نتایج جستجو برای: index species
تعداد نتایج: 931450 فیلتر نتایج به سال:
It is so important to apply suitable methods to have a reliable estimation of the spatial distribution of trees. This research was aimed to determine and evaluate the spatial pattern of five species by distance- and density-based indices (Quercus brantii, Acer moncepesulanum, Crataegus aronia, Pistacia atlantica & Amygdalus lycioides) in the Kalkhani Forest in Koudasht Lorestan province, Iran. ...
phytoplankton taxa composition of the caspian sea were evaluated by using samples collected at 12 stations along the iranian coast of the caspian sea between 1996 and 2010. this study identified 158 phytoplankton species consisted of diatoms (70 species), dinoflagellates (23 species), chlorophytes (29 species), cyanophytes (31 species), and euglenoids (5 species). the dominant species were the ...
Determining the potential of soil seed bank and its specific species is important for conservation goals and vegetation restoration of rangelands. In this study, the characteristics of soil seed bank and standing vegetation in Lazour mountain rangeland were investigated in order to estimate the rehabilitation ability of the study area in case of possible disturbances. In order to determine the ...
Since the halophytes species have an important role in such ecosystem balance and they have been grazed by livestock as supplementary forage, the awareness of livestock's desire to grazing and their preference values of these species is of high priority. Regardless of the importance of halophyte species in the livestock feeding in Iran, there is less published research on the livestock grazing ...
Phytoplankton taxa composition of the Caspian Sea were evaluated by using samples collected at 12 stations along the Iranian coast of the Caspian Sea between 1996 and 2010. This study identified 158 phytoplankton species consisted of diatoms (70 species), dinoflagellates (23 species), chlorophytes (29 species), cyanophytes (31 species), and euglenoids (5 species). The dominant species were the...
Zooplanktons have an important role in food chain of the aquatic ecosystems, which acts as a food chain link between producers (phytoplankton) and higher nutritional levels. The purpose of this research was to identify and study the zooplankton density in the southeastern basin of the Caspian Sea (Gorgan Bay). Sampling was performed seasonally and samples were collected by zooplankton net (36 c...
This study aims at investigating the effect of distance from source, species type and soil physical chemical properties on the absorption ability of heavy metals by tree species around the Nahavand cement factory. In the present research, soil and tree leaf (Pseudoacacia L, Populus nigra L, Elaeagnus angustifolia L, Fraxinus excelsior and Thuja orientalis L) samples were taken from 300, 500, 80...
forests are biologically diverse systems, representing some of the richest biological areas on earth. they offer a variety of habitats for plants, animals and micro-organisms. however, forest biodiversity is increasingly threatened as a result of deforestation, fragmentation, climate change and other stressors. biodiversity is the variation of life forms within a given ecosystem, biome, or on t...
Feeding habits of Grey sharpnose shark Rhizoprionodon oligolinx Springer, 1964 in coastal waters of eastern Hormozgan province from Bandar Sirik to Bandar Jask were studied by sampling 30 fish per month throughout one year. Mean values of fish total length and fish weight was 101.04 ± 4.09 cm and 1480.11 ± 94.71 g. The highest value of gastrosomatic index (GSI) was in spring and the lowest was ...
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