This occurs because caules of the turnip and the nabia is harvested together with the wheat and finishes for emperrar part of the equipment in the interior of the colheitadeiras, what it causes loss of time and, eventually, of resources directed to the concert of the equipment. Ademais, such species serve of green seasoning not only to the culture to be in benefited thesis, but also to other invading species that starts to infest the area (DENARDIN et al, 2010). In some few occasions were observed, however, the occurrence of invasions of vegetal species without the interference human being. A case that illustrates this fact has relation with the gigantic volcanic explosion that in 1883 esterilizou the island of Cracatoa completely, in Indonesia. In that place the life was completely extinct. Nine months after the explosion everything what it was obtained to observe in Cracatoa was the existence of a type of solitary spider that persistently weaveeed teias in attempt to capture inexistent canine tooth. However, less than 50 years after the explosion the island again was covered by dense forest, consisting of new trees and low transport, beyond a great amount of animals, also caramujos, rats and lagartixas. It was arrived the conclusion that the light seeds of grassy had been carried the island for the wind.
The coconuts, in turn, had been taken by the sea. Plants as the figueiras and mamoeiros had certainly had its seeds carried the island in the digestive pipes of some birds (FARB, 1982). Another area affected for the foreign vegetable invasion is Nairbi, in the Kenya. Particularly in that region the invasion of the native flora for species proceeding from other areas threat not only biodiversity as well as the sustenance of human beings and animal. This occurs because some native fruitful species of the Kenya are slowly losing the fight with other vegetables for the survival.