4th+grade+Desertification

 **Desertification**


 * desertification,** also called desertization, the process by which natural or human causes reduce the biological productivity of drylands (arid and semiarid lands). Declines in productivity may be the result of climate change, deforestation, overgrazing, poverty, political instability, unsustainable irrigation practices, or combinations of these factors. The concept does not refer to the physical expansion of existing deserts but rather to the various processes that threaten all dryland ecosystems, including deserts as well as grasslands and shrublands

 Causes of desertification
In general, desertification is caused by variations in climate and by unsustainable land-management practices in dryland environments. By their very nature, arid and semiarid ecosystems are characterized by sparse or variable rainfall. Thus, climatic changes such as those that result in extended droughts can rapidly reduce the biological productivity of those ecosystems. Such changes may be temporary, lasting only a season, or they may persist over many years and decades. On the other hand, plants and animals are quick to take advantage of wetter periods, and productivity can rapidly increase during these times. Since dryland environments are used for a variety of human purposes (such as agriculture and fuelwood collection), the various activities undertaken in them can exacerbate the problem of desertification and bring about lasting changes to dryland ecosystems.

What Causes Desertification?

-Overgrazing Overgrazing was not as large of a problem long ago because animals would move in response to rainfall. People would move with the animals so it prevented overgrazing in such areas. Now, humans have a steady food supply so they do not have to move about. Therefore, people use fences to keep their animals in one place which causes overgrazing. (Desertification, 2001)

-Farming of Average Land Farming of average land is causing desertification worldwide. Farmers are clearing average land, and using it which takes away the richness in the soil. People should let the average land replenish itself before farming. (Desertification, 2005)

-Destruction of Plants in Dry Regions Destruction of plants in dry regions is causing desertification to occur. People are cutting down trees to use them as a source of fuel. Once all these trees are cut down there is nothing to protect the soil. Therefore, it turns to dust and is blown away by the wind. (Desertification, 2005)

-Incorrect Irrigation in Arid Regions Causes a Buildup of Salt in the Soil Incorrect irrigation is commonly used in poorer areas. Farmers are using canal irrigation and other poor techniques because of the lack of water. This type of irrigation causes a buildup of salt in the soil. (Desertification, 2005) 

 Solutions to desertification
The struggle against desertification can occur at several levels. Since regional variations in climate are the main causes of the loss of dryland productivity, it is important to understand the influence of global warming in specific dryland regions. According to some models of climate change, many grasslands in western North America, for example, are predicted to be at greater risk of drought due to projected increases in summer temperatures and changes to existing rainfall patterns. Many authorities argue that since desertification and global warming are so closely related, one of the main solutions to the former may be the implementation of effective economic policies (such as carbon trading) and technical measures (such as carbon sequestration) that reduce the production of greenhouse gases. <span style="font-family: Times New Roman,serif;">At local scales, however, desertification is often the result of unsustainable land and soil management. To maintain the biological productivity of the land, soil conservation is often the priority. A number of innovative solutions have been devised that range from relatively simple changes in how people grow crops to labour-intensive landscape engineering projects. Some of the techniques that may help ameliorate the consequences of desertification in irrigated croplands, rain-fed croplands, grazing lands, and dry woodlands include:
 * 1) <span style="font-family: Times New Roman,serif;">Salt traps, which involve the creation of so-called void layers of gravel and sand at certain depths in the soil. Salt traps prevent salts from reaching the surface of the soil and also help to inhibit water loss.
 * 2) <span style="font-family: Times New Roman,serif;">Irrigation improvements, which can inhibit water loss from evaporation and prevent salt accumulation. This technique involves changes in the design of irrigation systems to prevent water from pooling or evaporating easily from the soil.
 * 3) <span style="font-family: Times New Roman,serif;">Cover crops, which prevent soil erosion from wind and water. They can also reduce the local effects of drought. On larger scales, plant cover can help maintain normal rainfall patterns. Cover crops may be perennials or fast-growing annuals.
 * 4) <span style="font-family: Times New Roman,serif;">Crop rotation, which involves the alternation of different crops on the same plot of land over different growing seasons. This technique can help maintain the productivity of the soil by replenishing critical nutrients removed during harvesting.
 * 5) <span style="font-family: Times New Roman,serif;">Rotational grazing, which is the process of limiting the grazing pressure of livestock in a given area. Livestock are frequently moved to new grazing areas before they cause permanent damage to the plants and soil of any one area.
 * 6) <span style="font-family: Times New Roman,serif;">Terracing, which involves the creation of multiple levels of flat ground that appear as long steps cut into hillsides. The technique slows the pace of runoff, which reduces soil erosion and retards overall water loss.
 * 7) <span style="font-family: Times New Roman,serif;">Contour bunding (or contour bundling), which involves the placement of lines of stones along the natural rises of a landscape. It helps to capture and hold rainfall before it can become runoff. It also inhibits wind erosion by keeping the soil heavy and moist. Contour bunding is similar to terracing.
 * 8) <span style="font-family: Times New Roman,serif;">Windbreaks, which involve the establishment of lines of fast-growing trees planted at right angles to the prevailing surface winds. They are primarily used to slow wind-driven soil erosion but may be used to inhibit the encroachment of sand dunes.
 * 9) <span style="font-family: Times New Roman,serif;">Dune stabilization, which involves the conservation of the plant community living along the sides of dunes. The upper parts of plants help protect the soil from surface winds, whereas the root network below keeps the soil together.
 * 10) <span style="font-family: Times New Roman,serif;">Charcoal conversion improvements, which include the use of steel or mud kilns or high-pressure compacting equipment to press the wood and other plant residues into briquettes. Conversion improvements retain a greater fraction of the heating potential of fuelwood.