Rain Forest Conservation

The South American (SA) Coastal and Interior Tropical Forests stretch through 17 Brazilian states, along nearly the entire coast of the continent. Beginning with the border at Uruguay to the south, all the way around the eastern tip, and up to the Guyana Shield to the north of Brazil. The historic range of the forest proceeded furthest inland in the south of Brazil, into the states of Goias, Mato Grosso do Sul, Minas Gerais, and into a significant portion of Paraguay to the west of Brazil.

However, at present only approximately 7.3% (94,000) of the original 1,290,692 square kilometers of Mata Atlântica remain in Brazil. As is often the case, the most biologically diverse places are also the most favorable for human settlement. Biologically diverse coastal areas in particular are threatened all over the Earth. The Atlantic Forest is a perfect example of this phenomenon. Over 100 million Brazilians live within the Atlantic Forest, including the cities of São Paulo, Rio de Janeiro, Belo Horizonte, and Porto Alegre. Given that only around 160 million people live in Brazil at present, it is clear that the Atlantic Forest has been vital for the growth of the country.

The Mata Atlântica

At present, large intact stretches of the forest are rare, with most being small, isolated patches. The largest remnants of the forest exist in the states of São Paulo, Parana, Santa Catalina, and Rio de Janeiro. Much of what remains of the forest has been cut over for pasture lands, agriculture, or forestry and has subsequently regrown with what is called Secondary Forest. Most of the undisturbed areas, or

Primary Forests, are isolated to steep hill-sides or are found in inaccessible areas. One of the locations that we will be visiting during the class, Intervales State Park, is a good example of how forests remain in steep areas.

The forest is so biologically diverse because of several reasons: forest refugia, Most of what is now the Mata Atlântica was under water during recent glacial periods, a fact that can be readily observed by the near total absence of rocks in many areas (although this is not true for the area around IPE's headquarters). The great diversity of elevation in the area formed many forest refugia, where native biodiversity remained until they were able to expand their range. These refugia, which are a special type of inland islands with each mountain being comparable to an island, served as the source populations from which the entire Mata Atlântica was repopulated. These refugia allowed for a great number of species to arise. The isolated populations could genetically diverge from other populations with whom they could previously interbreed (more on this during Module 3). Once the ranges were expanded and they had sufficiently diverged, the newly formed species could not interbreed with the other populations.

As a consequence, a great many species currently exist in the Mata Atlântica. Although the number of these forest refugia is debated, it is clear that there are around four of them in the forest. The refugia are of great interest as it is thought that they are some of the most biologically diverse areas in an already biologically diverse location and as a consequence, they are centers for a great many species that are found only there - called centers of endemism.

Many of the huge number of the species that are found within the Mata Atlântica are unique to this area, or are endemic. A listing available from Conservation International details 250 species of mammals (55 endemic), 340 amphibians (90 endemic), 1,023 birds (188 endemic), and approximately 20,000 trees, half of them endemic. For many higher level taxa (genus, family, order, etc.) like primates, more than two-thirds are endemic. Therefore the burgeoning threats posed to the Atlantic forest by human population promises to wipe out one of the most unique areas in the world. This is the reason why many organizations place the Mata Atlântica in the top five of the most important biological hotspots that head the list of areas to be conserved worldwide. We will discuss hotspots further in Module 16.

The Mata Atlântica has frequently been divided into domains that were established by the Brazilian Vegetation Map of IBGE (1988). Eight domains are usually recognized by this work: "ombrophilous dense atlantic forests; mixed ombrophlilous forests; open ombrophilous forests; semidecidual stational forests; decidual stational forests; the countryside swamps, the northeastern forest enclaves and the associated ecosystems - mangroves and restingas." We will plant trees in most of these domains, with the exception of the countryside swamps.