[thedoc (OP)]

We explore how invasive plant species can affect landscapes and indigenous wildlife...
 Read a transcript of the interview by clicking here

or [chapter podcast=3747 track=11.11.27/Naked_Scientists_Show_11.11.27_9384.mp3] Listen to it now[/chapter] or [download as MP3]

[Don_1]

I'm sure ramblers take great care not to disturb the countryside when they set off on a hike. But I am not so sure they understand that they can be the instrument of spreading invasive species and even transferring plants which might only grow at one end of the country to the other.

Doubtless many a rambler has been the unwitting accomplice in these long distance moves and the spread of Japanese Knotweed etc.

The problem is, how do you prevent this without spoiling the ramblers enjoyment of our beautiful countryside. Ensuring that boots, clothing, rucksacks etc are thoroughly cleaned between ventures may help, but some seeds can be very resilient.

[cheryl j]

Once species jump continents or mountain ranges, isn't it a losing battle? Does making hikers wipe their feet really help? The deer and the raccoons are not going to cooperate. Does spraying down your boat prevent zebra mussel infestation of lake, when there are thousands of ducks landing and taking off. Maybe slowing down the spread gives an eco system time to adjust, but I doubt you can stop invasive species if their a niche to fill.

[CliffordK]

Hikers often drive hundreds of miles to get to the prime hiking spot.  Sometimes they will travel from country to country, so it certainly is possible that they could bring unwanted pests with them. 

Usually my socks are clean going into the mountains.  Sometimes I wonder if the greater risk is to bring the invasive species back home before stuff gets into the wash.

It might be reasonable to design boots to minimize the risk of picking up seeds. 

• Less aggressive soles (also minimizes tracking mud into the house)
• Less fabric to pick up grass seeds.  Leather and plastics pick up fewer seeds
• Attention to crevices in the upper portion of the boot.

[Don_1]

Once species jump continents or mountain ranges, isn't it a losing battle? Does making hikers wipe their feet really help? The deer and the raccoons are not going to cooperate. Does spraying down your boat prevent zebra mussel infestation of lake, when there are thousands of ducks landing and taking off. Maybe slowing down the spread gives an eco system time to adjust, but I doubt you can stop invasive species if their a niche to fill.

What you say here is, of course, absolutely true, but migration of species by way of hitching a ride on another species, would have been taking place since species began to migrate. As you suggest, such migration would have been successful only where there was a niche to fill and nature would have had time to adjust accordingly.

But I would speculate that such migrations would probably have occurred many thousands of years ago and are today very unlikely. For example, it is likely that migrating Swallows from the UK to South Africa would probably have transferred viable UK species to S.Africa and S.African species to the UK many thousands of years ago. It is unlikely that they would now transfer any further species and extremely unlikely that they would change their destinations.

In contrast to these long defined natural migration habits, man moves in all directions at any time of the year, so has the potential to transport all manner of species all over the world. An early example of such being rat infested ships.

But we also transport species deliberately, such as the Romans bringing Rabbits to the British Isles and horticulturalists bringing Rhododendron and the accursed Japanese Knotweed. I'll grant you that these man-migrated species have the potential to now hitch a lift on the long established migrators and as such, we have probably put the cat among the pigeons well and truly. But this is no reason to just sit back and say 'Ah well, such is life'. Efforts need to be made to try to lessen the spread of these unwanted and often damaging invasive species.

[CliffordK]

There are, of course, invasive animal species, including invasive migratory species.

For example, Canadian Geese are considered an invasive species in Europe, so they would not have long traditional migratory patterns.  And, even in North America, their migration patterns are also slowly altering with climate changes (keeping in mind that the climate has been changing since the beginning of the Holocene).

In the USA, there may be a sharp distinction between Rocky Mountain species and Appalachian Mountain species due to the separation of the Great Plains.  However, if there is ever a jump between the ranges, or between continents, then local wildlife could spread the invasive species all over.

Anyway, animals can spread some flora...
But, humans are much better at doing it!!!

And some animals such as rats and mice have adapted to being human hitchhikers!!!