Leading large-scale research into grazing impacts on upland biodiversity.

Professor Robin Pakeman’s wide-ranging ecological research spans plant functional traits, the diets of Soay sheep, long-term vegetation change and conservation prioritisation. One of his most impactful projects is the twenty-year Glen Finglas Experiment.

Glen Finglas is 4,800-hectare estate in the Loch Lomond and the Trossachs National Park. Once an upland hill farm, it has been managed by the Woodland Trust for over a quarter of a century and is one of their flagship sites for restoration, now containing a mosaic of habitats from ancient oak woodland to montane grassland.

Since 2002, Robin and colleagues have managed a long-term, large-scale upland grazing experiment at Glen Finglas, one of 36 active Long Term Ecological Field Experiments in the UK, supported by the Ecological Continuity Trust. Twenty-four enclosed plots of 3.3 hectares each are subjected to different grazing pressures – from ungrazed to high intensity – by hill sheep and hardy Luing cattle, and the impacts on plants, invertebrates, small mammals, birds and carbon stocks are measured and monitored, giving a unique record of upland ecosystem responses to grazing, and crucial guidance for land-use managers on the ecological trade-offs that occur when management is changed.

No easy answers

Grazing in Scotland’s uplands remains contentious, with traditional farming practices often appearing in conflict with rewilding goals. Any changes to land use can have cascading impacts through ecosystems, so the provision of empirical data from the Glen Finglas experiment is vital to both land managers and policymakers.

“The main fact to highlight is that for any management change there will be winners and losers,” Robin says. Different management regimes benefit different suites of species. “For instance, moth diversity is promoted by removing grazing, but beetle diversity is highest with the highest density of grazing. The main bird we get in the experiment, the meadow pipit, also prefers higher disturbance [particularly by] cattle.”

“These trade-offs are usually ignored in debates about how we use the uplands,” Robin continues, “I hope our experiment can highlight that simple arguments are usually unhelpful.” While woodland creation provides suitable habitat for birds such as cuckoos and willow warblers, many others, such as curlews and meadow pipits, are birds of open ground.

The speed at which species react also varies, with meadow pipit nesting densities rapidly affected by the treatments, while plant communities alter more slowly. Woodland regeneration in particular can be “A very slow process,” Robin explains. “Without disturbance, seed establishment by many trees is rare.”

Excitement and creativity

Robin credits a number of educators in fostering his interest in science. “I was lucky enough to have some very good teachers and lecturers who conveyed the excitement and creativity of doing science rather than it being just a set of facts to learn.” But if pushed to highlight a single event, he says, “It would be picking up a remaindered copy of Silent Spring by Rachel Carson from Tameside Libraries [Greater Manchester]. It is still on my shelves, faded by the sun so the spine is unreadable, and a very influential 50p it proved to be!”

A white man with a short beard wearing a green cap and grey hoodie pulled over it, stands in front of a beautiful bay with green grass, white sand and blue sea
Professor Robin Pakeman

Robin gained his MA in Natural Sciences at the University of Cambridge, then did a PhD in physiological ecology at the University of Manchester. “The defining event that led to where I am now,” he believes, “was getting a job in a research institute rather than an academic post-doc.” Seven years at the Institute of Terrestrial Ecology (now the Centre for Ecology and Hydrology) in Huntingdon, Cambridgeshire, followed by 25 years for the Macaulay Land Use Research Institute (which in 2011 became, with SCRI, the James Hutton Institute) led him to create more applied and policy-focused research than many ecologists. It has also meant working on a wide range of projects and subjects, including contract work for organisations of direct relevance to policy.

Playing with data

Robin cites this chance to work on a wide range of projects across almost all of Scotland’s habitats, and to focus on applied research to solve real-world problems, as the things he most enjoys about his current role. “I’ve managed to get to exciting places like the machair of the Hebrides, and St Kilda, and then I get to play with the data when I get back!” he says.

While the Glen Finglas Experiment will continue, Robin’s own research is now shifting to work with more national datasets to try and understand the drivers of biodiversity change. “We’ve done some work showing that changes in the distribution of bryophytes and lichens correlate to climate and nitrogen pollution,” he says. “We’re now working on how to extend this approach to other groups of organisms.”

In the face of the escalating climate and biodiversity crises, this work has never been more important. “We need to find ways of managing landscapes to allow species to survive where they are or to migrate as the climate changes,” Robin says. In this, enhanced funding for biodiversity research is essential, to take advantage of Scotland’s huge expertise which is not currently being harnessed to its full potential. Biodiversity is still a ‘Cinderella science’ – “We must remember that it underlies all human existence” he concludes.

Professor Robin Pakeman is a plant ecologist at the James Hutton Institute, a Visiting Professor in the School of Biological Science at the University of Liverpool and a Fellow of The Chartered Institute of Ecology and Environmental Management. His work is supported by the Scottish Government, and the Glen Finglas experiment is a partnership with the Woodland Trust and the University of Newcastle. Find out more here.

This post is part of a series showcasing Scotland’s innovative, high-impact research supporting biodiversity conservation, in partnership with Scottish Government and NatureScot. Read the rest of the series here.

Further reading

Evans, D.M., et al. 2015. The cascading impacts of livestock grazing in upland ecosystems: a 10-year experiment. Ecosphere 6(3): 1—15. https://doi.org/10.1890/ES14-00316.1

Smith, S.W., et al. 2015. Combination of herbivore removal and nitrogen deposition increases upland carbon storage. Global Change Biology 21(8): 3036—3048. https://doi.org/10.1111/gcb.12902

Pakeman, R.J. et al. 2017. Drivers of species richness and compositional change in Scottish coastal vegetation. Applied Vegetation Science 20: 183—193. https://doi.org/10.1111/avsc.12283

Pakeman, R.J., et al. 2019. Long-term impacts of changed grazing regimes on the vegetation of heterogeneous upland grasslands. Journal of Applied Ecology 56(7): 1794—1805. https://doi.org/10.1111/1365-2664.13420

Crawley, M.J. et al. 2021. The dynamics of vegetation grazed by a food‐limited population of Soay sheep on St Kilda. Journal of Ecology 109: 3988—4006. https://doi.org/10.1111/1365-2745.13782

Pakeman, R.J. & Fielding, D.A. 2021. Increased grazing drives homogenisation but reduced grazing increases turnover in upland habitat mosaics. Biodiversity and Conservation 30: 4279—4295. https://doi.org/10.1007/s10531-021-02305-5 Pakeman, R.J., et al. 2022. Identifying drivers of change in bryophyte and lichen species occupancy in Scotland. Ecological Indicators 139: 108889. https://doi.org/10.1016/j.ecolind.2022.108889