Group members preparing summary: Jared Anderson and Don MillerLand use issues specifically pertain to land degradation. That is, the loss of the soil´s ability to provide beneficial products to the ecosystem. Paleoclimatology has shown that his declination has taken place since the time of the Maya´s and the Aztecs. Soil erosion is the most harmful form of land degradation. Sedimentation from soil erosion has a significant impact upon the already limited water supply in urban areas. Soil erosion also cannot take place for very long without causing detrimental effects to structures and watersheds. The human factors that lead to land degradation are: poor land management, inadequate technology, overpopulation, poverty, and decisions based on social and political agendas. The actual losses are difficult to measure because they occur so slowly. Studies have shown that eroded lands are 21% less productive than other "normal" lands of a similar climate. Even more striking are studies that indicate that 75% of the Earth´s land is being degraded.
In 1977 the United Nations set forth a Plan of Action to Combat Desertification (PACD) to iron out a global policy of desertification. However, global progress on this has been slow. In 1992, and again in 1995, United Nations Conferences on Environment and Development (UNCED) focused on global desertification and how to protect lands not yet affected. The method that was presented to initiate changes in soil erosion prevention was the bottom-up approach. Changes begin with those in the rural setting and then suburban and urban area problems are considered. While this is a good start to the problem at hand, it is also necessary to remember that it will take individualized solutions to each individual problem in degraded lands to reverse the effects that have already occurred.
The Warren and Agnew article describes at length the confusion resulting from multiple definitions of the term "desertification" by different authors, providing specific examples of its misapplication. These authors see desertification as one kind of land degradation, which they define as the loss of productivity and resilience. They also debunk the widely accepted myth that desertification is a phenomenon that occurs at the margins of deserts, and refers to the movement of sand dunes. They describe the different types of desertification (which can be area-specific), and clarify its relationship with aridity, drought and climate change. The authors also describe the political, cultural, and economic factors involved in the causes of desertification, which have sometimes been misused to assign blame. They describe the different soil types, vegetation, and locations that cause land degradation to occur. They also discuss the human factors, such as faulty management skills, ignorance, management inexperience, increasing population, problems with property sharing, societal inequalities and poverty, that contribute greatly to the problem. They conclude that the anthropogenic problems will be solved only when landowners are provided the economic incentive to not degrade the land, and are given more individual control over land management practices. They emphasize that research and education will play major roles in decreasing the rate of, and working to reverse, land degradation. However, this "agricultural transition" will be slow in coming, and small-scale plans utilizing the bottom-up approach will have the greatest chance for success.
Dialog Summary:
Decker - provides an example of land degradation "close to home" of an area in California facing soil salinity problems as the result of farmland irrigation. Continuing current practices will further degrade the land, but not doing so will result in lower crop yields, i.e., lower income for the area farmers.
Meade - describes the Iowa definition of land degradation as loss of soil quality and plant productivity while describing the many processes that occur in soil. He states that the bulk density of Iowa soil has increased in the A horizon due to loss of water and organic matter through erosion and conversion to CO2. Loss of clay has also occurred, resulting in the concurrent loss of the cation exchange capacity needed to hold nutrients in the soil. The pH has also shifted one full unit toward more acidic levels, again stressing that land degradation is occurring in Iowa.
Anderson - provides a website from the University of Oxford with information on soil erosion modeling and future trends. The three models he quotes all show increases in erosion due to increased precipitation over the next 50 years. Other research includes monitoring erosion to validate erosion models.