Investigators were surprised to note that most dead trees were in an area that had been free of cattle since 1961, which was before the major decline in the woodland environment. Furthermore, some of the woodlands that suffered the least decline had the highest density of people and cattle. These observations suggested that overgrazing by cattle was not responsible for loss of the trees.
The groundwater level rose as much as 3.5 m in response to unusually wet years in the 1960s. Analysis of the soils confirmed that the tree stands that suffered the most damage were those growing in highly saline soils. The study of environmental problems and their solutions has never been more important. Modern society in 2009 is hooked on oil. Production has declined.
The problem is that the Earth has not grown any larger, and the abundance of its resources has not increased in many cases, quite the opposite. How, then, can Earth sustain all these people. And what is the maximum number of people that could live on Earth, not just for a short time but sustained over a long period. These issues have to be evaluated in light of the interrelations between people and nature, and the answers ultimately depend on both science and nature.