نتایج جستجو برای: mixed and natural stands

تعداد نتایج: 16917246  

1999
Evelyn L. Bull Arlene K. Blumton

The effect of a fuels-reduction treatment on small mammals was investigated in lodgepole pine (Pinus contorta Dougl. ex Loud.) and mixed-conifer stands by trapping and track surveys in northeastern Oregon. The number of red squirrel (Tamiasciurus hudsonicus) and snowshoe hare (Lepus americanus) tracks decreased in lodgepole pine treatments after harvest. Only two snowshoe hare tracks were detec...

2015
Virginie Guyot Bastien Castagneyrol Aude Vialatte Marc Deconchat Federico Selvi Filippo Bussotti Hervé Jactel Andrew Hector

The impact of invasive herbivore species may be lower in more diverse plant communities due to mechanisms of associational resistance. According to the "resource concentration hypothesis" the amount and accessibility of host plants is reduced in diverse plant communities, thus limiting the exploitation of resources by consumers. In addition, the "natural enemy hypothesis" suggests that richer p...

2014
Brooks G. Mathewson Jeff Houlahan

The invasive insect pest Adelges tsugae (Hemlock Woolly Adelgid) threatens the ecologically unique Tsuga canadensis (Eastern Hemlock)-dominated forest type throughout its range. Relatively little is known about how the loss of this forest type will affect the relative abundance of amphibians. This study assessed the relative abundance of the juvenile phase of Notophthalmus viridescens viridesce...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیراز - دانشکده ادبیات و علوم انسانی 1391

‘romanticism’ and ‘romantic’ are among the most controversial terms in literature. most readers, when encountering these words, would think of the well-known period of romanticism of the first three decades of the nineteenth century and the great six english poets known as ‘the big six’ of this period. however, romanticism does not belong to certain artists in a special period; one may seek ele...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سمنان - دانشکده ادبیات و علوم انسانی 1393

from its emergence till present time marxist principles has undergone great changes since their promulgation by marx. many theorists and thinkers set at rectifying marxist tenets and introducing those of their own while others advocated its main concepts and attempted at improving them. among marxist philosophers who had an intensive study of marxs ideology, is louis althusser whose reflections...

Journal: :جنگل و فرآورده های چوب 0
مهدی کاکاوند دانشجوی کارشناسی ارشد، دانشکدة منابع طبیعی، دانشگاه تهران، کرج، ایران محمدرضا مروی مهاجر استاد گروه جنگل داری و اقتصاد جنگل دانشکدة منابع طبیعی، دانشگاه تهران، کرج، ایران خسرو ثاقب طالبی دانشیار پژوهش، مؤسسة تحقیقات جنگل ها و مراتع کشور، تهران، ایران کیومرث سفیدی استادیار، دانشگاه محقق اردبیلی، دانشکدة منابع طبیعی، اردبیل، ایران

this study was designed to investigate the structural characteristics of beech forests in the middle stage of ecological succession. in order to this purpose undisturbed beech stands in kheyroud forest had chosen and three one hectare sampling plot laid out. all of tree species measured with full callipering method and diameter and height of trees were recorded. natural regeneration within one ...

Journal: :Tree physiology 2011
Zhen-Ming Ge Seppo Kellomäki Heli Peltola Xiao Zhou Kai-Yun Wang Hannu Väisänen

A process-based ecosystem model was used to assess the impacts of changing climate on net photosynthesis and total stem wood growth in relation to water availability in two unmanaged Norway spruce (Picea abies) dominant stands with a mixture of Scots pine (Pinus sylvestris) and birch (Betula sp.). The mixed stands were grown over a 100-year rotation (2000-99) in southern and northern Finland wi...

Journal: :تولید گیاهان زراعی 0

in order to evaluate the interference effect natural population weeds and plant density, an experiment with randomized complete block design in factorial arrangement with 4 replications was conducted in 2006 in a field experiment at ramin agricultural and natural resources university, khouzestan. treatments included two factor, plant density of corn at three levels (4, 7 and 10 plants m-2) and ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان - دانشکده مهندسی عمران 1391

one of the most commonly used techniques to reduce the corrosion rate of rebar in concrete is addition substances named corrosion inhibitors into the concrete. corrosion inhibitor is chemical compounds that were added to concrete to prevent corrosion of steel in concrete. sodium nitrate is a type of anodic inhibitors that this study investigatesthe effect of this inhibitor on the properties of ...

2008
J. A. Rosette P. R. J. North J. C. Suárez

Canopy metrics from ICESat/GLAS lidar waveforms were applied to estimate stemwood volume for a mixed temperate forest. Gaussian decomposition from product GLA14 was used to infer a ground surface return from within the waveform. The region of the waveform returned from the vegetation was subsequently taken to be between this position and the beginning of the waveform signal. The heights of vege...

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