Ørkenområder

ørken

Vildmark eller ødemark, hvor jorden på grund af klima og vandmangel kun har ringe fauna og flora.
Et geografisk område, hvor den gennemsnitlige årlige nedbør er mindre end 250 mm. foruden høje temperaturer og stor fordampning.
En ørken er et område, hvor vandfordampningen er større end nedbøren.
Ifølge FN s ørkenkonvention er »ørkendannelse« [en] forringelse af jorden i aride, semi-aride og tørre subhumide områder som følge af forskellige faktorer, som klimavariationer og menneskelige aktiviteter. »Aride, semi-aride og tørre subhumide områder« [er også ifølge ørkenkonventionen] områder, bortset fra polar- og subpolarområder, hvor forholdet mellem den årlige nedbør og den potentielle evapotranspiration ligger inden for skalaen 0,05-0,65. Der er ørkener på alle jordens kontinenter og på planeten Mars.
Geografi: Store ørkenområder
Natur, klima. Biodiversitet. Fauna og flora: Fisk. Fugle. Koralrev. Vådområder.
Nature, climate. Flora and fauna: Botanical gardens. Fish. Birds. Coral reefs. Wetlands
Flore et faune: Poissons. Oiseaux. Les récifs coralliens. Les zones humides.
Flora y fauna: Fish. Pájaros. Los arrecifes de coral. Los humedales.
Natur, Klima. Flora und Fauna: Botanische Gärten. Fisch. Vögeln. Korallenriffe. Feuchtgebiet, Feuchtbiotop.
International Network of Basin Organizations / Det internationale netværk af flodbassin organisationer.
- http://www.inbo-news.org/spip.php?sommaire⟨=en:
Geologi og jordbundsforhold: Bjerge, vulkaner, jordskælv og ørkenområder:
Geology: Mountains, volcanoes, earthquakes and desert areas
Géologie: Montagnes, volcans, tremblements de terre et les zones désertiques
Geología: Montañas, volcanes, terremotos y zonas desérticas
Geologie: Berge, Vulkane, Erdbeben und Wüstengebiete
World Database on Protected Areas: Beskyttede områder og nationalparker.
Historie: Der var atomforsøgsområder under og efter den kolde krig i Gobi, Kalahari, Nevada, New Mexico og i Sahara.
Bekendtgørelse af De Forenede Nationers konvention af 17. juni 1994 om bekæmpelse af ørkendannelse i de lande, der er ramt af alvorlig tørke og/eller ørkendannelse, særlig i Afrika (FN s ørkenkonvention).
- https://www.retsinformation.dk/Forms/R0710.aspx?id=22872
- http://www.unccd.int/en/Pages/default.aspx
Se også: Beduiner ; oase ; steppe.

Litteratur

Global Deserts Outlook. United Nations Environment Programme (UNEP). 2006., a report in the Global Environment Outlook (GEO) series.
- https://web.archive.org/web/20060610/http://www.unep.org/geo/news_centre/
Namib Sand Sea World Heritage Nomination dossier to UNESCO for inscription into the World Heritage List. / : 2012 Namibia National Committee for World Heritage.
- http://whc.unesco.org/uploads/nominations/1430.pdf
Goudie, A. and Seely, M. (2011). World Heritage Desert Landscapes: Potential Priorities for the Recognition of Desert Landscapes and Geomorphological Sites on the World Heritage List. Gland, Switzerland: IUCN. 44pp.
- https://portals.iucn.org/library/efiles/documents/2011-006.pdf
Duncan C, Kretz D, Wegmann M, Rabeil T, Pettorelli N. 2014 Oil in the Sahara: mapping anthropogenic threats toSaharan biodiversity from space. Phil. Trans. R. Soc. B 369: 20130191.
- http://rstb.royalsocietypublishing.org/content/royptb/369/1643/20130191.full.pdf
'Deserts are among the most poorly monitored and understood biomes in the world, with evidence suggesting that their biodiversity is declining fast. Oil exploration and exploitation can constitute an important threat to fragmented and remnant desert biodiversity, yet little is known about where and how intensively such developments are taking place. This lack of information hinders local efforts to adequately buffer and protect desert wildlife against encroachment from anthropogenic activity. Here, we investigate the use of freely available satellite imagery for the detection of features associated with oil exploration in the African Sahelo-Saharan region. We demonstrate how texture analyses combined with Landsat data can be employed to detect ground-validated exploration sites in Algeria and Niger.'
Transactions of the Symposium on the Biological Resources of the Chihuahuan Desert Region, United States and Mexico by Wauer, Roland; Riskind, David. 1977
- https://archive.org/details/transactionsofsy00waue
The Otero Mesa
- https://archive.org/details/otero_mesa
The Chihuahuan Desert extends southward from New Mexico, Texas and Arizona into the Mexican Plateau. It covers an area of 250,000 square miles and is considered to be among the most biologically rich and diverse desert eco-regions in the world. The area is home to Pronghorn Antelope, migratory songbirds and independent cattle ranches that have been in operation for generations.
Despite local outrage and a 2005 law suit filed by New Mexico's governor against the Bush administration, the Bureau of Land Management has made the decision to nearly double the acreage available for oil and gas development on Otero Mesa. If it is turned into a full-scale oil and gas field, the Wilderness and much of the wildlife that live there will be threatened by groundwater pollution. Current drilling requires the use of a number of chemical agents (many of which are suspected carcinogens) that are used the entire length of a drilling process.
Plant dieback under exceptional drought driven by elevation, not by plant traits, in Big Bend National Park, Texas, USA. by Waring, Elizabeth F.; Schwilk, Dylan W., 2014 PeerJ, volume 2.
- https://archive.org/details/pubmed-PMC4106195
In 2011, Big Bend National Park, Texas, USA, experienced the most severe single year drought in its recorded history, resulting in significant plant mortality. We used this event to test how perennial plant response to drought varied across elevation, plant growth form and leaf traits. In October 2010 and October 2011, we measured plant cover by species at six evenly-spaced elevations ranging from Chihuahuan desert (666 m) to oak forest in the Chisos mountains (1,920 m). We asked the following questions: what was the relationship between elevation and stem dieback and did susceptibility to drought differ among functional groups or by leaf traits? In 2010, pre-drought, we measured leaf mass per area (LMA) on each species. In 2011, the percent of canopy dieback for each individual was visually estimated. Living canopy cover decreased significantly after the drought of 2011 and dieback decreased with elevation. There was no relationship between LMA and dieback within elevations. The negative relationship between proportional dieback and elevation was consistent in shrub and succulent species, which were the most common growth forms across elevations, indicating that dieback was largely driven by elevation and not by species traits. Growth form turnover did not influence canopy dieback; differences in canopy cover and proportional dieback among elevations were driven primarily by differences in drought severity. These results indicate that the 2011 drought in Big Bend National Park had a large effect on communities at all elevations with average dieback for all woody plants ranging from 8% dieback at the highest elevation to 83% dieback at lowest elevations.
Rendering Useless: South Africa’s Nuclear Test Shafts in the Kalahari Desert. / : David Albright, Paul Brannan, Zachary Laporte, Katherine Tajer, and Christina Walrond. November 30, 2011.
- http://isis-online.org/uploads/isis-reports/documents/Vastrap_30November2011.pdf
Report on Global Status of Biodiversity in the Drylands. For the UN Intergovernmental Negotiating Committee for a Convention to Combat Desertification.
UN Intergovernmental Negotiating Committee, 1994.
- https://archive.org/details/reportonglobalst94wcmc

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