A trait-based understanding of wood decomposition by fungi

Abstract

<jats:p>As the primary decomposers of organic material in terrestrial ecosystems, fungi are critical agents of the global carbon cycle. Yet our ability to link fungal community composition to ecosystem functioning is constrained by a limited understanding of the factors accounting for different wood decomposition rates among fungi. Here we examine which traits best explain fungal decomposition ability by combining detailed trait-based assays on 34 saprotrophic fungi from across North America in the laboratory with a 5-y field study comprising 1,582 fungi isolated from 74 decomposing logs. Fungal growth rate (hyphal extension rate) was the strongest single predictor of fungal-mediated wood decomposition rate under laboratory conditions, and accounted for up to 27% of the in situ variation in decomposition in the field. At the individual level, decomposition rate was negatively correlated with moisture niche width (an indicator of drought stress tolerance) and with the production of nutrient-mineralizing extracellular enzymes. Together, these results suggest that decomposition rates strongly align with a dominance-tolerance life-history trade-off that was previously identified in these isolates, forming a spectrum from slow-growing, stress-tolerant fungi that are poor decomposers to fast-growing, highly competitive fungi with fast decomposition rates. Our study illustrates how an understanding of fungal trait variation could improve our predictive ability of the early and midstages of wood decay, to which our findings are most applicable. By mapping our results onto the biogeographic distribution of the dominance-tolerance trade-off across North America, we approximate broad-scale patterns in intrinsic fungal-mediated wood decomposition rates.</jats:p>

Complementary Roles of Wood-Inhabiting Fungi and Bacteria Facilitate Deadwood Decomposition

“…The versatility of white-rot basidiomycetes, enabling them to rapidly colonize wood by degrading both lignin and cellulose, is the likely reason for their high abundance and functional dominance in the majority of decomposing logs. Moreover, rapid hyphal growth was found to be a key predictor of overall deadwood decomposition rate, showing that versatile groups have direct influence on this process ( 34 ).…”

Multiple distinct, scale‐dependent links between fungi and decomposition

“…These trends remained even after controlling for correlations between mass loss, distance from forest, and community diversity. Together, these findings suggest that the observed fine‐scale links between fungi and wood decomposition may be most critical in later decay stages, during which the presence of specific genera and the prevalence of combat, both of which are highly subject to chance, increase in importance (Figure 5) while variation in community trait averages, which are likely to more closely reflect the regional species pool, declines in predictive power (Lustenhouwer et al, 2020).…”

Species and intra-specific competition affect growth in greenhouse more than mycorrhizal colonization onQuercus rubraandAcer rubrumseedlings

“…Experimental results also underline this EM trait of organic N enzymatic processing (Bödeker et al, 2014) especially in those ectomycorrhiza descended from white rot as opposed to brown rot saprotrophic fungi (Stuart & Plett, 2020). Trait-based experimental design and analysis is increasingly recognized as a valuable method for characterizing guild differences (Lustenhouwer, Maynard, Bradford, Lindner, & Oberle, 2020;Mcgill, Enquist, Weiher, & Westoby, 2006;Zanne et al, 2020). Considering current projections of atmospheric CO2 increase, nitrogen deposition, phosphorus limitations, and the degradation and loss of forests worldwide (Crowther et al, 2016;Fitter, Heinemeyer, & Staddon, 2000;IPCC, 2014), clarifying the ecological function of mycorrhizal symbiosis is timely and relevant.…”