Dynamics, Patterns and Causes of Fires in Northwestern Amazonia

According to recent studies, two widespread droughts occurred in the Amazon basin, one during 2005 and one during 2010. The drought increased the prevalence of climate-driven fires over most of the basin. Given the importance of human-atmosphere-vegetation interactions in tropical rainforests, these events have generated concerns over the vulnerability of this area to climate change. This paper focuses on one of the wettest areas of the basin, Northwestern Amazonia, where the interactions between the climate and fires are much weaker and where little is known about the anthropogenic drivers of fires. We have assessed the response of fires to climate over a ten-year period, and analysed the socio-economic and demographic determinants of fire occurrence. The patterns of fires and climate and their linkages in Northwestern Amazonia differ from the enhanced fire response to climate variation observed in the rest of Amazonia. The highest number of recorded fires in Northwestern Amazonia occurred in 2004 and 2007, and this did not coincide with the periods of extreme drought experienced in Amazonia in 2005 and 2010. Rather, during those years, Northwestern Amazonia experienced a relatively small numbers of fire hotspots. We have shown that fire occurrence correlated well with deforestation and was determined by anthropogenic drivers, mainly small-scale agriculture, cattle ranching (i.e., pastures) and active agricultural frontiers (including illegal crops). Thus, the particular climatic conditions for air convergence and rainfall created by proximity to the Andes, coupled with the presence of one of the most active colonisation fronts in the region, make this region differently affected by the general drought-induced fire patterns experienced by the rest of the Amazon. Moreover, the results suggest that, even in this wet region, humans are able to modify the frequency of fires and impact these historically well preserved forests

A systematic comparison of deforestation drivers and policy effectiveness across the Amazon biome

The Amazon biome, spanning nine countries, has one of the highest rates of deforestation worldwide. This deforestation contributes to biodiversity loss, climate change, the spread of infectious diseases, and damage to rural and indigenous livelihoods. Hundreds of articles have been published on the topic of deforestation across Amazonia, yet there has been no recent synthesis of deforestation drivers and deforestation-control policy effectiveness in the region. Here we undertook the first systematic review of papers published between 2000 to 2021 that have causally linked proximate and underlying drivers and policies to deforestation outcomes in Amazonia. In the 155 articles that met our inclusion criteria, we find that causal research is concentrated in Brazil, and to a lesser degree Peru, Ecuador, and Bolivia. There has been little study of the Guianas, Venezuela or Colombia. Large- and small-scale agriculture linked to improved market access and high agricultural prices are frequently researched proximate drivers of deforestation across the heavily researched regions. In the Guianas research focuses on mining with little focus on underlying causes. Research on infrastructure expansion, mining and oil extraction and on technological, sociocultural, and institutional factors remains sparse. Many public and private policies have been found to be effective in controlling deforestation across the biome, with protected areas standing out as particularly successful in slowing deforestation, vis-à-vis supply chain approaches. Our findings indicate a greater need for research on: i) additional deforestation drivers beyond agriculture and economic factors; ii) the complex interactions between different drivers and deforestation control policies; iii) causes underlying deforestation in low or new deforestation areas; and iv) the dynamics between Amazonian subregions and countries. Better understanding of all deforestation drivers and the effectiveness of existing deforestation mitigation policies is a prerequisite for completely halting deforestation in Amazonia

Characterising fire spatial pattern interactions with climate and vegetation in Colombia

Vegetation burning in tropical countries is a threat to the environment, causing not only local ecological, economic and social impacts, but also large-scale implications for global change. The burning is usually a result of interacting factors, such as climate, land-use and vegetation type. Satellite-derived monthly time series datasets of rainfall, burned area and active fire detections between December 2000 and 2009 were used in this study. A map of vegetation types was also used to determine these factors' spatial and temporal variability and interactions with the total amount of burned area and active fires detected in Colombia. Grasslands represented the vegetation most affected by fires every year in terms of burned area (standardised by their total area), followed by secondary vegetation, pasture and forests. Grasslands were also most affected by active fires, but followed closely by pasture, agricultural areas, secondary vegetation and forests. The results indicated strong climate and fire seasonality and marked regional difference, partly explained by climatic differences amongst regions and vegetation types, especially in the Orinoco and Caribbean regions. The incidence of fire in the Amazon and Andes was less influenced by climate in terms of burned area impacted, but the strength of the ENSO phenomenon affected the Orinoco and the Andes more in terms of burned area. Many of the active fires detected occurred in areas of transition between the submontane and lowland Andes and the Amazon, where extensive conversion to pasture is occurring. The possible high impact of small fires on the tropical rainforest present in this transition area and the Amazonian rainforest deserves more attention in Colombia due to its previous lack of attention to its contribution to global change. © 2010 Elsevier B.V

A pan-tropical cascade of fire driven by El Niño/Southern Oscillation

The El Niño/Southern Oscillation (ENSO) has a pronounced influence on year-to-year variations in climate 1 . The response of fires to this forcing 2 is complex and has not been evaluated systematically across different continents. Here we use satellite data to create a climatology of burned-area and fire-emissions responses, drawing on six El Niño and six La Niña events during 1997-2016. On average, reductions in precipitation and terrestrial water storage increased fire emissions in pan-tropical forests by 133% during and following El Niño as compared with La Niña. Fires peaked in equatorial Asia early in the ENSO cycle when El Niño was strengthening (Aug-Oct), before moving to southeast Asia and northern South America (Jan-Apr), Central America (Mar-May) and the southern Amazon (Jul-Oct) during the following year. Large decreases in fire occurred across northern Australia during Sep-Oct of the second year from a reduced fuel availability. Satellite observations of aerosols and carbon monoxide provided independent confirmation of the spatiotemporal evolution of fire anomalies. The predictable cascade of fire across different tropical continents described here highlights an important time delay in the Earth system's response to precipitation redistribution. These observations help to explain why the growth rate of atmospheric CO2 increases during El Niño 3 and may contribute to improved seasonal fire forecasts