Wood decomposition is fundamental to carbon and nutrient cycling. Fungal community composition plays a critical role in wood decay, because fungi produce lignocellulolytic enzymes that degrade wood polymers and fungi vary in their ability to efficiently degrade these polymers. Fungal community composition can be influenced by the characteristics of the wood they are decaying as well as the characteristics of the surrounding environment. Furthermore, wood characteristics can be influenced by both species-specific traits and environmentally mediated changes in wood composition. In this project, we examine the impact of wood species and wood nutrient concentration on fungal community composition, enzyme activity, and mass loss across a range of soil characteristics. We grew saplings of four tree species under different nutrient treatments to obtain wood with 30-fold variation in wood phosphorus, 6-fold variation in nitrogen, and 5-fold variation in potassium concentrations. Wood samples from these saplings were then placed in different soil nutrient treatments in a long-term soil fertilization experiment in a seasonally moist tropical forest in Panama.
Results/Conclusions
We found that wood nutrient treatments and wood species significantly impacted wood mass loss and fungal community composition. A significant interaction between wood nutrient treatment and species identity affected both wood mass loss and fungal community composition, with wood characteristics explaining 36% of variation in wood mass loss and 14% of variation in fungal community composition. This shows that both species-specific and environmentally induced variation in wood characteristics can influence mass loss and fungal communities. However, soil plot also impacted mass loss (9% of variation explained) and fungal community composition (22% of variation explained), indicating that soil characteristics and the surrounding environment can also have a direct effect on wood mass loss and fungal communities. In addition, fungal community composition explained over 20% of the variation in mass loss and activity of cellulose and hemicellulose degrading enzymes, suggesting that fungal community composition plays an important role in wood decomposition. Determining the relative importance of species-specific and environmentally induced wood characteristics on fungal communities and decay is critical to the development of a mechanistic understanding of the biological processes that influence ecosystem carbon and nutrient cycling.