When we go to a supermarket we want to make sure we get the best value for our money, so why not do the same when it comes to conservation actions for wildlife?
Once upon a time woodland covered most of the UK’s land. But thousands of years ago humans began chopping wood to build their shelters and clearing land to plant their crops and rear their sheep. The climate also changed. Landscapes were gradually modified and very little woodland survived. By the beginning of the 20th century only 5% of the UK was covered by trees, and only 2% was actually ancient woodland. But since then we’ve realised how dependent we (and many wildlife species) are on this habitat, and we’ve started planting more trees. Woodland creation schemes were introduced over 25 years ago and are contributing to the slow return of the woods to the UK. Yet, the British landscape as we now know it still has only about 12% woodland cover and this often consists of small, isolated and degraded patches immersed in an agricultural matrix that dominates the landscape. We’re told by scientists that we need more, bigger, better and well-connected habitats for our wildlife to thrive in (Lawton et al., 2010). But more often than not, it’s not feasible to have it all. Conservationists need to prioritise between alternative actions. The challenge is that there is limited empirical evidence on the relative merit of each of these actions for conserving species.
Bird studies suggest that increasing woodland patch size (bigger) and availability at the landscape level (more) particularly benefits woodland specialists, whereas having spatially contiguous (well-connected) woodlands is most useful for generalist species (Dolman et al., 2007). But of course life’s never so simple and different species respond differently to habitat fragmentation and therefore require different conservation strategies. For instance, creating large woodland patches located close to other woodlands is likely to benefit relatively low mobility species, such as micro-moths (a group of moth families comprising mostly small species; Fuentes-Montemayor et al., 2012). This spatial arrangement, which in theory allows more species to colonise new habitat patches, fits well with most current guidelines for woodland planting schemes. In contrast, some higher mobility groups, such as many bat species, make a more intensive use of woodland in small and isolated woodland patches, and in areas where this habitat is scarce (Fuentes-Montemayor et al., 2013). So for these groups it might actually be better to create new woodlands in scarcely wooded landscapes.
But it’s not only about ‘where’ to plant new woodlands. It’s also about ‘how’ to plant them to meet the requirements of woodland species. There’s relatively little information on how to improve woodland for wildlife and thus new woodlands are often planted or managed with limited guidance on how to make them better for biodiversity. The recommendations that do exist are strongly biased towards birds and mammals, often disregarding smaller taxa such as insects. In addition, the value of these woodland patches, in terms of biodiversity gains, is rarely assessed.
So, are woodland planting schemes mainly benefiting species with limited dispersal abilities while bats and other high mobility species are potentially missing out? Are we creating woodlands which may not be good quality habitats for woodland species? The answer to both questions is: we don’t know. And that’s why it’s imperative to conduct more research and assess the relative importance of alternative conservation actions for woodland-dependent species. A project is currently underway at the University of Stirling (in collaboration with Forest Research, Natural England and Scottish Natural Heritage) aiming to gather evidence on this subject (more on this project here). This information is essential to ensure that future actions are implemented in the most effective ways and areas to maximise conservation outcomes.
Woodlands provide essential ecosystem services. They are one of the most biologically diverse systems on Earth. In the UK they support more wildlife species than any other habitat. So let’s do our best to ensure that actions to conserve them and their wildlife are efficient. Let’s get the best value when it comes to conserving our woodland biodiversity.