Indicator plant species and functional trait related to animal grazing in the steppic rangelands

Identifying indicator species and plant functional trait facilitate predicting ecological characteristics of arid and semi-arid ecosystems and help managers to introduce appropriate plant species in order to rangeland management reclamation. This study focused on indicator species related to three grazing regimes (exclosure, moderate and high grazing intensity) in steppic rangelands of Borojen, Chaharmahal and Bakhtiari province. Sampling was according to a random-systematic method in which the cover of plant species estimated within 10 plots established along three transects in each grazing regime. Plant traits include growth forms (annual forb and grass, perennial forb and grass and shrub), life form (Terophytes, hemi- cryptophytes, cryptophytes, chamaphytes and phanerophytes), vegetation structure (Rosette, semi-rosette and erect), plant palatability (Class I, II and III) and plant height. In order to identify indicator species and examine of changes in plant community composition, we used indicator species analysis and non-metric multidimensional scaling. Results of indicator species analysis showed that 16, 8 and 8 indicator species were identified for exclosure, moderate and high grazing intensity regimes, respectively. There were also indicator functional traits for each grazing regime including hemi-cryptophytes, cryptophytes, perennial grass and palatable plant class I was related to exclosure, annual forb, perennial grass and erect forb related to moderate grazing and finally annual grass, therophytes, rosette and palatability class III related to high grazing intensity. Results indicate that grazing was responsible for changes in indicator species and finally resulted in a significant shift in community wide trait composition. As a consequence grazing regimes can be identified using indicator species, however, several species and functional traits indicator should be into account.