Land Degradation is a universal problem and not necessarily one for the developing countries. It is not merely an agricultural problem but has ramifications in all aspects of society. Land degradation either natural or induced by humans is a continuing process. It has become, however, an important concern affecting the wealth of nations, food security, and is impacting the livelihood of every person on earth. Food security is directly related to the ability of the land to support the population. Due to declining quality of the land, urban migration is on the rise in almost every country in the world.
Environmental sustainability focuses on overall viability and normal functioning of natural systems. For ecological systems, sustainability is defined by a comprehensive, multiscale, dynamic, hierarchical measure of resilience, vigor and organization. Resilience is the ability of ecosystems to persist despite external shocks, i.e., the amount of disruption that will cause an ecosystem to switch from one system state to another. An ecosystem state is defined by its internal structure and set of mutually re-inforcing processes. Vigor is associated with the primary productivity or growth of an ecosystem. Global grasslands become the area of focus when thinking about desertification. Natural resource degradation, pollution and loss of biodiversity are detrimental because they reduce resilience, increase vulnerability, and undermine system health. Overgrazing of grasslands reduces their productivity and ultimately destroys them. Worldwide, there are now 680 million hectares (1 680 million acres) of degraded grasslands. Desertification is estimated to involve 3 600 million hectares (8 896 million acres) of land—roughly 25% of the world’s total surface area.
Grasslands cover roughly 40% of the Earth’s land surface. They are natural landscapes where the dominant vegetation is grass. Shrublands can also be considered grasslands. Grasslands typically receive more water than deserts but less than forested regions.
Worldwide, these ecosystems provide livelihoods for nearly 800 million people.Most of the world’s meat comes from animals that forage on grasslands.
Grasslands and their soils store about one-third of the global stock of carbon in terrestrial ecosystems.
Worldwide, the quality of surviving grasslands is declining. This is due primarily to human-induced modifications such as agriculture, excessive or insufficient fire, livestock grazing, fragmentation, and invasive plants and animals.
While irrigation could enhance food production, its inefficient application could also be a risk, particularly in terms of salinization. For example, about 10% of the world’s irrigated land has been damaged by salt.
Although soil erosion and desertification are very old global problems compared to other global environmental problems which have arisen over the last few decades, they are probably the most serious but the least noticeable ones.
It is estimated that 73% of the world’s grazing land has so deteriorated that it has lost at least25% of its animal carrying capacity.
With 180 million people worldwide now trying to make a living tending 3 300 million cattle, sheep, and goats, grasslands are under heavy pressure. As a result of overstocking and overgrazing, grasslands in much of Africa, the Middle East, Central Asia, the northern part of the Indian subcontinent, Mongolia, and much of northern China are deteriorating.
Desertification is a worldwide phenomenon that affects more than 100 countries (1/3 of the earth's land surface - 4 billion hectares) and directly threatens 2.6 billion people. Africa, Asia and Latin America are the most threatened.
24 billion tons of fertile soil disappear annually.
Drylands contain 43% of the world’s cultivated lands.
Significant climate and human-induced changes to dryland ecosystems underscore the urgent need for robust information on quantitative and qualitative changes to water, soil and biodiversity as well as information on the demographic, social and economic status and trends in drylands.
Drylands are characterized by limited availability of arable land, limited and highly variable rainfall and scarcity of water resources. The drylands of the world (estimated to cover 35-40% of the earth's surface) are considered the most threatened by desertification.
Irrigation of arid and arid semi-arid lands has developed at a steep rate since the 1950's - more than doubling in area since then. Generally, high hopes for increased agricultural production in these irrigated arid-zones are materialised only during a relatively short period of time - typically, 2-4 decades. A series of decline processes are set in the irrigated land immediately upon the initiation of large-scale irrigation causing (on regional scales) slow but steady yield declines. One of the major and most grave decline processes is the development of secondary salinization, frequently followed by sodification of soils. This form of land degradation grossly affects the semi-arid and arid-regions.
Sodicity is the name given to water or soil that has a high concentration of sodium in comparison to calcium and magnesium. Sodicity is often confused with salinity. Salinity is the total concentration of salts dissolved in water or soil and affects the ability of plants to extract moisture from the soil. Sodicity affects plant growth by altering the soil structure. Poor soil structure occurs when clay particles clog soil pores leading to surface crusting, reduced water infiltration and low aeration of the soil profile. As a result there is less water available for plant growth.
Refugee movements are often an indication of larger population displacements. This is especially valid for the environmentally motivated displacements in West Africa and the Sahel region.
An important contribution to combat the effects of desertification and land degradation is to stimulate the conceptual development of integrated terrestrial and space-borne observation concepts into this field of study.
Asia has the largest land area affected by desertification; 71% of it is either moderately or seriously impoverished. In Latin America, the rate is 75%. Two thirds of Africa's areas are deserts or dry land, and 73% of the arid agricultural regions there are also moderately or seriously impoverished.
Over the past 20 years, the total surface area lost is equal to all of the farmland of the United States of America.
It can take 500 years for 2.5 cm (1 inch) of soil to form. globally, soils are eroding at a rate much faster than they can form.
Desertification and land degradation have substantial environmental and societal implications. Decision-makers and politicians are seeking solutions on national and global levels while land managers are actively tackling the problem on local areas with a strong emphasis on prevention and mitigation strategies.
Africa
2/3 of the continent of Africa is desert or drylands.
While Africans constitute only 12% of the global population - around 28% (i.e. 3.2 million) of the world’s 11.5 million refugees and just under 50% (i.e. 9.5 million) of the world’s internally displaced persons are to be found in Africa. These numbers do not include the so-called “economic refugees” and the “environmental refugees”.
Asia
The long and uncontrolled use of the Sirdariya and Amudariya river waters for irrigation, reduced river flows into the Aral Sea leading to the exposure of a 30,000 square kilometer saline sea floor. Annually, 75 million tons of salt dashed out by wind erosion from this surface polluting the environment for hundreds of kilometers.
Australia
Australia covers an area roughly the size of the lower 48 continental United States, yet it supports less than one-tenth the US population. To worsen Austalia's dry conditions and water scarcity, one-third of agricultural water, on average, is lost to leakage, seepage, evaporation, and faulty metering.
Europe
12% of Europe's land area is in danger of desertification.
Approximately 50% of Spain is arid. In its arid regions, about 70% is moderately desertified.
North America
Off-road vehicles significantly increase soil loss in the delicate desert environment of the western United States. In a few seconds, soils that took hundreds of years to develop can be destroyed.
30% of the land in the United States is affected by desertification.
South America
Latin America encompasses approximately one fourth of the desert and arid lands of the world.
The Mayan Civilization was among the great ancient civilizations of Mesoamerica. At the peak of their glory, around 800 A.D., the Maya ranged from Mexico's Yucatán peninsula to Honduras. Then, almost in an instant, a society of some 15 million people imploded, leaving deserted cities, trade routes, and immense pyramids in ruins. The sudden demise is one of the greatest archeological mysteries of our time. What caused the collapse of the great Maya civilization? A drought hypothesis is not new. However, a recent study of nearby lakes found man-made effects, such as deforestation and soil erosion, and therefore didn't reflect a purely climate-related demise. Maya were particularly susceptible to long droughts because about 95% of their population centers depended solely on lakes, ponds, and rivers containing on average an 18-month supply of water for drinking and agriculture. Maya cities encircled the bajos. Satellite images show that the bajos harbor ancient drainage canals and long-overgrown fields. That ingenious method of agriculture may have backfired.
A biome is a major ecological area – such as a tropical rainforest, grassland or desert. In Brazil, the Cerrado is the country’s second largest biome, occupying about 204 million hectares (24% of the country) and contains about 5% of the planet’s biodiversity.
Copyright 2010 Dimidia, LLC All rights reserved. Last Update: March 02, 2010
