Understanding the reproductive phenology of Avicennia marina at its northwestern range in the Arabian Peninsula supports improved afforestation planning

Understanding the population dynamics of mangrove trees along their range limits requires information on their life cycles, including phenology and reproduction. This study examines the reproductive cycle of Avicennia marina in the northern Saudi Arabian Red Sea, providing new insights into the phenology of the species at its northern latitudinal range, where it experiences limiting conditions in a hyper-arid environment. We observed distinct patterns in bud formation, flowering, and propagule production that correlate with air temperature, sea surface temperatures, and solar radiation. Precipitation and sea surface salinity had a non-significant or weak influence on the phenological cycle, reflecting the species’ tolerance and adaptation to extreme environments. Avicennia marina exhibited a latitudinal gradient in peak propagule production, with southern sites forming propagules earlier. Through identification of peak propagule seasons and estimates of the Maximum Sustainable Yield (MSY) for various sites, we demonstrate a framework to optimize propagule harvesting and improve nursery operations. These findings highlight the importance of understanding local reproductive dynamics as a foundation for the success of the growing number of large-scale afforestation projects worldwide and their long-term sustainability.