Woodlands provide essential ecosystem services and support more wildlife species than any other habitat. Historic deforestation over much of Europe has drastically reduced woodland cover and much of it now consists of non-native plantations or small, isolated and degraded patches immersed in an agricultural matrix that dominates the landscape. In the UK recent woodland creation schemes were introduced over 25 years ago and are contributing to the slow rise in woodland cover but we currently have little information on how these schemes are performing. For our woodland wildlife to thrive we need bigger, better quality, more and more joined-up woodland habitats, but with limited resources where do we focus our efforts? A new collaborative project, Woodland Creation & Ecological Networks (WrEN), aims to tackle this question and provide evidence to underpin future conservation efforts to create and enhance ecological networks for woodland species.
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Ecological networks and species conservation
The concept of ecological networks, and their focus on landscape-scale conservation, is seen by many as an effective response for biodiversity conservation in fragmented landscapes and is now a major policy driver for many countries. As a result many conservation activities, such as habitat restoration and creation, are being targeted towards the establishment of ecological networks. These networks are typically conceptualised as a suite of core areas connected by buffer zones, corridors and smaller stepping stone patches that allow species or their propagules to move between them (Lawton et al., 2010; Figure 1). Although this is a very appealing concept, based on a number of sound scientific principles, there are limited empirical data on the relative importance of the different elements of ecological networks and hence much uncertainty on how to prioritise conservation actions - for example, is it more important to have bigger patches, or to ensure that patches are close together?
Figure 2. Woodland fragments
Using historic woodland creation to evaluate the ecological network concept
The long history of woodland creation within the UK since about the turn of the 20th Century has inadvertently created a series of historical test landscapes containing patches of woodland of varying sizes, shapes and spatial configurations (Figure 2). Importantly, many new woodlands were established at a known date on former agricultural land. As such they act as a blank canvas, with no woodland species existing within these sites before the date of woodland establishment. Whilst it may be many years or decades before the impacts of current landscape-scale conservation projects on biodiversity are known, the underlying idea behind WrEN is to "go back in time" to assess the impact of historic land use change on current biodiversity, using woodland as an example habitat. In this way we can improve our understanding of the relative importance of the different elements of ecological networks, and develop practical guidelines for planning and implementation of future conservation work.
WrEN started in 2013 in Scotland. In 2014 work was continued in Scotland and a second study area established in central England (Figure 3). In both study areas we selected a replicated chronology of woodland creation sites, and their surrounding landscape, to represent distinct elements of ecological networks (Figure 2). These elements consist of both site-level and landscape-level attributes encompassing the bigger, better, more and joined principles put forward in the Making Space for Nature report (Lawton et al., 2010). The bigger and better principles are covered by considering area, shape and quality of new woodland habitat (site-level attributes). The more and joined principles are addressed by assessing the area of surrounding woodland habitat, distance between new and existing woodlands, and types land cover in the surrounding landscape.
These woodland sites are being assessed for selected species groups (see below; photo credit left JD Altringham) to assess the relative effect on biodiversity of the full range of spatial and temporal variables. This will enable us to address some questions of urgent importance to conservation delivery, such as:
Woodland and species selection
Figure 3. Study sites (red) in Scotland and central England.
Using an automated selection protocol, woodland sites of different age, size and connectivity have been identified in the two study areas (Figure 3) using various digital woodland data sets including Woodland Grant Scheme, the National Forestry Inventory and the Ancient Woodland Inventory. We focussed on woodlands in arable and mixed agricultural land, to control as far as possible for environmental variables such as soil and climate.
Key species groups for survey were identified through a literature review, reflecting the range of habitat specificity, dispersal abilities, matrix (non-wooded habitat) sensitivity and other network-related traits of woodland-dependent species (Figure 4). Current surveying is focussing on vascular plants, ground beetles and spiders, small terrestrial mammals, bats, birds, and lower plants (lichens and bryophytes), but in the future we would like to expand this to include other taxanomic groups. As of September 2014, 67 sites in Scotland and 40 in England have been surveyed for at least some of the taxonomic groups listed above, and analytical work is on-going.
Comparison with ancient woodlands
Work in 2016 has extended the WrEN project by incorporating data on diversity and abundance of key taxa in ancient woodlands (defined as continually wooded since 1750 in Scotland and 1600 in England), and examining differences between secondary and ancient woodlands. We will use these ancient woodlands as reference sites to identify the potential biodiversity pool which could feed into the WrEN sites. We are also quantifying differences in woodland structure which can be critical in determining the suitability of woodlands for wildlife species.
Figure 4. Some of the species groups currently being surveyed as part of the WrEN project.
Watts K, Fuentes-Montemayor E, Macgregor NA, Peredo-Alvarez V, Ferryman M, Brown N, Bellamy C & Park KJ (2016). Using historic woodland creation to construct a long-term, large-scale natural experiment: the WrEN project. Ecology & Evolution 6: 3012-3025.
Humphrey JW, Watts K, Fuentes-Montemayor E, Macgregor NA, Peace AJ & Park KJ (2015). What can studies of woodland fragmentation and creation tell us about ecological networks? A literature review and synthesis. Landscape Ecology 30:21–50.
Humphrey, J., Watts, K., Fuentes-Montemayor, E., Macgregor, N. & Park, K. (2013) The evidence base for ecological networks: lessons from studies of woodland fragmentation and creation. Report from the WrEN Project, Forest Research, Farnham, Surrey.
|Dr Kirsty Parkemail@example.com||+ 44 (0) 1786 467799||University of Stirling|
|Dr Elisa Fuentes-Montemayorfirstname.lastname@example.org||+ 44 (0) 1786 467810||University of Stirling|
|Dr Kevin Watts||Kevin.Watts@forestry.gsi.gov.uk||+44 (0)1420 22255||Forest Research|
|Dr Nicholas Macgregor||nicholas.macgregor
|+ 44 (0) 7901 716353||Natural England|
WrEN is a collaborative project between University of Stirling, Forest Research and Natural England. We work in partnership with a range of government advisory agencies and non-governmental organisations including Scottish Natural Heritage, The National Forest, Defra, Woodland Trust and the company Tarmac.
Lawton JH, Brotherton PNM, Brown VK, Elphick C, Fitter AH, Forshaw J, Haddow RW, Hilborne S, Leafe RN, Mace GM, Southgate MP, Sutherland WJ, Tew TE, Varley J, Wynne GRD (2010) Making space for nature: a review of England’s wildlife sites and ecological network. Defra, London. PDF report available here