Ecological and functional effects of fungal endophytes on wood decomposition

Abstract

Abstract1. Despite the central role of saprotrophic fungi in wood decomposition and terrestrial carbon cycling, the diversity and functioning of wood endophytes (i.e. fungi that asymptomatically colonize living plant tissue) on decay remains poorly understood.2. In a 4-year field experiment in a boreal forest in the upper midwestern United States, we investigated whether endophytes influenced fungal community structure and subsequent wood decomposition via priority effects. We compared decay of sterilized and non-sterilized birch (Betula papyrifera) logs using both highthroughput sequencing and wood physiochemical analyses (i.e. density loss, dilute alkali solubility, ratio of lignin loss relative to density loss).3. Endophyte presence significantly altered initial fungal species composition during the first 2 years and enhanced mass loss over the experiment's duration. Results suggest that following tree death the immediate utilization of organic substrates by wood endophytes significantly alters establishment patterns of later arriving fungal saprotrophs.4. Independent of endophyte presence, white rot was the wood decay outcome at all sampling times, despite an initial presence of both brown and white rot fungi. 5.Collectively, these findings demonstrate that wood endophytes can affect early community assembly and subsequent decay rates, although environmental filtering leads to consistent selection for fungi with lignin-targeted decay strategies. K E Y W O R D Sendophyte, fungal community, historical contingency, priority effects, wood decomposition

Environmental filtering structures fungal endophyte communities in tree bark

“…Distinct fungal assemblages across tree species may drive divergent decay trajectories if they impact the establishment and activity of subsequently arriving wood decay fungi by exerting priority effects (Fukami, ). Consistent with this reasoning, wood endophyte communities have been shown to impact the community assembly and function of subsequently arriving saprotrophic fungi by producing a range of bioactive exudates (Cline, Schilling, Menke, Groenhof, & Kennedy, ; Heilmann‐Clausen & Boddy, ).…”

Dispersal and nutrient limitations of decomposition above the forest floor: Evidence from experimental manipulations of epiphytes and macronutrients

“…Given our ground‐biased understanding of decomposition, these findings demonstrate the need for holistic studies of decomposition that consider community assembly in suspended debris and its consequences for future ground‐level decomposition (i.e. priority effects; Cline, Schilling, Menke, Groenhof, & Kennedy, ; Osono, ).…”

“…Despite its advantages, our approach also limited the scope of organismal effects on decomposition. By sterilizing substrates, we excluded the saprotrophic and priority effects of microbiota that colonize plant matter before decomposition begins (Cline et al, ; Osono, ). We also did not account for invertebrate decomposition, and despite evidence that canopy‐level decomposition is controlled by micro‐organisms (Law et al, ), it is possible that invertebrates influenced the patterns reported in our study.…”

The foliar endophytePhialocephala scopiformisDAOMC 229536 secretes enzymes supporting growth on wood as sole carbon source

“…In addition, it has been shown that other root-and foliage-associated DSEs will utilize a wide spectrum of substrates (15, 16). Thus, latent saprotrophy may be widespread among DSEs including, at least in the initial stages, the decomposition of forest litter (47), twigs (48, 49) and logs (50). Considering this enormous carbon pool (51), DSEs likely play an important role in the carbon cycle and merit consideration in current ecosystem models (52–54).…”