Distribution of some important rangeland species under the influence of edaphic and topographic factors (Case study: Northern rangelands of West Azerbaijan Province)

In a rangeland ecosystem, it is important to pay attention to environmental factors and their effect on the distribution and establishment of plants in order to plan exploitation. The purpose of this research is to investigate the relationship between the cover of some species and environmental factors in the north of West Azerbaijan province. For this purpose, in the period from mid-May to the end of June 2021, sampling of vegetation in eight rangelands sites with different vegetation combinations in Chaipareh and Khoy Counties in a systematic-random method with the establishment of transects and plots one square meter was done. In each of the rangeland sites, the percentage of rangeland species coverage was recorded. Topographical factors including elevation above sea level, slope percentage and geographical aspect of the range were recorded for each site. Soil samples were taken from each of the sites at five points from 0 to 20 cm depth and taken to the laboratory to measure soil parameters. The results of the use of detrended correspondence analysis (DCA) showed that the importance of the axes based on the specific value decreases from the first axis to the second and third axis, and as a result, the major contribution of changes in the distribution of plant species is related to the first and second axis. The results of DCA showed that the specific value of the first axis is (0.36) and the second axis is (0.23). Changes in species distribution due to soil and topography factors were investigated using the linear redundancy Detrended Analysis (RDA) method. The results of the redundancy analysis showed that the four axes explain a total of 83% of the variance of species composition changes by environmental factors, and therefore this indicates that the investigated parameters have a direct effect on the distribution of species, but because the first axis, it has the highest value (0.295) and is related to different soil parameters, and this indicates that the contribution of soil on the distribution of species in the study sites is more than the topographical parameters. The general results of this study showed that the distribution of rangeland species in the study sites is influenced by soil and topographical factors. It seems that the higher the altitude, organic carbon, saturated moisture, percentage of sand, silt and clay, the slope and direction of the range and calcium in the rangeland site, the more frequent the presence of some species such as Artemisia fragrans Willd, Antemis koteschyana Boiss, L., Cynodon dactylon and Ceratocephalus falcatus L. increases and as the amount of soil cations, electrical conductivity, lime percentage and soil acidity decrease, the abundance of some other species such as Phlomis olivieri Benth, Teucrium polium L., Alyssum minutum Schltdl. and Tanacetum polycephalum Sch.Bip is more common in study sites. Using the results of this research, the growth conditions of the existing species have been determined to some extent, and considering that some species have economic and medicinal value, if the user's goal is to use the species for planting of medicinal plants, it is recommended to pay attention to the soil and topography of the region if they are economic under the conditions of hand planting in similar areas.