Soy and Native Forests (E. Viglizzo)

Agriculture in all of Argentina and, particularly, agriculture in the Pampas region has expanded in the past 20 years within a modern technological matrix characterized by transgenic crops, direct seeding, increased use of fertilizers and pesticides and, to a lesser extent, practices associated with precision agriculture (Satorre, 2005; Viglizzo et al. 2010).
Soy farming led to the adoption of technologies due to the expansion of transgenic varieties (resistant to Glyphosate herbicide) and the exponential use of this herbicide. The impact was soon seen with increases in seeded areas, crop yields and profitability of production systems (Martínez-Ghersa y Ghersa, 2005; Trigo, 2005). But this transformation triggered other important changes in the ecology and the environment (Pincén et al., 2010). The dominant system included few high productivity crops with high genetic homogeneity that in addition to maximizing production and profitability, simplified management and the use of time but at the cost of concentrating higher climatic, economic and biological risk (pests and diseases), loss of organic matter, and over-extraction of some macro- and micronutrients (Casas, 2001). The response to these problems was the development of direct seeding and other forms of reduced tilling and, to compensate the extraction of nutrients and the expansion of pests, increased fertilization and use of pesticides.
In recent years, the expansion of soy crops has generated much debate. As the dominant crop of the last decades, soy has been equally sanctified and demonized by different sectors. For some, soy enabled the recovery of the Argentine economy because of its high productivity and profitability and its positive impact on our trade balance surplus. They note its plasticity, management simplicity and high financial returns of its technological model which, as mentioned, is based on a simple system comprising direct seeding, transgenic varieties and Glyphosate. For others, soy is the crop that led to the rapid deforestation of native forests in the NW region of the country, concentrated the wealth in the hands of large commercial corporations, destroyed rural employment, expelled aboriginal communities and affected the ecology and the environment.
There is one thing that is undeniable: in the 1950s and first decade of the XXI century the expansion of agriculture and livestock production on rangelands caused a significant reduction in the natural forests area. Extrapolating data developed by Gasparri et al. (2008) and SAyDS (2004), in the periods 1956-60, 1986-90 and 2001-05, estimated occupation values (expressed in Km2) were: i) 22,870, 16,940 and 13,812 for the Paranaense rainforest or Atlantic Forest in the NE eco-region, ii) 275,000, 242,000 and 206,200 for the Chaco eco-region, and iii) 49,910, 49,720 and 35,850 for the Yungas rainforest, respectively. Compared to the area they occupied in the mid 1950s, approximately 60 %, 75 % and 72 %, respectively, of these forest biomas currently persist.
According to the literature, deforestation of native forests causes loss of organic carbon in the biomass and soil (Viglizzo et al., 2010) which increases greenhouse gas emissions (Gasparri et al., 2008) and, in the long term, deteriorates natural sinks of this element (Carreño et al., 2010). Data developed by Taboada (2004) indicates that deforestation is one of the main sources of greenhouse gas emissions in Argentina. Using satellite imaging data for the Northwest of Argentina (Volante et al., personal communication) and data on the estimated soy seeded area provided by SAGPyA (2004), Pincén et al. (2010) identified a high correlation (R2 = 0.92) between the area seeded with soy and the deforestation of native forests. This very high correlation could not be demonstrated in the other forest regions of the country.
Other undesirable effects (which have not yet been evaluated) of the encroachment of agriculture and husbandry on native forests is the loss of ecosystem services. In a recent study, Carreño and Viglizzo (2010) demonstrated that the Atlantic Forest, the West Subhumid Chaco (Chaco Salteño or Umbral al Chaco), and the region of the Yungas seem to be the biomas that were most affected by the loss of ecosystem services. The Atlantic Forest, for example, – where the encroachment of soy production is low –, is the bioma that, because it provides the greatest relative number of services (such as regulation and purification of water, protection of the soil against erosion, regulation of the local climate and air purification, protection against storms because it acts as a windbreaker, carbon sequestration and supply of habitat), seems to have been most affected by deforestation. The region of the Yungas, the Chaco forest and the Espinal forest follow in magnitude of intervention.
Undoubtedly, the debate on the expansion of soy production and deforestation of native forests will continue in coming years. It is part of the popular myth – with no empirical data to support it – that soy is the main culprit in the loss of native forests. This is actually true in some forest regions of the country but not in all. Human activities such as agriculture, husbandry, urbanization, road construction, land intrusion and real estate developments, among others, are the ones that really explain the high rate of deforestation currently seen in Argentina. With its pros and cons soy is not a cause but an involuntary tool of deforestation; it is one more of the many crops grown by man who is really the one that positively or negatively impacts the ecology and the environment.

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