Abstract

Due to the intensive use of land and global warming, the response of species within the plant community to environmental changes and the developmental trend of the community have attracted global attention. Affected by human disturbance and rising sea levels, mangrove forests are undergoing a significant reduction in plant density. Due to unfavorable factors such as increased salinity and prolonged flooding time accompanying rising sea levels, it is difficult to predict how the growth and physiological processes of different mangrove individuals will respond to these factors and what impact these responses will bring to the development of mangrove plant communities. In this study, we simulated rising sea levels by controlling light intensity, seawater salinity, and flooding time, and studied the physiological and ecological response mechanisms of six representative mangrove species on Hainan Island, China, to rising sea levels with the goal to predict the development of mangrove plant communities in this region. The results showed that tree species distributed at high tidal levels were more susceptible to rising sea levels than those growing at medium and low tidal levels. Due to the rise in sea level, increasing flooding time, and high salinity stress, mangroves would naturally migrate inland. However, due to human disturbance that resulted in shoreline hardening, the mangrove retreat space is inadequate as their distribution area gradually becomes smaller and disappears. If measures are not taken to restore the natural environment of the offshore coast and allow mangroves to advance and retreat freely, global warming and rising sea levels will affect in particular the mangrove species growing at high tidal levels, such as Excoecaria agallocha, Lumnitzera littorea, Lumnitzera racemosa, Bruguiera sexangula, and Ceriops tagal.