The effect of waterway distance on species diversity and Plant Functional Groups in mountainous rangelands of Anbaran Chai, Ardabil

The plant communities locating at the margins of the waterways play a vital role in the ecological processes and ecosystem services in the semi-arid mountainous regions. In this study, variations of plant diversity and composition at different distances from the waterway and its slope aspects were investigated. For this purpose, 15 sub-basins with a variety of area and length of waterway, in both northern and southern directions, were selected in the mountainous rangelands of Anbaran Chai. For measurements 20 plots of 1m2 in each sub-basin were established and vegetations were surveyed. Different distances from the waterway (0-25, 25-50 and 50-75 m) were selected for the measurements in the growing season in 2017. By grouping the species into scientific groups and calculating species diversity, statistical comparison of the parameters was performed by one-way ANOVA and t-test. The results showed that the highest diversity happens at the second distance group (25-50 m).This put emphasis on the hypothesis of occurring maximum diversity in the medium environmental disturbance conditions. In this regard, Shannon-Wiener species diversity index values ​​were 1.38, 1.40 and 1.39 for first to third distances, respectively. Northern slopes are more diverse (1.45) than southern slopes (1.30) due to high humidity. The results suggests that if the goal of range management is to prioritize the area on the basis biological practices emphasis should be put on the first and third distances from the waterway.