The baobabs are noted for their longevity but are they under threat?
Within an ecosystem there are numerous biological interactions between different members of the flora and fauna, weaving a complex web of interrelationships upon which the overall stability of the ecosystem is believed to partly depend. No species survives in isolation; each plays a part within an intricate mesh of organisms. Those organisms that were entirely dependent on a species that is now lost will also become extinct and, since nature abhors a vacuum, others will fill their place. The balance among the remaining organisms will be adjusted to meet the change. Our present state of knowledge of the interdependency of organisms and their roles within an ecosystem is minimal. We therefore destroy a species at our peril (Wickens 2001).
In his ‘keystone mutualism’ concept, Gilbert (1980) stresses the importance of some organisms in stabilising a given ecosystem. Thus, if an individual organism is the only available source of a particular resource upon which other organisms rely, the extinction of that source could have a destabilising effect throughout the ecosystem. Keystone plant species can be defined as those species that provide essential resources, such as food or shelter, for a guild of animals in return for which the guild of animals provides an essential service, or mobile links, such as pollination or diaspore dispersal. For example, the baobabs play an important biological role in the conservation of ecosystems of which lemurs, sunbirds and hawk moths are important constituents (Baum 1996).
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