Why is bramble on of the most aggressive plants?

Answer 1

Bramble has to be a fast-growing plant to survive in it's natural habitat. Brambles evolved in Woodland. When a tree fell it would open the canopy allowing light to reach the ground. This means that grasses, wild-flowers and weeds can grow there. brambles are slower-growing than them and will eventually fill the sunlit area. This will shade the ground. The only plants which can survive in these conditions are slow-growing plants like trees, which then grow over the bramble and shade it, killing the bramble. The bramble has to be aggressive to take advantage of the small window of time offered by the fallen tree. If it grew slowly then it might not produce as many (or any) blackberries as a quick-growing individual and so wouldn't leave any seeds. The only way to get rid of brambles permanently is to dig it up at the roots and them mow the area as you would mow lawn. That way only very very fast-growing plants (like grass and some small weeds) can grow. (or of course you could plant enough large trees to for a complete canopy (but that takes longer))