|
Native species are considered preferable to non-natives by
conservationists, as they represent integrity of habitats
and ecosystems. Species of plants, animals, fungi and other
micro-organisms within a habitat are highly interdependent
and the introduction of new species can destabilise existing
interactions. For example a non-native sycamore tree may take
up space that would otherwise be occupied by a native oak.
Compared with an oak, the sycamore supports only a limited
variety of other species, such as leaf-eating insects or small
mammals that feed on the seeds. This, in turn, may affect
other species, such as insectivorous birds or mammals.
Although it may not always be the case that a particular
native species supports more biodiversity than an equivalent
non-native, this is likely to be the usual situation as native
species have had much more time to develop stable interactions
with one another.
A small proportion of non-native species are especially problematic.
These are those species which are described as ‘alien
invasives’. Invasive species spread rapidly in their
new environment where they are freed from constraints which
controlled their population growth in their native habitats,
such as fungal pathogens, or leaf and seed-eating animals.
In this case they may displace native vegetation in an uncontrolled
manner and may have huge impacts on the local ecology.
Page 2 of 2. Back
to Wild Science index >>>
|
