ABSTRACT
Many natural systems are being affected by climate change, a process that has been sped up by human beings in recent years (Thomas et al. 2004). Current scientic evidence indicates that global warming is progressing due to an increase in anthropogenic activities; that is, man-made greenhouse gas concentrations, which are mostly due to industrial development and population growth (Mearns et al. 1999). People in South America are heavily dependent on the continent’s natural resources (rangelands, plants and animals, sheries, etc.) as well as on agricultural production (crops, forestry production, and livestock) (Solbrig 2005). Agriculture is the major transforming agent of natural landscapes, and it spreads over an extensive area of the Brazilian and Argentinean territories and remains an important part of the economy in both countries. In Brazil, the expansion of soybean farming is concentrated in Goiás and Mato Grosso, displacing the rich native biota of the savannas and the Amazonian forest (Solbrig 2005). Between May 2000 and August 2006, Brazil lost nearly 150,000 km2 of Amazonian rainforest (Malhi et al. 2008) that have been devastated by the actions of poor subsistence cultivators, land clearing for pastureland, commercial exploitation of forest resources, and government subsidized agriculture and colonization programs. In Argentina,
CONTENTS
13.1 Introduction ................................................................................................ 237 13.2 Changing Environment and Mycorrhiza ............................................... 239 13.3 Relationship between Mycorrhizal Infection Capacity and
Environmental Degradation: Tropical Dry Forests in Brazil .............. 240 13.4 Tropical Dry Forests-Caatinga .............................................................. 244 13.5 Conclusions and Perspectives .................................................................. 247
the original vegetation structure was also displaced by agriculture (Solbrig 2005). In comparison to the rest of the agroecological areas, grain crops had faster expansion in the Rolling Pampas, replacing the pristine natural lands. Since 1990, soybean production has increased by 66% worldwide (from 108 million tons in 1990 to 179 million tons in 2002). The Americas, Brazil, and Argentina account for most of the increase (88%). The major change in the agricultural production of Argentina in the last 20 years has been the dominance of soybean as the principal crop of the Pampa (Solbrig 2005). According to the National Directorate of Forests, Argentina is experiencing the most intense deforestation in its history due to the replacement of its forests with soybean plantations, and Córdoba is the province with the most devastating environmental damage. The high deforestation rate in the country resulted in numerous areas that suffer water shortages due to climate change caused by the felling of the forests (Castrillo Marin 2009).
