Climate Change

Saturday, July 29, 2006

SOME MORE DOOM AND GLOOM… A SHORT SUMMARY OF A PAPER BY MIDGLEY et al. (2002)


We are privileged to live in one of only 25 global biodiversity hotspots (Myers et al. 2000) of the world. (South Africa is the only country that actually has three hotspots contained within one country!) The Cape Floristic Region is however set to change should the scenarios on climate change turn out to be true after all. Midgley et al. (2002) in “Assessing the vulnerability of species richness to anthropogenic climate change in a biodiversity hotspot” used bioclimatic modeling to produce a climate envelope for the current Fynbos Biome. They also created bioclimatic envelopes for all 330 species of the family Proteaceae. These envelopes were created using five parameters pertaining to temperature and water-availability (from Schulze 1997), which are deemed critical for plant survival.

They then used general circulation models (HadCM2 and CSM) to generate climate scenarios for 2050. In the biome-based approach, they looked at the decrease in area suitable for the Fynbos biome by 2050 and then overlayed that “lost” area with data from the Protea Atlas Project, to determine the extinction risk for the Proteacea family. In the species-based approach, this was done for each species and if there was no overlap between the current and the future projected range, the species has an almost certain extinction risk.

The results once again predict doom and gloom. A loss of range between 51% and 65% is predicted for the Fynbos biome. There would be an areal loss at all altitudinal ranges, with the northern biome limits loosing the most. This could be translated into a 10% loss of species. But if one looks at the species-based approach, one-third of all species do not have overlapping ranges between the current an projected future ranges and that could mean they could become extinct. Plants in the Fynbos biome simply would not be able to migrate fast enough, because they need fire to germinate and many are dependant on specialized dispersal agents like ants…

This paper thus clearly indicates that biome-based studies might underestimate the potential loss of species. Species-based approaches are needed to develop methods to monitor climate change impacts, monitor the accuracy of climate predictions and detect early signs of plant stress. Here it would thus be wise to monitor species in the areas predicted to be lost altogether (thus northern limits of Fynbos biome). Such scenarios should also be used as guidelines for planning future protected areas and corridors.


References:

Midgley GF, Hannah L, Millar D, Rutherford MC and Powrie LW. 2002. Assessing the vulnerability of species richness to anthropogenic climate change in a biodiversity hotspot. Global Ecology & Biogeography 11:445-451.

Myers N, Mittermeier RA, Mittermeier CG, da Fonseca GAB and Kent J. 2000. Biodiversity Hotspots for conservation priorities. Nature 403(6772):853-858.

Schulze RE. 1997. South African atlas of agrohydrology and climatolog. Report TT82/96. Water Research Commission, Pretoria.


Karen Marais
BCB Hons NISL student
University of the Western Cape
Private Bag X17
Bellville

E-mail 2657211@uwc.ac.za

Web http://brit-journal.com/karen2006bcbnisl/

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