Preserving all forms of life holds for a more promising eco-future
THE new buzz word in environment
circles is biodiversity which is the
diversity of life in all its ramifications - the different communities
that make up an ecosystem, the different species that make up communities, the variable individual organisms that belong to each species, and
the genetic variation that we see
between and within individual
The strongest arguments yet for conservation are economic: benefits like food and medicines, not to speak of useful genes in the wild plants, animals and microbes which may be useful and even necessary some day. But if that is all there is to it, why really worry about biodiversity per se? As long as we have some representative samples of various species surviving somewhere in the world, our needs - present and future - should be satisfied. Is it really necessary to preserve biodiversity in its totality? While there was not much scientific evidence to support this viewpoint earlier, research has now established the importance of preserving biodiversity in its entire whole. The complex network of interrelationships between different species in each ecosystem need to be preserved for the well being of not only our ecosystems and but also the health of their life support systems.
A recent experiment conducted at the Imperial College in England provides convincing evidence that biodiversity per se is indeed essential for the well being of ecosystems (Nature, No 368, 1994). The experiment used 14 models of terrestrial microcosms maintained in an ecotron. A microcosm, as the name implies, is a miniature ecosystem maintained as naturally as possible and an ecotron is a system of controlled environmental chambers designed for maintaining such microcosms. Each microcosm in the experiment contained producer species, primary consumers, secondary consumers and decomposers. Six of the microcosms had high biodiversity with 31 species each, four microcosms had intermediate levels of biodiversity with 15 species each and another four microcosms had low levels of biodiversity with nine species each.
Self-pollinating herbaceous annual plants represented the producers; mollusks and insects represented the prima- ry consumers; insect parasitoids represented the secondary consumers and collembola and earthworms played the role of decomposers. There was clear evidence that biodiversity levels altered the functioning of the ecosystems. Perhaps the most important finding was that carbondioxide consumption as well as plant productivity decreased with decreasing biodiversity. Decomposition, nutrient retention and er retention rates were also sigwat nificantly affected by levels of biodiversity, although they did not vary between high, intermediate and low biodiversity microcosms in a consistent manner.
Taken together these results provide the first clear dernonstration that loss of biodiversity indeed alters the functioning of ecosystems. We can now argue with greater justification that merely saving individual species in different locations is not enough. It is important to preserve the natural levels of biodiversity in different habitats and retain the complex networks of species relationships.
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