Investigation on the Responses of Forbs Species to Some Environmental Variables in the Rangeland of Glandrood watershed

The current study was conducted in the rangeland of Glandrood watershed in the province of Mazandaran. The main objective of this study was to investigate the responses of forbs species to some environmental gradients. For these purpose 153 plots of 1m2 were established along the altitude gradient and Trasp. The sampling method was randomized-systematic. In the area sampled, frequency of forbs species, altitude and slope were recorded. Soil samples were taken from 0-20 cm in each quadrate. In each sample plot, pH, nitrogen (N), electrical conductivity (EC), organic matter, organic carbon, percentage of sand, silt and clay were measured. In this study, HOF function were used to describe the realized ecological niches of forbs species to the primary axis of classification or floristic gradient, as extracted by Detrended Correspondence Analysis (DCA) and the ecological variables were assessed with standard Spearman rank correlation tests. The data were analyzed by R ver.3.0.3 software. The results showed that the most species have monotonically increasing or decreasing (19%), symmetric (15%), unimodals (23%) or skewed (35%) and only (4%) one species have flat response curves. For altitude variable of the 26 forbs species included in the general analysis, 4 species showed symmetric (HOF model IV), 9 skewed (model V), 5 species monotone (model II) and 7 species flat (model I) response curves. Among the forbs species, Colchicum kotschy, Medicago rigidula, Tecrium polium, platyloba Echinopora and Campanula stevenii had the narrowest niche ecological. . .