|MadSci Network: Environment/Ecology|
Josie Chesterman asked:
What happens when a botanical species disappears in the Amazon rainforest?
How does the dissapearance of one specific rainforest botanical species affect the ecosystem and the food chain of mammals and insect life or ecosystems as a whole and how might it affect us here in America?
I'll (try) to reply to Josie by answering each question in turn. So...
It depends...(the ecologist's answer to anything). In many ecosystems there appear to be species which are very important in the (physical) structure and (ecological) function of that system. Some ecologists are now calling these species "ecosystem engineers"; an older, and still commonly used, term is "keystone species". As both of these names suggest, such species are of fundamental importance to the ecology of the ecosystem: if one of these disappears, the consequences for the ecosystem are likely to be severe. (Note that these species are oftenalthough not alwaysfairly common.)
The situation with other, less common, species is not so clear. It may be that some of these are not essential; that there are a number of alternative species which could fulfil the same role (that is, do the same job, ecologically speaking). At present, however, we really do not understand manyif anyecosystems well enought to know whether or not such redundant species exist. This is almost certainly the case with the Amazonian rainforest, as it is with tropical forests worldwide. These are extremely diverse ecosystems which, relatively speaking, we know very little about.
It would, obviously, depend on the actual species which disappeared. In the biological world there are many intricate and very specific relationships between animals and plants. Some animals have very precise needs and would suffer if a particular type of food was not available. Some plants rely on particular animals to pollinate them and cannot reproduce if those species are not present. Some plants may, therefore, be indirectly affected by changes in other plants. For example, if a plant required by an animal for food is not available then that species of animal may not be able to survive in an area: other plants which rely on that animal may then suffer.
If, however, the plant is one of a group fulfilling similar ecological functions, then there may be no marked change in the ecosystem (other than a small decrease in biodiversity) and no effect on the foodchains.
Unless the effect was catastrophic and affected global processes, such as weather, there would probably be no direct effect on the people and ecosystems of America: after all, many species have gone extinct in many places without catastrophic effects even in the same country. (And extinction is, in geological terms, a common process.)
The major effect would probably be indirect through a reduction in the benefits America receives from tropical regions, such as the Amazon (eg, foods, products, medicines, etc.).
Keith A. McGuinness
School of Biological & Environmental Sciences
Northern Territory University
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