نتایج جستجو برای: species evenness

تعداد نتایج: 548668  

2012
Abderrahim El Keroumi Khalid Naamani Hassna Soummane Abdallah Dahbi

In this study we describe the structure and composition of ant communities in the endemic Moroccan Argan forest, using pitfall traps sampling technique throughout the four seasons between May 2006 and February 2007. The study focused on two distinct climatic habitats within the Essaouira Argan forest, a semi-continental site at Lahssinate, and a coastal site at Boutazarte. Thirteen different an...

2005
Norman W. H. Mason David Mouillot William G. Lee J. Bastow Wilson

Functional diversity is hypothesised as being beneficial for ecosystem functions, such as productivity and resistance to invasion. However, a precise definition of functional diversity, and hence a framework for its quantification, have proved elusive. We present a definition based on the analogy of the components of species diversity / richness, evenness and divergence. These concepts are appl...

Akbarzadeh, Kamran, Dehghan, Omid , Enayati, Ahmadali , Eslamifar, Masoumeh , Fazeli Dinan, Mahmoud, Jafari, Ali , Jafari, Fatemeh, Motevalli Haghi, Farzad, Nikookar, Seyed Hassan , Sheikhi, Masoomeh, Yazdani-Cherati, Jamshid ,

Background and purpose: Flies have a high diversity and are able to transmit many pathogens due to their adaptation and close relationship with humans. Therefore, this study was performed to identify the fauna of medically important flies in the city of Joybar in northern Iran. Materials and methods: This descriptive-analytical study was conducted twice a month in Juybar at selected sites, inc...

Journal: :The Journal of parasitology 2007
Devon B Keeney Robert Poulin

Most efforts aimed at elucidating the factors responsible for the variation in species richness among different parasite communities have focused on host characteristics such as body mass or diet. Independently of host features, however, the way in which parasites use resources within the host may also affect the species richness of the community. The distribution of parasite individuals or bio...

The aim of this study was to investigate the role of species of Trifolium genus on the composition, diversity, forage value and quantitative vegetation parameters and interaction between Trifolium species and invasive species Leucanthemum vulgare Lam. in Fandoghlou rangelands in Ardabil province. In determining the sampling locations, six sites by systematic random method and due to the distrib...

Journal: :جنگل و فرآورده های چوب 0
سمیه کرمی راد دانشگاه تهران احسان عبدی دانشکده منابع طبیعی باریس مجنونیان دانشگاه تهران وحید اعتماد دانشگاه تهران هرمز سهرابی دانشگاه تربیت مدرس

road construction is one of the effective factors for ecological changes which affects diversity and species composition in forest roads edges. this research was performed in kheirud forest to evaluate herbaceous diversity and tree regeneration establishment in different distances from road edge. for this purpose, we sampled herbaceous and tree species regeneration in 0,5,10,25, 50 and 100 m di...

Journal: :Journal of the Textile Machinary Society 1957

Journal: :جنگل و فرآورده های چوب 0
بیت الله امان زاده دانشجوی دکتری علوم جنگل، دانشکدﮤ منابع طبیعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران محمد رضا پورمجیدیان دانشیار، دانشکدﮤ منابع طبیعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران خسرو ثاقب طالبی دانشیار پژوهش، مؤسسة تحقیقات جنگل‏ها و مراتع کشور، تهران، ایران سید محمد حجتی دانشیار، دانشکدﮤ منابع طبیعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران

in order to study the effect of canopy gap size on species diversity and composition in mixed stands, a reserved area which located in asalem forests was selected. all of gaps in this area identified and were divided into four categories: small gaps (1000 m2). in each category, 21 of gaps with a relatively homogeneous in terms of an aspect and slope were selected. the major and minor diameter o...

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