Patterns of natural fungal community assembly during initial decay of coniferous and broadleaf tree logs

Abstract

Abstract. Community assembly processes do not only influence community structure, but can also affect ecosystem processes. To understand the effect of initial community development on ecosystem processes, we studied natural fungal community dynamics during initial wood decay. We hypothesize that fungal community assembly dynamics are driven by strong priority effects of early-arriving species, which lead to predictable successional patterns and wood decay rates. Alternatively, equivalent colonization success of randomly arriving spores has the potential to drive stochastic community composition and wood decay rates over time. To test these competing hypotheses, we explored the changes in fungal community composition in logs of two tree species (one coniferous and one broadleaf) during the early stages of wood decomposition in a common garden approach. Initial communities were characterized by endophytic fungi, which were highly diverse and variable among logs. Over the first year of decomposition, there was little evidence for priority effects, as early colonizers displaced the endophytic species, and diversity fell as logs were dominated by a few fungal species. During this period, the composition of colonizing fungi was related to the decomposition rates of sapwood. During the second year of decomposition, fungal community composition shifted drastically and the successional dynamics varied considerably between tree species. Variation in fungal community composition among coniferous (Larix kaempferi) logs increased, and there remained no evidence for any priority effects as community composition became stochastic. In contrast, early colonizers still dominated many of the deciduous (Quercus rubra) logs, with a temporally consistent impact on community composition. For both tree species, wood decay rates levelled off and the relationship with fungal community composition disappeared. Our results indicate that priority effects are relatively minimal in naturally occurring fungal community assembly processes. Instead, fungal successional dynamics are governed predominantly by combative abilities of colonizing fungi, and factors that shape fungal communities over time can differ considerably between tree species. Our results indicate that an increased focus of competitive strength among species, rather than priority effects, may be key to predict community assembly and the ecosystem process they provide.

Wood construction more strongly shapes deadwood microbial communities than spatial location over 5 years of decay

“…Because of different dependencies and tolerances of microbial taxa on moisture, we expect that microbial communities will shift with spatial location both within stems (Fig. 1: within stem position) (Kubartová et al ., 2012; van der Wal et al ., 2016) and within watersheds (Fig. 1: within watershed position) (Tedersoo et al ., 2014).…”

Potential links between wood‐inhabiting and soil fungal communities: Evidence from high‐throughput sequencing

“…Advances in metabarcoding approaches using high‐throughput sequencing (HTS) platforms enable detailed analysis of community composition and have been harnessed to reveal a more complete picture of fungal diversity in a wide range of habitats, including soil and deadwood (Goldmann, Schöning, Buscot, & Wubet, ; Hiscox et al, ; Hoppe et al, ; van der Wal, Klein Gunnewiek, Cornelissen, Crowther, & Boer, ; van der Wal, Ottosson, & Boer, ). Recent studies have demonstrated that diverse taxonomic and ecological functional groups of WIF colonize deadwood (Ottosson et al, ; Purahong et al, ; Song, Kennedy, Liew, & Schilling, ).…”

When to cut your losses: Dispersal allocation in an asexual filamentous fungus in response to competition

“…Microbial metacommunities are receiving a large amount of recent attention (Fuhrman, ; Fukami et al, ; Hiscox, Savoury, Müller et al, ; Maynard et al, ; Nemergut et al, ; Peay, Bruns, Kennedy, Bergemann, & Garbelotto, ; Prosser et al, ; Van der Wal et al, ), and dispersal is increasingly identified as a key unknown with respect to the maintenance and continuity of these communities in a dynamic landscape (Calhim et al, ; Davison et al, ; Kneitel & Miller, ; Lancaster & Downes, ; Smith, Steidinger, Bruns, & Peay, ). We have demonstrated that fungi can acquire information from the environment, subsequently affecting changes to their allocation strategies to dispersal when faced with competition within the confines of the trade‐off between growth and dispersal.…”

“…Access to resources held by other fungi often requires combative antagonism to breach an already occupied space. Variation in competitive ability is common, with distinct hierarchies formed by interactions bound in a substrate (Boddy, ; Stenlid & Gustaffson ; Haňáčková et al, , Van der Wal, Klein Gunnewiek, Cornelissen, Crowther, & Boer, ). Thus, delaying dispersal through delaying reproduction may result in low fitness if a fungal colony cannot withstand the combative assault of a competitively superior fungus.…”