**3. The history of fragmentation of the Atlantic forest biome**

The Atlantic forest is the most uncharacterized Brazilian biome (IBGE, 2004). Since the beginning of European colonization, from 1500, several economic cycles of exploration occurred, generating successive impacts in a growing area (Dean, 1996). Brazil has the most diverse flora of the planet and also had its name inspired in a tree, Brazil-wood (*Caesalpinia echinata* Lam), a typical species of coastal forests of the southeast. The first cycle of the ancient Portuguese colony was the exploitation of this species, highly valued for producing a resin which conferred a reddish color to fabrics. Later, with the largest reserves of this wood already exhausted, other exploitation or agricultural cycles began, such as the sugar cane, gold, and ultimately, coffee. They all contributed strongly to clearance and degradation of new areas (Dean, 1996). From the late 19th century and throughout the 20th century, new development and national integration projects have come and settled a consistent process of industrialization and urbanization exactly in the area originally occupied by the Atlantic Forest. Nowadays, these urban areas have the highest population densities and lead the economic activities in the country (IBGE, 2004). An estimated 112 million people live in this area, which accounts for 61% of the population of Brazil (IBGE, 2007). The current results are the almost complete loss of primary forests and a continuous process of destruction of existing remnants, which place the Atlantic Forest biome in unworthy position in the world: as one of the most endangered ecosystems (SOS Mata Atlantica and Instituto Nacional de Pesquisas Espaciais (INPE), 2011). In sum, predatory economic cycles and projects of development and national integration have led, throughout the biome area, to the expansion of the agricultural frontier, the establishment of industrial activities, mining and power generation and intense and disorganized urbanization process, causing the destruction of, approximately, 92% of the original vegetation, which had, in 1500, 1,315,460 square kilometers (Fundação SOS Mata Atlântica and INPE, 2011). The remaining 8% are highly fragmented, separated by a matrix that includes pastures, crops, water reservoirs, industrial plants, mining and urban areas, especially on the margins of water bodies and mountain areas with highly tilted ground. Even so, one should not underestimate the importance of these fragments. For example, in terms of species richness, occur, even today, in the Atlantic Forest biome, about 20.000 species of vascular plants, of which 6.000 are endemic (Fundação SOS Mata Atlântica and INPE, 2011).

If on one hand the historical processes of economic development led to a predatory pattern of destruction with the formation of relictual fragments of sizes and levels of isolation and different anthropic impact, on the other, the Brazilian environmental legislation, considered one of the most advanced of the planet, through his last Forest Code, established in 1965 and improved in recent decades, defined areas of permanent preservation and legal reserve (Medeiros et al., 2004). The first has the function of conservation of ecosystem services, encompassing riparian forests, river headwaters, hills tops and mountains, hillsides with slopes greater than 45 °, "restingas" and mangroves. The second has the goal of biodiversity conservation and must have, at least, 20% of the property area in the southern and southeastern Brazil, reaching 80% of the area in the Amazon region. Thus, the historical process that led to the intense fragmentation of the Atlantic Forest biome has suffered, in recent decades, the influence of an environmental legislation more effective for conservation. The result is that most of the remaining fragments can be found in permanent preservation areas and legal reserves, especially in riparian areas and steep slopes with unstable soils.

At this time, Brazilian society is burned with a heated debate, in the Brazilian National Congress, on the proposed changes to the Forest Code. In one side, the sectors of society and policymakers linked to the economically strong Brazilian agricultural sector require the flexibility of code, aiming to reduce the need for recovery and conservation of areas of permanent preservation and legal reserve, in order to result in the release of more land for agriculture. In the other side, the Brazilian Society for Science Progress, urban sectors of society and policymakers linked to the environmental movement strongly oppose the proposed changes. There is a concern that, if these changes are approved, the fragmentation process of natural areas and the destruction of relictual fragments will be intensified, which would result in ecological and evolutionary consequences for populations of many species present in these natural areas.
