نتایج جستجو برای: species changes and species
تعداد نتایج: 16982894 فیلتر نتایج به سال:
Due to the recent destructive pressures on the Caspian environment, an effect on phytoplankton communities is expected in different aspects such as cell size and form. This paper aims to survey the size and form in the dominant phytoplankton species in the years of 1996, 2001, 2006, 2009, 2011 and 2012 in the Iranian coast of the Caspian Sea. Results of current study showed that the dominant sp...
photosynthetic characteristics and induction of crassulacean acid metabolism (cam) by drought stress were investigated in sedum album, sedum stoloniferum and rosularia elymaitica from crassulaceae. titratable acidity, malate content, phosphoenolpyruvate carboxylase (pepc) activity and gas exchange parameters were determined in plants at the end and beginning of the photoperiod. results showed t...
abstract the influence of cation?? and anion?? interactions on the strength and nature of n…h hydrogen bond has been investigated by quantum chemical calculations in s-triazine…3hf complex. ab initio calculations were performed at mp2/6-311++g(d,p) level of theory. the natural bond orbital (nbo) analysis and the bader’s quantum theory of atoms in molecules (aim) were also used to elucidate t...
flora and fauna of rocky coastal habitats are versatile in adapting to the prevalent tidal fluctuations. the current study was undertaken to evaluate the diversity of fouling and associated species around the port blair coastal areas of andaman and nicobar islands. except tss, the hydrographical parameters (temperature, salinity, ph and dissolved oxygen) did not significantly vary among the 5 s...
every year a large number of migratory wintering water birds, rest in the wetlands situated in the northern provinces of iran. the wetlands are very important ecosystems for these creatures. due to ecological importance of water birds, the results of this study (the birds’ populations and their changes) are helpful to monitor them and are especially important to manage the wetlands. in this stu...
Abstract Various resistances to salinity are due to plants genetically variations, and selection on the basis of one factor will not be a suitable criterion in measurement of resistance to salinity, therefore in choosing resistant varieties, it is necessary to notice to a set of resistant indexes to salinity, creating changes in physiology, anatomy and morphology of plant species. This resear...
To study the macrobenthos of the lower reaches of Zayandehrud River, a distance of approximately 160 km, between Birds Garden and Varzaneh Town was investigated. Hence, eight stations, based on substrate structure, were selected using Sorber and Ekman samplers and PVC tube macrobenthos of the river were collected twice each season for a full year (2003-2004). Samples were sorted out and identif...
The aim of this research was to identify the plant species, introducing the flora and plant geographical distribution of Islamabad Gharb area, Kermanshah province. This area, with 4654 km2, is located in Kermanshah province. The method of plant collection was field survey which is one of classical methods of floristic studies. The geographical distribution and life form of plant species were de...
Introduction: One of the ways of restoration and reclamation of damaged rangeland is to use different methods of rain harvesting such as pitting, counter furrowing, flood spreading, small arc basins system and etc., along with the reduction of runoff, it increases the soil moisture content and thus increases vegetation cover. Biodiversity is most commonly used to describe the number of species....
the distribution and abundance of high aquatic plants in the gorganroud river was examined at five stations in four seasons (20 samples) over one year period during 2009-2010. we identified 21 species of aquatic plants from 21 genera, belonging to 9 families. these species were determined as 3 halophytic species (14.2%) and 18 high aquatic plants (85.7%).the highest species diversity was observ...
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