scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Agricultural intensification increases deforestation fire activity in Amazonia

TL;DR: In this article, the authors estimated the contribution of fires from the deforestation process to total fire activity based on the local frequency of active fire detections from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors.
Abstract: Fire-driven deforestation is the major source of carbon emissions from Amazonia. Recent expansion of mechanized agriculture in forested regions of Amazonia has increased the average size of deforested areas, but related changes in fire dynamics remain poorly characterized. We estimated the contribution of fires from the deforestation process to total fire activity based on the local frequency of active fire detections from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors. High-confidence fire detections at the same ground location on 2 or more days per year are most common in areas of active deforestation, where trunks, branches, and stumps can be piled and burned many times before woody fuels are depleted. Across Amazonia, high-frequency fires typical of deforestation accounted for more than 40% of the MODIS fire detections during 2003-2007. Active deforestation frontiers in Bolivia and the Brazilian states of Mato Grosso, Para, and Rondonia contributed 84% of these high-frequency fires during this period. Among deforested areas, the frequency and timing of fire activity vary according to postclearing land use. Fire usage for expansion of mechanized crop production in Mato Grosso is more intense and more evenly distributed throughout the dry season than forest clearing for cattle ranching (4.6 vs. 1.7 fire days per deforested area, respectively), even for clearings >200 ha in size. Fires for deforestation may continue for several years, increasing the combustion completeness of cropland deforestation to nearly 100% and pasture deforestation to 50-90% over 1-3-year timescales typical of forest conversion. Our results demonstrate that there is no uniform relation between satellite-based fire detections and carbon emissions. Improved understanding of deforestation carbon losses in Amazonia will require models that capture interannual variation in the deforested area that contributes to fire activity and variable combustion completeness of individual clearings as a function of fire frequency or other evidence of postclearing land use. © 2008 The Authors Journal compilation © 2008 Blackwell Publishing.

Summary (3 min read)

Introduction

  • Agricultural expansion is the main cause of tropical deforestation (FAO, 2006), highlighting the tradeoffs among ecosystem services such as food production, carbon storage, and biodiversity preservation inherent in land cover change (Foley et al., 2005).
  • Expansion of intensive agricultural production in southern Amazonia, led by the development of specific crop varieties for tropical climates (Warnken, 1999) and international market demand (Naylor et al., 2005), contributed onethird of the growth in Brazil’s soybean output during 1996–2005 (IBGE, 2007).
  • Reductions in forest biomass from selective logging before deforestation are small, averaging o10 Mg C ha 1 (Asner et al., 2005).
  • Evaluating fire detections over large regions of homogenous land cover can be instructive (e.g. Mollicone et al., 2006; Aragão et al., 2007), but geolocation errors and spurious fire detections may complicate these comparisons, especially in regions of active land cover change and high fire activity such as Amazonia (Eva & Fritz, 2003; Schroeder et al., 2008).
  • The goals of this research are to (1) test whether fire frequency distinguishes between deforestation fires and other fire types and (2) characterize fire frequency as a function of postclearing land use to enable direct interpretation of MODIS active fire data for relevant information on carbon emissions.

Data

  • The authors analyzed active fire detections from the MODIS sensors aboard the Terra (2002–2007) and Aqua (2003– 2007) satellite platforms to determine spatial and temporal patterns in satellite fire detections from deforestation in Amazonia during this period.
  • Figure 1 shows the location of the study area and administrative boundaries of the nine countries that contain portions of the Amazon Basin.
  • Beginning in 2007, MODIS products were transitioned to Collection 5 algorithms.
  • Seasonal differences in fire activity north and south of the equator related to precipitation (Schroeder et al., 2005) were captured using different annual calculations.

Identifying high-frequency fires

  • The simple method the authors propose for separating deforestation and agricultural maintenance fires is based on evidence for repeated burning at the same ground locations.
  • The geolocation of MODIS products is highly accurate, and surface location errors are generally o70 m (Salomonson & Wolfe, 2004).
  • A 1-km radius is also consistent with fire spread rates of 200–5000 m h 1 (4.8–140 km day 1) for grass, grass/shrub, and deforestation fuel types (Scott & Burgan, 2005), such that even slow-moving grassland fires would spread beyond the 1-km search limit on sequential days.
  • Specifically, the variety of days on which fires were detected was determined for each cell of the standard MODIS 250-m grid using a search radius of 1 km to interpret the center locations of all high-confidence fire detections for each year.
  • This gridded product of fire days was then used to select those fire detections contributing to high-frequency fire activity and characterize fire frequency for recent deforestation events.

Fire types in Amazonia

  • To determine whether active fire detections associated with the conversion of forest to other land uses are unique in terms of fire frequency, the authors compared active fire detections from recently deforested areas with four additional types of fire management.
  • For individual deforestation events 425 ha in size, the authors also evaluated differences in patterns of active fire detections for conversion of forest to pasture, forest to mechanized agriculture, and forest conversions not in agricultural production (NIP).
  • The authors utilized data on historic deforestation and recent land use changes to identify maintenance fires on agricultural lands in Mato Grosso state.
  • The typical lot size in these settlements is 100 ha, of which 20–50 ha may be cleared for agricultural use.
  • The majority of Brazil’s sugarcane industry is located in the southern and northeastern regions of the country.

Basin-wide analysis

  • The authors analyzed the high-confidence subset of the MODIS active fire data record for the entire Amazon Basin to distinguish the contribution of deforestation and agricultural maintenance fires to overall fire activity during 2003–2007.
  • The authors provide fire-type statistics for each Amazon country and Brazilian state.
  • Finally, the authors summarize the ratio of high-frequency to low-frequency fires at 0.251 spatial resolution to evaluate interannual variations in deforestation fire activity across the basin.

Deforestation fires

  • High-frequency fire activity (42 fire days per year) is common in areas of recent deforestation but rare for other fire types in Amazonia (Table 1).
  • Total fire detections in central Mato Grosso decreased slightly between 2004 and 2005, while fire detections in drought-stricken northern Rondônia, southern Amazonas, and eastern Acre states in Brazil show higher total fire activity in 2005 than in 2004.
  • For those areas that showed no clear pasture or cropland phenology in the years following deforestation, fire activity was minimal.
  • For pasture deforestation, fire frequency is consistently higher in the year following deforestation mapping than the year before detection of deforestation.

Deforestation fires in Amazonia

  • The number of days on which fires are detected at the same ground location is higher for areas undergoing deforestation than for other fire types in Amazonia, and fires on 3 or more days at the same ground location are almost exclusively linked with forest conversion.
  • During 2003–2007, more than 40% of all high-confidence MODIS fire detections within Amazonia were associated with deforestation.
  • Combustion completeness and fire emissions from recent deforestation may be higher than previous estimates for deforestation carbon losses.
  • Different timing for cropland and pasture deforestation fires is consistent with management practices for intensive agriculture; mechanized crop production with chemical fertilizers is less reliant on the ash layer from deforestation fires for soil fertility than cattle pasture or smallholder agriculture land uses.
  • Deforestation fires for both cropland and pasture in Mato Grosso state were common during July and August of 2003–2005 despite local regulations prohibiting fires during these months to minimize the risk of unintended forest fires (Schroeder et al., in press).

Uncertainties

  • The authors approach to quantify the contribution of deforestation to satellite-based fire activity and characterize individual forest conversions in terms of fire frequency is intentionally conservative.
  • Because of issues of both omission and commission of fires by the MODIS sensors, it is not possible to determine the exact timing or frequency of all fires for the conversion process.
  • The authors begin with a high-confidence subset of active fire detections to reduce data errors from spurious fire detections over tropical forest (Schroeder et al., 2008).
  • Therefore, low-frequency and omitted fires likely increase the fraction of total fire activity in Amazonia linked to deforestation.
  • Because of omission of active fires by MODIS, a more robust method to estimate combustion completeness of the deforestation process may be to combine active fire detections from multiple sensors with other satellite data on deforestation or vegetation phenology to follow the fate of cleared areas over time.

Conclusions

  • The spatial and temporal patterns of fire activity in Amazonia characterize the differences in fire frequency for deforestation and agricultural maintenance.
  • The authors present the fraction of MODIS fire detections associated with forest conversion, quantifying the disproportionate contribution of high-frequency burning for conversion of forest to mechanized cropland in satellite-based fire detections.
  • Fire activity for both cropland and pasture deforestation may continue over multiple years, contributing to higher combustion completeness compared with previous estimates of carbon losses from deforestation.
  • The trend toward more intensive land management in Amazonia is clearly linked with an increase in the frequency of fire usage for deforestation.
  • In addition, combining the frequency of active fire detections with existing deforestation monitoring approaches could assist in the identification of mechanized forest clearing typical of intensive agricultural production.

Did you find this useful? Give us your feedback

Figures (9)

Content maybe subject to copyright    Report

Citations
More filters
Journal ArticleDOI
TL;DR: In this paper, the authors used a revised version of the Carnegie-Ames-Stanford-Approach (CASA) biogeochemical model and improved satellite-derived estimates of area burned, fire activity, and plant productivity to calculate fire emissions for the 1997-2009 period on a 0.5° spatial resolution with a monthly time step.
Abstract: . New burned area datasets and top-down constraints from atmospheric concentration measurements of pyrogenic gases have decreased the large uncertainty in fire emissions estimates. However, significant gaps remain in our understanding of the contribution of deforestation, savanna, forest, agricultural waste, and peat fires to total global fire emissions. Here we used a revised version of the Carnegie-Ames-Stanford-Approach (CASA) biogeochemical model and improved satellite-derived estimates of area burned, fire activity, and plant productivity to calculate fire emissions for the 1997–2009 period on a 0.5° spatial resolution with a monthly time step. For November 2000 onwards, estimates were based on burned area, active fire detections, and plant productivity from the MODerate resolution Imaging Spectroradiometer (MODIS) sensor. For the partitioning we focused on the MODIS era. We used maps of burned area derived from the Tropical Rainfall Measuring Mission (TRMM) Visible and Infrared Scanner (VIRS) and Along-Track Scanning Radiometer (ATSR) active fire data prior to MODIS (1997–2000) and estimates of plant productivity derived from Advanced Very High Resolution Radiometer (AVHRR) observations during the same period. Average global fire carbon emissions according to this version 3 of the Global Fire Emissions Database (GFED3) were 2.0 Pg C year−1 with significant interannual variability during 1997–2001 (2.8 Pg C year−1 in 1998 and 1.6 Pg C year−1 in 2001). Globally, emissions during 2002–2007 were relatively constant (around 2.1 Pg C year−1) before declining in 2008 (1.7 Pg C year−1) and 2009 (1.5 Pg C year−1) partly due to lower deforestation fire emissions in South America and tropical Asia. On a regional basis, emissions were highly variable during 2002–2007 (e.g., boreal Asia, South America, and Indonesia), but these regional differences canceled out at a global level. During the MODIS era (2001–2009), most carbon emissions were from fires in grasslands and savannas (44%) with smaller contributions from tropical deforestation and degradation fires (20%), woodland fires (mostly confined to the tropics, 16%), forest fires (mostly in the extratropics, 15%), agricultural waste burning (3%), and tropical peat fires (3%). The contribution from agricultural waste fires was likely a lower bound because our approach for measuring burned area could not detect all of these relatively small fires. Total carbon emissions were on average 13% lower than in our previous (GFED2) work. For reduced trace gases such as CO and CH4, deforestation, degradation, and peat fires were more important contributors because of higher emissions of reduced trace gases per unit carbon combusted compared to savanna fires. Carbon emissions from tropical deforestation, degradation, and peatland fires were on average 0.5 Pg C year−1. The carbon emissions from these fires may not be balanced by regrowth following fire. Our results provide the first global assessment of the contribution of different sources to total global fire emissions for the past decade, and supply the community with an improved 13-year fire emissions time series.

2,494 citations


Cites background from "Agricultural intensification increa..."

  • ...More fires are observed in the same location when forest is replaced with agriculture 15 that requires near-complete removal of biomass than when land use following deforestation is pastureland (Morton et al., 2008)....

    [...]

  • ...More fires are observed in the same location when forest is replaced with agriculture that requires nearcomplete removal of biomass than when land use following deforestation is pastureland (Morton et al., 2008)....

    [...]

Journal ArticleDOI
24 Apr 2009-Science
TL;DR: What is known and what is needed to develop a holistic understanding of the role of fire in the Earth system are reviewed, particularly in view of the pervasive impact of fires and the likelihood that they will become increasingly difficult to control as climate changes.
Abstract: Fire is a worldwide phenomenon that appears in the geological record soon after the appearance of terrestrial plants. Fire influences global ecosystem patterns and processes, including vegetation distribution and structure, the carbon cycle, and climate. Although humans and fire have always coexisted, our capacity to manage fire remains imperfect and may become more difficult in the future as climate change alters fire regimes. This risk is difficult to assess, however, because fires are still poorly represented in global models. Here, we discuss some of the most important issues involved in developing a better understanding of the role of fire in the Earth system.

2,365 citations

Journal ArticleDOI
TL;DR: For the period 1990-2009, the mean global emissions from land use and land cover change (LULCC) are 1.14 ± 0.18 Pg C yr−1 as discussed by the authors.
Abstract: . The net flux of carbon from land use and land-cover change (LULCC) accounted for 12.5% of anthropogenic carbon emissions from 1990 to 2010. This net flux is the most uncertain term in the global carbon budget, not only because of uncertainties in rates of deforestation and forestation, but also because of uncertainties in the carbon density of the lands actually undergoing change. Furthermore, there are differences in approaches used to determine the flux that introduce variability into estimates in ways that are difficult to evaluate, and not all analyses consider the same types of management activities. Thirteen recent estimates of net carbon emissions from LULCC are summarized here. In addition to deforestation, all analyses considered changes in the area of agricultural lands (croplands and pastures). Some considered, also, forest management (wood harvest, shifting cultivation). None included emissions from the degradation of tropical peatlands. Means and standard deviations across the thirteen model estimates of annual emissions for the 1980s and 1990s, respectively, are 1.14 ± 0.23 and 1.12 ± 0.25 Pg C yr−1 (1 Pg = 1015 g carbon). Four studies also considered the period 2000–2009, and the mean and standard deviations across these four for the three decades are 1.14 ± 0.39, 1.17 ± 0.32, and 1.10 ± 0.11 Pg C yr−1. For the period 1990–2009 the mean global emissions from LULCC are 1.14 ± 0.18 Pg C yr−1. The standard deviations across model means shown here are smaller than previous estimates of uncertainty as they do not account for the errors that result from data uncertainty and from an incomplete understanding of all the processes affecting the net flux of carbon from LULCC. Although these errors have not been systematically evaluated, based on partial analyses available in the literature and expert opinion, they are estimated to be on the order of ± 0.5 Pg C yr−1.

903 citations


Cites background from "Agricultural intensification increa..."

  • ...…captures how many times a fire is seen in the same grid cell, and is related to the completeness of conversion; multiple fire events are needed for complete removal of biomass, resulting in high fire persistence (Morton et al., 2008) and high combustion completeness (van der Werf et al., 2010)....

    [...]

  • ...The fraction and fate of biomass removed as a result of LULCC varies depending on the land use following clearing (Morton et al., 2008)....

    [...]

Journal ArticleDOI
TL;DR: In this article, the authors present a comprehensive assessment of global anthropogenic particulate matter (PM) emissions including the consistent and harmonized calculation of mass-based size distribution (PM1, PM2.5, PM10), as well as primary carbonaceous aerosols including black carbon (BC) and organic carbon (OC).
Abstract: . This paper presents a comprehensive assessment of historical (1990–2010) global anthropogenic particulate matter (PM) emissions including the consistent and harmonized calculation of mass-based size distribution (PM1, PM2. 5, PM10), as well as primary carbonaceous aerosols including black carbon (BC) and organic carbon (OC). The estimates were developed with the integrated assessment model GAINS, where source- and region-specific technology characteristics are explicitly included. This assessment includes a number of previously unaccounted or often misallocated emission sources, i.e. kerosene lamps, gas flaring, diesel generators, refuse burning; some of them were reported in the past for selected regions or in the context of a particular pollutant or sector but not included as part of a total estimate. Spatially, emissions were calculated for 172 source regions (as well as international shipping), presented for 25 global regions, and allocated to 0.5° × 0.5° longitude–latitude grids. No independent estimates of emissions from forest fires and savannah burning are provided and neither windblown dust nor unpaved roads emissions are included. We estimate that global emissions of PM have not changed significantly between 1990 and 2010, showing a strong decoupling from the global increase in energy consumption and, consequently, CO2 emissions, but there are significantly different regional trends, with a particularly strong increase in East Asia and Africa and a strong decline in Europe, North America, and the Pacific region. This in turn resulted in important changes in the spatial pattern of PM burden, e.g. European, North American, and Pacific contributions to global emissions dropped from nearly 30 % in 1990 to well below 15 % in 2010, while Asia's contribution grew from just over 50 % to nearly two-thirds of the global total in 2010. For all PM species considered, Asian sources represented over 60 % of the global anthropogenic total, and residential combustion was the most important sector, contributing about 60 % for BC and OC, 45 % for PM2. 5, and less than 40 % for PM10, where large combustion sources and industrial processes are equally important. Global anthropogenic emissions of BC were estimated at about 6.6 and 7.2 Tg in 2000 and 2010, respectively, and represent about 15 % of PM2. 5 but for some sources reach nearly 50 %, i.e. for the transport sector. Our global BC numbers are higher than previously published owing primarily to the inclusion of new sources. This PM estimate fills the gap in emission data and emission source characterization required in air quality and climate modelling studies and health impact assessments at a regional and global level, as it includes both carbonaceous and non-carbonaceous constituents of primary particulate matter emissions. The developed emission dataset has been used in several regional and global atmospheric transport and climate model simulations within the ECLIPSE (Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants) project and beyond, serves better parameterization of the global integrated assessment models with respect to representation of black carbon and organic carbon emissions, and built a basis for recently published global particulate number estimates.

448 citations

Journal ArticleDOI
16 Aug 2011-PLOS ONE
TL;DR: Analyzes the global tropical forest biome using forest fires as a high resolution proxy for deforestation; disaggregates impacts by remoteness, aproxy for deforestation pressure; and compares strictly protected vs. multiple use PAs vs indigenous areas to suggest some compatibility between global environmental goals and support for local livelihoods.
Abstract: Protected areas (PAs) cover a quarter of the tropical forest estate. Yet there is debate over the effectiveness of PAs in reducing deforestation, especially when local people have rights to use the forest. A key analytic problem is the likely placement of PAs on marginal lands with low pressure for deforestation, biasing comparisons between protected and unprotected areas. Using matching techniques to control for this bias, this paper analyzes the global tropical forest biome using forest fires as a high resolution proxy for deforestation; disaggregates impacts by remoteness, a proxy for deforestation pressure; and compares strictly protected vs. multiple use PAs vs indigenous areas. Fire activity was overlaid on a 1 km map of tropical forest extent in 2000; land use change was inferred for any point experiencing one or more fires. Sampled points in pre-2000 PAs were matched with randomly selected never-protected points in the same country. Matching criteria included distance to road network, distance to major cities, elevation and slope, and rainfall. In Latin America and Asia, strict PAs substantially reduced fire incidence, but multi-use PAs were even more effective. In Latin America, where there is data on indigenous areas, these areas reduce forest fire incidence by 16 percentage points, over two and a half times as much as naive (unmatched) comparison with unprotected areas would suggest. In Africa, more recently established strict PAs appear to be effective, but multi-use tropical forest protected areas yield few sample points, and their impacts are not robustly estimated. These results suggest that forest protection can contribute both to biodiversity conservation and CO2 mitigation goals, with particular relevance to the REDD agenda. Encouragingly, indigenous areas and multi-use protected areas can help to accomplish these goals, suggesting some compatibility between global environmental goals and support for local livelihoods.

411 citations


Cites background from "Agricultural intensification increa..."

  • ...[48] of screened ‘highconfidence’ fire detection with a deforestation measure based on high resolution Landsat imagery found that 87% of crop-related deforestation and 73% of pasture-related deforestation is associated with at least one such fire....

    [...]

References
More filters
Journal ArticleDOI
22 Jul 2005-Science
TL;DR: Global croplands, pastures, plantations, and urban areas have expanded in recent decades, accompanied by large increases in energy, water, and fertilizer consumption, along with considerable losses of biodiversity.
Abstract: Land use has generally been considered a local environmental issue, but it is becoming a force of global importance. Worldwide changes to forests, farmlands, waterways, and air are being driven by the need to provide food, fiber, water, and shelter to more than six billion people. Global croplands, pastures, plantations, and urban areas have expanded in recent decades, accompanied by large increases in energy, water, and fertilizer consumption, along with considerable losses of biodiversity. Such changes in land use have enabled humans to appropriate an increasing share of the planet’s resources, but they also potentially undermine the capacity of ecosystems to sustain food production, maintain freshwater and forest resources, regulate climate and air quality, and ameliorate infectious diseases. We face the challenge of managing trade-offs between immediate human needs and maintaining the capacity of the biosphere to provide goods and services in the long term.

10,117 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated fire emissions during the 8 year period from 1997 to 2004 using satellite data and the CASA biogeochemical model, and found that on average approximately 58 Pg C year −1 was fixed by plants as NPP, and approximately 95% of this was returned back to the atmosphere via R h.
Abstract: Biomass burning represents an important source of atmospheric aerosols and greenhouse gases, yet little is known about its interannual variability or the underlying mechanisms regulating this variability at continental to global scales. Here we investigated fire emissions during the 8 year period from 1997 to 2004 using satellite data and the CASA biogeochemical model. Burned area from 2001–2004 was derived using newly available active fire and 500 m. burned area datasets from MODIS following the approach described by Giglio et al. (2006). ATSR and VIRS satellite data were used to extend the burned area time series back in time through 1997. In our analysis we estimated fuel loads, including organic soil layer and peatland fuels, and the net flux from terrestrial ecosystems as the balance between net primary production (NPP), heterotrophic respiration ( R h ), and biomass burning, using time varying inputs of precipitation (PPT), temperature, solar radiation, and satellite-derived fractional absorbed photosynthetically active radiation (fAPAR). For the 1997–2004 period, we found that on average approximately 58 Pg C year −1 was fixed by plants as NPP, and approximately 95% of this was returned back to the atmosphere via R h . Another 4%, or 2.5 Pg C year −1 was emitted by biomass burning; the remainder consisted of losses from fuel wood collection and subsequent burning. At a global scale, burned area and total fire emissions were largely decoupled from year to year. Total carbon emissions tracked burning in forested areas (including deforestation fires in the tropics), whereas burned area was largely controlled by savanna fires that responded to different environmental and human factors. Biomass burning emissions showed large interannual variability with a range of more than 1 Pg C year −1 , with a maximum in 1998 (3.2 Pg C year −1 ) and a minimum in 2000 (2.0 Pg C year −1 ).

1,639 citations


"Agricultural intensification increa..." refers background in this paper

  • ...…persistence, has been used previously to assess Amazon forest fire severity (Elvidge et al., 2001), adjust burned area estimates in tropical forest ecosystems (Giglio et al., 2006b), and scale combustion completeness estimates in a coarse-resolution fire emission model (van der Werf et al., 2006)....

    [...]

  • ...Fires for land clearing and management in Amazonia are a large anthropogenic source of carbon emissions to the atmosphere (Houghton et al., 2000; DeFries et al., 2002; van der Werf et al., 2006; Gullison et al., 2007)....

    [...]

Journal ArticleDOI
23 Mar 2006-Nature
TL;DR: It is reported that protected areas in the Amazon basin—the central feature of prevailing conservation approaches—are an important but insufficient component of this strategy, based on policy-sensitive simulations of future deforestation.
Abstract: 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.

1,201 citations


"Agricultural intensification increa..." refers background in this paper

  • ...…deforestation dynamic alters fire use and carbon emissions from deforestation in Amazonia is germane to studies of future land cover change (Soares-Filho et al., 2006), carbon accounting in tropical ecosystems (Stephens et al., 2007), and efforts to reduce emissions from tropical…...

    [...]

  • ...How this changing deforestation dynamic alters fire use and carbon emissions from deforestation in Amazonia is germane to studies of future land cover change (Soares-Filho et al., 2006), carbon accounting in tropical ecosystems (Stephens et al....

    [...]

Journal ArticleDOI
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


"Agricultural intensification increa..." refers background or methods in this paper

  • ...Concentrated fire activity in Mato Grosso state during 2003–2004 is consistent with peak deforestation for cropland, driven, in part, by high prices for soybean exports (Morton et al., 2006)....

    [...]

  • ...The postclearing land use for each deforestation event was identified previously using phenological information from time series of MODIS data at 250 m resolution (Morton et al., 2006)....

    [...]

  • ...ings for mechanized crop production are larger, on an average, than clearings for pasture, and the forest conversion process is often completed in o1 year (Morton et al., 2006)....

    [...]

  • ...…the MODIS sensors, information on fire frequency r 2008 The Authors Journal compilation r 2008 Blackwell Publishing Ltd, Global Change Biology, 14, 2262–2275 at 1-km resolution is commensurate with clearing sizes for mechanized crop production in Amazonia that average 3.3 km2 (Morton et al., 2006)....

    [...]

  • ...…1 1 301 314 9299, e-mail: morton@geog.umd.edu r 2008 The Authors 2262 Journal compilation r 2008 Blackwell Publishing Ltd ings for mechanized crop production are larger, on an average, than clearings for pasture, and the forest conversion process is often completed in o1 year (Morton et al., 2006)....

    [...]

Journal ArticleDOI
21 Oct 2005-Science
TL;DR: This work developed a large-scale, high-resolution, automated remote-sensing analysis of selective logging in the top five timber-producing states of the Brazilian Amazon, equivalent to 60 to 123% of previously reported deforestation area.
Abstract: Amazon deforestation has been measured by remote sensing for three decades. In comparison, selective logging has been mostly invisible to satellites. We developed a large-scale, high-resolution, automated remote-sensing analysis of selective logging in the top five timber-producing states of the Brazilian Amazon. Logged areas ranged from 12,075 to 19,823 square kilometers per year (±14%) between 1999 and 2002, equivalent to 60 to 123% of previously reported deforestation area. Up to 1200 square kilometers per year of logging were observed on conservation lands. Each year, 27 million to 50 million cubic meters of wood were extracted, and a gross flux of ∼0.1 billion metric tons of carbon was destined for release to the atmosphere by logging.

925 citations


"Agricultural intensification increa..." refers background in this paper

  • ...…to high-frequency fire detections, such that fires must be detected at the same ground location on 2 or more days, despite omission of fires from MODIS attributable to fire size (Cardoso et al., 2005), orbital coverage (Schroeder et al., 2005), and the diurnal cycle of fire activity (Giglio, 2007)....

    [...]

Related Papers (5)
Frequently Asked Questions (15)
Q1. What have the authors contributed in "Agricultural intensification increases deforestation fire activity in amazonia" ?

Morton et al. this paper estimated the contribution of fires from the deforestation process to total fire activity based on the local frequency of active fire detections from the Moderate Resolution Imaging Spectroradiometer ( MODIS ) sensors. 

The authors present the fraction of MODIS fire detections associated with forest conversion, quantifying the disproportionate contribution of high-frequency burning for conversion of forest to mechanized cropland in satellite-based fire detections. 

Most areas cleared for pasture had 0–1 years of high-frequency fire usage, although a small portion (14%) had frequent fire detections over 2–3 years typical of mechanized forest clearing. 

Because of more frequent fire usage in preparation for mechanized agriculture, few areas deforested for cropland in 2004 had no high-confidence fire detections during 2004 (12%). 

In addition to deforestation-linked fires, slow-moving forest fires and contagion of other accidental burning events may also have contributed to the higher fraction of repeated fire activity in these regions. 

fires on 2 or more days during the same dry season accounted for 36–47% of the annual fire activity in Brazilian Amazonia during 2003–2007, with greater contributions from repeated fires in years with highest fire activity. 

Low-frequency fire detections are typical of fires in Cerrado woodland savannas and for agricultural maintenance, because grass and crop residues are fully consumed by a single fire. 

Combining daytime and night-time observations from multiple sensors may better characterize the duration of individual fires to allow more direct interpretation of satellite data for trace gas emissions. 

If emissions ratios do change during the course of the deforestation process as a function of the size or moisture content of woody fuels, the frequency of satellite-based fire detections provides one method to characterize time-varying trace gas emissions for Amazonia. 

Mechanized equipment can remove stumps and woody roots inpreparation for cropland (Morton et al., 2006) such that both above and belowground forest biomass are burned. 

The carryover of fire activity from forest clearing into subsequent years is a cumulative process, such that total high-frequency fire activity in any year represents burning for multiple years of forest loss (Fig. 5). 

High-frequency fire activity may last for several years following initial forest clearing, further increasing the expected combustion completeness of the deforestation process (Fig. 4). 

Findings in this studyr 2008 The Authors Journal compilation r 2008 Blackwell Publishing Ltd, Global Change Biology, 14, 2262–2275suggest that average combustion completeness for recent deforestation may be two to four times greater than that estimated for deforestation during 1989–1998 (Houghton et al., 2000), increasing per-area gross fire emissions for the current decade by a similar magnitude in regions where mechanized deforestation is common. 

The trend toward more intensive land management in Amazonia is clearly linked with an increase in the frequency of fire usage for deforestation. 

Because of issues of both omission and commission of fires by the MODIS sensors, it is not possible to determine the exact timing or frequency of all fires for the conversion process.