نتایج جستجو برای: acer mazandaranicum
تعداد نتایج: 3584 فیلتر نتایج به سال:
کیکم یکی از گونه های مهم موجود در جنگلهای غرب کشور می باشد که معمولا با بلوط همراه بوده و در سالهای اخیر به شدت از جمعیت آن کاسته شده است. بذر آن دارای خواب دوگانه بوده و جوانه زنی آن با مشکل مواجه است. در این بررسی، تأثیر سرمادهی به مدت 3 و 6 ماه، تیمار با اسید جیبرلیک (250 و500 میلی گرم در لیتر) پس از اعمال سرمادهی، خراش دهی با اسیدسولفوریک در دو زمان 10 و 20 دقیقه (تیمارهای فوق روی دو بستر ک...
The aim of this study was to investigate soil respiration in the plantation stands of Acer velutinum, Quercus castaneifolia, Fraxinus excelsior and Pinus brutia and to compare them with the natural stands in Sari educational-research forest of Darabkola. In order to measure physical and chemical properties of soil in each stand, 10 points were selected systematic randomly and samples were taken...
Tree seedling flooding tolerance for 22 species was assessed under controlled field condi tions. Initial heights under control (freely draining soil, n = 20 per species) and flooded (stand ing water, depth = 10 cm, n = 20 per species) conditions were measured in March 1990. Sur vival, height and diameter growth were determined after 120 days. Recovery from flooding effects was assessed in th...
To examine the causes of landscape variation in forest community composition, we have quantified sapling mortality as a function of growth and soil moisture for seven dominant species in transition oak-northern hardwood forests of the northeastern USA. We located saplings in sites that encompassed a wide range of variation in soil moisture and light availability. In mesic conditions, the probab...
The northern hemisphere tree genus Acer comprises 124 species, most of them monoecious, but 13 dioecious. The monoecious species flower dichogamously, duodichogamously (male, female, male), or in some species heterodichogamously (two morphs that each produce male and female flowers but at reciprocal times). Dioecious species cannot engage in these temporal strategies. Using a phylogeny for 66 s...
We quantified the damage caused by a major ice storm to individual trees in two 1-ha permanent plots located at Mont St. Hilaire in southwestern Québec, Canada. The storm, which occurred in January 1998, is the worst on record in eastern North America; glaze ice on the order of 80-100 mm accumulated at our study site. All but 3% of the trees (DBH > or = 10 cm) lost at least some crown branches,...
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