Comparison of the ecological amplitude of Bromus tomentellus B., and Festuca ovina L. to some environmental variables using the function HOF (Case study: 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 compare between the ecological amplitude of Bromus tomentellus. and F.ovina, using the function HOF along the gradient of the environmental variables. For these purpose 153 plots of 1m2 were established along the altitude gradient. The sampling method was randomized-systematic. In the area sampled, frequency of Bromus tomentellus and F.ovina, altitude and slope were recorded. Soil samples were taken from 0-20 cm in each quadrate. Shape of response curve and the ecological optimum in relation to the mentioned variables, HOF function was used with binomial distribution function. The data were analyzed by R ver.3.0.2 software. The two species Bromus tomentellus and F.ovina mainly showed different ecological amplitude along the gradient environmental variables. The results showed that the ecological amplitude for two species has been recorded 2125-2975m. Ecological optimum along altitude gradient for Br.tomentellus and F.ovina has been recorded 2417.66 and -2585m respectively.. Also the response curve of Br. tomentellus and F.ovina to the altitude variable had increasing threshold behavior. Generally, this study showed that, Br. tomentellus and F.ovina species are native to mountain regions and cool, but the tolerance of F.ovina against low temperature was more than Br. tomentellus.