نتایج جستجو برای: simpson diversity

تعداد نتایج: 191705  

Journal: :Physics Today 2002

Journal: :The Lancet 1831

2013
Jie Zhang Xue Zheng hu Jian Xiaowa Qin Fenghui Yuan RunJie Zhang

The diversity and community structure of arthropods in an organic double-cropped rice ecosystem in Guangdong Province, China was studied. We compared the arthropod communities in the early season (Apr-Jul) crop to those in the late season (Aug-Nov) crop in 2009. The comparisons were undertaken using a combination of community assessment approaches, including morphospecies richness, the Shannon-...

Fariba Noedoost Mohammad Jankju

Rangeland ploughing and cultivation using dry land farming crops may be amajor reason for the destruction of natural resources in the semiarid and sub-humid regionswhich may significantly change the composition and reduce the stability of the affectedcommunities. In present research, an abandoned ploughed site was compared with a nearbyreference site in the semiarid rangelands of Baharkish, Quc...

Journal: :Blood 2014
Ying Taur Robert R Jenq Miguel-Angel Perales Eric R Littmann Sejal Morjaria Lilan Ling Daniel No Asia Gobourne Agnes Viale Parastoo B Dahi Doris M Ponce Juliet N Barker Sergio Giralt Marcel van den Brink Eric G Pamer

Highly diverse bacterial populations inhabit the gastrointestinal tract and modulate host inflammation and promote immune tolerance. In allogeneic hematopoietic stem cell transplantation (allo-HSCT), the gastrointestinal mucosa is damaged, and colonizing bacteria are impacted, leading to an impaired intestinal microbiota with reduced diversity. We examined the impact of intestinal diversity on ...

2009
R. Musehane F. A Netshiongolwe L. Masisi F. V. Nelwamondo T. Marwala

The paper presents the investigation and implementation of the relationship between diversity and the performance of multiple classifiers on classification accuracy. The study is critical as to build classifiers that are strong and can generalize better. The parameters of the neural network within the committee were varied to induce diversity; hence structural diversity is the focus for this st...

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...

Abas Jamshidi Bakhtar, Khosro Sagheb-Talebi Maziar Haidari, Mohamad Reza Marvi Mohajer

Fire, as a natural ecological disturbance factor in forest, this study located in the Marivan region, Northern Zagros forest, and western Iranian state of Kurdistan. In each burned and unburned area 30 circle sample plot (1000 m2) were collected by randomized–systematic method in the 100×200 m net (in total 60 plots). In every sample plot the kind of species, number of tree, the heig...

Abas Jamshidi Bakhtar, Khosro Sagheb-Talebi Maziar Haidari, Mohamad Reza Marvi Mohajer

Fire, as a natural ecological disturbance factor in forest, this study located in the Marivan region, Northern Zagros forest, and western Iranian state of Kurdistan. In each burned and unburned area 30 circle sample plot (1000 m2) were collected by randomized–systematic method in the 100×200 m net (in total 60 plots). In every sample plot the kind of species, number of tree, the heig...

Journal: :Journal of environmental biology 2008
Ramazan Ozcelik Altay Ugur Gul Jan Merganic Katarina Merganicova

We studied the effects of stand parameters (crown closure, basal area, stand volume, age, mean stand diameter number of trees, and heterogeneity index) and geomorphology features (elevation, aspect and slope) on tree species diversity in an example of untreated natural mixed forest stands in the eastern Black Sea region of Turkey. Tree species diversity and basal area heterogeneity in forest ec...

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