Artificial forests threaten the biodiversity of the Pampas

Eucalyptus and pine cultivation for the pulp and paper industry already occupies 25% of the biome, which is also impacted by the expansion of agriculture and inadequate cattle management.

By Karina Toledo

Agência FAPESP – The Amazon Forest in such states as Mato Grosso and Pará is being transformed into pastureland. However, the problem is the opposite in Rio Grande do Sul: the field vegetation of the Pampas – which for years has existed harmoniously with cattle rearing – is being decimated to make way for forests planted by humans.

Although the visual impact of the destruction could be greater in Amazonia, anyone who considers that the biological loss in the Pampas Biome is smaller is mistaken. According to a study coordinated by Professor Ilsi Boldrini of Universidade Federal do Rio Grande do Sul (UFRGS), a vegetation diversity is concentrated in the southern region that is three times greater than that of the forests when the area occupied by each is taken into consideration.

These data were presented in the second meeting of the 2013 Cycle of Conferences BIOTA-Education, organized by the BIOTA-FAPESP Program, the theme of which was the Pampas. 

Covering 176,000 km², the biome was considered until 2004 to be part of the Atlantic Rainforest and originally occupied 63% of Rio Grande do Sul’s territory. Today, only 36% of this area is still covered by the original vegetation.

“The rural landscape could appear homogenous and poor to those who do not know it, but we mapped 2,169 taxa in this small remaining biome, with the majority being different species from 502 genera and 89 families. Of these, 990 taxa are exclusive to the Pampas, which is a very large number for a very small area. In the Cerrado, for example, there are 7,000 species in 3 million km²,” stated Boldrini.

According to the researchers, approximately 1 million hectares – or 25% of the Pampas Biome – in the last five years was occupied by eucalyptus and pine forests that are aimed at supplying the pulp and paper industry.

Because there is very little light available and the species native to open plains require a lot of sun, few native plants survive below the trees. “When the trees are cut, only stumps and bare soil remain – an environment ripe for invasive species, such as capim-annoni (Eragrostis plana Nees) or grama paulista (Brachiaria plantaginea), which are very fibrous and not suitable for pasture,” explained Boldrini.

However, according to Boldrini, the oldest and main factor causing the destruction of the Pampas is agriculture. “Soybean and wheat crops are produced on drier land and rice crops on more humid areas near rivers. Farming began on the plains and is spreading throughout the Pampas, though livestock raising is most suitable for the region,” she argued.

Even beef cattle raising, which was introduced in Rio Grande do Sul by Jesuits at the end of the 16th century, has become a threat due to the lack of appropriate management.

“The producers use a very high animal load. As a result, much of the vegetation is removed, and there is little available pasture in the winter. Then, they apply herbicides to eliminate the native vegetation to allow the planting of exotic winter species, such as rye grass, white clover and birdsfoot trefoil,” asserted Boldrini.

The practice not only threatens the local biodiversity but also contaminates the soil and water and diminishes the productivity of the cattle raisers. Ideally, according to Boldrini, there would be a three to four times higher supply of fodder than the cattle can eat. That way, the animal chooses the most appropriate species for its diet, develops more quickly and reproduces more efficiently.

“The average productivity of the state today is 70 kg of meat per hectare annually. With proper management, this value could reach 200 kg to 230 kg per hectare per year. Furthermore, the quality of the meat also improves. All it takes is making sure that the animal does not decimate the vegetation,” Boldrini said.

According to data from the Environment Ministry, the Pampas is today the second most devastated biome in the country – behind the Atlantic Rainforest. Among the endemic plant species that have been described, 151 are threatened with extinction. “Some plants, such as Pavonia secreta, exist only in a small region of the Pampas. When that place is destroyed, these plants will be extinct,” explained Boldrini.

The disappearance of local flora threatens not only the fauna associated with it but also the springs of the regions, commented the researchers. “The sources of all tributaries and subtributaries of the state’s large rivers, such as Jacuí, Ibicuí and Uruguai, are completely interconnected to the vegetation in the area. If we do not take care of the banks of these springs, it will be of little benefit to plant pine forests,” affirmed the professor.

Lack of awareness

During the event, Márcio Borges Martins, of UFRGS, affirmed that one of the main obstacles to the preservation of the Pampas is a lack of awareness about the local biodiversity. “There are many studies being conducted, but almost nothing has been published. This makes it difficult to define the priority areas for conservation.”

The lack of information about the species of animals in the region was also highlighted by Eduardo Eizirik of the Pontifícia Universidade Católica do Rio Grande do Sul (PUC-RS), who presented the workshop “Origin, evolution and diversity of vertebrate fauna in the Pampas Biome.”

Organized by the BIOTA-FAPESP Program, the 2013 Cycle of Conferences has the objective of improving science teaching. In May 16, 2013, the topic will be the “Cerrado Biome.” On June 20, the cycle with cover the “Caatinga Biome.” On August 22, the “Atlantic Rainforest Biome” will be the main subject, followed by: the “Amazon Biome” on September 19; “Marine and Coastal Environments” on October 24 and, finally, “Biodiversity in Anthropic Environments – Rural and Urban” on November 21.