In an effort to ensure energy independence and exploit mineral resources, the governments of Amazonian countries are embarking on a major dam building drive on the basin’s rivers, with 191 dams finished and a further 246 planned or under construction. This rush to harvest the basin’s vast renewable energy capacity has come without proper consideration of the likely negative environmental externalities on the world’s most speciose freshwater and terrestrial biotas. Here we highlight the economic drivers for hydropower development and review the literature to summarise the impacts of dam building on Amazonian biodiversity. We identify both direct and indirect impacts through the anticipated loss, fragmentation and degradation of riparian habitats. We then propose a series of measures to assess, curb and mitigate the impacts of destructive dams on Amazonian biodiversity

Brazil has presided over the most comprehensive agrarian reform frontier colonization program on Earth, in which ~1.2 million settlers have been translocated by successive governments since the 1970’s, mostly into forested hinterlands of Brazilian Amazonia. These settlements encompass 5.3% of this ~5 million km2 region, but have contributed with 13.5% of all land conversion into agropastoral land uses. The Brazilian Federal Agrarian Agency (INCRA) has repeatedly claimed that deforestation in these areas largely predates the sanctioned arrival of new settlers. Here, we quantify rates of natural vegetation conversion across 1911 agrarian settlements allocated to 568 Amazonian counties and compare fire incidence and deforestation rates before and after the official occupation of settlements by migrant farmers. The timing and spatial distribution of deforestation and fires in our analysis provides irrefutable chronological and spatially explicit evidence of agropastoral conversion both inside and immediately outside agrarian settlements over the last decade. Deforestation rates are strongly related to local human population density and road access to regional markets. Agrarian settlements consistently accelerated rates of deforestation and fires, compared to neighboring areas outside settlements, but within the same counties. Relocated smallholders allocated to forest areas undoubtedly operate as pivotal agents of deforestation, and most of the forest clearance occurs in the aftermath of government-induced migration.

Protected areas form a quintessential component of the global strategy to perpetuate tropical biodiversity within relatively undisturbed wildlands, but they are becoming increasingly isolated by rapid agricultural encroachment. Here we consider a network of 788 forest protected areas (PAs) in the world’s largest tropical country to examine the degree to which they remain intact, and their responses to multiple biophysical and socioeconomic variables potentially affecting natural habitat loss under varying contexts of rural development. PAs within the complex Brazilian National System of Conservation Units (SNUC) are broken down into two main classes—strictly protected and sustainable use. Collectively, these account for 22.6% of the forest biomes within Brazil’s national territory, primarily within the Amazon and the Atlantic Forest, but are widely variable in size, ecoregional representation, management strategy, and the degree to which they are threatened by human activities both within and outside reserve boundaries. In particular, we examine the variation in habitat conversion rates in both strictly protected and sustainable use reserves as a function of the internal and external human population density, and levels of land-use revenue in adjacent human-dominated landscapes. Our results show that PAs surrounded by heavily settled agro-pastoral landscapes face much greater challenges in retaining their natural vegetation, and that strictly protected areas are considerably less degraded than sustainable use reserves, which can rival levels of habitat degradation within adjacent 10-km buffer areas outside.

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Public land grabbing, concomitant with hinterland colonization and agrarian reform programs, translocated millions of rural migrants into remote regions of Brazil, most recently to the Amazonian forest domain. Despite state-of-the-art command-and-control and remote sensing monitoring systems in Brazil, effective law enforcement in a country of ∼8.5 million km2 remains a huge challenge, and particularly difficult in times of lenient central-government environmental policies. Cropland and pasture expansion is the most important factor in land use change in Brazil, and the leading driver of primary habitat conversion worldwide. This essay discusses the most likely business-as-usual agricultural frontiers in Northern and Central Brazil to make room for new farmland: the MaToPiBa region in the transitional Cerrado-Caatinga biogeographic zone; the northernmost Cerrado areas of Amapá; and the opening-up of Indigenous Lands to industrial scale agriculture. We discuss the origins, recent developments and implications to conservation of these new agricultural frontiers.