Disentangling mechanisms of co-adaptation between trees and soil food webs in response to environmental perturbations

Trees interact with thousands of tiny animals and microorganisms living in soil beneath them. They do this indirectly and directly. Indirect interactions occur via production of dead litter, especially leaves. When litter is produced, soil animals and microorganisms break it down and recycle nutrients, and the composition of the community doing this breakdown process can be influenced by the nature of the litter itself, such as how much nitrogen it contains or how tough it is. Direct interactions occur because some microorganisms are intimately associated with tree roots and actually form mutually beneficial associations with trees. These organisms rely on trees for their energy in the form of sugars, and their activity fuels many processes essential for tree health and nutrition. A big question in ecology is how these interactions will be affected by components of global climate change, such as drought and elevated concentrations of carbon dioxide in the atmosphere? Our project will tackle this question. A further question concerns whether components of global change will affect these indirect and direct interactions in different ways, and our proposal will also address this issue.

We will tackle these issues by undertaking experiments in the laboratory where we have lots of control of various important factors, but also by using two amazing field-based experiments. These experiments artificially manipulate concentrations of carbon dioxide and the incidence of drought frequency and severity in mature oak forests, where the trees are taller than most houses. The experiments are big, and we are fortunate to have the benefit of multi-million pound investment in infrastructure and support. The laboratory experiments will use state-of-the-art stable isotope tracer experiments, which enable us to trace the fate of carbon atoms from plants to soil to soil organisms.

Our findings will generate new mechanistic insight into the way that plants interact and shape their own biotic environment in soil, and how this is modified by climate change. Understanding these interactions is important because in managing land for food, fuel, fibre, and other ecosystem services, we routinely disconnect co-adapted food webs deliberately or inadvertently. Broader societal impact will be enhanced by using this new knowledge to inform strategies for creating, conserving and managing oak woodland (see Pathways to Impact).

We aim to engage the general public through educational and KE activities associated with the project (see Pathways to Impact). We think the general public is a crucial group to inform, especially given the general lack of awareness of the key roles fungi play in many processes, and the public interest in how ancient woodlands might respond to climate change.

The work has important implications for a range of stakeholders involved in management of forests and mitigation of effects of climate change. The Forestry Commission will be particularly interested in the role of ectomycorrhizal fungi and their interaction with food webs in affecting biogeochemical cycles. Current environmental policies aim to both maintain and enhance biodiversity and yet reduce losses of carbon and nutrients, and it is possible for these two aims to conflict.

The Forestry Commission will also be further interested in how soil communities co-adapt with plant species. The Forestry Commission also has a key role in maximising soil carbon storage because of the vast area of forests that they manage. Increasing carbon storage is a central part of UK legislation and out data will provide evidence that may help develop effective management strategies that optimise carbon storage. This aim requires a better understanding of the carbon cycle more generally in forests, and a key component of our work quantifies the flux of carbon into soils, and its release as CO2.

Other stakeholders include: Scottish Natural Heritage (SNH), Natural Resources Wales and Natural England who will be interested because they have a statutory requirement to protect and enhance UK's biodiversity, including fungi. Our results will help demonstrate the key roles ectomycorrhizal biodiversity and its interaction with soil fauna plays in enhancing ecosystem functioning.

Inter-agency Plant Conservation Working Group; this is a multi-agency group based in the UK aiming to develop plant conservation good practice.

Other conservation groups are also increasingly interested in the role ectomycorrhizal fungal diversity and their effects on plants (e.g. Plantlife International, Trees for Life, Woodland Trust). Indeed, there has been a recent move to strengthen the profile of fungi across the UK that has involved groups like Plant Life, British Mycological Society, and the UK Fungal Conservation Forum.

The needs of the UK Biodiversity Research Advisory Group (UK BRAG) who highlight the urgent need to understand the link between plant and microbial functional diversity.