The removal of forest cover often leads to the invasion of weedy and undesirable plants, which have seeds more able to survive heat and dryness. Species which are best able to adapt to new extreme conditions will become the dominant plants. For example, the babassu palm, Orbignya phalerata, is highly tolerant of such conditions and has colonized deforested areas along the Transamazonian Highway, as well as swamp forests along the banks of small tributaries and upland plateaus in which gaps have been formed by deforestation. The invasion of this palm decreases the development of canopy trees by shading their seedlings and smothering them in leaf litter.

In the Neotropics, in general, there are many slow-growing, shade-tolerant trees which do not grow well in large gaps, and relatively few with light-tolerant seedlings, so that large gaps are often filled with woody climbers and fast-growing sun-loving trees such as Cecropia. In other cases, the drier and hotter conditions after deforestation have led to the invasion of cut-over areas by grasses and scrub trees and the conversion of the forest to savannah or grasslands. Natural reforestation occurs only where there are large “banks” of seeds remaining, particularly those of climax species. In Para State, Brazil, many cattle ranches were abandoned when they became unprofitable, but since no tree seeds or seedlings remained, the pastures became filled with low, woody vegetation rather than rainforest trees.