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SPECIAL BIOTA EDUCATION IV

Open-air laboratory

The Cerrado, the world’s most diversified tropical savannah, holds a little-explored universe of molecules with commercial potential

Great backlands: vegetation consisting of grasses and small and medium-sized trees, one of the typical physiognomies of the Cerrado

FABIO COLOMBINIGreat backlands: vegetation consisting of grasses and small and medium-sized trees, one of the typical physiognomies of the CerradoFABIO COLOMBINI

“The Cerrado won’t reveal its mysteries to one who is not captive on this little piece of earth,” wrote Brazilian novelist João Guimarães Rosa in describing the whims of the landscapes that dominate central Brazil. Many of the secrets of the Cerrado, the world’s largest tropical savannah, may have scientific, social or economic value, yet they are not exposed to view. They belong to the molecular universe. “The Cerrado is a highly sophisticated chemistry laboratory,” said researcher Vanderlan da Silva Bolzani, a professor at the Chemistry Institute at the Universidade Estadual Paulista (Unesp) campus in Araraquara and member of the coordinating team for the Biota-FAPESP program. Her audience was an enthusiastic group of high school students who were attending another meeting in the Biota-FAPESP Education Conference Cycle, held on May 16 in São Paulo.

The Cerrado, Bolzani explained, is a mosaic of environments identified by their different types of soils, climatic conditions and landscapes. Its biological diversity, as with every kind of life form on Earth, is “a result of evolution mediated by chemical processes that, over time, have become increasingly complex.” She believes that the substances produced by the flora of the Cerrado, which are essential to the adaptation and equilibrium of the plants, insects, animals and microorganisms of this ecosystem, may also be useful to humans. Bolzani was referring specifically to secondary plant metabolites, which are the byproducts of a metabolic cycle that begins with photosynthesis, the process by which plants transform solar energy into organic matter. Generally speaking, these compounds, often produced in small quantities, are important mechanisms that plants use to defend against predators or to attract pollinators. They can display biological activity that is useful for designing new drugs. “Scientific research on biodiversity can be a valuable strategy for supplying goods and services that are essential to humans,” Bolzani pointed out. About 100,000 secondary compounds have already been isolated from plants and are being used to make foods, agrochemicals, fuels, cosmetics and other products. This universe that cannot be seen with the naked eye, the chemist noted, adds value to our biodiversity. “And everything that has value needs to be protected.”

But that is not what we are seeing there. According to data from the Ministry of the Environment, between 2002 and 2008 the percentage of deforestation in the Cerrado rose from 43.7% to 47.8%–an area equivalent to 85,000 square kilometers (km²). The average annual deforestation in the region today is 14,200 km². This transformation of the original landscape has placed the Cerrado among the world’s 25 most threatened ecosystems. “But it also continues to be one of the richest,” said biologist Vânia Regina Pivello, a professor in the Ecology Department of the University of São Paulo (USP), who is a guest speaker for the conference cycle. The Cerrado is the second-largest ecosystem in Brazil, covering an expanse of about two million km², or 23% of its national territory. It is smaller than only the Amazonia ecosystem, which, at 3.5 million km², occupies nearly half the country’s total area. According to Pivello, the Cerrado hosts an enormous variety of flora, numbering about 6,000 to 7,000 species (44% of which are endemic to the region), many of them still not sufficiently well known.

These plants are distributed over very distinct landscapes. Specialists generally classify them into at least three physiognomies: campo, composed predominantly of grasses; savannah, consisting of open fields with small to medium-sized trees (5-12 meters in height); and woodland or cerradão, with trees that can reach 20 meters high. “The Cerrado is the world’s most diversified tropical savannah,” Pivello commented.

These formations arose from very specific environmental conditions. One such condition is climate, which in the Cerrado is distinctly seasonal, with well-defined periods of drought interspersed with periods of heavy rain. The depth of the water table is another factor that influences the diversity of the landscapes in this ecosystem. The reason is that the trees there do not adapt well to moist soils. Hence, the closer to the surface the water table is in a given area, the fewer the trees or shrubs. Pivello thinks that this situation promoted the formation of herbaceous vegetation, predominantly grasses.

A third environmental factor that played a role in molding the Cerrado is its very old, low-fertility soil, which is acidic and high in aluminum. “Compared to the soil of other savannahs, in particular those in Africa, the soil of the Cerrado has a low nutrient content,” she said. The soil’s low fertility reduces the occurrence of large grazing animals such as Pampas deer (Ozotoceros bezoarticus). Pivello thinks that the most abundant grazers of the Cerrado are termites and sauba ants, which increase the availability of nutrients for the plants, especially trees and shrubs.

Biologist Vânia Pivello, left, and chemist Vanderlan Bolzani

EDUARDO CESARBiologist Vânia Pivello, left, and chemist Vanderlan BolzaniEDUARDO CESAR

Fire, once again
The preservation and evolution of the plants of the Cerrado are also influenced by fire, which is important for maintaining other Brazilian ecosystems such as the Pampas in the state of Rio Grande do Sul, where burn-offs serve to contain advancing forests of araucária, or Brazilian pine, as well as the densification of woody plants (see Pesquisa FAPESP Issue No. 206).

Fires in the Cerrado are generally short-lived, Pivello explained. “Most fires are caused by man. But there are also cases of natural burn-offs caused by lightning.” In either situation, fire promotes the spouting of many plants and stimulates flowering, opening of fruits and release of seeds. “There are a number of characteristics peculiar to this ecosystem that we now understand to be the result of the vegetation’s adaptation to fire,” the biologist noted. One characteristic possibly shaped by fire are the thick layers of bark that cover the trunks of some trees and also function as thermal insulators. The frequency of fires also influences the physiognomy of the vegetation by reducing the number of trees and increasing the herbaceous stratum, particularly grasses, whose roots are superficial and use nutrients deposited in the form of ash.

Pampas deer, in an area of the Cerrado consumed by fire

FABIO COLOMBINI Pampas deer, in an area of the Cerrado consumed by fireFABIO COLOMBINI

Just as it benefits the Cerrado, fire also can be harmful. “You have to be attentive to the frequency of the burn-offs, the timing of their occurrence and the intensity of the heat they produce,” Pivello said. “These are important factors in determining their effects on the local vegetation.” Because of the potentially devastating effect of fires, she defends controlled management practices in the region as a way to prevent accidental fires from burning out of control.

One reason that contributes to the high frequency of burn-offs in the Cerrado is the fact that the vegetation contains flammable chemical substances, Bolzani explained. It is believed that over the course of several generations, plants tend to have lower levels of flammable compounds and an increase in other compounds that protect them from fire. “From an evolutionary standpoint, species tend to develop chemical defense mechanisms that enable them to adapt,” she said.

Invisible potential
In addition to having molecules with economic potential produced by several species, the Cerrado is an important agricultural hub, notably for growing soybeans, cotton, beans, rice, corn and coffee. According to data from Companhia Nacional de Abastecimento (Conab), a state-owned company linked to the Ministry of Agriculture, the production of grains, oilseeds such as cacao, and protein sources such as soybeans is increasing exponentially in the Cerrado. Nearly half of the soybean-growing area in Brazil is located in this ecosystem. “Even with a lot of research aimed at improving soybean production, deforestation in the region continues to advance and eliminate many species of plants that produce molecules with the potential to provide society with goods and services that have high added value,” Bolzani said.

One example of a pharmaceutical created as a result of the biodiversity of the Cerrado is Fitoscar, a scar cream launched on the market in 2007 by Apsen Laboratories. This phytotherapy product is made from the dried extract of Stryphnodendron adstringens—or true barbatimão, as it is most widely known—a plant of the family Fabaceae that is readily found in the Cerrado. The cream was developed under a partnership between the laboratory and the School of Medicine of the University of Ribeirão Preto (Unaerp). “It’s the first anti-scarring agent approved by the National Health Monitoring Agency (ANVISA) to use a plant typical of this ecosystem,” Bolzani pointed out. She thinks that the pharmacological potential of the region needs to be used to greater benefit in Brazil.

To better investigate that universe, the Center for Natural Products Bioassays, Biosynthesis and Eco-physiology (NuBBe), a research network that maintains a database of natural products isolated from chemical elements of Brazilian biodiversity, is studying substances with promising pharmaceutical properties. The objective is to isolate anticarcinogens, antifungals, antimalarials, and other compounds. BIOprospecTa, another network under the Biota-FAPESP program, focuses on looking for biologically active substances in the biodiversity of the state of São Paulo. Its aim is to identify chemical models that can be used in designing drugs and cosmetics. “The country has a lot to gain from the discovery of natural products with pharmacological properties,” Bolzani said. “In the end, the Cerrado is a little-explored bank of molecules, and its biodiversity is a source of raw material for a number of uses.”

The Biota-FAPESP program has been partnering with Pesquisa FAPESP since February to promote a series of lectures focused on discussing the challenges involved in preserving Brazil’s principal ecosystems: Pampa, Pantanal, Cerrado, Caatinga, Atlantic Forest and Amazonia, in addition to the marine and coastal environments and biodiversity in anthropic environments, urban and rural. The lectures, to be presented between now and November under the topic, The commitment to improve education in the science of biodiversity in Brazil, are intended to present state-of-the-art scientific knowledge created by researchers throughout Brazil. Using accessible language, they will be aimed at improving the quality of environmental and science education for high school teachers and students in Brazil.

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