Most non-native garden plants that escape cultivation are neither terribly successful nor very harmful. Britain's naturalised garden escapees are not widespread, not spreading especially quickly, and often less of a nuisance than vigorous native climbers such as bramble. The arrival of new species almost always increases biological diversity in a region; in many cases, a flood of newcomers drives no native species to extinction. One reason is that these escapees tend to colonise disturbed habitats like roadside verges and abandoned quarries, where little else grows. They are nature's opportunists.

Which one of the following is the most logical and rational inference that can be made from the above passage?