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W. Nentwig
widely accepted that it is futile to manage particular invasions without
attending to ill-managed landscapes.
We have only limited information on the spreading capabilities of species,
their pathways to the invaded habitats, and on the differences in invasibility of
ecosystems. Apart from expressing concern, we can often offer too few reliable,
concrete data on the impact of an alien species in an invaded ecosystem.
This point is particularly important because more precise information would
enable us to prioritize a given set of aliens, and to focus at first on those
species with the most detrimental impact. In addition, high-quality inventories
of alien species and of experts working on these species are rare.
Thus, one of our utmost urgent needs is to intensify research on alien
species and biological invasions. More experimental research is needed at the
ecosystem level, notably on how invasive species alter ecosystem services. We
also need to learn more about the effects of invasive species in conjunction
with global change, including climate and land use, and other key factors such
as the cycling and enrichment of N, P or other critical substances, hydrological
changes and impacts of fire. In particular, supporting and regulating services
presently feature only low levels of research, although both are highly
significant elements of our combat against biological invasions. Recognition
of the value of ecosystem services would, among others, raise the awareness of
the general public.
For the development of appropriate conservation strategies, detailed
knowledge of the ecology of alien species is required. Currently, in many cases
negative impacts of invasive species on native species have been deduced
from correlative evidence, since experimental studies on interactions between
invasive and native species are largely lacking. Also, the management and
conservation of native taxa threatened by hybridization with invading taxa
need more studies which integrate ecological (including genetic) information
at the level of local populations.
One special group of alien species are genetically modified organisms,
which will become increasingly part of our future environment. Similarly to
alien species, their introduction into the natural environment is also irreversible,
potentially causing hazard to ecosystems.We need to understand the
mechanisms and impacts of introduced genes as well as their potential
impact on biodiversity or ecosystem functions.
24.2 Management from Detection to Eradication or Control
Greater efforts have to be made to eradicate several key alien species in certain
regions. Experience clearly shows that, with proper planning, substantial
financial support and adequate political and social assistance, it is indeed
possible to successfully eradicate alien species. However, there are numerous