Rewilding: How does the cessation of livestock grazing affect upland food-webs?
Extensive ecosystem restoration is increasingly seen as being central to conserving biodiversity  and stabilizing the climate of the Earth . Rewilding, defined as “the reorganisation of biota and ecosystem processes to set an identified social–ecological system on a preferred trajectory, leading to the self‐sustaining provision of ecosystem services with minimal ongoing management” , is increasingly being considered as an environmental management option in many British upland areas. For the past decades, policy and practice in the British uplands has primarily focused on food production (mainly livestock grazing) and forestry, with secondary goals of supporting biodiversity and providing additional ecosystem services. However, exiting the EU and the likely associated changes in subsidy regimes, combined with the UK government’s stated policy of “public money for public goods”, has made understanding the consequences of management decisions about the future of the uplands urgent . Yet the scientific evidence required to make such decisions, in particular how rewilding will affect upland biodiversity (especially species of conservation concern), is lacking.
The Glen Finglas livestock grazing experiment was established in 2002 to examine how changes in sheep and cattle stocking densities affects upland bird and animal communities. Detailed monitoring of plants, invertebrates, mammals and birds is carried out regularly, providing a unique long-term dataset for examining how upland food-webs change as a result of reduced livestock grazing pressure, or when it is completely removed. After 15 years of experimental grazing treatments, significant changes in plant and animal communities became evident, with species such as bog asphodel, bracken and blaeberry benefitting from the removal of grazing  and a significant increase in bird species richness . Thus, vegetation structural changes as a result of livestock removal is likely to affect other trophic levels within the food-web, but this is yet to be examined using the long-term Glen Finglas dataset.
This project will maximise the long-term Glen Finglas dataset by constructing highly-resolved species-interaction networks that incorporate plants, arthropods, mammals and birds using state-of-the-art techniques that account for uncertainty in the complex food-webs. Ecological networks not only describe the interactions between species, but also provide a way of examining the underlying structure of communities and the function and stability of ecosystems. Uniquely, it will investigate how livestock grazing treatments affect the structure, complexity and robustness (i.e., the attack tolerance of the network to species extinction) of upland food-webs, providing policy-relevant evidence on how changes in upland management affects ecosystem resilience. Furthermore, the project will incorporate much-needed temporal dynamics into the study of food-webs under different levels of perturbation, allowing novel insights into how biological networks ‘rewire’, which can then be used to predict restoration outcomes in adaptive network models .
The project has three interlinked objectives:
OBJ. 1: Construct upland food-webs consisting of plants, arthropods, mammals and birds based on observed and inferred species-interactions over a 20 year period.
OBJ. 2: Compare the structure, complexity and robustness of upland food-webs under different experimental grazing treatments.
OBJ. 3: Predict long-term management outcomes for the uplands using adaptive network models that incorporate long-term data
There will be opportunities for fieldwork at Glen Finglas with trained staff to improve network construction methods and/or test specific hypotheses devised by the student and supervisory team.
Impact summary: The Glen Finglas experiment is hosted by Woodland Trust Scotland and the results are used to guide management decisions across their estate (as well as other NGOs). Outputs from the experiment to date have informed Government agencies, in particular regarding livestock management for biodiversity. In the current context of rewilding, the project will provide a much-needed evidence base for decision making after the UK has exited the EU.