Deforestation is continuing in the Amazon basin as the cattle and soy industries expand. The main conservation policy there involves ‘protected areas’: areas designated by national governments that are left undisturbed to allow natural vegetation to develop. But this alone may not protect the rainforest ecosystem from collapse. An new estimate of forest losses made using the SimAmazonia 1 computer model suggests that by 2050, agricultural expansion will eliminate two-thirds of the forest cover of five major watersheds and ten ecoregions. One in four mammalian species examined will lose 40% of their forest habitat. Although an improved network of protected areas could avoid up to a third of projected forest loss, forest conservation on private properties will be essential if the Amazon landscapes and watersheds are to be maintained. Expansion of the cattle and soy industries in the Amazon basin has increased deforestation rates and will soon push all-weather highways into the region's core1,2,3,4. In the face of this growing pressure, a comprehensive conservation strategy for the Amazon basin should protect its watersheds, the full range of species and ecosystem diversity, and the stability of regional climates. Here we report that protected areas in the Amazon basin—the central feature of prevailing conservation approaches5,6,7,8—are an important but insufficient component of this strategy, based on policy-sensitive simulations of future deforestation. By 2050, current trends in agricultural expansion will eliminate a total of 40% of Amazon forests, including at least two-thirds of the forest cover of six major watersheds and 12 ecoregions, releasing 32 ± 8 Pg of carbon to the atmosphere. One-quarter of the 382 mammalian species examined will lose more than 40% of the forest within their Amazon ranges. Although an expanded and enforced network of protected areas could avoid as much as one-third of this projected forest loss, conservation on private lands is also essential. Expanding market pressures for sound land management and prevention of forest clearing on lands unsuitable for agriculture are critical ingredients of a strategy for comprehensive conservation3,4.

Modelling conservation in the Amazon basin

Forest fires are growing in size and frequency across the tropics. Continually eroding fragmented forest edges, they are unintended ecological disturbances that transcend deforestation to degrade vast regions of standing forest, diminishing ecosystem services and the economic potential of these natural resources. Affecting the health of millions, net forest fire emissions may have released carbon equivalent to 41% of worldwide fossil fuel use in 1997-98. Episodically more severe during El Nino events, pan-tropical forest fires will increase as more damaged, less fire-resistant, forests cover the landscape. Here I discuss the current state of tropical fire science and make recommendations for advancement.

Fire science for rainforests

Intensive mechanized agriculture in the Brazilian Amazon grew by >3.6 million hectares (ha) during 2001–2004. Whether this cropland expansion resulted from intensified use of land previously cleared for cattle ranching or new deforestation has not been quantified and has major implications for future deforestation dynamics, carbon fluxes, forest fragmentation, and other ecosystem services. We combine deforestation maps, field surveys, and satellite-based information on vegetation phenology to characterize the fate of large (>25-ha) clearings as cropland, cattle pasture, or regrowing forest in the years after initial clearing in Mato Grosso, the Brazilian state with the highest deforestation rate and soybean production since 2001. Statewide, direct conversion of forest to cropland totaled >540,000 ha during 2001–2004, peaking at 23% of 2003 annual deforestation. Cropland deforestation averaged twice the size of clearings for pasture (mean sizes, 333 and 143 ha, respectively), and conversion occurred rapidly; >90% of clearings for cropland were planted in the first year after deforestation. Area deforested for cropland and mean annual soybean price in the year of forest clearing were directly correlated (R2 = 0.72), suggesting that deforestation rates could return to higher levels seen in 2003–2004 with a rebound of crop prices in international markets. Pasture remains the dominant land use after forest clearing in Mato Grosso, but the growing importance of larger and faster conversion of forest to cropland defines a new paradigm of forest loss in Amazonia and refutes the claim that agricultural intensification does not lead to new deforestation.

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Cropland expansion changes deforestation dynamics in the southern Brazilian Amazon

Brazil's Amazon forest remained largely intact until the "modern" era of deforestation began with the inauguration of the Transamazon Highway in 1970. Amazonian deforestation rates have trended upward since 1991, with clearing proceeding at a variable but always rapid pace. Amazonian forests are cut for various reasons, but cattle ranching predominates. The large and medium-sized ranches account for about 70% of clearing activity. Profit from beef cattle is only one of the income sources that make deforestation profitable. Forest degradation results from logging, ground fires (facilitated by logging), and the effects of fragmentation and edge formation. Degradation contributes to forest loss. The impacts of deforestation include loss of biodiversity, reduced water cycling (and rainfall), and contributions to global warming. Strategies to slow deforestation include repression through licensing procedures, monitoring and fines. The severity of penalties for deforestation needs to be sufficient to deter illegal clearing but not so great as to be inapplicable in practice. Policy reform is also needed to address root causes of deforestation, including the role of clearing in establishing land claims for both small and large actors.

http://philip.inpa.gov.br/publ_livres/Preprints/2005/Cons%20Biol-Amazon%20deforestation%20-%20FINAL.pdf

Deforestation in Brazilian Amazonia: History, Rates, and Consequences

Agricultural expansion and climate variability have become important agents of disturbance in the Amazon basin. Recent studies have demonstrated considerable resilience of Amazonian forests to moderate annual drought, but they also show that interactions between deforestation, fire and drought potentially lead to losses of carbon storage and changes in regional precipitation patterns and river discharge. Although the basin-wide impacts of land use and drought may not yet surpass the magnitude of natural variability of hydrologic and biogeochemical cycles, there are some signs of a transition to a disturbance-dominated regime. These signs include changing energy and water cycles in the southern and eastern portions of the Amazon basin.

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The Amazon basin in transition

Road paving, fire regime feedbacks, and the future of Amazon forests

Throughout human history, the world9s great forest formations have yielded to logging, cattle ranching, and agricultural expansion after transportation corridors made them accessible to frontier settlers. The Brazilian Amazon could prove to be an exception to this historical trend, however. Recent advances in Brazil9s environmental management could potentially preserve most Amazonian forests while fostering economic development, as demonstrated by the CuiabA©a -SantarA©m highway, soon to be paved.

https://science.sciencemag.org/content/sci/295/5555/629.full.pdf

Frontier Governance in Amazonia

he Amazon region of Brazil contains billions of cubic meters of high-quality wood whose overall value after sawing would be several trillion dollars. Given this timber wealth, it is common to consider forestry as the natural vocation for Amazonia (Pandolfo 1974). Already, well over half of the wood consumed in Brazil comes from Amazonia, and this domestic demand for Amazonian roundwood is expected to grow (Verissimo et al. 1992). Foreign consumption of Amazonian wood, although low at present, is also likely to increase as Asian tropical hardwood stocks decline. Brazil, which possesses almost one-third of the world's rain forest

/pdf/natural-resource-management-in-the-brazilian-amazon-an-1un3mygh40.pdf

Ana Cristina Barros

Papers

Road paving, fire regime feedbacks, and the future of Amazon forests

Frontier Governance in Amazonia

Natural Resource Management in the Brazilian Amazon An integrated research approach

Sensitive development could protect Amazonia instead of destroying it.

Logging along the Amazon River and estuary: Patterns, problems and potential