نتایج جستجو برای: irans forests

تعداد نتایج: 39516  

Journal: :journal of ornamental plants 2014
achar devaraja am jakhar mamta jakeer p shetty kpv

in the present study, randomly amplified polymorphic dna (rapd) markers were used to analyze the genetic diversity in 20 varieties of philodendron. the polymerase chain reaction was performed with 60 rapd primers, out of which 21 primers showed clear amplification as well as more polymorphism. in total, 354 scorable rapd loci with 348 polymorphic bands (98%) were observed. percentages of polymo...

2006
Petteri Muukkonen Raisa Mäkipää Raija Laiho Kari Minkkinen Harri Vasander Leena Finér

In the present study, the aboveground biomass of the understorey vegetation of boreal coniferous forests was modelled according to the percentage cover. A total of 224 observations from 22 stands in upland forests and 195 observations from 14 different studies in peatland forests were utilized for the present analyses. The relationships between biomass and percentage cover can be used in ecosys...

2014
Dennis C. Odion Chad T. Hanson André Arsenault William L. Baker Dominick A. DellaSala Richard L. Hutto Walt Klenner Max A. Moritz Rosemary L. Sherriff Thomas T. Veblen Mark A. Williams

There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increas...

2002
Paul V. A. Fine PAUL V. A. FINE

Current research efforts to understand the relative invasibility of different plant communities have mostly ignored tropical forests. Only a few studies have treated invasive species in tropical forests, and recent worldwide analyses have not provided clear predictions concerning the relative invasibility of tropical forests. In this review, the extent to which exotic species have invaded tropi...

Journal: :Revista de biologia tropical 2012
Victor P Zwiener Jochen H Bihn Márcia C M Marques

Animal-plant interactions are important for the recovery of diversity and processes in secondary forests, which increasingly dominate the tropical landscape. We used a combination of observational and experimental approaches to study the interactions of ants with diaspores across a successional gradient of forests in Southern Brazil, from August 2007 to April 2008. In addition to diaspore remov...

Journal: :جنگل و فرآورده های چوب 0
فرخ پورشکوری اله ده دانشجوی دکتری جنگل‏داری، دانشکدۀ منابع طبیعی دانشگاه تهران، کرج، ایران علی اصغر درویش صفت استاد دانشکدۀ منابع طبیعی دانشگاه تهران، کرج، ایران فرهاد صمدزادگان استاد دانشکدۀ فنی دانشگاه تهران، تهران، ایران پدرام عطارد دانشیار دانشکدۀ منابع طبیعی دانشگاه تهران، کرج، ایران

moderate resolution imaging spectroradiometer (modis) have been widely used for active fire detection in the world as the specific channels used for the fire detection have made the modis images applicable. the main objective was to explore the capability of modis images for active fire detection in the zagross forests using the modis contextual algorithm. the study was performed in the marivan...

2009
Ariel E. Lugo

In 1966 Eugene P. Odum delivered a speech before the Ecological Society of America that transformed the way ecologists looked at succession. His comparison of mature and successional systems lead ecologists to place secondary forests in an inferior position relative to mature ones to the point that today, prominent tropical biologists argue for and against the conservation value of secondary fo...

2012
Joachim Krug Michael Koehl Dierk Kownatzki

UNLABELLED BACKGROUND Unmanaged or old-growth forests are of paramount importance for carbon sequestration and thus for the mitigation of climate change among further implications, e.g. biodiversity aspects. Still, the importance of those forests for climate change mitigation compared to managed forests is under controversial debate. We evaluate the adequacy of referring to CO2 flux measurem...

2007
Luohui Liang Sachiko Kuwahara

Currently, forests cover about one-third of the world’s land area, just under 4 billion hectares (ha) (FAO, 2006a). It is estimated that 70% of the world’s forests are natural (self-generating), 20% semi-natural (regeneration with some degree of human intervention), 10% anthropogenic (established or significantly transformed by humans) (MA, 2005). 75% of the world’s forests are located in two b...

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