نتایج جستجو برای: desertification is specific phenomenon of arid

تعداد نتایج: 21482172  

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1997
J H Brown T J Valone C G Curtin

Natural ecosystems contain many individuals and species interacting with each other and with their abiotic environment. Such systems can be expected to exhibit complex dynamics in which small perturbations can be amplified to cause large changes. Here, we document the reorganization of an arid ecosystem that has occurred since the late 1970s. The density of woody shrubs increased 3-fold. Severa...

Journal: :international journal of advanced biological and biomedical research 0
zahra bayat m.sc. student of desertification, faculty of natural resources, university of semnan, semnan, iran seyed hassan kaboli assistance professor of desertification, faculty of natural resources, semnan university, iran mohammad rahimi assistance professor of desertification, faculty of natural resources, semnan university, iran shima nikoo ph.d of desertification, faculty of natural resources, university of semnan, semnan, iran mohammadkia kianian instructor of desertification, faculty of natural resources, university of semnan, semnan, iran neda soleiman dehkordi m.sc. student of desertification, faculty of natural resources, university of semnan, semnan, iran

desertification could be traced back to one or many factors. thus, to cope with such a phenomenon, there exists a need for a profound understanding of the processes and the causes. the study area of the current paper is the extent of shahrekord’s marghzar as an important case amongst the important ones of the province. in order to evaluate the roots of desertification in the area, the iranian m...

2010
Kensuke KAWAMURA Tsuyoshi AKIYAMA

In the arid and semi-arid regions of Northeast Asia, grassland degradation has become a major environmental and economic problem, so sustainable utilization of resources is crucial in terms of not only supporting the local and animal production but also thinking about the global environment. Especially in Mongolia and North China, grassland degradation has mainly been induced by artificial fact...

2010
Alan Grainger

This document presents proposals for the design and implementation of a Baseline Survey for the UN Convention to Combat Desertification (UNCCD). It has been prepared at the request of the Secretariat of the UNCCD. The Baseline Survey is to be initiated as part of the UNCCD's Ten Year Strategic Plan, and will form the starting point for monitoring long-term trends in desertification so that prog...

2011
Fernando T. Maestre María D. Puche César Guerrero Adrián Escudero

Shrub encroachment is a worldwide phenomenon with implications for desertification and global change. We evaluated its effects on the activities of urease, phosphatase and b-glucosidase in Mediterranean semiarid grasslands dominated by Stipa tenacissima by sampling 12 sites with and without resprouting shrubs along a climatic gradient. The presence of shrubs affected the evaluated enzymes at di...

پایان نامه :وزارت بهداشت، درمان و آموزش پزشکی - دانشگاه علوم پزشکی و خدمات بهداشتی درمانی استان کرمانشاه 1370

cml in breif cml is characterized by the proliferation of large numbers of immature wbc in the blood and bone marrow. in most of the patients , it is a clonal disorder in which all cell lines, express the philadelphia chromosome)q/22 translocation(it accounts for 20 of all leukemias and most cases occur over 25 yrs of age. the disease usually begins insidiously,but symptoms referable to anemia ...

Land degradation in order to eliminate the natural vegetation, which in the definition of the international community refers to desertification, is widely regarded as one of the main considered problems also the salination of the soil is an important factor in desertification. One of the dynamic properties of soil is the soil salinity this characteristic is one of the main problems in arid and ...

پایان نامه :0 1374

this experimental study has been conducted to test the effect of oral presentation on the development of l2 learners grammar. but this oral presentation is not merely a deductive instruction of grammatical points, in this presentation two hypotheses of krashen (input and low filter hypotheses), stevicks viewpoints on grammar explanation and correction and widdowsons opinion on limited use of l1...

پایان نامه :0 1375

investigation the archetype of mother can help the reader to understand poes works, especially his fiction, better, if not fully. motivated by internal and external drives to get into the universe in its manifold form poe was impelled to art and, from various modes of art, to symbolism. how much was poe successful to produce works of art has been a matter of dispute among critics. however, ther...

2005
M. Greco

The paper deals some important aspects concerning the study of desertification phenomenon that has significantly interested all European countries of the Mediterranean basin in the last decades. The territorial sensibility, qualitatively and/or quantitatively, of the risk related to the desertification processes has been valued as grade of susceptibility to the phenomenon in the study area, wit...

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