Improving understanding of climate change impacts

Global change ecologist, Professor Alistair Jump explores the impacts of climate on ecological systems, our dependence on and our place within them. His wide-ranging projects cover topics from sustainable harvesting of non-timber forest products in Nepal, to predicting drought-linked forest declines across Europe.

Monitoring mountains

Alistair’s research programmes include studying how climate change is causing mountain plant communities to shift and reassemble, in some cases threatening species with extinction. He draws examples from two very different parts of the world: Scotland, and the endemic-rich island of Taiwan.

Long-term study with Taiwan’s National Pingtung University of Science and Technology and Endemic Species Research Institute shows that changes to montane forests impact on both the diverse alpine flora above the treeline and the community of forest-dependent organisms such as lichens. Back in Scotland, Alistair works with PhD student Sarah Watts to monitor arctic-alpine plant communities such as on Ben Lawers – the only UK site for some plant species. They have observed notable changes to the flora, with the range of key indicator species retracting as their lower limits are eroded by competitors expanding upwards.

In both places, providing empirical data to refine and test model-based predictions of biodiversity loss and change is crucial. “You might expect,” Alistair explains, “to see a consistent rise in the treeline, and shrinking of the habitat above. But it’s actually much patchier than that. We get pockets where alpine species persist for longer periods. This enables us to identify where we may have the most time to intervene positively for biodiversity.

“For instance, in Scotland,” he continues, “we can suggest where controlling grazing is likely to have greatest benefits for arctic-alpine species.” The same goes for many other conservation measures, from managing visitor routes to planting trees or establishing new populations of rare species. “It’s only by understanding where losses are likely to occur that we can frame mitigation measures to slow them and avoid actions that might hasten their demise,” he summarises.

Dealing with drought

In a second long-term programme, Alistair studies the present and future impact of intensifying droughts on European forests, using data from multiple sources including tree rings, ground-based surveys and remote sensing. Drought impact can manifest in multiple ways: through dieback, slower growth or changing community composition. Work with PhD student Tom Ovenden shows a complex picture: in some cases forests can compensate by growing faster in wetter years, but this may result in ‘overshooting’ the average water availability, rendering them more susceptible to dieback in future.

Again, this work helps refine our predictive models. “The expectation,” Alistair explains, “is that drought impacts would concentrate at the edge of each species’ distribution closest to the equator, where the climate is already hottest and driest. But actually, the literature shows massive die-off events right across these distributions. So it’s critically important to understand why, because it throws a lot of our modelling and planning into disarray.”

Interestingly, their results suggest that resilience to drought relates to climatic history, depending not only on the absolute level of drought, but also on the magnitude of change relative to past climates. This knowledge can help future planning for both conservation and timber production.

Sprouting seeds

Alistair can pinpoint his first interest in plants to a single day at Blaise Primary School in Bristol, England, growing peas and beans on blotting paper in a pint mug: “Just watching them grow, seeing the root and shoot develop, absolutely blew my mind! It was the most fantastically wonderful thing to be able to watch plants grow like this.”

A smiling man wearing black-rimmed glasses and a red checked shirt, in front of a blurred green vegetation background
Professor Alistair Jump

He also recalls being fortunate to have access to nature as a child, particularly woodlands, and immediately questioning the diversity around him. “Why were the leaf shapes all different? What did they do? Did they do something different because they look different? So I think biodiversity bit me really early on just because I noticed it, and I wanted to know about it.”

That excitement and curiosity stayed with him, through a PhD on thistles at Sheffield, consultancy work with the Peak District National Parks Authority, EU Marie Curie fellowships at the Centre for Ecological Research and Forestry Applications, Barcelona, and the University of York, and finally to Stirling as Lecturer, Professor, and now Dean.

Alistair’s work is highly collaborative, engaging individuals, institutions, businesses and landowners across Scotland and the world. This, he says, is crucial to ensuring research meets societal needs. “Working with multiple stakeholders helps generate questions that take into account the diversity of people, the diversity of history and the diversity of potential future impacts.” He says. “When you pull people together from very different disciplines and sectors, you find the exciting bits in the middle that can really allow us to understand systems better.” Scotland is a good place for this, Alistair believes, because of its small size, proximity of institutes and outward-looking focus, all of which make Scottish science very well networked: “I think that’s a key way in which we drive innovation.”

Recapturing the wonder

Alistair’s research provides vital insights into the threats facing biodiversity in an era of rapid global change. However, he says, the real challenge is what to do about it. “Once we know, for example, that we are likely to lose large areas of unique high elevation habitats and the species within them, what do we actually do?” He sees this as both a practical and a moral dilemma, and one for which leadership is crucial. “Responsibility for addressing the climate and biodiversity crises cannot be placed only on the individual: many people are in challenging circumstances that cause them to focus on their most immediate concerns. We need systemic change and visionary leadership from governments who must engage with these existential threats to our societies.”

“We must recapture that broader connection with biodiversity,” he continues. “We’ve seen a strong emphasis on the utility value of biodiversity, with concepts such as natural capital and ecosystem services, but there’s a risk that these perpetuate an exploitative narrative around biodiversity. I’m lucky enough to still hold that sheer delight in biology that got me into doing what I do now – we need to embed that wonder around biodiversity, and understanding of our reliance upon it, across society … So many people can benefit so much from interacting with nature, and biodiversity can help us find solutions to many of the major problems that we face.”

Professor Alistair Jump is Dean of Natural Sciences at the University of Stirling. His work is supported by NERC, the Royal Society, the Royal Society of Edinburgh, the National Trust for Scotland, the National Science Council of Taiwan, Scottish Forestry Trust, the Leverhulme Trust, Forest Research, the Woodland Trust and the Corrour Estate. 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

Jump, A.S., et al. 2017. Structural overshoot of tree growth with climate variability and the global spectrum of drought-induced forest dieback. Global Change Biology 23(9): 3742—3757. https://doi.org/10.1111/gcb.13636

Greenwood, S., et al. 2017. Tree mortality across biomes is promoted by drought intensity, lower wood density and higher specific leaf area. Ecology Letters 20(4): 539—553. https://doi.org/10.1111/ele.12748

Ruiz-Benito, P., et al. 2017. Climate- and successional-related changes in functional composition of European forests are strongly driven by tree mortality. Global Change Biology 23(10): 4162—4176. https://doi.org/10.1111/gcb.13728

Ovenden, T.S., et al. 2021. Life after recovery: Increased resolution of forest resilience assessment sheds new light on post-drought compensatory growth and recovery dynamics. Journal of Ecology 109(9): 3157—3170. https://doi.org/10.1111/1365-2745.13576

Martinez de Castillo, E., et al. 2022. Climate-change-driven growth decline of European beech forests. Communications Biology 5: 163. https://doi.org/10.1038/s42003-022-03107-3

Watts, S.H., et al. 2022. Riding the elevator to extinction: Disjunct arctic-alpine plants of open habitats decline as their more competitive neighbours expand. Biological Conservation (in press). https://doi.org/10.1016/j.biocon.2022.109620