Ecosystem Studies & Management
Understanding Fire in the Brazilian Amazon
Fire is an important agent of transformation in the Amazon landscape. It is used as a tool for maintaining agricultural lands in the Amazon. Most forest fires are a result of these management fires escaping into neighboring forest. These tend to be low-intensity, when compared to fires seen in North America, but every year they burn thousands of hectares of Amazon forest with drought years. El Niño years are particularly damaging. For example, more than 750,000 acres burned in the southern Amazon in 2005. These types of fires are common, yet the long and short term ecological impacts are poorly documented and understood.
After the burn, a census is taken of the trees to see how many were unaffected, scorched, or how they may be reacting or recovering from the burn. Canopy density is measured at monthly intervals throughout the year, to monitor the impact of the fire and rate of tree mortality and recovery. Temperature and humidity are monitored at multiple spots in each forest throughout the year, to detect changes in the microclimate of the forest; and soil moisture is measured at set points in the parcels and in two 10-m deep pits at regular intervals, to see how the changes in forest density may affect the water available in the soil.
Field researchers taking measurements just prior to the 2009 experimental burn.
These experimental fires are a crucial part of understanding what is happening in the Amazon today, as fires set by landholders to improve their pastures or to burn recently felled forest in preparation for planting often escape beyond their intended boundaries. Undisturbed forests are resistant to burning because their dense leaf canopy prevents much of the incoming solar radiation from reaching the forest interior, keeping the litter layer too moist to sustain a fire. Now large areas of forest are selectively logged prior to being settled, leaving holes in the canopy; longer, more intense dry seasons provoke leaf thinning; and both of these changes allow the litter to become dry enough to sustain a fire. Once a forest has burned a first time, the combination of a more damaged forest canopy and a stock of larger fuel from trees killed by prior fires make it even more vulnerable to subsequent fires. When humans move into an area and begin clearing forest, they seldom abandon it and move away, so until education can alter their behavior, repeated sources of ignition in the future are all but guaranteed.
One of the soil pits – each nearly 10 meters deep – at the Fazenda Tanguro.
This “savannization experiment” is a learning laboratory for Brazilian students who live in the Amazon transition forest. School groups frequently visit the research station, and several undergraduate and graduate students are conducting their theses research within the project. The Grupo Maggi, the world’s largest private producer of soybeans, owns the study site. By conducting this work on this property, it is hoped that the fire experiment, along with concurrent studies of riparian zone recuperation, soil management, and water quality, will help this and other companies improve the ecological management of their properties. Grupo Maggi provides no funding for this research.
Through this work, researchers are learning not only how to predict the ways in which current trends in land use and climate change might alter forests throughout the southern Amazon in the near future but also what mitigation strategies can be effectively applied to reduce human impacts regionally and globally. Additionally, information gathered in this project assists in many other projects including; understanding of how the forest degradation affects the global carbon cycle and climate change; creating models to predict forest vulnerability to fire; and developing methods for satellite monitoring of forest fires to help enhance enforcement capabilities, develop zoning strategies and improve techniques for identifying and measuring the area affected by these fires.
The Amazon Environmental Research Institute (IPAM) is a key collaborator in this work.
Much of the Center’s work at Fazenda Tanguro is supported by NSF and by the Gordon and Betty Moore Foundation.
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- Linking Land-Use Change to Economic Drivers and Biophysical Limitations of Agricultural Expansion in the Brazilian Cerrado
- Understanding the Influence of Agricultural Expansion on the Water, Energy, and Climate Cycles in the Brazilian Amazon
- Feedbacks between Water and Deforestation in Tropical South America
- Promoting Good Land Stewardship through the Registry of Social-Environmental Responsibility
- Community Forestry and Sustainable Livelihoods along Brazil’s Tapajós River
- Fire and Carbon Sequestration in Boreal North America