following my previous question about scientific theory needed for my ecology coursework which was the effect of trampling on thistle on Burford Spur surrey, so do i need to look at the adaptations of this plant to trampling is there any theory that i need to include anything to do with plant growth/soil conditions? Can you suggest any websites/books for natural selection?
I don't think you can really do anything about adaptations to trampling. I have no idea why some plants are more resistant to trampling than others. There are one or two things that help, e.g. plants like dandelions which have hardly any stem and are already pretty flat, will not get easiloy damaged by trampling. However, some other plants do have a stem yet are still resistant. The scientific theory is basically natural selection and competition. Those plants that are naturally resistant to trampling (for whatever reason) are the only ones that survive and breed in the trampled zone. They often DON'T appear in the non-trampled zones because they cannot compete well with other plants when their trample resistance is no longer relevant.
There are loads of sites that deal with Darwin's theory. A good one is http://www.spaceandmotion.com/Charles-Darwin-Theory-Evolution.htm - this has a brief summary of the theory so is not too heavy.