نتایج جستجو برای: arid and semiarid climate

تعداد نتایج: 16861318  

2007
Paolo D’Odorico Kelly Caylor Gregory S. Okin Todd M. Scanlon

[1] Soil moisture is the environmental variable synthesizing the effect of climate, soil, and vegetation on the dynamics of water-limited ecosystems. Unlike abiotic factors (e.g., soil texture and rainfall regime), the control exerted by vegetation composition and structure on soil moisture variability remains poorly understood. A number of field studies in dryland landscapes have found higher ...

2004
D. R. McQueen

There are at least three hypotheses to account for the abundance of divaricating shrubs in New Zealand: 1) Ratites in the form of 11 species of moa, led to divarication for browse protection (Greenwood and Atkinson, 1977); 2) Divarication evolved as a microclimatic shield (McGlone and Webb, 1981); 3) Divarication evolved to aid leaves in light harvesting (Kelly, 1994). In Patagonia before human...

Journal: :محیط زیست طبیعی 0
سمیه حدادی نیا کارشناس ارشد محیط زیست، دانشکدۀ منابع طبیعی، دانشگاه تهران، ایران افشین دانه کار دانشیار گروه محیط زیست، دانشکدۀ منابع طبیعی، دانشگاه تهران، ایران کورش عشقی استاد دانشکدۀ صنایع، دانشگاه صنعتی شریف، تهران، ایران علی اصغر درویش صفت استاد دانشکدۀ منابع طبیعی، دانشگاه تهران، تهران، ایران محمد کابلی دانشیار دانشکدۀ منابع طبیعی، دانشگاه تهران، تهران، ایران

tourism as a growing industry needs special attention in developing countries. during last decades, nature based tourism has been growing faster than other tourism fields and it seems to grow even faster. ever growing demand for nature based tourism emphasizes the necessity of a holistic planning for preserving environment against degradation. objective of this study is to present a nature base...

Journal: :ecopersia 0
rezvan alijani former m.sc. student, department of watershed management engineering, faculty of natural resources, tarbiat modares university, iran mehdi vafakhah associate professor, department of watershed management engineering, faculty of natural resources, tarbiat modares university, iran arash malekian assistant professor, department of rehabilitation of arid and mountainous regions, faculty of natural resources, university of tehran, karaj, iran

drought is a complex natural phenomenon that can occur in any climate. hydrologic drought in the river flow of arid and semi-arid areas causes serious shortages, threatens the quality of life, and impacts on the economy. understanding this feature is then essential for the management of water resources. hydrologic drought in the sense of deficient river flow is defined as the periods that river...

Journal: :Ecological Informatics 2011
You-Shi Wang Cheng-Jin Chu Kai Zhu Ze-Hao Shen

a MOE Key Laboratory of Western China's Environmental Systems, Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou 730000, China b MOE Key Laboratory of Arid and Grassland Ecology, Lanzhou University, Lanzhou 730000, China c Nicholas School of the Environment, Duke University, Durham, North Carolina 27708, USA d Department of Ecology, College of Urban and Environ...

Journal: :Journal of dairy science 2007
J Bohmanova I Misztal J B Cole

Meteorological data (1993 to 2004) from 2 public weather stations in Phoenix, Arizona, and Athens, Georgia, were analyzed with test day milk yield data from herds near weather stations to identify the most appropriate temperature-humidity index (THI) to measure losses in milk production due to heat stress in the semiarid climate of Arizona and the humid climate of Georgia. Seven THI with differ...

2003
Alfredo Huete Tomoaki Miura Xiang Gao Carlos Borghi Ricardo Ojeda

Land degradation impacts on several critical environmental issues such as food security, diminishing quality and quantity of fresh water resources, preservation of natural resources, loss of biodiversity, and global climate change. Land degradation is responsible for soil erosion and can eventually lead to desertification. The International Convention to Combat Desertification (CCD) defines des...

Journal: :caspian journal of environmental sciences 2013
al. et e. khosropour

this research was carried out in order to quantify throughfall (tf) and interception loss (i) and to compare the chemical composition of tf, i.e. lead (pb) and cadmium (cd) as well as electrical conductivity (ec) and ph beneath pinus eldarica and cupressus arizonica plantations and the open field rainfall. the research was accomplished in the chitgar forest park, a semi-arid polluted urban area...

Journal: :دانش آب و خاک 0
همایون فقیه پژوهشگر، مرکز تحقیقات کشاورزی و منابع طبیعی کردستان، سنندج، ایران

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