fundamental role in this process, however, our knowledge about their successive changes is very limited, and their potential abilities under global warming are unknown. The objective of this study was to evaluate the diversity of the cultivable soil fungi during the annual cycle of aspen leaves and branches decomposition in laboratory experiments at different temperatures. Monthly soil fungi were quantified by plating technique followed by estimation of the morphological data and identification to genus level by the authentic manuals. Successional changes in fungal communities were revealed, and 102 cultures of the frequent fungal morphotaxa were isolated. It was found that the fungal communities were dominated by Ascomycota and Mortierellomycota. Eleven representative isolates were chosen for further molecular phylogenetic analysis of the nuclear ribosomal internal transcribed spacer (ITS1 and ITS2) DNA sequencing. It was found that Penicillium, Mucor and Mortirella were dominated at the early stage of succession and occurred most frequently throughout the decomposition process. During litter decomposition the predominance and diversity of Ascomycota increased, especially at 12oC. The frequency of Pseudogymnoascus, Cephalotrichum and Trichocladium was higher at 2oC, whereas temperature rise to 22oC led to an increase in Oidiodendron abundance. We propose that succession was driven by a decrease in the easily degradable carbohydrates and a rise in stable compounds content. Our study demonstrated that temperature was a strong determinant of the soil fungi species composition during litter decomposition.
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