جستجوی مقالات مرتبط با کلیدواژه "شرایط اقلیمی" در نشریات گروه "زیست شناسی"

In order to model the emission of pollutants, it's necessary to know the amount of mixing depth, which in most modeling, only for the climate of the region, values for the mixing depth is assumed. The aim of this study show the relationship between the depth of mixing in the atmosphere, and the pollutants measured by monitoring stations in Tehran Poonak. Methods Review Emission rate of pollutants CO, NO2 , PM10, SO2 , O3 and PM2.5 the urban air quality station of Poonak region and the comparison of the average daily and monthly concentrations of air pollutants is done based on the information received from the measuring station of the quality control company with the values of convective boundary layer height and mechanical boundary layer height of mixing. Results shows the height of urban mixing increases in proportion to changes in ambient temperature. On the other hand, synoptic conditions prevent the displacement and convection of the air mass of the boundary layer. As well as factors affecting the pollution of air, the characteristics of meteorological, topographic terrain and intensity Production of pollutants is not to increase or decrease the concentration of the scale of local and area of lead becomes.

Grazing is an effective factor on many aspects of plant species and communities. This anthropogenic factor, which became a destructive operant in Iran due to mismatch to range capacity, can affect the individuals of a plant species and thus, alter its spatial distribution. In the current study, the effect of short term exclosure on geographical distribution of two cool season grasses (Bromus tomentellus and Agropyron trichophorum) investigated using historical presence data. To do so, SRE modeling method (which is a presence-only model) was used to generate distribution maps before and after applying the exclosure. Presence coordinates of each species determined from 98 permanent exclosures. The number of B. tomentellus presence spots were 31 and 37 points before and after applying exclosures; respectively. The number of A. trichophorum presence spots were 16 and 25 points before and after applying exclosures; respectively. 19 bioclimatic variables used as environmental variables. The results indicated that the area of suitable climatic habitat of B. tomentellus before applying the exclosure (125868 ha) was considerably more than A. trichophorum (32515 ha). Nonetheless, applying the exclosure caused a 58% increase in suitable habitat of A. trichophorum versus 9% increase for B. tomentellus; which suggest that the grazing had a higher relative influence on A. trichophorum and removing the grazing pressure capacitated this species to retrieve its habitats. It should be emphasized that B. tomentellus should be considered as a more tolerant species to climatic conditions due to its prevalent distribution.