ALLELOPATHY AND FIRE CYCLE IN BRAZILIAN CERRADO

Resumo

Allelopathy refers to the effect of biochemical interactions from one plant to another plant including inhibitory and stimulatory effects. The products, allelochemicals are highly toxic, and the production of these compounds not only can be stimulated by plants and microorganism, but also by environment factors e.g. water stress, nutrient deficiency and temperature where these conditions are commonly found in the cerrado enviroment. Cerrado region is rich of plants which produce secondary metabolite, especially phenolic compounds and numerous vegetations have been investigated of their inhibitory effects on other crops developments. It is known that allelopathy is a key process regulating plant regeneration in many world ecosystems including savanna/cerrado. The interest of allelopathic study in shrub ecosystems rises as a result of inadequate natural regeneration and reduced growth of planted seedlings that has been attributed to the release of allelochemicals by herbaceous vegetation. Fires, whether they are natural or human made, are a common characteristic of this biome and its presence is considered to be an important ecological factor and responsible for regulating species diversity. Following fire, the negative effects of allelochemicals are removed or reduced. However, numerous ecological factors of cerrado have been associated with seedling survival, not only caused by plant toxin, but also low soil fertility, low water, temperatures and animal predation. This paper reviews the presence of cerrado vegetation that launched toxic compounds and their allelopathic effects on other plants, the presence of savanna fire and post-fire ecological impacts. In general, the main objective of this paper is to point out the allelopathy and fire-related impacts to provide us to solve ecological issues concerning to the sustainable development of the cerrado.