South Africa's efforts...
In South Africa, they have done a cost analysis showing exactly how much are we losing by having certain invasive species in their native ecosystems. They have found that shrubs from Australia and trees from Europe are invading their water sheds and are using more water than the native vegetation. Water is costly; they calculate how much it costs for the lost water. They have found that it's cheaper to have people go in, routing out the invaders, thus making more water go to the reservoir, than it is to leave the invasives there.
We need to adopt a new policy that says that any potential introduction is guilty until it's proven innocent. We don't have that policy now. You can take any seed of any noxious plant, put it in a first class envelope and send it anywhere in the world. This is a very risky proposition.