Forest fires and deforestation in the central Amazon: Effects of landscape and climate on spatial and temporal dynamics.

Forest fires and deforestation are the main threats to the Amazon forest. Extreme drought events exacerbate the impact of forest fire in the Amazon, and these drought events are predicted to become more frequent due to climate change. Fire escapes into the forest from agriculture and pasture areas. We assessed the potential drivers of deforestation and forest fires in the central Brazilian Amazon and show that over a period of 31 years (1985-2015) forest fires occurred only in years of extreme drought induced by El Niño (1997, 2009 and 2015). The association of forest fires with strong El Niños shows the vulnerability of forest to climate change. The areas deforested were closely associated with navigable rivers: 62% of the total deforestation from 2000 to 2018 was located within the 2 km of rivers. There was a notable increase in deforestation and forest fire during the 2015 El Niño in comparison to previous years. Only a small part of the forest that burned was deforested in the years following the wildfires: 7% (1997), 3% (2009) and 1.5% (2015). Forest close to roads, rivers and established deforestation is susceptible to deforestation and fire since these areas are attractive for agriculture and pasture. Indigenous land was shown to be important in protecting the forest, while rural settlement projects attracted both forest fire and deforestation. Of the total area in settlement projects, 40% was affected by forest fires and 17% was deforested. Rivers are particularly important for deforestation in this part of Amazonia, and efforts to protect forest along the rivers are therefore necessary. The ability to predict where deforestation and fires are most likely to occur is important for designing policies for preventative actions.

Deforestation Dynamics on an Amazonian Peri-Urban Frontier: Simulating the Influence of the Rio Negro Bridge in Manaus, Brazil.

Peri-urban expansion is an increasingly important source of tropical deforestation, and a bridge over the Rio Negro in Brazil's state of Amazonas provides an unusual opportunity to quantify these impacts with clear "before" and "after" periods. Inaugurated in 2011, the bridge connects Manaus to forest areas on the right bank of the river, thus opening a new frontier for peri-urban expansion. We used the AGROECO model in the Dinamica-EGO software to simulate "Bridge" and "No-bridge" scenarios to evaluate the spatial dynamics of deforestation in the municipalities (counties) of Iranduba, Manacapuru and Novo Airão. Simulated deforestation between 2011 and 2030 for the study area as a whole was 106% higher with the bridge. The portion of the study area with expansion of roads had four times more deforestation in the Bridge scenario than in the No-bridge scenario. A change in the spatial distribution of the deforested area was detected, with an advance of deforestation in the municipality closest to the bridge. Deforestation also expanded in more distant regions. Peri-urbanization in the Bridge scenario demonstrates the possible increase in the spatial distribution of deforestation activity beyond the already-consolidated frontier, making the deforestation pattern more diffuse and leaving the remaining forest even more vulnerable. Impact of the bridge could further increase due to additional factors, such as the planned opening of a highway (BR-319) connecting Manaus to Brazil's "arc of deforestation."