Estimating above-ground phytomass (AGP) is required to evaluate ecosystem structure and function. This research explains the temporal variation in AGP during the growing season in various management units of the Marjan rangeland-Borojen. AGP was modeled using satellite and field data collected from various dates during growing season. Plant production was measured from 19 sampling points with distances of 400 to 1000 m along 10 km transect. Nine quadrates were placed in each sampling point and in total, plant production of 380 quadrates were measured in four sampling stages. Regression model was used to estimate plant production in four sampling stages using field measurements and vegetation index derived from Landsat 8 data. The produced model was generalized for another 4 stages in the growing season and production maps were produced accordingly. ARVI index was identified as the best vegetation index for estimating AGP (R²= 0.61). We calculated AGP (Kg/ha) in 8 vegetative growth stages for all the management units in the study area. The highest production in Marjan rangeland was observed in May. Although the measured AGP was relatively homogeneous during the growing season, it has considerable spatial heterogeneity. Highest production and production stability was observed in the management unit with one specific rancher compared to the other management units.
 

Keywords: Vegetation index, Rangeland growing season, Change of above-ground phytomass, Landsat 8.

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