Climate change in conservation areas of South Africa and its potential impact on floristic composition: a first assessment

Abstract

Summary Projected climate change has been suspected of affecting the biota of conserved nature areas in different and significant ways. Nevertheless, strategic management within some nature conservation agencies appears relatively unprepared for the possible consequences of climate change. National level planning of reserve design networks has also tended to skirt the issue, possibly owing to insufficient analysis. This paper provides a first assessment of the possible effects of climate change on plant diversity within the protected area network of South Africa. A climate change scenario of increased temperature but no change in precipitation resulted in derived optimum growth days increasing in some reserves through increased temperature extending the growing season. In some other reserves optimum growth days declined through greater evapotranspiration. We concentrated on the larger reserves of the latter group for which conditions that are more limiting were predicted. Plant species were evaluated in terms of their critical limits in growth days and minimum temperature. Over a third of the species analysed for one reserve (Augrabies Falls National Park and Melkbosrand) was indicated to become locally extinct with climate change. Another reserve in the region showed fewer than 1% local extinctions. It is clear that although a certain magnitude of climate change is a prerequisite for these extinctions, the rate and number of extinctions depend strongly on the different environmental tolerances of the specific biotic components of the conserved area. Potential immigration of other species to Augrabies Falls/Melkbosrand required to balance the projected extinctions with climate change would need migration abilities and conditions that are unlikely to be met. A net decrease in plant diversity may thus be expected. The results confirm that with the climate change scenario used, the concept of sustaining species through fixed protected areas may be fundamentally flawed, at least in certain areas.

A conservation plan for a global biodiversity hotspot—the Cape Floristic Region, South Africa

“…Hobbs, 1992;Simberloff et al, 1992;Beier and Noss, 1998) remains unresolved, at least in the sense that there appears to be no design appropriate for all components of a regional biota (Lindenmayer and Nix, 1993;Laurance and Laurance, 1999). Certainly, it is unlikely that the many thousands of CFR plant species that are dispersed short distances by ants (Bond, 1983) will be capable of migrating sufficiently fast to avoid the impacts of anthropogenic climate change (Rutherford et al, 2000;Midgley et al, 2003;see also van Dorp et al, 1997). Also of concern is the location of the upland-lowland and macroclimatic gradients.…”

Climate change and its impact on Australia's avifauna

“…Several studies from elsewhere in the world may provide a model for such analysis (e.g. Rutherford et al 1999;Burns et al 2003). The Threatened Species Scientific Committee, set up under the Act, concluded that 'along with the issues of emissions reduction, the adaptation requirements of species and communities likely to be affected by climate change should be given greater priority' (http://www.deh.gov.au/biodiversity/ threatened/ktp/greenhouse.html).…”

Rapid plant diversification: Planning for an evolutionary future

“…Further rapid climate change is likely to cause the extinction of many of the range-restricted and habitat-specialist members of the actively speciating flocks in the CFR (44)(45)(46)(47). However, by changing habitat characteristics and promoting population isolation, climate change may also enhance turnover of actively diversifying lineages.…”

“…The representation of biodiversity pattern (species, habitats, etc.) is only one component of an effective conservation plan; an explicit consideration of the evolutionary processes that will maintain biodiversity in the long term is also required (11,12), especially in a world that is increasingly threatened by habitat loss and climate change (44,45).…”