هانا اعتمادی

Nowadays it is essential to use ecological criteria such as biomass for knowing the status of sensitive ecosystems like mangrove habitats and for knowing about their monitoring and evaluation during the time. The present study aims to investigate the trend of temporal and spatial variations of Iranian mangroves and also to find the relation between data values of landsat 8 and Above Ground Biomass achieved from Allometric equations in Nayband National Park mangroves and presenting an appropriate relation for evaluating the Above Ground Biomass and above ground carbon. At first, for the study of spatial and temporal variations of Iran's mangroves four plant criteria including NDVI, SAVI, LAI, and RVI were evaluated. Radiometric, atmospheric, and geometric correction were done on the images and then output images of criteria were prepared, categorized, and the proportioned area and plant coverage percentage using criteria relations. The result of the survey showed increase in all Iran's mangrove areas during 1990 to 2019. This increase amount was estimated on average to be in Bidkhoun from 32.96 to 123.93, in Basatin from 4.23 to 31.68, in Qeshm from 6962.22 to 8078.49, in Bandar Abbas from 140. 42 to 1324.44, in Sirik from 461.9 to 847.44, Western Jask from 50.72 to 68.355 and Eastern Jask from 248.67 to 396.23, in Gabrik from 135.81 to 425.52 and finally in Govatr from 275.76 to 396.72. Some of the major causes of changes in the Nayband region are the construction of a road with no culverts, the influx of flowing sands and also the harvesting from the main branches for providing fossil fuel resources and feeding animals. In the region of Qeshm, the reasons for forests decreasing are the Persian Gulf War at 1990, turning forests to agricultural fields, freshwater diversion, salt extraction, aquaculture, and especially the drought of the 1990s and among the reasons for forest increasing is forestry since 2002. In Bandar Abbas and Sirik, climate change and the increase