Regenerating forests will involve restoring ecosystems and not just culling deer - Christopher J Sandom

Some years ago I worked at the Alladale Wilderness Reserve in the Highlands and restoring the Caledonian Pine Forest was a key goal. But the red deer at a density of around 13/km² were a barrier, eating the saplings, and the simplest solutions were to reduce their numbers or to fence them out. We felt the deer population was too, even unnaturally, high and they were “overbrowsing”.

Much has been written about UK deer numbers, their threat to the countryside, reducing deer populations and more robust management. But, are their numbers that high when, for example, sites of similar productivity in Africa cope with far higher numbers of large herbivores?

Alladale’s head stalker/ranger pointed out the answer to me. The effects of large herbivores depend not only on their densities but on the condition of the environment. And it wasn’t the deer that ate all the mature trees in the first place – these trees were felled to provide timber for buildings and ships. People degraded the ecosystem, and this is why red deer are having a strong, limiting effect on natural tree regeneration. Few old trees exist in the landscape today, they spread little seed, dense swaths of heather, bracken, and grass offer little space for trees to germinate and very few seedlings get established so virtually any deer present will limit their success.

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So, browsing by deer is reducing the number of trees regenerating, but are deer the villains of piece? The problem was created by people and the solution needs to be focused on restoring nature as a system.

Christopher J Sandom is Senior Lecturer in Biology at the University of Sussex and chair of Rewilding SussexChristopher J Sandom is Senior Lecturer in Biology at the University of Sussex and chair of Rewilding Sussex
Christopher J Sandom is Senior Lecturer in Biology at the University of Sussex and chair of Rewilding Sussex

Restoration may involve reducing large herbivore numbers now, but this is an opportunity for restoration to allow richer, more diverse and abundant nature in the future, from plants to large predators. A resultant more diverse community of large herbivores, including red deer, will be able to use and help create a diverse mixture of habitats – open grassland, moorland, scrubland and woodland – by driving their critical ecological processes.

While we perceive herbivore numbers to be really high in many parts of the world, compared to the more intact ecosystems in Africa (or comparisons with the past) herbivore communities are actually severely degraded in their numbers of species and abundance.

Outside Africa degraded ecosystems will likely take longer to recover and may need recovery of vegetation and carnivores first. But it may be possible to have our own spectacular recoveries of nature, including large numbers of magnificent large herbivores like red deer.

We need more research. We must examine the consequences for our deer populations as we promote the recovery of natural habitats to help combat the climate and biodiversity emergencies and, whilst early on this may require reductions in deer numbers, longer term we may see a more diverse ecosystem with a high abundance of red deer playing their important role as an ecosystem engineer.

For the science see Exploring a natural baseline for large-herbivore biomass in ecological restoration (November 2021) with thanks to lead author Camilla Flojgaard and to my co-authors Jens-Christian Svenning, Pil Pedersen and Rasmus Ejrnæs.

Christopher J Sandom is Senior Lecturer in Biology (Evolution, Behaviour and Environment) School of Life Sciences, University of Sussex, Director, Wild Business and Chair of Rewilding Sussex

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