RT - Journal Article T1 - Investigating the response of Bromus tomentellus Boiss. to environmental gradinets using HOF function in Galandrood watershed rangelands JF - rangelandj YR - 2017 JO - rangelandj VO - 11 IS - 1 UR - http://rangelandsrm.ir/article-1-451-en.html SP - 1 EP - 15 K1 - Bromus tomentellus K1 - Ecological optimum K1 - HOF function K1 - Environmental variables K1 - Response curve AB - The objective of this study was to investigate the response of Bromus tomentellus species to some environmental variable using HOF function in Galandrood watershed rangeands - Mazandaran province. Randomized-systematic approach was used to collect environmental data such as elevation, slope, aspect and the frequency of B. tomentellus in 153 quadrates of 1m2 was measured. Soil samples were collected from 0-20 cm in each quadrate and their pH, N, EC, organic carbon, sand, silt and clay percentages were measured. HOF with binomial distribution function was used to produce response curve of the species against environmental variables, and identify the ecological optimum of the species. The data was analysed by Rver.3.0.2 computer porgramme. The results showed that B. tomentellus occurs in the areas with elevation range of 2125 to 2975m. According to the respose curve of the species, B. tomentellus frequency had monotonically decreasing trends to clay, silt, aspect and pH, but its frequency against organic carbon, sand and N had monotonically increasing trend. Although the species frequency had an increasing threshold behavior against elevation and slope, it had decreasing threshold behavior to precipitation and temperature variables. Elevation was identified as the most important variable affecting B. tomentellus occurrence in the study area as it affects most ecological parameters. LA eng UL http://rangelandsrm.ir/article-1-451-en.html M3 ER -