Could climate change favours our native species on ‘glacis’? |11 July 2011

These are all regions which are already showing clear signs of water stress. The findings of the survey also show that an acceleration of the world's hydrological cycle is anticipated as rising temperatures increase the rate of evaporation from land and sea.

It is estimated that countries will suffer from higher frequencies in droughts and floods and water will become scarce as the world is expected to become drier and hotter. The FAO report mainly focuses on the challenges the world will have as a result of the negative impact of water scarcity on the production of food to feed the ever increasing world population.

There is however another kind of implication that the report does not focus on because it is not the core mandate of the FAO but that is equally important. This is the impact of drought on biodiversity.

Locally the extreme drought that Seychelles, Mauritius and the eastern African states are experiencing is not only having adverse effects on people and their livelihood but also on biodiversity and the ecosystem services they provide.
Populations of species like mosses, lichens and amphibians that depends on a wet or moist ecosystem are especially at risk as the habitat they depend on become more restricted. Such extreme drought conditions if sustained for a prolonged period may go beyond the tipping point of such species’ ability to survive.

For years several local plant experts have been pondering on the impact of climate change, especially in the form of prolonged droughts, on the distribution of rare endemic species which even today have very limited distribution pattern due to limited available habitat. Further concerns are linked to the potential exponential expansion of notorious invasive species like cinnamon Cinnamonum verum, guava Psidium cattleianum, albizia and clidemia, Clidemia hirta could have, should such adverse conditions favour their distribution, establishment and growth. 

Although, these concerns are still very relevant, there may be a new twist to these ideas especially in relation to the species confined or adapted to ‘glacis’ environment.  Recently it was observed that guava Psidium cattleianum which is one of the most difficult invasive species to control in the forest, was greatly under stress due to the prevailing drought. Even the fruits which were almost matured could not developed further and showed clear signs of water stress.

The foliage of the plants which were exposed to the sun was brown and showed clear signs of having been burned from the rays of the sun. In comparison to the guava plants most of the endemic or indigenous plants seemed to be in relatively good conditions.

These observations clearly showed the need for further monitoring and research of these habitats and the various species that make up the vegetation composition and how these may change in the future.  This drought although undesired because of the hardship it has brought to the local population does pose local biodiversity scientists and academia with a clear opportunity to learn more about the effect of climate change on biodiversity and also their ability to adapt and survive in the long term. 

In the case of ‘glacis’ vegetation it is possible that our native species are better adapted to survive extreme climatic conditions than the invasive species which may require milder conditions to grow. This is something that we should do our utmost to find out and document.

Contributed by Environment Department