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Agriculture
Hot and arid areas are complex environments that pose many challenges for the management of agriculture. With rapidly growing population, climate change and uncertain rain patterns many arid environments are at risk of desertification and other regions are witnessing the migration of desert dunes. However, there are many successful examples of countries greening the desert for agriculture. These include intensive rain fed schemes like those found in Egypt and Saudi Arabia, to small scale permaculture projects such as those found in the arid and savannah regions of Kenya. Soil management and ecology are increasingly becoming more sophisticated and through shared knowledge, cooperatives and the work of NGO networks to share good practice, the knowledge of simple and appropriate solutions such as stone lines, fencing, reafforestation programmes is spreading. Excellent examples include tassa construction through women's cooperatives in Niger. Another idea with growing support is the mindset changing ideas of Alan Savory who promotes holistic management of grasslands through the expansion of herds. All these ideas face their own challenges, both global and local, covering the environmental and socio-economic.
Aridity and Infertility
Before exploring different examples of agricultural opportunities and challenges it is important to distinguish environments that suffer aridity from environments that suffer from infertility. In short arid soils lack moiture while infertile soils lack vital nutrition such as nitrogen, phosphorous and potassium. However these two problems are often closely associated. The causes of increasing aridity are complex and thought to be both natural and man-made. Arid environments and their location are determined by their climate and so enjoy intense periods of heat and short but often intense rain in a seasonal climate known as Tropical Wet and Dry. What rain that falls often lands on sparsely vegetated soils and quickly evaporates away. Arid and semi-arid areas have a negative water balance meaning that evapotranspiration and stores of water exceed the inputs of precipitation. Infertility is caused by low organic content and biomass decay, thin soils and therefore limited mineral content, and weak leaching leading to a bulid up of salt from transpiration. However interference through population pressure, over cultivation, deforestation, overgrazing or according to Savory's growing evidence, undergrazing, soils become exposed to rainfall and soil erosion increases. These factors increase the fragility of soils and threaten agricultural practice in hot and arid environments.
Aridity and Infertility
Before exploring different examples of agricultural opportunities and challenges it is important to distinguish environments that suffer aridity from environments that suffer from infertility. In short arid soils lack moiture while infertile soils lack vital nutrition such as nitrogen, phosphorous and potassium. However these two problems are often closely associated. The causes of increasing aridity are complex and thought to be both natural and man-made. Arid environments and their location are determined by their climate and so enjoy intense periods of heat and short but often intense rain in a seasonal climate known as Tropical Wet and Dry. What rain that falls often lands on sparsely vegetated soils and quickly evaporates away. Arid and semi-arid areas have a negative water balance meaning that evapotranspiration and stores of water exceed the inputs of precipitation. Infertility is caused by low organic content and biomass decay, thin soils and therefore limited mineral content, and weak leaching leading to a bulid up of salt from transpiration. However interference through population pressure, over cultivation, deforestation, overgrazing or according to Savory's growing evidence, undergrazing, soils become exposed to rainfall and soil erosion increases. These factors increase the fragility of soils and threaten agricultural practice in hot and arid environments.
The Challenge of Desertification
Desertification is defined by the United Nations as ‘ land degradation in arid, semi-arid and sub-humid areas resulting from various factors including climatic variations and human activities’. It remains one of the biggest environmental problems of today and is affecting more than 110 countries. The impacts of desertification vary from place to place. For example as Fran Brady states, the United States has the highest percentage of drylands at 74%, Sub-Saharan Africa, because of its dependence on land, is more deeply affected. In Kenya, around 80% of the land surface is threatened by desertification.
Desertification is generally caused by climate variability and unsustainable human activities caused principally by population growth and resource mismanagement. Due to global climate change some regions of the world are warming faster than others and rainfall patterns are changing in regard to frequency and intensity. These changes are more signifcant in hot arid regions. The graphs below show the average global near-surface land temperature and rainfall patterns of the Sahel region of Africa. The pattern shows a clear warming over the last 100 years as well as changing pattern of rainfall with periods of below average rainfall as well big variations over the short term. These natural factors create environmental stress and add pressure to fragile soil resources.
Population increase is most rapid in developing countries of the world and especially in Sub-Saharan Africa. This places enormours pressure on land and water resources through deforestation, over cultivation and unsustainable grazing. The map and graphic below both show that many Sub-Saharan African countries will more than double their population between 2010 and 2050.
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The human causes of desertification relate to mismanagement of the land, often through a combination of factors due to population pressure. These factors include deforestation for fuel and for agriculture, over cultivation, which exhausts the nutrient base of soils and unsustainable grazing, which exceeds the carrying capacity of soil. These three factors have led to the systamatic removal of nutrients and the loss of binding roots and nutrient fixing trees. As a result, soil becomes easily eroded and degraded.
Deforestation leads to a loss of fertility through soil erosion and runoff. The soils become shallow and of low fertility. This reduces the water-holding capacity of the soil. When heavy rains arrive rivers flood excessively. 82% of the total energy used in the Sahel comes from wood directly and through charcoal. Wood is the most accessible and affordable energy. As the supply decreases rural people who used to enrich farmlands with animal manure are forced to use manure for fuel and this restricts the vital nutrition feed into the soils, |
causing impoverishment of soil resources. Unsustainable grazing strips the land of its vegetation and compacts the ground. As a consequence it loses its ability to support plant growth and to hold moisture. Some African nations favour more western models of agriculture and view nomadic pastoralism as a backward system. Instead they promote sedentary farming. This has led to a decline in more sustainable nomadic patterns of farming, which allows soils time to recover. The work of Alan Savory on holistic management of grasslands however suggests that herd numbers in contrast to being reduced actually need to be increased but sytamatically moved on in a replication of how natural nomadic herds such as the wilderbeast migrate. This idea suggests that larger herds should mimic natural herds but migrates over larger territories. You can view his TED talk below.
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Due to a number of factors, such as inheritence laws and larger family size as well as the tendency of crop farmers after a period of good years to extend their cropping onto more marginal lands, overcultivation is placing increasing degrees of stress on hot arid soils. This stress is compounded by the common practice of monocultures, whereby only one or two staple crops are repeatedly grown in the soils as well as limited crop rotation, whereby the same crop is planted repeatedly in the same field. Both of these practices place stress on the nutrient base of soils as the same nutrient is extracted by the crop. The soil therefore declines in productivity. In other areas the growth of cash crops for export forces poorer farmers onto more marginal land less suitable for crop production. This not only increases
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overcultivation but also brings sedentary farmers into conflict with more nomadic farmers.
Salinisation
Salinisation is the accumulation of soluble salts, such as sodium, magnesium and calcium in soil to the extent that soil fertility is severely reduced. It is regarded as a major cause of soil degradation and is therefore a leading factor in the process of desertification. There are a number of causes of salinisation in hot arid environments, principally increased salinity is caused by the evapotranspiration of water from the surface, which leaves deposits of soluble salt in the soil. The heat of the sun draws water and salts upwards and it crystalises in the upper layers. This can can impede root growth and infiltration rates that in turn increases surface run-off or can cause surface waterlogging where impermeable crystal layers form. In hot arid environments where vegetation cover is limited and under pressure due to deforestation, overcultivation and unsustainable grazing, infiltration rates can be increased, which leads to a rising of the water table. This in turn increases salinity through a process of capillary rise. In addition, waterlogging due to excessive irrigation practices and leaching methods also increase salinity in soils. The two diagrams below show how both irrigation and forest removal due to agriculture can lead to salinisation.
Salinisation is a huge probelm in many dry countries and is in fact affecting almost every country where intensive irrigation is being deployed. The following videos based in Australia explain the problem of salinisation in hot arid environments and explore management projects that can overcome the problem.
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The Greening of the Desert
There are many examples of turning the desert green. In fact mankind's ability to control water and floods enabled the great civilisations of Egypt amd Mesopotamia to prosper in the first place. Today massive greening projects are underway all over the world from the USA to China and across North Africa and the Middle East. These intensive greening projects produce, cotton, date palms, wheat and even potatoes through the industrialisation of irrigation and use of artificial fertilizers and herbicides. The agricultural greening projects rely on massive amounts of freshwater that is extracted from non-renewable groudwater acquifers. The sustainability of these projects in regard to both energy and water use is highly questionable and whilst clearly profits are there to made it is unlikley that this type of agriculture can be sustained long term. The following video explores the challenges of farming wheat in Saudi Arabia and the production of potatoes bound for European consumption in the deserts of Egypt.
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Permaculture
Permaculture is an ecological design system for sustainability in farming and soil management. It's a self maintained agricultural system modelled on natural ecosystems. It has its roots in the close biological field research of Bill Mollison in the deserts of Australia. It is now being applied globally in dry arid environments all over the world. The following video shows how an intensely farmed and declining area of land in Jordon was converted back to health and production through rainfall harvesting, swales and mulching of organic matter and nitrate fixing trees.
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Bottom-up Strategies and Women Cooperatives
There are many examples of successful bottom-up strategies that improve the productivity of hot arid environments. Some of the more well known examples include the use of stone lines or magic stones, which are simple lines of stones placed around contours to form small terraces. These lines prevent soil erosion and help trap run-off. When done effectively they have been known to increase land productivity by up to 50 percent. In northern Niger villages are fighting a battle against the encroachment of dunes from the Sahara. They do this through fixing dunes with fences and afforestation programmes. In Tahoua, Niger, women's cooperatives have achieved incredible results through the innovative but labour intensive practice of tassa construction. Tassas are made on plateaus or glassy land where the land is flat and the soil has been washed away and hardened. Tassas are small depressions that drain the water. In Tahoua the women have revived 200 hectares of unproductive land through tassa construction and afforestation but this has created a gender based rivalry. The videos below highlight some of the achievements in Niger.
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Mineral Extraction.
Due to the nature of the physical environment and geological age and structure of many desert environments there is often an abundance of mineral resources to be found. The Middle East has built its development and prosperity through the abundance of fossil fuels such as oil and natural gas. Oil and gas can be found in Algeria, Bahrain, Iran, Iraq, Kuwait, Libya, Qatar, Saudi Arabia and the United Arab Emirates. Saudi Arabia, Kuwait, Qatar and Iraq possess over 60 percent of the world's easily accesible oil reserves. Many other arid environments boast large reserves of minerals. Chilli boasts huge reserves of copper in the Atacama desert, making it the largest exporter in the world, with almost 5 times greater production than its closest rival. Almost 24 percent of rough diamond production comes from Australia (>13%), Angola and Namibia. In addition, Australia produces almost 10 percent of worldwide gold production and is the leading exporter of opals. Salt production and export is found in all arid countries. However, despite the apparent abundance of minerals their exploitation is often challenging. The map below shows the quatity of mineral mine sites in Australia.
Australia is often referred to as the 'mine to the world' and has an industrial approach to mining that has brought Australia vast quantities of wealth. In total it amounts to just less than 10 percent of its economy.
In the following two videos and PDF resources you can learn how Namibia has the opportunity to exploit uranium and other minerals including diamonds. Namibia has one of the best transport infrastructures in Africa and so has a fantastic economic base on which to grow it mineral industries, however with limited regulation and education workers are exposed to damaging health impacts.
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The following video based in Mali in West Africa shows how families living in poverty are exploited to work in gold mines. This type of poverty robs children of their education and exposes workers to great hardships for undervalued gold.
This last video provides an insight into the mining process at the Sudanese goldfields of Abu Hamed and Gab Gaba. The backdrop of the video shows many shallow mines crowded with young men at work. Again the men are exposed to horrendous work conditions and toxic materials including the handling and burning of mercury. Due to the remoteness of mining communities they are often dominated by a male demographic and with this comes problems linked with alcholism, violence and prostitution. This is not just linked to Sudanese mining communities but any mining community that employs a large migrant male work force.
The Opportunities and Challenges of Permafrost Regions
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The Opportunities and Challenges of Tourism in the Antarctic
The following site, Discovering Antarctica.org provides an excellent case study investigating the impacts of tourism on Antartica.
To what extent do consider human activity in extreme environments to be unsustainable?
This type of question tests your ability as a geographer to connect all that you have learned on human activity during the extreme environments course as well as discuss it in relation to sustainbility. This question is therefore synoptic. What is sustainability and what do we mean by unsustainbable human activity in extreme environments? These questions need to be addressed thoroughly. Sustainability directly relates to the theory of carrying capacity and refers to that relationship between environment and its resources with population and human activity. You will need to show an understanding of the challenges of human activity in extreme environments as well as the environmental and social consequences of that activity. At the same time you should provide examples that describe the ways that these challenges can be overcome. In some cases there may well be unsustainable examples, for example, tourism growth in Antarctica, increased oil exploration in Alaska or mining in Australia. You should show a critical understanding. To what extent are the inevitable environmental and social impacts of these activities manageable? Can they be contained or limited to within justifiable levels for the obvious economic gains to be had. In addition, there are also good arguments to present an optimistic account. For example a more expansive deployment of permaculture techniques and more sustainable soil and tree management in arid environments. You need to bring in a variety of place examples to show the diversity of extreme environments. Moreover, there are a number of overarching pressures, like population growth, conflict and climate change that will continue to place stress on the carrying capacity of extreme environments. To what extent will these pressures reduce the carrying capacity to sustain human activity? Don't be afraid to use small examples not fully covered in the course. For example the shrinking of alpine glaciers and the impacts that has on tourism and fresh water supplies for mountain communities.
The following video presents the LIUC interdisplinary unit for sustainable economy's project for providing development that is related to the needs of the nomadic people of Mongolia.
The following video presents the LIUC interdisplinary unit for sustainable economy's project for providing development that is related to the needs of the nomadic people of Mongolia.
The impact of global climate change on indigenous populations, settlement and economic activities in extreme environments.
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