Fire management benefits tree growth and survival in the Brazilian savanna

The Cerrado has evolved with natural fires. However, human activities have altered fire regimes; in protected areas (PA), fire has been suppressed for years. Fire exclusion increases fuel loads busting the risk of wildfires, especially during the late-dry season. An Integrated Fire Management (IFM) program was implemented in Cerrado's PAs in 2014 to reduce wildfires. However, there is limited information about the effects of management burns on vegetation. Considering the demands of PA managers, we compared woody plant responses to management burns, wildfires, and fire exclusion for 5 years and assessed factors determining these responses, including fire behavior and pre-fire plant size. For this, we selected seven sites in open savanna areas of Northern Brazil. In each site, three 50 x 100m plots were assigned to the following treatments: mid-dry season biennial fires, similar to management burns; late-dry season biennial fires, similar to wildfires; and total fire protection. From 2015 to 2018, we assessed changes in vegetation structure by calculating basal area and stem density and evaluated the plant damages and responses to each treatment. Mid-dry season fires resulted in less topkill, more resprouting, and higher rates of non-damaged plants than late-dry season fires. This difference was influenced by flame height and by pre-fire stem diameter. Mid-dry season fires led to minimal changes in vegetation structure. However, continuous vegetation monitoring is essential in managed areas to detect changes and should be part of a fire management program.