Most degraded biome in Brazil, Pampa is turning into soy and sand

  • Between 1985 and 2022, according to data from MapBiomas, Pampa Gaucho lost almost 3 million hectares — a reduction of 30% in four decades.
  • Soybean cultivation and forestry are among the main factors behind the deforestation of native vegetation, which has one of the highest biodiversity per square meter in Brazil.
  • Pampa also suffers from sandstone, a natural process aggravated by economic activity; local producers have been trying to reverse it.

With an area of ​​just 176 thousand km², or a mere 2% of the national territory, Pampa — roughly speaking, the southern half of Rio Grande do Sul — is a practically “invisible” biome in Brazil. While the world's eyes and attention are focused on the Amazon and, to a lesser extent, the Pantanal and Cerrado, the extreme south of the country is being degraded without almost anyone paying attention.

According to data from MapBiomas , between 1985 and 2022, 2.9 million hectares of its rural vegetation were destroyed to make way for agriculture and forestry areas. The reduction in these 38 years is equivalent to 32% of the area that existed in Brazil in 1985, when it extended over 9 million hectares.

According to the MapBiomas survey, between 1985 and 2022, agricultural land use in Pampa Gaucho — especially for soybean cultivation — increased by 2.1 million hectares. In the case of forestry (pine and eucalyptus), the increase in its extension was more than 720 thousand hectares in the period, which corresponds to a growth of 1,667%.

The MapBiomas study went beyond Brazil and verified the situation of the entire South American Pampas, which extends across Brazil, Argentina and Uruguay for almost 110 million hectares (equivalent to two Frances). The data collected shows that, between 1985 and 2022, there was a total reduction of 20% in rural vegetation in the biome, including 9.1 million hectares of native fields.

According to agronomist Tales Tiecher, from the Federal University of Rio Grande do Sul (UFRGS), Pampa Gaucho has the greatest biodiversity of plants per square meter among Brazilian ecosystems , but has suffered a drastic reduction in its area of ​​native vegetation. “Proportionally, the biome is among the most degraded in the country, ahead of the Amazon and the Cerrado,” he says.

The loss of grassland vegetation is the main threat to local fauna and flora, adds Tiecher. “Around a quarter of rural birds are subject to some degree of threat of extinction in at least one part of the biome and around 30 species of mammals are at risk of disappearing forever”, he warns. “In addition, several species of reptiles, amphibians and plants are also threatened.”

Biologist Juliano Ferrer dos Santos, from the Department of Zoology at UFRGS, says that the advancement of agricultural culture in Pampa is so rapid that researchers are unable to monitor the real state of conservation of all of them. “On each trip to the biome to monitor and research annual fish, my object of study, we are faced with a more critical situation in relation to known areas of occurrence and others suitable for their survival”, he says.

He explains that annual fish , or cloud fish, which include seven species in this category (genus Austrolebias ), inhabit small lakes, less than 100 m², which form during the rainy season in winter in the middle of the fields. Pampa. “When they hatch, they grow very quickly and are already reproducing, because at the end of spring their aquatic environments dry out and they die”, explains Santos. “But their eggs are buried in the clay and will only hatch next year. When lakes dry up, there is no indication that unique species of fish live there.”

The sand problem

The advance of agriculture and forestry — and the consequent destruction of large areas of rural vegetation and native fields — is also contributing to aggravating an old problem in the Brazilian Pampas.

These are the so-called areais, or sandy regions, which exist in Brazil in Rio Grande do Sul and the Central-West Region. Its origin dates back 200 million years, when most of central-southern Brazil was an immense desert. Today this area is known geologically as the Botucatu Formation. It is a poor soil, with a lot of sand in its composition.

The basic difference between a desertified area and a sandy area is the amount of rain the area receives. The 1st United Nations Conference on Desertification, held in Kenya in 1997, defined the first as “the reduction or destruction of the biological potential of the land, which could ultimately result in desert-type conditions”.

The Gaucho territory is, therefore, not a region affected by desertification. It is located in a region with a subtropical climate, with an average annual rainfall of 1,400 millimeters. Therefore, it is outside the area where climate and human action have been the main reason for degradation, as is the case of the Caatinga . Today, sandy beaches in Brazil are considered an area of ​​special attention.

Geographer Roberto Verdum, from the UFRGS Institute of Geosciences, explains that sandization is the process of formation of sandy deposits of fluvial and aeolian origin dating from the Pleistocene (from 2.5 million to 11.7 thousand years ago) and Holocene (from 11 thousand years ago to the present), associated with factors such as climate, relief and vegetation cover. They may or may not be related to agricultural activities.

According to him, the genesis of these sandy patches is related to the susceptibility of the rocks and soils of Pampa to the dynamics of torrential rains and periods of drought. “Thus, the sands are constantly being reworked by climate agents, essentially water and wind,” he explains.

Agricultural activities in naturally fragile areas, combined with a substrate that is highly susceptible to sand formation, can, however, enhance the factors that initiate and contribute to the evolution of this process.

“The impacts of poor soil use and management, with the use of technologies that are inappropriate for the fragile soils of this region, may be one of the main contributing factors to the emergence of new areas of sandization in the current context”, warns Verdum.

According to geographer Neemias Lopes da Silva, also from UFRGS, what is occurring in Pampa is the intensification of erosion processes associated with sandization by human action.

“The soils are fragile and poorly consolidated. Activities such as heavy grazing, or the weight of agricultural machinery itself, can compact the land and help in the development of furrows through which water will flow in a concentrated manner until ravines and, later, gullies develop”, he explains. According to Silva, such processes move and expand sandy sediments through the action of water and wind.

Reversing sandization

According to Verdum, even though the sands have not expanded spatially since monitoring carried out since the 1980s, they can be aggravated by agricultural production. Today they total 3,663 hectares, spread across the municipalities of Alegrete, Cacequi, Itaqui, Maçambará, Manuel Viana, Quaraí, Rosário do Sul, São Borja, São Francisco de Assis and Unistalda.

The area of ​​the sands may be small compared to the total extent of the Pampa, but it is significant individually for each owner whose land is affected by the phenomenon.

This is the case of rice producer and president of the Rural Union of Itaqui and Maçambará, Raul Borges. His own land covers 120 hectares, 46 of which were sandy when he purchased it more than 15 years ago. “It may seem small, but for me it was very significant, as it amounted to more than a third of my property,” he says.

Therefore, he decided to recover the sand. After many failed attempts, Borges achieved good results by covering the sand with rice husks or its ashes. “Today, around 25 to 30 hectares have been recovered,” he says. “In part of the area, natural vegetation has returned.”

In addition to the lack of action to recover sandy areas, another problem is the inadequate attempts to do so, as is the case in forestry. Since the 1970s, there have been projects, including some with support from the state government of Rio Grande do Sul, to recover the sands by planting eucalyptus trees on them.

“Many of the proposals for economic activities, which see the sands only as a problem to be combatted, are responsible for interventions that distort the landscape and alter the dynamics of this ecosystem”, says Silva. “This is the case of forestry, with the idea of ​​forming a matrix of forestry production in these areas.”

According to him, this alternative does not solve anything. “Where forestry is developed, the sand is not recovered, it is only hidden in aerial images and all the biodiversity adapted to the area is replaced by eucalyptus and leaves on the ground”, he criticizes. “Some plant species are endemic to sandy fields. The erosion processes do not cease and the natural dynamics are altered, not to mention the landscape transformation, which alters the herbaceous and shrubby vegetation with sandy areas into a large 'green wall'.”

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