Road paving, fire regime feedbacks, and the future of Amazon forests
TL;DR: In this article, the authors show that paving, recuperate or constructing 6245 km of roads in the Amazon may have the opposite effect of increasing forest fire in the region, and that road paving will accelerate deforestation, logging, forest fire, smoke-related illness, and displacement of small-scale farmers.
About: This article is published in Forest Ecology and Management.The article was published on 2001-12-01. It has received 639 citations till now. The article focuses on the topics: Forest management & Fire regime.
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TL;DR: 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.
Abstract: 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.
954 citations
TL;DR: Brazil's Amazon forest remained largely intact until the "modern" era of deforestation began with the inauguration of the Transamazon Highway in 1970, but deforestation rates have trended upward since 1991, with clearing proceeding at a variable but always rapid pace.
Abstract: 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.
952 citations
Cites methods from "Road paving, fire regime feedbacks,..."
...The Avança Brasil program, a development package for the period 2000–2007, included US$20 billion in infrastructure in the Amazon region (Laurance et al. 2001; Nepstad et al. 2001; Fearnside 2002a), mostly driven by the perceived need to transport soybeans....
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Woods Hole Research Center1, Empresa Brasileira de Pesquisa Agropecuária2, National Institute of Amazonian Research3, University of São Paulo4, State Street Corporation5, Universidade Federal do Acre6, University of Brasília7, Columbia University8, United States Forest Service9, Harvard University10, University of Maryland, College Park11, Universidade Federal de Minas Gerais12
TL;DR: Signs of a transition to a disturbance-dominated regime include changing energy and water cycles in the southern and eastern portions of the Amazon basin.
Abstract: 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.
921 citations
Cites background from "Road paving, fire regime feedbacks,..."
..., and those that are not cleared have a high risk of burnin...
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TL;DR: Despite evidence of rapid forest recovery following large-scale deforestation, many degraded areas of today’s tropics will require human assistance to recover forest structure, species composition, and species interactions typical of mature tropical forests.
Abstract: Land-use history interacts with natural forces to influence the severity of disturbance events and the rate and nature of recovery processes in tropical forests. Although we are far from an integrated view of forest recovery processes, some generalizations can be made. Recovery of forest structure and composition is relatively rapid following disturbances that primarily impact forest canopies, such as hurricanes. Recovery is considerably slower following disturbances that heavily impact soils as well as aboveground vegetation, such as bulldozing, heavy or long-term grazing, and severe fires, often with long-lasting effects on species composition. The landscape matrix plays a critical role in local recovery processes. Proximity of disturbed areas to remnant forest patches promotes more rapid recovery, which depends heavily on seed dispersal. Recovery of aboveground biomass is constrained by soil fertility and texture across regions as well as across soil types within a region. Restoration of soil fertility may be a prerequisite for forest recovery on sites with severely degraded soils. Despite evidence of rapid forest recovery following large-scale deforestation, many degraded areas of today’s tropics will require human assistance to recover forest structure, species composition, and species interactions typical of mature tropical forests.
919 citations
Cites background from "Road paving, fire regime feedbacks,..."
...Examples are the establishment of fire-breaks to prevent runaway forest fires (Nepstad et al. 2001), application of reduced-impact logging techniques (Davis 2000), and restoration of abandoned farmland to establish wildlife corridors and re-establish forests (Janzen 1988; Lamb et al. 1997; Kaiser…...
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...Examples are the establishment of fire-breaks to prevent runaway forest fires (Nepstad et al. 2001), application of reduced-impact logging techniques (Davis 2000), and restoration of abandoned farmland to establish wildlife corridors and re-establish forests (Janzen 1988; Lamb et al....
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...Nepstad et al. (2001) describe three positive feedback loops that drive expansion of forest fires in Amazonia: (1) fire can directly promote drought by reducing rainfall; (2) fire increases susceptibility of forests to recurrent burning; and (3) fires destroy agricultural and forestry systems,…...
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TL;DR: The recent 70% decline in deforestation in the Brazilian Amazon suggests that it is possible to manage the advance of a vast agricultural frontier Enforcement of laws, interventions in soy and beef supply chains, restrictions on access to credit, and expansion of protected areas appear to have contributed to this decline, as did a decline in the demand for new deforestation as mentioned in this paper.
Abstract: The recent 70% decline in deforestation in the Brazilian Amazon suggests that it is possible to manage the advance of a vast agricultural frontier Enforcement of laws, interventions in soy and beef supply chains, restrictions on access to credit, and expansion of protected areas appear to have contributed to this decline, as did a decline in the demand for new deforestation The supply chain interventions that fed into this deceleration are precariously dependent on corporate risk management, and public policies have relied excessively on punitive measures Systems for delivering positive incentives for farmers to forgo deforestation have been designed but not fully implemented Territorial approaches to deforestation have been effective and could consolidate progress in slowing deforestation while providing a framework for addressing other important dimensions of sustainable development
887 citations
Cites background from "Road paving, fire regime feedbacks,..."
...During the last three decades, Amazon deforestation has taken place where the costs of access are low, near paved highways; as of 1998, three fourths of all clearing had taken place within 50 km of a paved highway (54, 55)....
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References
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Book•
01 Jan 1965
TL;DR: In this paper, Boserup argues that changes and improvements occur from within agricultural communities, and that improvements are governed not simply by external interference, but by those communities themselves using extensive analyses of the costs and productivity of the main systems of traditional agriculture.
Abstract: This book sets out to investigate the process of agrarian change from new angles and with new results. It starts on firm ground rather than from abstract economic theory. Upon its initial appearance, it was heralded as "a small masterpiece, which economic historians should read--and not simply quote"--Giovanni Frederico, Economic History Services. The Conditions of Agricultural Growth remains a breakthrough in the theory of agricultural development. In linking ethnography with economy, developmental studies reached new heights. Whereas "development" had been seen previously as the transformation of traditional communities by the introduction (or imposition) of new technologies, Ester Boserup argues that changes and improvements occur from within agricultural communities, and that improvements are governed not simply by external interference, but by those communities themselves Using extensive analyses of the costs and productivity of the main systems of traditional agriculture, Ester Boserup concludes that technical, economic, and social changes are unlikely to take place unless the community concerned is exposed to the pressure of population growth.
3,639 citations
TL;DR: In this article, the authors estimate that half of the closed forests of Brazilian Amazonia depend on deep root systems to maintain green canopies during the dry season, and as much as 15% of this deep-soil carbon turns over on annual or decadal timescales.
Abstract: DEFORESTATION and logging transform more forest in eastern and southern Amazonia than in any other region of the world1–3. This forest alteration affects regional hydrology4–11 and the global carbon cycle12–14, but current analyses of these effects neglect an important deep-soil link between the water and carbon cycles. Using rainfall data, satellite imagery and field studies, we estimate here that half of the closed forests of Brazilian Amazonia depend on deep root systems to maintain green canopies during the dry season. Evergreen forests in northeastern Para state maintain evapotranspiration during five-month dry periods by absorbing water from the soil to depths of more than 8m. In contrast, although the degraded pastures of this region also contain deep-rooted woody plants, most pasture plants substantially reduce their leaf canopy in response to seasonal drought, thus reducing dry-season evapotranspiration and increasing potential subsurface runoff relative to the forests they replace. Deep roots that extract water also provide carbon to the soil. The forest soil below 1 m depth contains more carbon than does above-ground biomass, and as much as 15% of this deep-soil carbon turns over on annual or decadal timescales. Thus, forest alteration that affects depth distributions of carbon inputs from roots may also affect net carbon storage in the soil.
1,288 citations
TL;DR: In this article, the authors present field surveys of wood mills and forest burning across Brazilian Amazonia which show that logging crews severely damage 10,000 to 15,000 km2 of forest that are not included in deforestation mapping programmes.
Abstract: Amazonian deforestation rates are used to determine human effects on the global carbon cycle1,2,3 and to measure Brazil's progress in curbing forest impoverishment1,4,5. But this widely used measure of tropical land use tells only part of the story. Here we present field surveys of wood mills and forest burning across Brazilian Amazonia which show that logging crews severely damage 10,000 to 15,000 km2 yr−1 of forest that are not included in deforestation mapping programmes. Moreover, we find that surface fires burn additional large areas of standing forest, the destruction of which is normally not documented. Forest impoverishment due to such fires may increase dramatically when severe droughts provoke forest leaf-shedding and greater flammability; our regional water-balance model indicates that an estimated 270,000 km2 of forest became vulnerable to fire in the 1998 dry season. Overall, we find that present estimates of annual deforestation for Brazilian Amazonia capture less than half of the forest area that is impoverished each year, and even less during years of severe drought. Both logging and fire increase forest vulnerability to future burning6,7 and release forest carbon stocks to the atmosphere, potentially doubling net carbon emissions from regional land-use during severe El Nino episodes. If this forest impoverishment is to be controlled, then logging activities need to be restricted or replaced with low-impact timber harvest techniques, and more effective strategies to prevent accidental forest fires need to be implemented.
1,286 citations
TL;DR: In this paper, the authors present results from a global climate model with sufficient resolution in the tropics to adequately represent the narrow equatorial upwelling and low-frequency waves, when the model is forced by a realistic future scenario of increasing greenhouse-gas concentrations, more frequent El-Nino-like conditions and stronger cold events in the tropical Pacific Ocean.
Abstract: The El Nino/Southern Oscillation (ENSO) phenomenon is the strongest natural interannual climate fluctuation1. ENSO originates in the tropical Pacific Ocean and has large effects on the ecology of the region, but it also influences the entire global climate system and affects the societies and economies of manycountries2. ENSO can be understood as an irregular low-frequency oscillation between a warm (El Nino) and a cold (La Nina) state. The strong El Ninos of 1982/1983 and 1997/1998, along with the more frequent occurrences of El Ninos during the past few decades, raise the question of whether human-induced ‘greenhouse’ warming affects, or will affect, ENSO3. Several global climate models have been applied to transient greenhouse-gas-induced warming simulations to address this question4,6, but the results have been debated owing to the inability of the models to fully simulate ENSO (because of their coarse equatorial resolution)7. Here we present results from a global climate model with sufficient resolution in the tropics to adequately represent the narrow equatorial upwelling and low-frequency waves. When the model is forced by a realistic future scenario of increasing greenhouse-gas concentrations, more frequent El-Nino-like conditions and stronger cold events in the tropical Pacific Ocean result.
1,279 citations
Book•
01 Jan 1992
TL;DR: In this paper, the authors examined the costs and benefits of an aggressive program of global action to limit greenhouse warming, focusing on efforts over a long run of 200 to 300 years with much greater warming and damages than associated with the conventional benchmark (a doubling of carbon dioxide in the atmosphere).
Abstract: This study examines the costs and benefits of an aggressive programme of global action to limit greenhouse warming An initial chapter summarizes the scientific issues from the standpoint of an economist The analysis places heavy emphasis on efforts over a long run of 200 to 300 years, with much greater warming and damages than associated with the conventional benchmark (a doubling of carbon dioxide in the atmosphere) Estimates are presented for economic damages, ranging from agricultural losses and sea-level rise to loss of forests, water scarcity, electricity requirements for air conditioning, and several other major effects A survey of existing model estimates provides the basis for calculation of costs of limiting emissions of greenhouse gases After a review of the theory of term discounting in the context of very-long-term environmental issues, the study concludes with a cost-benefit estimate for international action and a discussion of policy measures to mobilize the global response
1,172 citations