Document Type

Honors Project On-Campus Access Only

Abstract

Brown rot wood-decaying fungi have a chemical and biological nutritional mode that is very distinct from those of white rots. The former selectively degrade carbohydrates and leave most of the lignin (organic polymer in the plant cell wall) intact in soil residues, while the latter generate oxidized residues that have little lignin left. Studying the competition between wood-decaying fungi with different nutritional modes is important because their early assembly history (fungal community composition and advancement) has a huge effect on the rate of decomposition and the fate of carbon in soils. 80% of Earth’s aboveground biomass carbon is stored in wood, so understanding how fungi decay wood will enhance the models for loss of biomass and carbon accounting. In this study, I researched competitive success of Fomitopsis betulina (brown rot) in mesocosms with soil and logs of Betula papyrifera. This new nested experimental design included three categorical independent variables (soil, log, and inoculum), where the binary was whether the log and/or the soil were sterilized, and whether the log was inoculated with Fomitopsis betulina. Lignin:density loss (L:D; higher for white rot) values were calculated to infer the rot type in the samples. The results illustrate that competitive interactions between fungal species affect colonization success, which in turn has significant consequences on the outcomes of wood decomposition. I saw predictable patterns that are in line with the life history of Fomitopsis betulina; however, there was a lot of variability in the L:D values. Moreover, the mesocosm design led to some unavoidable contamination. The next step is to perform targeted DNA comparisons within the nested design to examine the effects of the microbial community on competition within the wood.

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