The effects of elevated carbon dioxide on fungal communities and their dispersal in a mature oak woodland

Baird, Aileen Bryony ORCID: 0000-0001-7340-6085 (2024). The effects of elevated carbon dioxide on fungal communities and their dispersal in a mature oak woodland. University of Birmingham. Ph.D.

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Abstract

Forests are a key habitat in our understanding of how the climate and biodiversity crises will affect our planet. Often overlooked in climate models, fungi play critical roles in carbon and nitrogen cycling in forests and are a vital part of woodland biodiversity. Although there is a considerable body of research using long time series to investigate the impacts of climate change on fungal fruiting in real time, and extensive laboratory study; there have been a limited number of climate manipulation facilities incorporating fungal studies into their research programmes.

To investigate the effects of elevated CO\(_2\) on forest fungal communities, a variety of complementary studies were undertaken at the Birmingham Institute of Forest Research (BIFoR) Free Air Carbon dioxide Enrichment (FACE) facility from 2017 to 2021. The FACE facility is located within a mature deciduous oak (Quercus robur) woodland in Staffordshire, UK, where areas of the woodland are treated with +150ppm CO\(_2\) during the oak growing season. A total of six studies were completed, studying the impacts of elevated CO\(_2\) (eCO\(_2\)) on fungal communities at different stages of the fungal life cycle. Chapters 3 and 4 investigated airborne spore concentrations and their dispersal, Chapter 5 fungal fruiting patterns, and Chapters 6, 7, and 8 soil fungal communities.

Optical Particle Sensors (OPCs) were used to investigate the impacts of eCO\(_2\) on bioaerosols in Chapters 3 and 4. There were stark differences in bioaerosol patterns between the 2018 and 2019 measurement campaigns, with differences in how eCO\(_2\) appeared to affect bioaerosol concentrations. Relative humidity did not affect airborne bioaerosol concentrations, however other meteorological conditions such as wind speed and temperature did alter bioaerosol levels.

Using fungal fruiting surveys (Chapter 5), neither the number of fungal species fruiting or the weight of sporocarps were significantly affected by eCO\(_2\) across the two-year survey campaign. Saprotrophic species were most commonly found fruiting, however some ectomycorrhizal species were also common, with significant overlap in the fungal communities fruiting in eCO\(_2\) and aCO\(_2\) arrays.

In soil DNA barcoding studies (Chapters 6 – 8), soil horizon was shown to have a significant effect on fungal community composition, however there were no significant differences in communities between seasons. Elevated CO\(_2\) consistently affected fungal community composition, however in the early years of treatment there were no effects of eCO\(_2\) on community richness or relative abundances of fungal phyla or functional groups. After four years of eCO\(_2\) treatment, there were some shifts in fungal relative abundance, for example, relative abundance of ectomycorrhizal fungi decreased in eCO\(_2\) treatment arrays.

These results demonstrate that elevated CO\(_2\) can have wide-ranging and diverse effects on fungal communities, and these effects are often not consistent between species, functional groups, seasons, and years. There has been a lack of fungal studies in FACE experiments worldwide, and several of the studies reported within this thesis are the first of their type in a forest FACE experiment. They provide a valuable contribution to our understanding of the effects of climate change on fungi in forest systems, and provide evidence for the importance of fungi in policy around woodland creation and the protection of existing woodlands.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):