جستجوی مقالات مرتبط با کلیدواژه « ecological factors » در نشریات گروه « اکولوژی »

Knowing the ecological characteristics of plant species and their response to environmental factors provides the necessary information for managing vegetation and improving  of rangelands. Due to the importance of the  Chaerophyllum macropodum and its role in soil protection and forage production, we conducted a study of the ecological needs and determining the ecological factors affecting in plant cover and the response of the species to changes in ecological factors, using the Canonical Correspondence Analysis method ( CCA) and Generalized Additive Models (GAM) in Mazandaran province. The results of conventional comparative analysis showed that environmental factors such as altitude, aspect, phosphorous, organic carbon, organic material, pH, Ec, %sand, saturated moisture percentage and lime  of soil, respectively with the expression of 5.9, 5.6, 2, 2, 1.8, 1.7, 1.7, 1.6 and 1.3 percent of the variance in plant composition had an important role in the changes of plant cover in the studied habitats. The response of the species to the amount of phosphorus and potassium follows the monotonic decrease model. The response of species to the percentage of silt, sand, organic material, organic carbon,nitrogen,line and aspect  follows the bell model (Unimodal) and the optimal growth limit For each of these factors, it is 20%, 55%, 5%, 35,0.45 and north and westnorth slopes. The study of the response of the species  to environmental and soil factors provided valuable information to determine the ecological needs of this species, which can be taken into consideration in the operation of rangelands improvement in similar areas.

One of the fields in vegetation ecology is understanding the relationships between plant species and environmental factors and analyzing species reactions along the slope of environmental factors. Considering the importance of Salsola arbusculiformis Drob in soil conservation and forage production, the reaction of this species to environmental factors was investigated using the Generalized Additive Model in Shoghan region of North Khorasan province. For this purpose, a systematic random-method was used to measure plant parameters and environmental factors. Canonical Correspondence Analysis was used to examine the relationship between vegetation and environmental factors. The results showed that environmental factors such as percentage of sand, sulfate ions and soil bicarbonate, annual rainfall and altitude, respectively, expressed 5.8, 11.4, 5.7, 9.1 and 7% of the existing variance and have an important role in vegetation changes in the studied habitat. The study of the reaction of this species to environmental factors showed that out of 25 environmental variables studied, 14 variables had a significant effect on plant yield (p <0.01). The response pattern of the studied species along the slope of factors such as acidity, percentage of sand and clay, altitude and finally the percentage of slope was unimodal. The optimal growth limit for each of the above factors was 8.4, 66%, 28%, 1452 meters and 5%, respectively. The response of this species to the amount of sulfate and percentage of soil lime followed a decreasing model, so that with increasing the values of these factors, its yield decreased. The response pattern of the desired species was in two modes, along the slope of factors such as chlorine, sodium, organic carbon, nitrogen, soil salinity and average annual temperature. This model indicates a competitive constraint startsrecalong the peripheral slope. The results also showed that this species has the highest yield in the northern slopes. Studying the reaction of the desired species along the slope of topographic and soil factors provided valuable information for determining the ecological needs of this species, which can be considered in rangeland improvement operations in similar areas.

Non-living environmental factors have a major impact on the distribution and yield of plant species. To this end, the relationship between soil and topographic variables on the response of Salsola kerneri (Wol.) Botsch plant species in Yazd province is evaluated. Generalized Additive Models (GAM) were used to investigate the speciesresponse to environmental factors. The results showed that S. kerneri grows in areas with cold arid climate with an average rainfall of about 100 to 120 mm and an average temperature of about 14 to 16 ° C. According to the studied habitats, S. kerneri is distributed at an altitude of 1750 to 2350 meters a.s.l. This species grows in clay-sandy loam soils with salinity between 0.7 to 4.5 and acidity of 8.2 and nitrogen content of 0.04. The average canopy cover of this species in Sadrabad and Khoranagh habitats is 1.8 and 1.3 percent, respectively. Response pattern of S. kerneri along the saturation moisture and litter percentage of soil surface, followed the monotonic increase model, and with the increase of these values, its frequency and percentage of vegetation increased. Conversely, the response of this species along the slope of the amount of electrical conductivity (EC) follows the monotonic decrease model, and with the increase of this factor, the presence and percentage of vegetation has decreased. response pattern S. kerneri followed the Unimodal model along the slope of sand, clay, limestone and altitude, and its optimal growth rate for these factors was 59, 23, 12 and 2200 meters above sea level, respectively. The results of S. kerneri phenology studies showed that the growth of this plant begins in the second half of March. Flowering usually begins in early July and seeds are formed in the third decade of September. Seed shedding begins in mid-November and continues until the first week of December, when the seed stage arrives. The best time to collect seeds is late October. Examining the ecological needs of S. kerneri in relation to topographic and soil factors, provided valuable information about this species that can be considered in vegetation management and rangeland improvement operations in similar areas.