نتایج جستجو برای: desertification is specific phenomenon of arid

تعداد نتایج: 21482172  

Journal: Desert 2014

Desertification in arid, semi-arid and dry sub-humid regions is a global environmental problem. Considering theincreasing importance of desertification and its complexity, the necessity of giving attention to desertification criteria andindices is essential. Models and methods such as MEDALUS, UNEP-FAO, and others have been proposed on local andnational scales. In this research, IMDPA was selec...

Risk assessment provides the possibility of planning and management to prevent and reduce the risk of desertification. The present study is aimed to assess the hazard and risk of desertification and to develop management programs in the semi-arid western regions of Golestan Province in Iran. Desertification rate was obtained using the Iranian model of desertification potential assessment. Since...

Journal: :global journal of environmental science and management 0
m. akbari department of watershed and arid zone management, faculty of range land and watershed, gorgan university of agricultural sciences and natural resources, gorgan, iran m. ownegh department of watershed and arid zone management, faculty of range land and watershed, gorgan university of agricultural sciences and natural resources, gorgan, iran h.r. asgari department of watershed and arid zone management, faculty of range land and watershed, gorgan university of agricultural sciences and natural resources, gorgan, iran a. sadoddin department of watershed and arid zone management, faculty of range land and watershed, gorgan university of agricultural sciences and natural resources, gorgan, iran h. khosravi department of arid and mountainous regions reclamation, faculty of natural resources, university of tehran, tehran, iran

risk assessment provides the possibility of planning and management to prevent and reduce the risk of desertification. the present study is aimed to assess the hazard and risk of desertification and to develop management programs in the semi-arid western regions of golestan province in iran. desertification rate was obtained using the iranian model of desertification potential assessment. since...

Journal: :journal of rangeland science 2010
victor r. squires

the unccd has been ratified by over 190 countries. it is the attempt by nations, both rich and poor to control the scourge of desertification. the definition of which is “land degradation in arid, semiarid, and dry subhumid areas resulting from various factors, including climatic variations and human activities. it is now widely accepted that desertification is not the relentless advance of des...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه یاسوج - دانشکده علوم 1391

in this investigation the effect of external field on the electron density of nanostructures of cds, cdse, cdte, gaas and polymeric structure of three, four, five and six units of cds as a kind of nanosolar cells has been studied theoretically. as modeling this system in nanodimension, molecular structures has used. specific properties of molecular structures permit us to consider different sym...

Victor R. Squires

The UNCCD has been ratified by over 190 countries. It is the attempt by nations, both rich and poor to control the scourge of desertification. The definition of which is “land degradation in arid, semiarid, and dry subhumid areas resulting from various factors, including climatic variations and human activities. It is now widely accepted that desertification is not the relentless advance of des...

2010

There is no single agreed definition of the term drylands. Two of the most widely accepted definitions are those of FAO and the United Nations Convention to Combat Desertification (UNCCD, 2000). FAO has defined drylands as those areas with a length of growing period (LGP) of 1–179 days (FAO, 2000a); this includes regions classified climatically as arid (Plate 1), semi-arid and dry subhumid. The...

Journal: :Ecology letters 2009
Fernando T Maestre Matthew A Bowker María D Puche M Belén Hinojosa Isabel Martínez Pablo García-Palacios Andrea P Castillo Santiago Soliveres Arántzazu L Luzuriaga Ana M Sánchez José A Carreira Antonio Gallardo Adrián Escudero

The worldwide phenomenon of shrub encroachment in grass-dominated dryland ecosystems is commonly associated with desertification. Studies of the purported desertification effects associated with shrub encroachment are often restricted to relatively few study areas, and document a narrow range of possible impacts upon biota and ecosystem processes. We conducted a study in degraded Mediterranean ...

2014
Guang-Lei Gao Guo-Dong Ding Bin Wu Yu-Qing Zhang Shu-Gao Qin Yuan-Yuan Zhao Yan-Feng Bao Yun-Dong Liu Li Wan Ji-Feng Deng

BACKGROUND Biological soil crusts are common components of desert ecosystem; they cover ground surface and interact with topsoil that contribute to desertification control and degraded land restoration in arid and semiarid regions. METHODOLOGY/PRINCIPAL FINDINGS To distinguish the changes in topsoil affected by biological soil crusts, we compared topsoil properties across three types of succe...

Ali Akbar Fakhireh Ali Reza Shahryari Gholam Reza Rahdari, Hassan Khosravi Mohammad Reza Rahdari

Today one of the ecological crisis is the phenomenon of desertification that affecting the world. Desertification is more related to social and anthropogenic issues than natural causes and it becomes more important over the time. Monitoringis the systematic collection and analysis of information as a project progresses. In this study, using AHP method and GIS techniques has been to assess deser...

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