نتایج جستجو برای: arid

تعداد نتایج: 18687  

Journal: :Evolution; international journal of organic evolution 2013
John J Wiens Kenneth H Kozak Natalia Silva

Deserts occupy approximately 12% of the Earth's land surface, and are thought to have species poor but highly specialized biotas. However, few studies have examined the evolutionary origins of desert biotas and of diversity patterns along aridity gradients. Further, it is unclear if species occurring in more extreme conditions on a given niche axis (i.e., precipitation) are more specialized for...

2017
Guoqing Chen Mingjiu Wang Zhengjia Liu Wenfeng Chi

The biogeophysical effects of land cover change (LCC) on land surface temperature are largely understood, especially in tropical and boreal zones, but fewer studies have reported the biogeophysical consequences of ecological restoration of mining areas located in arid and semi-arid temperate zones. In this study, we employed 2000–2015 satellite-based net radiation (Rn) and latent heat flux (LE)...

2007
Sujith Ravi Paolo D’Odorico Gregory S. Okin

[1] Hydrological and aeolian processes redistribute sediments and nutrients within arid landscapes with important effects on the composition and structure of vegetation. Despite the relevance of wind and water erosion to the dynamics of arid and semiarid ecosystems, the interactions between these two processes remain poorly understood. In this paper we present the results of an intensive set of...

2014
Varun Kumar Rajesh Gera

Arid regions pose a serious problem for crop production by suppressing plant growth. The use of plant growth promoting rhizobacteria (PGPR) as bioinoculant may be promising to enhance the crop yield in arid conditions. In the present investigation, four strains of cultivable bacteria associated with the rhizosphere of Saccharum L. grown in arid region were isolated using N-free media. Assessmen...

2017
Xiaotao Huang Geping Luo Xinxin Wang

Arid grassland ecosystems are widely distributed across Central Asia. However, there is a lack of research and observations of the land–atmosphere exchange of water and heat in the arid grasslands in this region, particularly over complex surfaces. In this study, systematic observations were conducted from 2013 to 2015 using an HL20 Bowen ratio and TDR300 and WatchDog1400 systems to determine t...

2017
Ajoke R. Onojeghuo Heiko Balzter Paul S. Monks

The annual cycles of soil moisture and NO2 have been analysed across the climate zones of West Africa using two satellite data sets (OMI on AURA and ASCAT on MetOp-A). Exploring the sources and sinks for NO2 it is clear that the densely populated urban cities including Lagos and Abuja had the highest mean NO2 concentrations (>1.8 × 10 15 molecules cm -2 ) indicative of the anthropogenic urban e...

2009
Mingyuan DU Seiichiro YONEMURA Hiroyuki DEN Zhibao SHEN Yanbo SHEN

Monthly mean air temperature and precipitation data, monthly dust storm frequencies (times of dust storm occurrences) of 107 stations in North China were analyzed to clarify the relationship between the climate change and dust storm occurrence. Arid regions of North China were divided into five and trends of dust storm occurrence and climate changes showed different patterns for these regions, ...

2008
Girolamo Fiorentino Donatella Magri K. J. Willis K. D. Bennett S. G. Haberle

It has been suggested that climates during the Holocene have varied on timescales of about 1500 years, forced by oscillations of a solar cycle. These climatic changes have been implicated as the cause of changes in geological records from, mostly, marine sediments. If there were such changes, and if they were of great enough amplitude to force changes in marine sedimentation, it would be reason...

2007
Susan Buffler Craig Johnson John Nicholson

................................................................................................................................................... ii Preface...................................................................................................................................................... 1 Background ..............................................................................

2016
Jinhong Wan Ruoxi Li Wenxin Wang Zhongmei Liu

Recent literature shows that income diversification is an important strategy for rural households to manage drought risk in arid and semiarid regions. This article examines whether income diversification can help rural households to overcome the adverse impact of drought in Northern China. Based on field interview data from 291 rural households in 13 townships of Northern China, we found that r...

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