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The degradation of the soil and native ecosystems and the dispersion of exotic species are the largest threats to the biodiversity. Brazil is considered one of the most biodiversity countries in the world, where it is concentrated about 10% of whole terrestrial biota (Mittermeier et al., 1997). Studies have shown that the Brazilian diversity was already greater than is recorded nowadays. Even with the disappearance of species, the biodiversity of the Cerrado is still quite expressive and notable. Depending on the taxonomic group, 20 to 50% of species occurring in the Brazilian Cerrado. The great diversity of species of animals and plants of the Cerrado is associated with spatial heterogeneity (the variation of ecosystems over space) of this biome, which allows the coexistence of different physiognomic forms in the same region. The variation of environments makes possible species of animals and plants present a strong association with local ecosystems, being closely tied to natural environments, such as the Antilophia galeata which are found only in gallery forests, and the Mauritia flexuosa that are closely associated with the paths. This relation fauna-flora-Cerrado illustrates the importance of maintaining of the natural vegetable covering of this biome, as a basic strategy for maintaining biological diversity expressive. Recent studies indicate that a loss up to 25% of bird species associated with the gallery forest of the Cerrado may occur, just if there is the destruction of natural environments to the neighboring woods, even though it remains untouched (Machado, 2000; Machado et al ., 2004). Furthermore, excessive reduction of native areas will cause the extinction of species from fragments of small size (Hass, 2002). The Cerrado is a biome originally covered by vegetation ranging from grassland (country) to Cerradao and has two well-defined seasons: dry winter and rainy summer. This biome shelters deciduous species and presents a nutrient-poor acidic soil with high iron and aluminum content. According to Eiten (1979), the Cerrado vegetation varies from sparse trees to dense forest vegetation. The variation in the Cerrado physiognomies has been attributed to the action of fire, soil factors (Eiten, 1972; Coutinho, 1978; Rizzini, 1979), topography and water (Furley & Ratter, 1988). The Cerrado biome is the second largest biogeographic region of Brazil covering an area of 2,036,448.00 km2 (Fig. 1), around 23% of the national territory (Ratter et al., 1997). |
