Seeing the woods for the trees: do woodland networks benefit biodiversity?

Overview

The concept of ecological networks, and their focus on landscape-scale conservation, has been promoted globally as a key approach to biodiversity conservation in fragmented landscapes. These are typically conceptualised as patches of biodiverse habitat connected by buffer zones, corridors and smaller stepping stone patches that allow species to move between them (1). Although this is a very appealing concept, based on sound scientific principles, there is little real-world evidence to support it. This has resulted in much debate on the relative merit of, and balance between, alternative conservation actions (e.g. improving local habitat quality vs. landscape-scale connectivity; 2,3,4). Particularly during a time of limited resources, it is important to ensure that conservation actions are evidence-based and effective to ensure real biodiversity benefits. This project will provide vital evidence on the effectiveness of alternative network design principles for a range of woodland species within a fragmented agricultural landscape.

Specific Objectives are to:
1. Determine the relative impacts of alternative components of ecological networks on animal and plant communities;
2. Determine the relative importance of local vs. landscape-scale conservation actions on different species;
3. Quantify the temporal lag between habitat creation and species responses to new ecological networks.

This PhD will represent a new research component within the WrEN project (Woodland Creation & Ecological Networks; http://www.wren-project.com/). WrEN is a collaboration of academics, policy makers and practitioners interested in landscape-scale restoration, and how to prioritise actions to restore ecological networks. Ultimately, we want to provide evidence to underpin future conservation efforts to create and enhance ecological networks for wildlife. This is especially important at a time when national (e.g. UK Government’s 25 Year Environment Plan) and international (e.g. the Convention on Biological Diversity Aichi Target 11) policy has moved to focus on conserving and restoring “well-connected systems” of habitats.

Methodology

The WrEN project uses a “natural experiment” approach, which involves overlaying an experimental design on a system where active manipulation has occurred beyond the control of the researcher. This approach can overcome the spatial and temporal challenges of doing landscape-scale studies on the effects of habitat creation and restoration (4). However, this does mean there is little control over potentially influential environmental factors. JIGSAW (Joining and Increasing Grant Scheme for Ancient Woodlands) presents a rare opportunity to take a more experimental approach to evaluating the effects of habitat creation at large spatial scales. This PhD will focus on the effects of the JIGSAW initiative implemented on the Isle of Wight in the early 2000s (5). The aim of JIGSAW was to encourage spatial co-ordination in woodland creation to most effectively reduce habitat fragmentation. Subsequent research has demonstrated that this spatial targeting was at least partially successful (compared to untargeted grant-aided woodland expansion). While this spatial targeting may yield biodiversity benefits, wildlife responses to this new woodland network have not been evaluated.

JIGSAW presents a range of research possibilities to address how network structure affects a range of animal and plant species. We envision that in year 1 woodland patches across a gradient of network attributes (i.e. size, isolation) will be surveyed for a range of taxa (e.g. bats, invertebrates, plants). These patches will be selected from both the targeted planting schemes (i.e. JIGSAW) and untargeted plantings. Data will also be collected on woodland characteristics (e.g. tree density, amount of understorey). The surrounding landscape will be described using land cover maps and GIS to quantify connectivity metrics at a range of scales. Subsequent analyses will explore the associations of different taxa with site-specific and landscape-scale variables encompassing the ecological network concept. In years 2 & 3, field work will be determined by research questions designed primarily by the student; these could include examining the extent to which the colonisation of new habitat patches are constrained by habitat quality or by species’ dispersal abilities.

The PhD will be based at Stirling with fieldwork on the Isle of Wight. The student will visit CEH and Forest Research stations for meetings, seminars and specific training. It is anticipated that the student would spend approximately one month at working with researchers based at Forest Research (Edinburgh, Surrey). For information on training provision please go to: http://www.iapetus.ac.uk/iap2-18-69-seeing-the-woods-for-the-trees-do-woodland-networks-benefit-biodiversity/