Alien Species.vp - IUCN

something other than what was originally introduced. This example also questions our notions
of area of origin, or historical range: how do we determine that?
From these initial questions it is already evident that we face not only conceptual problems
when we have to identify alien species, but also value choices, the basis of which are not always
clear. For example: the human introduction criterion requires us to make distinctions between
non-humanized and less-humanized ecosystems existing independently of humans on the one
hand, and humanized ecosystems on the other, dependent upon or the result of human action.
The value of naturalness is introduced here, but this raises the question of the basis for the
preference indicated in this value. The conceptual criterion of evolutionary origin also requires
us to draw a line in the history of an evolving ecosystem and to identify the state in which that
ecosystem was before that timeline as original, while its state after that time represents a
deviation from that original state. At the same time it requires us to determine areas of origin
inside of which species are native, and outside of which species are not. This introduces the
values of originality and authenticity, again showing that the concept of alien species is not
purely dependent upon objective ecological criteria, but on the kind of time-space
demarcations we use to identify origin or authenticity. For a clear understanding of the problem
of IAS and the arguments informing our policy responses to it, we are then obliged to also
explore the “subjective” side of the equation – to explicate the basis for the conceptual as well
as value distinctions we make in this regard.
Similarly, the conceptual criterion of historical or natural range requires us to demarcate in
space and time a certain area of origin and what it means to be “inside” and “outside” of that
area. And like the conceptual criterion of human introduction, this context requires us to
determine the borderlines of natural and unnatural. The conceptual criterion of ecological
degradation and membership of an ecological community raises similar problems. Even if we
grant the fact that much highly valuable work has been done in invasion ecology to develop
objective criteria to determine the kind and extent of ecological degradation brought about by
alien species, it is still humans who introduce the value distinctions between healthy and
unhealthy, between harmed and unharmed ecosystems, or between “good” and “bad” nonnative
species. In so far as harm and health and good and bad are anthropogenic concepts (after
all, nature cannot articulate that it has been harmed, is healthy, is good or bad), our criteria to
determine this beg the question as to the basis on which we make these value distinctions.
To apply the conceptual criterion of membership of an ecological community, we make
value judgements regarding the extent to which a species has been integrated into an
ecosystem. Applying this criterion therefore assumes that we have answered a number of other
value questions. For example: what is an ecological community? What does it mean to be a
member of an ecological community? What does it mean to be a good member of an ecological
community? What does integration mean? Balance? Mutual dependence on other members of
the ecological community? Subject to mutual controls exerted by the respective members of the
ecological community?
Given the framework of the postmodern condition within which we live, and the substantive
loss that we experience within this condition of fixed points of reference, it is clear that the
seemingly simple task of applying a concept such as “IAS” becomes highly problematical. As
we have argued, it is not only a matter of conceptual determinations that have to be clarified, but
also a number of interrelated value choices. And on both levels, we do not have clear guidelines
as to what we should choose. Yet, we cannot avoid making these choices. So where do we turn
to for help in this regard?
An ethic of conceptual responsibility
From a moderate interpretation of our postmodern condition, “help” – if we want to call it that –
is available from an ethic of conceptual responsibility in which narrative is taken seriously.
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Human dimensions of invasive alien species