Fungal diversity and abundance and nitrogen accumulation during forest succession.

Abstract

Succession following a disturbance event can radically alter a forest’s ecosystem. Although many aspects of the community are affected, we chose to analyze the effect succession has on nitrogen levels and fungal diversity and functional groups. We looked at three plots that had each been burned once to study this relationship. At the three sites, we analyzed soil for percent nitrogen levels and did a survey of mushroom species composition, specifically focusing on the functional groups of fungi, mycorrhizal and wood-decomposers. We determined Shannon diversity indices for all the species across the three plots and ran a Chi-squared test to see if the proportion of each functional group was the same throughout the sites. Our soil data showed no significant difference in mean percent nitrogen levels across the three plots. Furthermore, there was no meaningful difference in species diversity, but there was a significant difference in the proportion of functional groups based on the burn year. Although our results were insignificant, other research has indicated that nitrogen levels peak at intermediate stages when organic leaf litter is high, but coarse woody debris is low. Furthermore, we concluded that early successional stages are associated with low fungal species diversity due to low leaf litter and availability of dead wood. Finally, we determined that younger forests have proportionately higher levels of mycorrhizal fungi than wood-decomposers due to the lack of coarse woody debris on which decomposers can live. Having such knowledge about nutrient availability and fungal succession is important for forest management, particularly for understanding the short and long-term consequences a prescribed burn can have on the ecosystem.