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Desertification
Desertification is a type of land degradation in drylands in which biological productivity is lost due to natural processes or induced by human activities whereby fertile areas become increasingly arid. It is the spread of arid areas caused by a variety of factors, such as climate change and overexploitation of soil as a result of human activity. Throughout geological history, the development of deserts has occurred naturally. In recent times, the potential influences of human activity, improper land management, deforestation and climate change on desertification is the subject of many scientific investigations. Definitions of words As recently as 2005, considerable controversy existed over the proper definition of the term "desertification." Helmut Geist (2005) identified more than 100 formal definitions. The most widely acceptedGeist (2005)p. 2/ref> of these was that of the Princeton University Dictionary which defined it as "the process of fertile land ''transforming into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Desertification Map
Desertification is a type of land degradation in drylands in which biological productivity is lost due to natural processes or induced by human activities whereby fertile areas become increasingly arid. It is the spread of arid areas caused by a variety of factors, such as climate change and overexploitation of soil as a result of human activity. Throughout geological history, the development of deserts has occurred naturally. In recent times, the potential influences of human activity, improper land management, deforestation and climate change on desertification is the subject of many scientific investigations. Definitions of words As recently as 2005, considerable controversy existed over the proper definition of the term "desertification." Helmut Geist (2005) identified more than 100 formal definitions. The most widely acceptedGeist (2005)p. 2/ref> of these was that of the Princeton University Dictionary which defined it as "the process of fertile land ''transforming into d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United Nations Convention To Combat Desertification
The United Nations Convention to Combat Desertification in Those Countries Experiencing Serious Drought and/or Desertification, Particularly in Africa (UNCCD) is a Convention to combat desertification and mitigate the effects of drought through national action programs that incorporate long-term strategies supported by international cooperation and partnership arrangements. The Convention, the only convention stemming from a direct recommendation of the Rio Conference's Agenda 21, was adopted in Paris, France, on 17 June 1994 and entered into force in December 1996. It is the only internationally legally binding framework set up to address the problem of desertification. The Convention is based on the principles of participation, partnership and decentralization—the backbone of good governance and sustainable development. It has 197 parties, making it near universal in reach. To help publicise the Convention, 2006 was declared " International Year of Deserts and Desertificat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sahel Drought
The Sahel region of Africa has long experienced a series of historic droughts, dating back to at least the 17th century. The Sahel region is a climate zone sandwiched between the Sudanian Savanna to the south and the Sahara desert to the north, across West and Central Africa. While the frequency of drought in the region is thought to have increased from the end of the 19th century, three long droughts have had dramatic environmental and societal effects upon the Sahel nations. Famine followed severe droughts in the 1910s, the 1940s, and the 1960s, 1970s and 1980s, although a partial recovery occurred from 1975-80. The most recent drought occurred in 2012. While at least one particularly severe drought has been confirmed each century since the 17th century, the frequency and severity of recent Sahelian droughts stands out. Famine and dislocation on a massive scale—from 1968 to 1974 and again in the early and mid-1980s—was blamed on two spikes in the severity of the 1960-198 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deserts
A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the land surface of the Earth is arid or semi-arid. This includes much of the polar regions, where little precipitation occurs, and which are sometimes called polar deserts or "cold deserts". Deserts can be classified by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical location. Deserts are formed by weathering processes as large variations in temperature between day and night put strains on the rocks, which consequently break in pieces. Although rain seldom occurs in deserts, there are occasional downpours that can result in flash floods. Rain falling on hot rocks can cause them to shatter, and the resulting fragments and rubble strewn over the de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Land Degradation
Land degradation is a process in which the value of the biophysical environment is affected by a combination of human-induced processes acting upon the land. It is viewed as any change or disturbance to the land perceived to be deleterious or undesirable. Natural hazards are excluded as a cause; however human activities can indirectly affect phenomena such as floods and bush fires. This is considered to be an important topic of the 21st century due to the implications land degradation has upon agricultural productivity, the environment, and its effects on food security. It is estimated that up to 4% of the world's agricultural land is seriously degraded. According to the Special Report on Climate Change and Land of the Intergovernmental Panel on Climate Change: "About a quarter of the Earth's ice-free land area is subject to human-induced degradation (medium confidence). Soil erosion from agricultural fields is estimated to be currently 10 to 20 times (no-tillage) to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former term specifically to displaced soil. Soil consists of a solid phase of minerals and organic matter (the soil matrix), as well as a porous phase that holds gases (the soil atmosphere) and water (the soil solution). Accordingly, soil is a three-state system of solids, liquids, and gases. Soil is a product of several factors: the influence of climate, relief (elevation, orientation, and slope of terrain), organisms, and the soil's parent materials (original minerals) interacting over time. It continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering with associated erosion. Given its complexity and strong internal connectedness, soil ecologists regard soil as an ecosystem. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drylands
Drylands are defined by a scarcity of water. Drylands are zones where precipitation is balanced by evaporation from surfaces and by transpiration by plants (evapotranspiration). The United Nations Environment Program defines drylands as tropical and temperate areas with an aridity index of less than 0.65."Millennium Ecosystem Assessment, 2005. Drylands Systems". Chapter 22 in: ''Ecosystems and Human Wellbeing: Current State and Trends'', Volume 1. Island Press. One can classify drylands into four sub-types: * Dry sub-humid lands * Demi-arid lands * Arid lands * Hyper-arid lands Some authorities regard hyper-arid lands as deserts (United Nations Convention to Combat Desertification - UNCCD) although a number of the world's deserts include both hyper-arid and arid climate zones. The UNCCD excludes hyper-arid zones from its definition of drylands. Drylands cover 41.3% of the earth's land surface, including 15% of Latin America, 66% of Africa, 40% of Asia, and 24% of Europe. Ther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Climate Change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global average temperature is more rapid than previous changes, and is primarily caused by humans burning fossil fuels. Fossil fuel use, deforestation, and some agricultural and industrial practices increase greenhouse gases, notably carbon dioxide and methane. Greenhouse gases absorb some of the heat that the Earth radiates after it warms from sunlight. Larger amounts of these gases trap more heat in Earth's lower atmosphere, causing global warming. Due to climate change, deserts are expanding, while heat waves and wildfires are becoming more common. Increased warming in the Arctic has contributed to melting permafrost, glacial retreat and sea ice loss. Higher temperatures are also causin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drylands
Drylands are defined by a scarcity of water. Drylands are zones where precipitation is balanced by evaporation from surfaces and by transpiration by plants (evapotranspiration). The United Nations Environment Program defines drylands as tropical and temperate areas with an aridity index of less than 0.65."Millennium Ecosystem Assessment, 2005. Drylands Systems". Chapter 22 in: ''Ecosystems and Human Wellbeing: Current State and Trends'', Volume 1. Island Press. One can classify drylands into four sub-types: * Dry sub-humid lands * Demi-arid lands * Arid lands * Hyper-arid lands Some authorities regard hyper-arid lands as deserts (United Nations Convention to Combat Desertification - UNCCD) although a number of the world's deserts include both hyper-arid and arid climate zones. The UNCCD excludes hyper-arid zones from its definition of drylands. Drylands cover 41.3% of the earth's land surface, including 15% of Latin America, 66% of Africa, 40% of Asia, and 24% of Europe. Ther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sahel
The Sahel (; ar, ساحل ' , "coast, shore") is a region in North Africa. It is defined as the ecoclimatic and biogeographic realm of transition between the Sahara to the north and the Sudanian savanna to the south. Having a hot semi-arid climate, it stretches across the south-central latitudes of Northern Africa between the Atlantic Ocean and the Red Sea. The Sahel part of Africa includes – from west to east – parts of northern Senegal, southern Mauritania, central Mali, northern Burkina Faso, the extreme south of Algeria, Niger, the extreme north of Nigeria, Cameroon and Central African Republic, central Chad, central and southern Sudan, the extreme north of South Sudan, Eritrea and Ethiopia. Historically, the western part of the Sahel was sometimes known as the Sudan region (''bilād as-sūdān'' "lands of the Sudan"). This belt was located between the Sahara and the coastal areas of West Africa. There are frequent shortages of food and water due to the dry ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sahara
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Topsoil
Topsoil is the upper layer of soil. It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs. Description Topsoil is composed of mineral particles and organic matter and usually extends to a depth of 5-10 inches (13–25 cm). Together these make a substrate capable of holding water and air which encourages biological activity. There are generally a high concentration of roots in topsoil since this is where plants obtain most of their vital nutrients. It also plays host to significant bacterial, fungal and entomological activity without which soil quality would degrade and become less suitable for plants. Bacteria and fungi can be essential in facilitating nutrient exchange with plants and in breaking down organic matter into a form that roots can absorb. Insects also play important roles in breaking down material and aerating and rotating the soil. Many species directly contribute to the healt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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