Immediate responses of forests to understorey fires during the 2010 Amazonian drought

Despite an 82% decline in deforestation rates in Amazonia, fires are still on the rise. 2010 has been a year of severe drought and fire in Amazonia. Over the last months (July and August) the number of fire counts has reached 80% of the 2005 values, which was characterized as the drought of the century. Through the beginning of September, fire outbreaks have intensified in southwest Amazonia, including Brazil, Peru and Bolivia. This drought has been associated with warmer than average sea surface temperature in the tropical North Atlantic Ocean, in a scenario similar to the 2005 event. Amazon river levels near Iquitos and the Rio Negro near Manaus reached their lowest levels in the last 40 years and since the records began, respectively. This drought is perhaps the strongest ever recorded in this region. Droughts of this magnitude currently occur with a low frequency; however, their intensity and frequency are likely to increase in the 21st century, increasing the risk of severe wildfires in this fire-sensitive system. Understanding the impacts of forest fires on the carbon stocks and ecophysiology following the 2010 drought event is critical because these events may be common in the future climate of Amazonia. Moreover, we are still unable to predict the occurrence and extent of these droughts, we poorly understand how they affect forest fire patterns and how these fires impact the functioning of Amazonian forests. We therefore aim to quantify the impacts of drought-mediated fires on forest carbon stocks and functioning by investigating both the extent of the 2010 drought, and its influence on forest fires. In this project we will use this drought as a proxy for future climatic conditions in the region, which is likely to increase the probability of understorey forest fires. The Amazon is the largest tropical forest and most biodiverse ecosystem on the planet, storing around 86 billion tons of carbon in its biomass (currently similar to 10-years of fossil fuel emissions). Historically, fires in Amazonia have been reported to be rare, and it is unlikely that this biome is adapted to frequent fires. The increased trend in fire outbreaks in the last decades, associated to human activities, poses a growing risk to the stability of carbon stocks, functioning and diversity of Amazonian forests. Studying the effects of drought-induced fires on closed-canopy tropical forests can provide valuable insights regarding the responses of this ecosystem to future changes in the climate and environment. With our South American and American partners, this team is uniquely positioned to evaluate the effects of forest fires in Amazonia. This proposal brings together a multi-disciplinary group of local ecologists (which are currently tracking this drought on-the-ground), fire ecologists, climatologists as well as forest carbon and remote sensing experts in order to provide an integrative analysis of the climatology of this drought, the extent of forest fires and the carbon losses associated with this event. Working as a team, we will measure the different facets of this drought in multiple scales to provide a comprehensive assessment of its impacts. We will initially quantify the spatial extent of the drought and associated forest fires based on a combination of climate and remote sensing data. The team will then implement an extensive field survey to quantify the impacts of fires on carbon stocks and the functioning of the fire-affected forests. Finally, we will generate the first basin-wide map of the 2010 drought-induced fire impact on the Amazonian carbon stocks by integrating the previous data. Due to our close interaction with local governments and communities, we anticipate that this project will not only provide scientific information to help understand and diagnose the impacts of future events, but will also provide support for the development of public policies in order to mitigate climate change impacts in this region.