Evaluation of the Effect of Flood Spreading on the Fluctuations of Rangeland Plant Indices in the Aquifer Management Kowsar Station

Introduction and ObjectivesThe history of flood spreading in the lands adjacent the rivers and flood irrigation reaches several thousand years. There are evidences of the use of floods to increase plant production in different parts of Iran, including the cities of Qazvin, Baluchistan, Khorasan, Fars, Isfahan and Khuzestan. Surveys conducted in 20 arid and semi-arid regions of the country indicate that in most regions, production indices and the percentage of plant canopy cover have increased significantly in the field of flood spreading compared to the control. The purpose of this research is to investigate the effect of flood spreading on rangeland vegetation dynamics and to determine the fluctuations of plant indices corresponding to climatic indices in a 6-year period.Materials and MethodsIn order to monitoring and comparison the fluctuations of vegetation indices was selected in Aquifer Management Kowsar Station, 2 networks (representative of the flood spreading area) with the names Bisheshzard 1 and Bisheshzard 4 and adjacent to them an area of ​​5 hectares outside the networks spreading as a control. The representative of the area without flood spreading). From 2016 to 2022 for 6 years, in the second half of May every year, 10 transects with a length of 150 meters and 100 plots of one square meter were established in a systematic-randomness manner in the strips of networks and the control field. The rangeland type indice species of flood spreading Gareh Bygone Plain (GBP) of Fasa shrubs are Dendrostellera lessertii (Wikstr) Van Tiegh., Heliantemum lippii (L) Pers Astragalus ssp. with understory of annual Grasses and forbs respectively. Plant indices (species name, percentage of canopy cover, number of bases per square meter, vegetative form and species biomass) and soil surface coverage (percentage of stones and pebbles, percentage of litter and percentage of bare soil) were collected every year. Using the modified six-factor method, the rangeland condition in flood distribution networks was evaluated in wet years and in dry years. For the comparison of different rangeland treatments in the survey years, flood spreading networks and strips and control area from different statistical methods (split-split plot design in time and space in the form of complete random blocks), correlation coefficients, was used step by step regression to determine the forecasting model for the production and canopy cover of rangeland plants and for average comparisons Du