Journal of Rangeland

  This study aimed to evaluate the response of Festuca ovina to some environmental variables using HOF function in Galandrood watershed rangelands located in Mazandaran province. A randomized-systematic sampling was used to establish 150 quadrates of 1m² along an elevation gradient. Frequency of Festuca ovina, elevation from sea level, slope and aspect were recorded in the all quadrates. Soil samples were taken from 0-20 cm in each quadrates and bulk density, pH, N, EC, organic matter, organic carbon, sand, silt and clay percentages were measured. HOF function with binomial distribution was used to provide the response curves and identify ecological optimum point of F. ovina to the measured environmental variables. The data were analysed using R ver.3.0.2 program. The results showed a monotonically increasing trend for F. ovina frequency to elevation. The optimum frequency and elevation range of the species were 3037 and 2244 – 3037 meters from sea level, respectively. The behavior of F. ovina to EC, organic carbon, sand and slope was a monotonically increasing trend, but its frequency was decreased where the soil clay content was increased. It implies that F. ovina does not prefer heavy soil texture. F. ovina frequeny had a symmetric unimodal response to the soil pH.