SPECIES REDUNDANCY VERSUS NONREDUNDANCY - IS IT WORTH FURTHER DISCUSSION

The concept of species redundancy (i.e. the idea that some species are not necessary for normal functioning of a given ecosystem) is hardly useful for conservation biology and for ecology in general. However th e opposite statement according to which all species are needed for eco system functioning and sustaining its basic structure either cannot be grounded rationally. A great controversy that always accompanies the attempts to relate community structure (and species diversity as one o f its characteristic) to ecosystem functioning results from incompatib ility of population and ecosystem approaches. If we are even able to t rack the ecosystem functioning changes that take place while the speci es diversity of corresponding community is intentionally declining, we cannot rationally decide when the ''minimum permissible'' level of th is functioning is achieved. Therefore we cannot determine the level of ''obligatory'', ''non-redundant'' diversity.