a mosaic of different landforms and soil types, within which there is space for more intensive crop and animal production in areas of _cerrado_ and _terra roxa._ Although the area dedicated to these activities is proportionally limited at the biome scale, it is quite substantial, including agroforestry and silvipastoral systems operated by smallholders, managed timber and non-timber forest product extraction, and some reforestation, and perennial crop plantations whether with native or exotic species.

The Brazilian Amazon contains approximately 5.2 million km<sup>2</sup> of land, within which several forest and non-forest ecosystems exist. In the Amazon forest biome, if managed within the constraints of the 1965 Forest Code as initially revised by provisional measure in 1997, 80% of private lands were maintained in legal reserves under original or restored forest. It is conceivable even with such restrictions that the potential for harmonious regional development of these resources could be ensured. Such land use restrictions were relaxed to 50% of forest cover with the adoption of statewide Ecological-Economic Zoning (ZEE), a constitutional requirement in Brazil. The more recent (2012) revision in the Forest Code maintained the same requirements for conserving both legal reserves and riparian forests, although relaxed the obligation of forest restoration for past deforesters. According to estimates by Soares-Filho (2013), the revision of the Forest Code reduced by 59% the obligation to restore forests on private lands in the Brazilian Amazon.

Although ZEE has been conducted in several Amazon states, its promise to serve as a guideline to direct land use toward areas with greater productive and infrastructure potential has often been gerrymandered to allow incompatible activities. Successive frontier expansions have breached the restrictions posed by the literature and ZEE. The Belém-Brasília highway along the eastern rim of the basin, and BR-364 cutting across Mato Grosso, Rondônia and Acre to the southwest, served as principal corridors for migration and logistics. Econometric analyses have shown the close relationship between road expansion and deforestation in Amazon municipalities (SoaresFilho et al., 2006; 2010). Extensive cattle ranching is also closely related to deforestation, benefiting from the initial nutrient pulse provided by biomass burning, followed by low stocking rates associated with unimproved pastures, and in some cases abandonment. According to EMBRAPA & INPE (2008), 15 million hectares (21% of converted areas) are in abandoned secondary regrowth, mostly following pasture degradation.

Studies of the process of frontier expansion have noted its cyclical character (Schmink & Wood, 1992). Initial occupation occurred in many areas due to the biological provenance of rubber and related extractive species. With the decline in the natural rubber trade as plantations were established outside the Amazon, former tappers continued this activity at a lower level for modest trade, while engaging in small scale subsistence agriculture. Timber extraction began with these populations along riverbanks, but with increasing demand for wood as the Atlantic Forest was rapidly exhausted in the 1960s and 1970s, timber operations turned to the Amazon as a ready source of timber with lightly enforced restrictions to occupation and conversion.

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