Elevated tropospheric CO2 and O3 may not alter initial wood decomposition rate or wood-decaying fungal community composition of Northern Hardwoods

• Wood from trees grown in elevated CO2 and/or O3 did not have altered first-year decay rates.
• Wood-decaying fungal communities were unchanged by 12 years of elevated CO2 and/or O3.
• Wood placement in elevated CO2 and/or O3 conditions did not significantly alter decomposition.
• Tree species differed in wood decay rate and the fungal communities involved.
• Elevated CO2 and O3 may impact wood decay by altering forest community composition.

We examined the effects of elevated CO2 and/or O3 on the wood-decaying basidiomycete fungal community and wood decomposition rates at the Aspen Free-Air CO2 and O3 Enrichment (Aspen FACE) project. Mass loss rates were determined after one year of log decomposition on the soil surface, and wood-decaying basidiomycetes were isolated from decaying wood and identified via DNA sequencing. Aspen (Populus tremuloides Michx.) and birch (Betula papyrifera Marshall) wood differed significantly in wood-decaying basidiomycete fungal communities and decomposition rate. Twelve years of site exposure to elevated CO2 and/or O3 did not have significant effects on wood-decaying fungal communities. Growth under elevated CO2 and/or O3 did not produce wood that differed in decay rate from that grown under ambient atmospheric conditions. Similarly, wood decay rate was not altered significantly when decomposition occurred in elevated CO2 and/or O3 environments. Our results suggest that wood-decaying fungal community composition and decomposition rates of northern hardwoods may not be directly affected by elevated tropospheric CO2 and O3.