The study of habitat properties and response pattern of (Artemisia specigera C.Koch.) to environmental factors in rangelands of Mazandaran province

 Today, predictive models of plant species distribution play a crucial role in assessing, restoring, protecting, and developing rangeland ecosystems. It is one of the most important tools to learn about species distribution and habitat suitability. This research determined ecological factors affecting plant composition, species response to environmental factors changes, and the potential of the target species in the study area using multivariate analysis. Based on this, with a better understanding of the ecological niche of this plant, the necessary recommendations can be made for using the species in rangeland improvement programs in similar habitats.

 Vegetation sampling was done by a systematic-random method during 2016-2018.Vegetation studies were carried out, including the percentage of canopy cover of species and the density of species inside the plots. Also, the percentage of litter, bare soil, stones, and pebbles was determined in each plot. For this purpose, five transects with the same distance were used. Then, six plots (with 2 x 2 meters dimensions) were established on each with the same distance. To investigate the effect of environmental factors on the distribution of the studied species, three soil samples were taken from each plot at a depth of 0 to 30 cm, and their physical and chemical properties were measured in the laboratory. Climatic factors such as average rainfall and annual temperature were collected using data from weather stations near the study area. To investigate the relationship between effective and significant environmental variables and vegetation and to choose the appropriate linear and non-linear method, DCA was performed on the vegetation data, and the gradient length was determined. A generalized additive model predicted plant species' response to environmental changes. Canoco software version 4.5 was used to analyze the data in this section.

 The results of conventional comparative analysis showed that environmental factors such as clay percentage, geographical direction, acidity, sand, saturated moisture percentage, organic matter percentage, average annual temperature and soil lime percentage in the studied habitats, respectively 10.3, 4.4, 3.3, 3.3, 1.6, 1.4, 1.4 and 1.3 percent of the variance in plant composition, play an important role in changes in vegetation in the habitats.It showed that A.specigera species respond to the amount of phosphorus, percentage of organic matter, electrical conductivity, percentage of nitrogen, percentage of clay, percentage of organic carbon, and altitude. This is following the monotonic decrease model. The response pattern of this species to the percentage of silt, percentage of sand, average annual temperature, average annual rainfall, the direction of slope, acidity, potassium, the apparent specific gravity of soil, percentage of soil saturation and percentage of slope follows the bell model (Unimodal) and limit its growth optimum for each of these factors is 21%, 60%, 16°C, 400mm, for eastern and southern slopes, 8, 650mg/liter, 1.4g/cm3, 39% and 40-50%.

 The generalized incremental model provides valuable information to determine species' ecological needs. This information can be used in vegetation management and rangeland improvement operations in similar areas using the data from this research. Forage production is high in the studied species, suggesting its potential for increasing rangeland vegetation cover.