Variation of Plant Functional Groups along Livestock Grazing Gradient in Semi-steppe Rangelands (Case Study: Tangsayad Rangelands of Chaharmahal Bakhtiari Province, Iran

Assessment and monitoring of rangeland in different grazing managements seems necessary to manage rangelands. The plant functional groups can be used as appropriate responders for rangelands condition and management. Therefore, this study was performed and aimed to determine the most important traits that are influenced by rangeland variation and management. In order to this, three areas along a grazing gradient including national parks, protected area and free grazing were selected in Tangsayad rangelands of Chaharmahal Bakhtiari Province, Iran in 2015. A 100 m transect was established randomly in each site and within it five plots of 4 m2 area at 20 m intervals along transects were determined systematically. Plant species were identified and vegetation cover was recorded in each plot. The number and size of plots and transects were determined regarding to semi-arid rangeland sampling guidelines as well as the dimension of dominant plant species in plant community. Finally, some traits as leaf dimension, plant biomass and cover of species were measured. The results showed that the traits such as leaf length, leaf width, leaf area and leaf weight, grass growth forms and life forms of Hemicryptophyes and Geophytes had significant differences at least in one of three grazing managements sites (P<0/05). Also Principal Component Analyses (PCA) showed that traits as yield, overall weight of plants and perennial plants had high correlation with the first component and the traits such as leaf length, leaf width, leaf area, Hemicryptophyes had also high correlation with the second component. In general conclusion; leaf traits as leaf length, leaf width, leaf area and leaf weight, grass growth form, Hemicryptophytes and Geophytes life forms were introduced as good indicators for assessing and monitoring of grazing management.