Effects of Floodwater Spreading on the Vegetation Indices in the Poshtkooh Rangelands, Keyasar

Floodwater spreading (FS) is an efficient and appropriate method for the optimization of runoff utilization, particularly in arid and semiarid region. Beside the reduction of damage caused by the flooding, this technique is also useful in the artificial recharge of groundwater and rangeland restoration. Effects of floodwater spreading on species composition and functional groups were assessed in the Poshtkooh Rangelands of Sari in the Mazandaran Province. Vegetation sampling was evaluated in the FS area, enclosure and a without floodwater spreading (grazing). Sampling was carried out at representative and homogeneous areas of each treatment by the random-systematic method, thus the canopy cover of each plant species was measured in 90 plots of 1 m2/each. Results showed that there were 53 species in floodwater spreading area and 43 species in the enclosure but only 24 species were present in the control area spreading or grazing. Among the studied plant families. The canopy cover of Brassicaceae, Poaceae and Fabaceae was increased by floodwater spreading, shrubs and Chamophytes showed a significant reduction from due to FS as compare with the control area. Comparison of the most functional groups also indicated a reduction in their canopy cover percentage with an increase in floodwater spreading and enclosure. The multivariate analysis showed that the species composition and functional groups of the study area were affected by the FS practices and enclosure; that important and valuable species such as Agropyron elongatum and Onobrychis altissima responded most to such practice. To sum up, our results clearly showed that the FS practices carried out in the area had a positive effect on species composition and functional groups.