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.