[nakedgardener]

Human intervention surely plays a huge part in the bio-geography of Brittain, all of the habitats have been altered by what we do, even wilderness and nature reserves have to be managed and controlled.

In general species which tend to be generalist will do well, adaptable species, whether native or introduced can thrive. It's the more specialist species, that have evolved here to fill a niche that will suffer as we change the environment more and more, especially if they can't compete with alien species, or if we destroy the habitats which they need.

Introduced species can, and do increase biodiversity, conifer plantations have helped bird species such as siskins and crossbills, gardens provide a food source for many birds, so gardens have now far higher populations of some species than an equivelant area of woodland.

Other introduced species can and will be to the detriment of biodiversity, Japanese knotweed, Rhododendron ponticum, and Himalayan balsam are such thugs that they swamp out all other species, and don't add much to the food chain. Grey squirrels have pushed out our native reds (but it does mean we have 2 species instead of one!) American crayfish have pushed out our natives..... the list goes on....

The more we interfere, the more we will have problems new species will find there way here, some of which will cause damage, and this will only be made easier by climate change.

In the long run it will lead to a small number of globally sucessful species dominating, at the expense of more specialist species.... the World will be a much poorer place because of it.