نتایج جستجو برای: arid and semi arid regions

تعداد نتایج: 16868284  

2017
Anzhi Zhang Gensuo Jia Howard E. Epstein Jiangjiang Xia

Semi-arid ecosystems are key contributors to the global carbon cycle and may even dominate the inter-annual variability (IAV) and trends of the land carbon sink, driven largely by the El Niño-Southern Oscillation (ENSO). The linkages between dynamics of semi-arid ecosystems and climate at the hemispheric scale however are not well known. Here, we use satellite data and climate observations from...

Journal: :آب و خاک 0
موسوی موسوی رئیسی رئیسی

abstract earthworms are an important component of soil fauna, and play a crucial role in the improvement of soil properties. however, very little is known of the interactive influence of earthworms and organic materials on soil enzyme activities, particularly in arid and semi-arid soils. the low organic matter content and the significant role of earthworms in stimulating microbiological and bio...

Journal: :desert 2010
h. memarian khalilabad s. feiznia k. zakikhani

abstract erosion and sedimentation are the most complicated problems in hydrodynamic which are very important in water-related projects of arid and semi-arid basins. for this reason, the presence of suitable methods for good estimation of suspended sediment load of rivers is very valuable. solving hydrodynamic equations related to these phenomenons and access to a mathematical-conceptual model ...

Journal: :desert 2008
a. khalili h. rahimi z. agha shariatmadari

depth of frost penetration is one of the main indices in agriculture, civil and transportation engineering. soil temperature is a function of several factors including: topography, solar radiation, air temperature, moisture content and other physical properties of soil such as thermal capacity, coefficient of heat conductivity, and specific heat. the main objective of the present paper is to de...

2016
Yuting Yang Huade Guan Okke Batelaan Tim R. McVicar Di Long Shilong Piao Wei Liang Bing Liu Zhao Jin Craig T. Simmons

Drought is an intermittent disturbance of the water cycle that profoundly affects the terrestrial carbon cycle. However, the response of the coupled water and carbon cycles to drought and the underlying mechanisms remain unclear. Here we provide the first global synthesis of the drought effect on ecosystem water use efficiency (WUE = gross primary production (GPP)/evapotranspiration (ET)). Usin...

2016
S. K. Sharma R. S. Singh

The arid region is spread over 38.7 million hectares mainly in the states of Rajasthan. Gujarat, Haryana, Punjab, Karnataka, Andhra Pradesh besides cold arid region situated in Leh, Laddakh and Himachal Pradesh. The region is marked by extreme environmental constraints due to which the cultivation of traditional crops is not economical. In a situation such as this, arid horticulture has ample s...

Excessive use of water and soil resources, especially in arid and semi-arid regions, increases soil erosion, destructive storms, the occurrence of dust, and desertification. Therefore, to prevent environmental problems in these areas, it is necessary to efficiently manage water and soil resources in arid and semi-arid regions. Rainwater catchment systems are one of the management and operationa...

Journal: :desert 2015
amir reza keshtkar

knowledge about low flow statistics is essential for effective water resource planning and management in ungauged orpoorly gauged catchment areas, especially in arid and semi-arid regions such as iran. we employed a data set of 20 riverflow time-series from the iranian central plateau river basin, iran to evaluate the low-flow series using several frequencyanalysis methods and compared the resu...

Journal: :journal of rangeland science 2014
mohsen sharafatmandrad adel sepehry hossein barani

in arid and semi-arid rangelands, grazing as one of the natural or human induced processes has direct and indirect effects on structure and dynamics of plant community and ecosystems. a study was done to analyze the effects of grazing on plant species diversity and plant functional types‘ (pfts) diversity of arid and semi-arid rangelands. we analyzed plant richness and diversity data from 75 sa...

Journal: :journal of rangeland science 2012
sedigheh zare kia hossein arzani mohammad jafari seyyed akbar javadi ali ashraf jafari

this study aims to assess the effect of grazing intensity on vegetation structure, soil nutrient concentrations and soil physical properties. the study was carried out in steppe rangelands of saveh, markazi province, iran. four sites with four grazing intensities including very high, high, moderate and non-grazed with the same ecological conditions were selected. to study various vegetation and...

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