SOUTH BRAZILIAN CAMPOS GRASSLANDS: BIODIVERSITY, CONSERVATION AND THE ROLE OF DISTURBANCE, pp. 223-239
Authors: (Alessandra Fidelis, Laboratory of Landscape Ecology and Conservation, Department of Ecology, Universidade de São Paulo, Brazil)
Abstract: The South Brazilian Campos grasslands (also known as only Campos) are unique ecosystems. Located in the southermost part of Brazil, these ecosystems are rich in plant species, being more diverse than forest ecosystems in the same area. Due to their geographical position (humid subtropics), in a transitional region between tropical and temperate area, these grasslands show mixture of C3 and C4 grasses and a high diversity of other botanical families, with typical tropical and temperate species. Since the climate is subtropical humid, with rainfall regularly distributed all over the year, forest physiognomies would be expected to cover the area. However, diverse grasslands occur in vast areas, in contact (or not) with forest, raising one of the most interesting questions: are these grasslands natural? Paleopalinological studies already showed that these grasslands were present in the region before forest. Until the Holocene, Campos grasslands dominated. Afterwards, climate changed (hotter and more humid), enabling forest expansion. Therefore, Campos grasslands are natural ecosystems. However, even with no edaphic restrictions and a climate more propitious to forest expansion, forests do not dominate nowadays, raising another important question: why are Campos grasslands still present? Disturbance is probably the most important factor maintaining both grassland physiognomy and diversity. Both grazing and fire have important effects on grassland dynamics. South America does not have large native herbivores and cattle are the most important grazers in these grasslands. Jesuits introduced them in the XVII century and cattle raising is one of the most important economic activities in Southern Brazil. Before that, fire might have influenced vegetation dynamics and delayed forest expansion. Paleopalinological studies showed the presence of charcoal since the Holocene. Nowadays, fire still plays a great role on grassland dynamics, but is a very polemic issue. In this chapter, I intend to give the reader an overview about this unique ecosystem, almost unknown by the majority of international scientific community and ignored for its ecological relevance even by most of Brazilian scientific community. I will also show the role of disturbance in maintaining Campos biodiversity and dynamics as well as the importance of its conservation.