Nature reserves and other protected areas represent an important conservation investment in Britain. However, in a warmed world, the spaces occupied by such areas may become both increasingly precious and more vulnerable, as land use continues to change around them, and climate changes within them. Although global warming could have a profound effect on biodiversity the British 'Biodiversity Action Plan', which resulted from the Convention on Biological Diversity, contains only one direct reference to the threat to British wildlife from climate change in the whole report: - 'If it is established that climate change is likely to result from greenhouse gas emissions, there will be significant implications for biodiversity' (Bendall et al. 1994 p92). The Non-Governmental Organisations' (NGO) response to the Biodiversity Action Plan, 'Biodiversity Challenge' (2nd ed. Wynne et al. 1995) makes no mention of climate change. Twenty-year conservation Action Plans for 116 species and 14 habitats have been drawn up as a result of these initiatives and others will follow (Plowman 1995). The plans have been developed on the basis that climate change will be a relatively unimportant influence over this period of time but do not consider whether the conservation targets which are being instigated, are realistic as climate alters in the longer term.

At the time this study commenced a specific assessment of climate change impacts on areas set aside for their nature conservation interest had not been carried out. Within the wider debate on conservation strategies and the long-term merits of reserves (for example, see Shafer 1990), it is important to understand how existing reserves and the flora and fauna they contain, are likely to be affected by climate change, and what function they will fulfil in the future. In 1996 CCIRG (p53) stated 'A 1 degree C increase in temperature may significantly alter the species composition in about half of the statutory protected areas in the UK'. This statement was based on the opinion of experts (Dr M G R Cannell, ITE, pers. com.) due to a lack of quantitative research. The DoE's Core Model Programme expressed this insufficiency in a different way, identifying the need to study how 'changes in species' distributions affect designated areas for wildlife and landscape' (Parr & Eatherall 1994 p17). It was therefore considered appropriate that a more specific assessment should be made, in relation to individual reserves, and in the national context. The aim of this research was therefore, to develop a methodology to provide a quantitative assessment to answer the following question: Which, or what proportion of Britain's nature reserves will be climatically suited in the future to the species they support today, and which will not?

Results

The 'climate-space' of a sample of plant species was examined by constructing models describing the relationship between species' European distributions and seven combinations of temperature or temperature and moisture variables. Mean temperature of the warmest month and continentality (warmest month minus coldest month temperatures) were judged to be the most suitable variables by virtue of (i) simplicity, allowing assessments made using these variables to be monitored against actual climate change; (ii) results from a verification exercise in which simulated distributions were compared to observed distributions producing acceptable agreement for 82% of species; (iii) the fact that there is greatest confidence in scenarios of temperature change. Two climate-space models were constructed for 241 plant species occurring from a sample of 86 nature reserve communities in Great Britain. Convex Hull climate envelopes were used to compile Mutual Climatic Range diagrams for selected species from the plant assemblage at each site, which allowed values of present-day and potential future climates to be compared against the climatic ranges of the species. The diagrams indicated that under scenarios of climate change up to the year 2100, temperatures are likely to remain within the range of values recorded within the current European distribution of the majority of species at most of the sites examined. A new Combined Envelope was used to determine future climatic suitability for the suite of sample species at each site (defined as a change in probability of species' presence). Results indicate that the warming climate will be more favourable for a large proportion of plants on Scottish reserves (with the exception of montane species) and less favourable for many plants on reserves in the south of England. The situation appears to be one of 'no change' for the majority of species on Welsh reserves and those further north in England.

Publications

Dockerty, T, Lovett, A & Watkinson, A (2003) ‘Climate change and nature reserves: examining the potential impacts, with examples from Great Britain’ Global Environmental Change Vol. 13, pp 125-135.

Dockerty, T & Lovett, A (2003) ‘A location-centred, GIS-based methodology for estimating the potential impacts of climate change on nature reserves’ Transactions in GIS Volume 7. No. 3. (June 2003) pp 345-370.