Several important trends hold the potential to prevent or, at least, postpone a large-scale forest dieback and provide some elements of a comprehensive Amazon conservation strategy. First is the tendency of landholders to avoid the use of fire as a land management tool and to invest more in the prevention of accidental fire as they accumulate fire-sensitive investments on their properties (Nepstad et al. 2001
; Bowman et al. in press
). As long as cattle ranchers and farmers believe that their investments in orchards, tree plantations, improved forage grass and timber management will be lost to fire, they are less likely to make these investments and more likely to continue their extensive cattle ranching or swidden agriculture. However, as these fire-sensitive investments accumulate in the landscape, a tipping point may be reached beyond which the many landholders who have made these investments convince their fire-using neighbours to use fire more judiciously.
Second is the change in landholder behaviour that is already evident in places in Mato Grosso and that could rapidly become widespread when sound land stewardship and compliance with environmental legislation are viewed by a growing number of producers as the necessary conditions for participating in commodity markets and for obtaining access to credit and financing. The soya growers of Mato Grosso are in the midst of such a change today as they enter their second year of a moratorium imposed by the Associação Brasileira das Indústrias de Óleos Vegetais (The Brazilian Vegetable Oil Industry Associaton). This 2-year moratorium on the purchase of soya planted on soils recently cleared from Amazon forest was stimulated by a campaign against Amazon soya initiated by the environmental organization Greenpeace (Greenpeace 2006
). Soya producers and their organizations are currently developing criteria systems that would certify their farms as environmentally sound (Arini 2007
). It is in the context of market pressures and certification systems that landholders are agreeing to adopt fire prevention techniques such as fire breaks along their forest borders, to seek compliance with the private forest reserve requirements of federal legislation and to conserve their riparian zones.
Third is the prospect of restricting the advance of Amazon cattle ranching. Approximately one-quarter of the previously forested lands in the Brazilian Amazon are in some stage of abandonment (Houghton et al. 2000
), and most of these are degraded cattle pastures. The replacement of carbon- and species-rich forests with cattle production systems that support less than one animal unit per hectare presents very high societal costs and low societal benefits, thereby violating Brazil's own constitution, which states that the ‘social function’ of the land is to provide maximum economic and ecological benefits to the society (Benatti 2003
; Ankersen & Ruppert 2006
). One way to reduce deforestation driven by cattle ranchers, many of whom are using pastures to help stake claims to land parcels (Alston et al. 1999
; Alencar et al. 2004
), would be to prohibit the clearing of lands that are marginally suitable for mechanized agriculture (except where smallholder agriculture systems are appropriate). In an initial attempt to map the areas that are the most suitable for highly productive, mechanized agriculture, we employed the Shuttle Radar Topography Mission (Farr et al. 2007
) dataset to map slope and height above river channels (as a measure of potential for inundation), and the RADAMBRASIL and FAO soils maps (described in Nepstad et al. 2004
) to identify soils that typically contain rocks, impeding layers, and poor drainage (ultisols, lithosols, sands and hydromorphic soils; ). The resulting map correctly identifies large areas of arable land where the majority of Amazon soya production is located, in northern Mato Grosso and in the Santa Cruz region of Bolivia. It also indicates potential for agro-industrial expansion in southern Peru, in the Madre de Dios region. These regions have strong dry seasons and may be suitable for soya bean expansion and, perhaps, other crops that require a dry period. A large block of arable, forested land with very little rainfall seasonality is also found in northern Colombia, northwestern Amazonas state and Northern Peru. This area may be the target of oil palm expansion, which needs little rainfall seasonality. The total area of the Amazon that is ‘suitable’ for industrial agriculture (with no edaphic or climatic restrictions) is 33%, while the area that is ‘very suitable’ (with only one restriction) is 22%. Constraining cattle pasture expansion in the Amazon would not necessarily restrict the growth rate of the Amazon cattle herd. Cattle production systems that incorporate silage and agricultural residue into the diet of the herd can achieve grazing densities of more than six animals per hectare (Landers et al. 2005
; M. Reis et al
. 2007, personal communication), and will be favoured if land prices escalate through growing demands for Amazon soil.
Figure 4 Soil suitability map for mechanized agriculture in the Pan-Amazon region. Restrictions include slope (more than 2%), inundation risk and poor soil (ultisols, hydromorphic soils, sands and lithosols). See text for further methodological details. State (more ...)
The prospect of restricting the expansion of agricultural and livestock production in the Amazon to those lands of high suitability becomes plausible in the light of a fourth important trend. Most parks and biological reserves in the Amazon have been created far from the agricultural frontier, where the opportunity costs of conservation are low and where, unfortunately, these protected areas exert little influence on deforestation (Nepstad et al. 2006b
). But this historical trend may be changing. From early 2004 to 2006, 23
Mha of protected areas and national forest districts were created in the Brazilian Amazon, including large areas of protected land in the pathway of the expanding agricultural frontier (Campos & Nepstad 2006
). This historic achievement was made possible by a participatory, multiple-stakeholder, regional planning process that has emerged along the BR-163 (Santarém-Cuiabá) highway, which is slated for paving, and by the smallholder farmers’ movement of the Transamazon highway region, which successfully initiated the ‘Terra do Meio’ conservation mosaic (Campos & Nepstad 2006
). Through the combination of (i) regional, participatory planning processes that lead to effective land-use zoning systems, (ii) recent government demonstrations of political will in establishing protected areas expressed through the Amazon region protected area programme and in cracking down on corrupt government employees, and (iii) growing market demands for higher environmental and social performance of Amazon farmers and ranchers, it is conceivable that deforestation could be restricted to the one-quarter of the region that is suitable for modern mechanized production ().
A fifth potentially robust mechanism for counteracting the pressures to clear and degrade Amazon forest, and that could reinforce efforts to constrain the expansion of cattle ranching, is emerging within the United Nations Framework Convention on Climate Change (UNFCCC) negotiations. The proposal to compensate those tropical nations that succeed in reducing their nationwide emissions of greenhouse gases from deforestation (Santilli et al. 2005
) has gained momentum in the UNFCCC process (Gullison et al. 2007
), and it could provide an important economic incentive for countries and, in turn, landholders who reduce those land-use activities that release greenhouse gases to the atmosphere. Negotiation of this post-2012 component of the UNFCCC will be completed by the end of 2009. Since most of the Amazon carbon emissions are caused by forest conversion to cattle ranching with low profitability (Arima & Uhl 1997
; Kaimowitz et al. 2004
; Margulis 2003
), such a mechanism could restrict the expansion of this land use to the remaining forest regions of the Amazon, thus reducing the risk of a near-term forest dieback scenario. We estimate that deforestation in the Brazilian Amazon could be brought to approximately zero within 10 years within the context of a 30-year programme costing $8 billion, or less than $2 per tonne of reduced carbon emission (Nepstad et al. 2007b