نتایج جستجو برای: 30 and 120 sampling plots were taken around dead trees and control trees
تعداد نتایج: 17153044 فیلتر نتایج به سال:
mapungubwe cultural landscape (mcl) woody vegetation was characterized to establish structural and compositional attributes. stratified random sampling based on major soil types was used and nine plant variables were measured in 137(20x30) m2 sampling plots; these being genera, species and family names; basal circumference; plant height; depth and diameter of tree canopy; number of stems per pl...
writing as a productive skill requires practice in the basic sub-skills of vocabulary and grammar. in fact, grammar has been viewed as the core of programs in writing classes to help the students put the elements of sentence together and combine sentences of specific lengths to come up with an error-free work of art. conceptualizing l2 writing in this way introduces writing as a product and enc...
with the increasing population and the need for more food, as well as with the development of science and technology, human approach to unnatural and often chemical inputs to increase agricultural production has been a great expansion and problems such as increased cancers, chronic diseases has created environmental pollution. implementation of organic organic is a solution to these problems . ...
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 ...
investigation on structure and dynamics of natural forest ecosystems is an important issue for silvicultural decisions. the aim of this study is to analysis dynamics and structure of a beech stand during 5-year period in the shast kalateh forest in the caspian region, north of iran. data were collected from a 16.9ha permanent research plot established in a natural unlogged stand in 2006. all li...
the main objective in sampling is to select a sample from a population in order to estimate some unknown population parameter, usually a total or a mean of some interesting variable. a simple way to take a sample of size n is to let all the possible samples have the same probability of being selected. this is called simple random sampling and then all units have the same probability of being ch...
تغییرات جمعیت اسپورهای قارچی میکوریز وزیکولار- آربوسکولار در خاک جنگل‌های طبیعی پسته در استان خراسان
In order to investigate variations of spore population, root colonization and also to determine mycorrhizal symbiosis in the root and rhizosphere of Pistachio trees (Pistacia vera) in natural forests, two study stations in Kalat (Chachaeh) and Sarakhs (Shorlogh) regions were selected. Sampling from soil and root of the trees were taken from under the canopy and from a depth of 30 cm. On a month...
تغییرات جمعیت اسپورهای قارچی میکوریز وزیکولار- آربوسکولار در خاک جنگل‌های طبیعی پسته در استان خراسان
In order to investigate variations of spore population, root colonization and also to determine mycorrhizal symbiosis in the root and rhizosphere of Pistachio trees (Pistacia vera) in natural forests, two study stations in Kalat (Chachaeh) and Sarakhs (Shorlogh) regions were selected. Sampling from soil and root of the trees were taken from under the canopy and from a depth of 30 cm. On a month...
In the Shafaroud forest, logging operation is generally performed by using selective cutting methods. Chainsaw and cable skidder are two main forest machines for harvesting of this forest. However, forest harvesting operations result in serious residual stand damage during felling, winching and skidding operations in this forest. Residual stand damage resulting from selective cutting was asses...
Recent mortality in coast live oak (Quercus agrifolia), California black oak (Q. kelloggii), and tanoak (Lithocarpus densiflorus) exceeds historical levels in forests affected by the pathogen Phytophthora ramorum. We assessed the balance between recent mortality and seedling populations in these species to examine the status of regeneration in stands with varying levels of mortality caused by P...
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