1) Mad-cow disease leads to increased demand for Brazilian open-range cattle and soybeans. The soybeans are to be used as safe animal feed in Europe.
2) The increased demand encourages deforestation and a "continued push" into the Amazon.
3) An activist American nun determined to help protect Brazilian peasants while encouraging sustainable farming practices is executed by armed men working for the soybean farmers and loggers, who are moving peasants off land deemed suitable for cattle or soybeans.
4) The international outrage generated by her murder is largely responsible for the Brazilian government pushing through an order for the creation of two conservation areas in the Amazon, totaling 10 million acres. These areas have been coveted by environmentalists and industry alike.
Now the lines have been drawn. See the relevant article here.
Note: View the description of new conservation area at World Wildlife Fund website.