Continuing deforestation in the Amazon rainforest could undermine agricultural productivity in the region by reducing rainfall and boosting temperatures, warns a new study published in the journal Environmental Research Letters.
The research is based on a model that simulates the impact of forest loss and global climate change on local rainfall and temperature. The model then forecasts the effect on the productivity of soybean farms and cattle ranches, the two dominant forms of land use after deforestation in the Brazilian Amazon. The researchers find that climate change and deforestation will have a significant impact on agricultural yields in the region, reducing pasture productivity by 30-34 percent and soybean yields 24-28 percent, depending on the degree of forest loss. The study also projects a steep decline in the amount of carbon stored in vegetation, potentially worsening climate change through increased emissions.
“Large-scale agriculture expansion in Amazonia may introduce climate feedbacks that would reduce precipitation, leading agriculture expansion in Amazonia to become self-defeating: the results of this study suggest that the more agriculture expands, the less productive it becomes,” the authors, led by Leydimere Oliveira of the Federal University of Viçosa, write. “This would be a no-win situation, in which we all lose.”
Forest and agricultural land in the Brazilian Amazon in 2009. Photo by Rhett A. Butler
The findings suggest a limit to which agricultural expansion at the expense of forest should be permitted. However other research has indicated that limiting deforestation, at least in the Brazilian Amazon, may not limit agricultural production due to the current low-value use of large swathes of land. Intensification, even without the use of agrochemicals and industrial feedlots, could dramatically increase the volume of agricultural products that come out of the region. For example, some research has suggested that shifting low-intensity cattle pasture to oil palm plantations could boost carbon storage and local incomes, while maintaining more forest function relative to poorly managed cattle pasture. In some areas it may ultimately make economic sense to allow forests to regenerate, while focusing cattle production on smaller areas of land.
Study lead author Oliveira says that the study demonstrates the economic importance of maintaining forest cover in the Amazon.
“We were initially interested in quantifying the environmental services provided by the Amazon and their replacement by agricultural output,” Oliveira said in a statement. “We expected to see some kind of compensation or off put, but it was a surprise to us that high levels of deforestation could be a no-win scenario – the loss of environmental services provided by the deforestation may not be offset by an increase in agriculture production.”
“There may be a limit for expansion of agriculture in Amazonia. Below this limit, there are not important economic consequences of this expansion. Beyond this limit, the feedbacks that we demonstrated start to introduce significant losses in the agriculture production.”
Cattle in the Brazilian Amazon in 2009. Photo by Rhett A. Butler
CITATION: Leydimere J C Oliveira, Marcos H Costa, Britaldo S Soares-Filho and Michael T Coe (2013). Large-scale expansion of agriculture in Amazonia may be a no-win scenario. Environmental Research Letters 8 024021.
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