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Burning of lands can have negative effect

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Tue, Oct 2, 2012

Editor: Every year, at some point in the dry season, it is not uncommon to see the burning of hillsides as farmers attempt to clear their lands in order to begin agricultural activities. Frequently, the burnt areas stretch far beyond the portion of land to be utilised and hence is unnecessary.{{more}} Therefore, greater awareness of the impacts of such activities is necessary. Grass fires in St Vincent can have negative impacts on natural biota. Much of St Vincent was probably still very forested during Amerindian settlement, with large scale forest clearing occurring after Europeans settled.

Today, the coastal lands are heavily settled along with some parts of the interior. Along the coasts, grassed hillsides containing fragments of forest are not uncommon. There are areas where these fragments are just a few stands of trees, others where they are of considerable size. The forest fragments provide valuable ecosystem services. They act as refuges for natural biota, especially arboreal species such as birds (the barn owl) and opossums (manicou), (though the presence of opossums in very small fragments is questionable). On a whole, forests in St Vincent are expected to provide more valuable ecosystem services compared to grassland. However, on many hillsides, the recolonisation of the land by trees is being slowed or prevented by the persistent burning of these hillsides by farmers. The more fragmented and isolated (from other wooded areas) these wooded areas become, the more restricted is gene flow between these habitats, due to a reduction in the ability of organisms to disperse.

Genetic variability is important in organisms in order to make them adaptable to changes in their environment. These changes do not have to be on the macro level, but can include things such as the introduction of diseases into populations. Also, the ability of organisms to forage and escape predators becomes more difficult, due to increased exposure.

Greater fragmentation of forests also means reduced habitat areas, which can slow population growth in organisms such as the opossum, which studies have shown are very reliant on old growth forests. Additionally, the persistence of grass habitats will prevent the creation of wooded corridors that link these fragments to each other and larger forested areas. Just for the sake of understanding, it is important to note that the isolation of habitats can be useful in the event of disease outbreaks, because they can function to isolate populations from these diseases.

A suggested reading for anyone interested in the ecology of islands and fragmented habitats is Island Biogeography by Robert Whittaker.

Shamal Connell

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