نتایج جستجو برای: vegetation density and type

تعداد نتایج: 17047909  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه ارومیه - پژوهشکده ادبیات 1393

testing plays a vital role in any language teaching program. it allows teachers and stakeholders, including program administrators, parents, admissions officers and prospective employers to be assured that the learners are progressing according to an accepted standard (douglas, 2010). the problems currently facing language testers have both practical and theoretical implications but the first i...

Journal: :journal of agricultural science and technology 2011
o. esmailzadeh s. m. hosseini m. tabari

we assessed the size and composition of the soil seed bank and above-ground vegetation in 52 relevés representing a range of habitats within an old- growth, temperate deciduous forest at hyrcanian region, northern iran. we identified 63 taxa in the seed bank, with an average density of 4202 seeds/spores per m2 by seedling emergence method. hypericum androsaemum, cardamine impatiens, and rub...

ژورنال: علوم آب و خاک 2015
افیونی, مجید, جلالیان, احمد, خلیلی‌مقدم, بیژن, دهقانی, امیر‌احمد, عباسپور, کریم,

With the advent of advanced geographical informational systems (GIS) and remote sensing technologies in recent years, topographic (elevation, slope, and aspect) and vegetation attributes are routinely available from digital elevation models (DEMs) and normalized difference vegetation index (NDVI) at different spatial (watershed, regional) scales. This study explores the use of topographic and v...

2005
G. Meinel

* Corresponding author. Abstract – Caused by the importance of urban vegetation volume as an indicator for ecologically orientated city planning and since there are several cities which already use laser scanner data at leaf-off aerial flight times for creating 3D city models the idea merges of using this data for that purpose. This paper deals with the question whether laser scanner data that ...

Journal: :مرتع و آبخیزداری 0
جابر شریفی عضو هیت علمی مرکز تحقیقات کشاورزی و منابع طبیعی استان اردبیل ایران. مرتضی اکبرزاده استادیار پژوهشی بخش تحقیقات مرتع مؤسسه تحقیقات جنگل ها ¬و مراتع کشور، ایران.

a major part of the rangelands of iran are located in arid and semi-arid regions. in this climate, rainfall fluctuation is an important factor which affects vegetation and forage production. in dry years that rainfall decreases, surface vegetation and forage production is damaged. this study was conducted on semi-steppic rangelands of ardebil over nine years (1999-2007), to study of vegetation ...

Journal: :environmental resources research 2014
javad gholami tabasi mohammad jafary hossein azarnivand mahdi sarparast

planting shrub seedlings under oil mulches has frequently been used for stabilizing mobile sands in iran for during the last three decades. sandy desert of samad abad, sarakhs, northeast iran, has been fixed by cultivating seedling of haloxylon aphyllum under the oil mulches. therefore this study was designed to investigate the effects of the sand fixation project on soil and vegetation propert...

The present study aimed to assess the spatio-temporal changes in the natural vegetation cover of Ahl Iman watershed, Ardabil province. For this purpose, land use maps of the three years (2000, 2010, and 2020) were extracted from Landsat satellite images. Then, seven landscape metrics (patch density, edge density, patch richness, splitting index, contagion index, Euclidean nearest neighbor dista...

2017
Cui Li Bo Xiao Qinghai Wang Ruilun Zheng Juying Wu

To provide more insights into the responses of the soil seed bank and vegetation to human disturbance intensity, we selected four land use types, including: native grassland (no human disturbance), abandoned artificial grassland (light human disturbance), artificial grassland (moderate human disturbance), and farmland (severe human disturbance) in a semi-arid climate of northern China. The spec...

2010
Daniel S. Falster Åke Brännström Ulf Dieckmann Mark Westoby

1. Numerous plant traits are known to influence aspects of individual performance, including rates of carbon uptake, tissue turnover, mortality and fecundity. These traits are bound to influence emergent properties of vegetation because quantities such as leaf-area cover, average height, primary productivity and density of standing biomass result from the collective behaviour of individuals. Ye...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد تهران مرکزی - دانشکده اقتصادو علوم اجتماعی 1390

today, the route for economic development in most countries is the same as international open competitive economy. economic institutes well known that supportive public economy belonged on the past and they may compete in the global economy. it is obvious that if they have no competitive potency or not familiar with competition technique, they may be devastated. banking system aims to collect t...

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