This study was conducted by the aim of study the species composition and diversity in the north faced slopes of Sabalan (altitude profiles of Lahrood-Shabil) along 7 transects in three elevation classes of 1500 to 2000m, 2000 to 2500m and 2500 to 2700m in the grass-shrubland dominated habitats. Plant specimens were collected in the fieldworks, and then species were identified using the checklists and reliable literature. Overall, 64 identified species were belonged to 48 genera and 22 families. Poaceae family with 9 genera and 16 species, Fabaceae family with 4 genera and 8 species and Asteraceae family with 6 genera and 6 species are the dominant family and genera. According to the Rankaier's system hemicryptophytes with 50%, therophytes with 31%, geophytes with 16% and chamaephytes with 3% are the growing life forms at the study area. In terms of geographical distribution, 42% of the species are belong to Iran-Turonian region, 22% of those to Iran-Turonian and Euro-Siberian, 12% are cosmopolitan, 3% to Euro-Siberian and other 21% is belong to other regions. From the identified species 6 of them are in threatened status based on the International :::union::: for Conservation of Nature and Natural Resources (IUCN) criteria. Diversity and evenness of species were calculated using numerical indices. Results of numerical diversity indices (Simpson and Shannon-Weiner) showed significant change according to elevation. However, the evenness indices (Simpson and Smith and Wilson) show no significant change by elevation.

This study aimed to investigate the effect of ecological factors on the distribution and changes of vegetation and land cover in the Fakhr Abad-Shabil elevation gradient on the grass-shrubland physiognomic unit. After a field survey, considering the road accessibility, sampling at three elevation classes (1500-2000, 2000-2500 to 2000 and 2500-2700 ma.s.l.) along the seven transects, and 10 one square m plot at each transect were done.In each plot, the percentage of canopy cover and species density, and land cover parameters were recorded.Plant samples were collected and identified.Soil sample were collected from each transect and parameters were measured in the laboratory. Mean ccomparison of transects and elevation classes was conducted using Duncan test.Principal component analysis (PCA) and canonical correspondence analysis (CCA) to  group sampling location, and to evaluate the effect of ecological factors on the distribution of plant species were used.Results of the data analysis for seven transects and three elevation classes, showed that the effect of elevation on the canopy cover (P≤ 0.01) and species density (P≤0.05) is significant. According to the results of PCA with 94/18% of the variance, pH, organic matter particles, organic matter, sand, temperature, altitude, rainfall, phosphorus, mean weight diameter, electrical conductivity, bare soil, stone and gravel, potassium, clay, slope and litter from the first four components are the effective factors on the distribution of species. In the CCA method with 76/9% of the variance based on three components, potassium, percentage of silt and slope, rainfall, altitude, lime, phosphorus, temperature, electrical conductivity, percentage of bare soil, mean weight diameter, the percentage of organic matter particles, percentages of clay and gravel, organic matter, litter, sand and pH, respectively are the factors on the distribution of species.According to the results, the altitude in the grass-shrub land physiognomic unit is the most effective factor, and elevation gradientin is  associated with the change of vegetation. In addition, the selected ecological factors are effective in the distribution and change of vegetation. using the results and recognition inference, we can effectively manage the soil parameters in the management of Sabalangrass-shrubland physiognomic unit, especially in the rangeland restoration and introducing species in each altitude classes with regard to other ecological factors, particularly soil parameters.