ارزيابي اثر پارامتر هاي اقليمي بر فنولوژي درختان مانگرو در جنوب ايران با استفاده از داده هاي ماهواره اي

Iran’s mangrove forests are among the country’s valuable economic and ecological resources. However, due to ongoing human activities and climate change, the conservation, management, and study of the biological processes of these vital ecosystems have become imperative. The primary objective of this research is to examine the phenology and estimate the vegetation indices NDVI, NDPI, and SAVI for Avicennia marina species in eight regions, including the Nakhiloo Protected Area and Nayband National Park in Bushehr Province, the Khor khuran International Wetland, the Tiab-Minab Protected Area, and the Gabrik and Jask Protected Areas in Hormozgan Province, as well as the Gwatar Bay and Hoor Bahu in Sistan and Baluchestan Province. This study utilizes satellite imagery from Landsat 5, Landsat 7, and Landsat 8, along with the Google Earth Engine platform, for the period 1993 to 2023. Additionally, the impact of climatic parameters such as maximum and minimum temperatures, precipitation, and water salinity on phenological metrics—including start of season (SOS), end of season (EOS), and length of season (LOS)—derived from vegetation indices was examined. By estimating the reflectance patterns of Avicennia marina derived from the NDVI, NDPI, and SAVI indices and determining the start, end, and length of the growing season over 30 years, 30-year time-series charts were analyzed, and trends were eva‎luated using the Mann-Kendall method in R software. Additionally, the Generalized Additive Model (GAM) was applied to assess the effects of independent climatic variables and water salinity on phenological indices. According to the results, the start of the growing season for Avicennia marina occurs between mid-September and early October, corresponding to day 253 to 285 of the year, while the end of the growing season occurs between mid-May and early June, corresponding to day 131 to 161. The length of the growing season varies between 239 and 249 days. Furthermore, in all regions except for Khor khuran Wetland, the start and end of the growing season have been delayed over time since 1993, whereas in Khor khuran Wetland, these events have occurred earlier by several days. However, the length of the growing season in all areas has remained relatively stable, estimated at around 8 to 9 months over the past 30 years. An analysis of climatic data in relation to phenological parameters revealed that, since NDVI, NDPI, and SAVI exhibited a similar phenological trend over 30 years, only the NDVI-derived phenological data were analyzed alongside climatic parameters in R software using the GAM model. The results identified salinity and precipitation as the two most influential parameters affecting the start and end of the growing season. These findings highlight that remote sensing serves as an advanced and efficient tool for deep understanding and dynamic analysis of mangrove ecosystem phenology. By assessing the growth cycle of plants from the past to the present, remote sensing facilitates the prediction and modeling of plant life cycles in the future.

حسين مرادي , سعيد پورمنافي

پريناز رحيم زاده باجگيران

محسن احمدي , رضا جعفري