Feature

The winds of change

Dr Bob Scholes

What can be done to protect biodiversity from climate change?

There are strong indications that the exceptionally rich biodiversity of
southern Africa is vulnerable to climate change.

The global climate has changed repeatedly in the distant past. Although
these events are typically associated with a degree of species loss, overall
they often mark the beginning of a burst of new species. But two features
make the current human-induced climate change event different and
threatening: the rate at which the climate is projected to change is about
ten times faster than in the past; and the landscape through which the
plants and animals must migrate has been radically fragmented by human
activities.

Fig.1. The succulent karoo of the west coast of South Africa and Namibia is particularly threatened by climate change. It is home to about 3000 species of plants that occur nowhere else. A large fraction of the world's succulent flora comes from here. The area covered by the unique dry, winter-rainfall climate is projected to shrink or completely disappear under some future climate scenarios.

The conservation authorities, having been alerted to the possible
impact of climate change, need guidance on what practical steps to take to
protect the biodiversity in their care. Conservation planning in southern
Africa is relatively sophisticated, making use of tools such as C-plan
to optimise the layout of conservation areas in order to conserve the maximum number of species for a given total area protected. These tools assume an unchanging climate and a static land use pattern. Are the results invalid if these basic assumptions are violated? What mix of strategies is likely to be effective and affordable?

The adaptation options are being analysed in terms of their robustness
within uncertain futures, their cost to implement, the full cost including
loss of biodiversity value, and the fraction of the biodiversity that they
are predicted to protect. The options include:
· take no action;
· expand or relocate the reserve system;
· focus on sound conservation outside of the reserve system;
· assist the species to disperse; and
· conservation in zoos and gardens.

There is no existing body of theory and practice that can be directly
applied to answering these questions. A team of researchers, from South
Africa's Council for Scientific and Industrial Research, the National
Botanical Institute, the University of Pretoria and the University of
Stellenbosch have combined forces to address the problem.

The project, which began in 2002 and will last for three years, is funded by
the Global Environment Facility through a programme known as Assessing
Impacts and Adaptation to Climate Change (AIACC). It will use a new set of
climate projections, developed specifically for southern Africa, at fine
scale, by another AIACC project led by Prof Bruce Hewitson of University of
Cape Town.

The team is focussing on three case studies to develop and test the
adaptation planning tools. The first is the succulent karoo (Fig. 1),
where a diverse and unusual flora, often closely associated with particular
geological formations, is under severe threat. It is also the epicentre of
tortoise diversity in southern Africa. How can a slow moving, vulnerable
animal migrate to safety? Will its food-plants be able to keep up?

Fig. 2. The fynbos of the southern Cape, the world's smallest and richest plant kingdom on a per area basis, is now mostly confined to the rugged mountains of the region, since the valleys have been converted to agriculture. How can plants, birds and reptiles migrate in pursuit of their preferred climate, when there are wide barriers of unsuitable habitat between their present location and their future distribution?

The second case study is the Cape Floral Kingdom (Fig. 2), characterised
by a spectacularly high number of endemic species, often isolated in
mountainous country. It has recently been the focus of a detailed
conservation planning exercise. The question to be addressed is: how robust is the plan, if the climate changes?

Fig. 3. By some estimates, nearly half of the bird and animal species currently found in the world-famous Kruger National Park, may no longer occur there in a hundred years time.

The third is the wildlife-dominated savannas of the north east of South
Africa (Fig. 3). The issue here is how to preserve the complex set of
interactions that make up a functioning ecosystem.

The anticipated products of this research effort are a set of software
tools to help guide conservation decisions in a changing world, along with a
manual or guidelines for their application. The results of the
individual case studies will be published in the open scientific media. A
training workshop for conservation planners from throughout the SADC region is part of the plan.

More information:
Dr Bob Scholes is a systems ecologist and a Fellow of the CSIR.

Useful links:
LINK Climate change - the missing links.

References

Erasmus, BFN et al 2002 Vulnerability of South Arican taxa to climate
change. Global Change Biology 8: 679-693.

Ferrier S, Pressey RL and Barrett TW 2000 A new predictor of the
irreplaceability of areas for achieving a conservation goal, its
application for real-world planning and a research agenda for further refinement. Biological Conservation 93: 303-325.

IPCC 2002 Climate Change and Biodiversity. Intergovernmental Panel on
Climate Change Technical Paper 5.

Pressey RL and Cowling RM 2001 Reserve selection algorithms and the
real world. Conservation Biology. 15(1): 275-277

Roux, D, de Moor, F, Cambray, J and Barber-James, H 2002 Use of
landscape-level river signatures in conservation planning: a South
African case study. Conservation Ecology Vol 6, No 2, [online] URL:
http://www.consecol.org/vol6/iss2/art6

Rutherford, MC, Midgley, GF, Bond, WJ, Powrie, LW, Roberts, R and
Allsopp, J 1999 Plant biodiversity: Vulnerability and adaptation assessment. South African Country Study on Climate Change, Dept of Environment Affairs and Tourism. Pretoria.

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