Managing biodiversity and trophic cascades to enhance forest functioning and restoration

How will declining global biodiversity affect the maintenance of self-sustaining ecosystems and quality of human life? There is an urgent need to address this question in order to predict and therefore mitigate the consequences of human-driven changes to the natural world. Forests are an ideal setting in which to investigate this environmental challenge because they are hugely important reservoirs of biodiversity and provide many ecosystem services upon which humanity relies, such as the provision of food, soil security and the capture and storage of CO2. Furthermore, because of the importance of forests as homes for many of Earth's species and the ability of trees to remove carbon from the air, reforesting vast areas of land is a key strategy in reversing declines in biodiversity as well as the mitigation of climate change. In light of this, international initiatives have pledged to establish forests on a land area almost half the size of Australia by 2030 and the UK government is committed to planting 11 million trees in the UK by 2022.

Soil invertebrates and microbes are vitally important for carbon sequestration because of their key role in carbon and nutrient cycling, which underpin seedling establishment and tree growth. We know that ecosystems with a greater variety of above-ground vegetation species are more productive and capture more carbon, but we don't know how diversity in below ground communities effects these biodiversity-ecosystem productivity relationships. Furthermore, there remain gaps in our understanding of how current increases in deer and elk populations across Europe will influence soil biotic communities and the functioning and regrowth of forest ecosystems. Therefore, forest restoration initiatives that affect huge areas of the Earth's surface are being implemented without the necessary ecological knowledge to most effectively realise conservation and societal goals.

To redress these gaps in our understanding, my research aims to: i) determine how the diversity of complex below-ground communities affects carbon and nutrient cycling, tree growth and regeneration; and 2) quantify how large mammalian herbivores affect above and below-ground biotic communities, ecosystem processes and forest restoration.

Soil communities are extremely complex and diverse, with millions of species and billions of individuals living within a single ecosystem. However, because life in soil is so small and numerous, studying below-ground food webs is extremely challenging and time consuming. Therefore, an important outcome of this work will be the use of cutting-edge genetic sequencing techniques to determine, for the first time, how the diversity of these difficult to study organisms influences carbon sequestration and therefore climate change mitigation strategies. Furthermore, I will establish a mammal exclusion experiment across a broad range of forest types and climates in Europe, to investigate above and below-ground responses to the cessation of browsing. This will help us to understand how changes in browsing by large mammals affects forest regeneration and soil processes, and will form the basis of a long-term, large-scale field experiment, which will be extremely valuable for future studies aimed at understanding how ecosystems work.

Together, my research will help us to: 1) understand and mitigate the consequences of declines in global biodiversity for the ecosystem services that support humanity; and 2) generate data that will help manage the restoration of forests to reverse the decline in biodiversity and help mitigate global warming. The erosion of biodiversity represents a great loss to all those who are captivated by the intricacy of ecological interactions; my work will increase our ability to describe these complexities, and in doing so, deepen our understanding of the ways in which we are unravelling the natural world.

This work will improve understanding of how diversity in soil biotic communities affects ecosystem functioning in forests and the growth and regeneration of trees. It will therefore be beneficial to a broad range of disciplines, including the wider ecological community such as those working to understand how biodiversity influences the functioning of natural systems, and scientists focused on the consequences of species losses for the provision of ecosystem services and goods upon which humanity relies. Furthermore, this research will be of interest to macoecologists because I will generate data on continental patterns in below-ground diversity at an unprecedented level of detail and spatial scale, which will be useful for interrogating biogeographical theory on species occurrence and distribution. I will provide much-needed empirical evidence of the ecosystem-wide consequences of common land-management strategies for forest restoration and expansion: mammal exclusion to promote tree seedling establishment. Given that these practices are currently being put in place without a rigorous knowledge base of the effects on above and below ground invertebrates and microbes, and associated processes, researchers working in the fields of restoration and conservation biology will benefit from the outputs of my research. Similarly, my work will be of interest to scientists in any field of forest ecology because I will improve our fundamental understanding of the processes that maintain forest ecosystems. Academics working within taxonomy, bioinformatics, entomology and Earth System modelling will also benefit from the outcomes of this work because I will provide new genetic, morphology and distributional data on under-represented taxonomic groups. Furthermore, this project will generate detailed information about the factors that drive C storage and release from forest ecosystems, witch are increasing in area across the Northern Hemisphere and as such, the data will be useful for improvement of the accuracy of Earth System Models.

Woodland conservation, restoration and expansion are high on environmental policy agendas and have been featured as priorities on a number of resent UK and EU policy documents (e.g. The UK's "A Green Future: Our 25 Year Plan to improve the Environment", 2018; The Forestry Commission's "Government supported new planting of trees in England; report for 2017-2018"; The EU's "Protecting and restoring the world's forests: stepping up EU action to halt deforestation and forest degradation", 2019). Therefore, outputs from this work will be useful to land managers and conservation practitioners who are responsible for carrying out Government and independent initiatives to project and restore forests, e.g. The Woodland Trust and Natural England (see Letters of Support) as well as environmental policy makers because I will facilitate woodland expansion initiatives by improving our understanding of the biotic factors that drive tree growth and regeneration.

The outcomes of this work will benefit the general public through helping to improve the management of our natural environment, which will increase human quality of life. My research will deepen our fundamental understanding of the role of biological diversity for the provision of ecosystem processes and services, and will therefore add to our basic knowledge how Earth functions and could have far reaching effects on human society if used as evidence to help protect and restore natural ecosystems and prevent further declines in biodiversity. Through sustained efforts to engage in outreach events (see Pathways to Impact) my work will be of benefit to women in science. I will lead by example and make my work accessible to the general public and to children and young adults in particular, which will demonstrate to young women that a career in science is a possibility for them.