Specialist defends controlled burning in the Brazilian savannah

Controlled burning reduces the risk of accidental fires and could help to protect the biodiversity of the Cerrado, affirms researcher.

By Karina Toledo

Agência FAPESP – Major fires are frequent in the Cerrado (savannah region), particularly in the winter months, when strong winds, lack of rainfall, low humidity and dry vegetal mass help to spread the flames. It may seem counterintuitive, but many specialists believe that the best way to prevent the problem and protect the biodiversity of this threatened biome is the precisely controlled use of fire.

“Controlled burning not only reduces the risk of accidental fires but also offers benefits for vegetation. Two-thirds of the species in the Cerrado, which constitute a herbaceous stratum, are adapted to frequent fires, and many of them could disappear if fire is completely avoided,” warned Vânia Regina Pivello, professor at Universidade de São Paulo’s Biosciences Institute (IB-USP), during the fourth event of the 2013 Conference Cycle held by BIOTA Education, organized by the BIOTA-FAPESP program on May 16.

In the acidic, nutrient-poor soil of the Cerrado, explains Pivello, the leaves of the vegetation tend to accumulate a large quantity of lignin, a structural substance that does not decompose easily. Fire plays a role in accelerating the recycling process of nutrients, allowing them to be reutilized more quickly by the low-lying vegetation. In addition, the thermal shock caused by fire breaks the vegetative dormancy of seeds, causing fissures that favor the penetration of water and stimulate germination.

Thanks to millions of years of evolution under the influence of fire, affirms the professor, vegetation in the Cerrado, especially herbaceous vegetation, can recover quickly after a fire. The vegetation soon sprouts again, attracting several herbivores in search of new fodder. The same trees, which do not generally benefit from fire, have developed adaptive defense mechanisms, such as thick bark that covers the trunk and acts as thermal insulation.

“There are regions in the Cerrado where herbaceous species predominate, especially grass. There are other regions in which the majority of the vegetation is arboreus. There are also places where there is a balance between the two. One must preserve all these physiognomies. However, because fire tends to favor the herbaceous stratum and significantly damage trees, the ideal frequency of fires varies in accordance with each specific situation,” explained Pivello.

In addition to maintaining biodiversity, controlled burning has the objective of reducing the quantity of accumulated organic material that works as a fuel in fires caused by lightning or farming practices.

According to the professor, controlled burning can be performed when conditions are not as dry as in winter, such as April or May, and at night when the humidity in the air is greater. “If we do not anticipate accidental fire, major fires will happen every three or four years in the majority of the reserves that aim to protect the Cerrado. Inevitably, the Cerrado will burn, and it will be at a time when no one is controlling it,” she affirmed.

As an example, Pivello cites the large fire that affected 90% of the National Emu Park (Goías) in 2010. In cases like these, she affirmed, fauna are the hardest hit because they are without refuge.

Controlled burning, however, was prohibited in Brazil for a long time. A 1989 law authorized the practice, but according to Pivello it is still difficult to obtain the required license from environmental bodies. In addition to a general lack of knowledge about the importance of fire for the Cerrado, the professor points to a lack of structure for effective controlled burning.

“There is always the risk of fire racing out of control and reaching a neighboring farm, which would be a big problem. For this reason, there must be a well-trained and well-equipped fire brigade. However, both federal and state conservation units lack human and material resources,” she affirmed.

The professor also stressed the need for studies that allow the preparation of an appropriate fire management plan for every region in the Cerrado. “This depends on experimentation. We have taken advantage of accidental fires to reach our conclusions, but ideally we would conduct projects to test controlled burning programs. Otherwise, we will never be sure what type of handling is most adequate for each location,” she said.

Lost treasure

The lack of adequate controlled burning, however, is not the only threat to biodiversity in the Cerrado, which originally covered 22% of the Brazilian territory. Thanks mainly to soybean production (but also to livestock production, industrialization, urbanization and timber extraction for charcoal production for use in steel mines), more than 55% of the biome has been deforested or discharacterized.

“The Cerrado is one of the planet’s 25 ecosystems with a high risk of extinction,” stressed Vanderlan Bolzani, full professor at the Universidade Estadual Paulista’s Chemistry Institute (IQ-Unesp), when presenting the workshop “Beauty & Inspiration in the Micromolecular Universe of Biodiversity in the Cerrado,” which was part of the programming of the fourth event in the 2013 Conference Cycle.

“This area has aroused intense interest from agribusiness. The production of oilseed has been growing exponentially in the Cerrado, which poses a problem because we are taking out all the vegetation that could bring us value. The country can gain economic advantages with the discovery of natural products with pharmacological properties of interest,” evaluates Bolzani.

During her presentation, the Unesp professor gave an example of medicine produced by national and international companies based on the scientific investigation of plants in the Cerrado. She also presented work developed by the NuBBE Database, which collects data on natural products isolated from Brazil’s biodiversity and brings together information about 640 compounds of natural origin studied in the last 15 years.

The initiative, which developed under the auspices of the BIOTA-FAPESP Program, was born of cooperation between researchers on development and sustainable use from the Núcleo de Bioensaios, Biossíntese e Ecofisiologia de Produtos Naturais (NuBBE), Universidade Estadual Paulista (Unesp) and the Chemical Medicinal and Computational Laboratory (LQMC) at Universidade de São Paulo’s São Carlos Physics Institute (USP-São Carlos).