نتایج جستجو برای: some perennial plants may cause accumulation of seed bank under their canopy
تعداد نتایج: 21397331 فیلتر نتایج به سال:
BACKGROUND Management regimes for vegetation restoration of degraded grasslands can significantly affect the process of ecological succession. However, few studies have focused on variation in the soil seed bank during vegetation restoration under different management regimes, especially in saline-alkaline grassland habitats. Our aim was to provide insights into the ecological effects of grassl...
reinsurance is widely recognized as an important instrument in the capital management of an insurance company as well as its risk management tool. this thesis is intended to determine premium rates for different types of reinsurance policies. also, given the fact that the reinsurance coverage of every company depends upon its reserves, so different types of reserves and the method of their calc...
this research aims at answering the questions about translation problems and strategies applied by translators when translating cultural concepts. in order to address this issue, qualitative and quantitative study were conducted on two groups of subjects at imam reza international university of mashhad. these two groups were assigned as beginner and advanced translation students (10 students). ...
126 abstract: in this research we studied the effects of cyclic hydration and dehydration of cysts of artemia urmiana and artemia parthenogenetica on the hatching percentage, survival and growth. the experiment was carried out in 3 treatments (1-3 hydration/dehydration cycles) with 3 replicates for each treatment. later effects of cold preservation at -20°c during three time periods were ...
A fundamental goal of plant population ecology is to understand the consequences for plant fitness of seed dispersal by animals. Theories of seed dispersal and tropical forest regeneration suggest that the advantages of seed dispersal for most plants are escape from seed predation near the parent tree and colonization of vacant sites, the locations of which are unpredictable in space and time. ...
in this project, some new polyaspartimides, (pas)s, have been synthesized form michael addition reaction between new synthetic bismaleimide (bmi) and some aromatic diamines. a characteristic property of this polyaspartimides is a pendent carboxylic group, which introduced to these polymers from new bismaleimide. bismaleimides (bmi) is one of the interesting compounds, which can be self-polymeri...
Secondary fallow vegetation in parts of the Papua New Guinea lowlands is dominated by the shrub Piper aduncum L. that originates from South America. Here we report on its seed bank, growth rate and biomass accumulation. P. aduncum accounted for 69 % (408 m) of the seed bank in the forest and 53 % (1559 m) of the seed bank under fallow. About 90 % of the tree seed bank at the fallow site was dom...
studies on vegetation changes of rangelands under grazed and non-grazedconditions are of great importance in the range management planning programs. to determinethe change process of vegetation, this study was performed in inche shorezar site of golestanprovince for nine years (1997-2005). the vegetation parameters were measured every year inseveral fixed plots inside and adjacent of exclosures...
Our main aim was to determine the contribution of the seed bank to vegetation regeneration following a disturbance consisting in a deep ploughing and a thorough homogenisation of a perennial grassland. In the seed bank prior to disturbance, seed distribution through the vertical soil profile was evaluated to determine the initial seed species structure. Then, several characteristics of the shal...
to evaluate the effects of planting date and plant density on morphological characteristics, including essential oil content of ajowan (trachyspermum ammi) a study was conducted during the years 2003 and 2004 at the experimental farm, faculty of agriculture, ferdowsi university of mashhad. treatments were laid out in a factorial form based on a complete randomized block design of three replicat...
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