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Abstract Bark decomposition is an underexamined component of soil carbon cycling and soil community assembly. Numerous studies have shown faster decomposition of leaf litter in “home” environments (i.e. within soil adjacent to the plant that produced the leaves), suggesting potential legacy effects from previous deposition of similar litter. This is expected to occur through, in part, accumulation of microorganisms that metabolize substrates the litter provides. Whether a similar “home-field advantage” (HFA) exists for bark decomposition is unknown, but this dynamic may differ because annual bark deposits to soil are minimal relative to leaf deposits. We hypothesized that (1) as with leaf litter, bark will be better decomposed near to the tree from which it was collected, and (2) that decomposing bark can initiate change in soil microbial composition. To test these hypotheses, we used a full factorial design that included two bark types (collected from eastern hemlock, Tsuga canadensis , and white oak, Quercus alba ) and two soil types (‘home’ and ‘away’) within a temperate mixed hardwood forest at the Shale Hills Catchment in central Pennsylvania, USA. Bark was excised from 25 replicates of each tree type, buried in either home or away soil, and incubated belowground from July 2017 to June 2018. Decomposition was assessed through proportionate mass loss over time, while microbial composition in the bark and adjacent soil was assessed through high-throughput sequencing of 16S rRNA gene and fungal ITS fragments. Overall, bark degraded faster in white oak soils, and there was also an effect of bark type on decomposition. Although white oak bark decomposed more quickly in its home environment, this could be due to either soil conditioning or inherent differences in the soils in which each species grows. Soil microbial assemblages also sorted according to bark type rather than soil type, suggesting that bark strongly influences the composition of nearby microorganisms during decomposition. Our results suggest that both bark type and soil type are important factors during bark decomposition, but our findings suggest no clear evidence for HFA. 

The “Gadgil effect” hypothesizes that root associations may slow down decomposition through pre‐emptive competition. In the context of recalcitrant litter decomposition, specifically coarse wood debris, it is uncertain as to what is the relative importance of soil communities associated with living roots when compared to those without roots. Here, it is hypothesized that the presence of live roots and active photosynthates will enhance wood decomposition. To test this hypothesis, the presence or absence of temperate tree roots was used in this study. Sugar maple (Acer saccharum) and white oak (Quercus alba) roots were manipulated at three sites of either limestone or shale parent rock residuum. At each site, wood substrate was placed in soils beneath the canopy of eitherA. saccharumorQ. alba, while in the presence of roots (root⁺). At the same time, wood substrate was placed in the same soil community, but live root exposure was eliminated by trenching (root⁻). This eliminated active photosynthate supply to the soil microbial community. Results determined that live root exposure promoted faster decomposition and greater mycelial colonization of wood substrate. Also, sites of shale parent rock residuum had higher rates of decomposition in comparison with limestone parent rock residuum. Although additional work is needed to determine the extent in which roots and lithology can facilitate wood decomposition, these findings suggest that living roots impact decomposers and provide a pathway towards humus and soil organic matter formation.