The Effect of Vegetation on Surface Elevation in Coastal Mangrove Areas

Rising sea levels pose a serious threat to global coastal mangroves. The ability of surface elevation to change synchronously with rising sea level is the key to the survival of mangroves. Mangrove vegetation can have a variety of effects on surface and subsurface processes; therefore, it has an important role in surface elevation changes. In this study, rod surface elevation table marker horizon (RSET-MII) technology was used to study changes in surface elevation and accretion between nonvegetated and vegetated mangrove areas at three different sites. The results showed that the existence of vegetation had a significant effect on elevation changes, with increased surface elevation in vegetation areas observed to be significantly greater than those in nonvegetation areas. In addition, the subsurface changes in vegetated area showed expansion, whereas the nonvegetation area showed subsidence. Surface accretion showed variable trends in different research sites, although these could he related to their geographical location and thus he affected by many factors. Moreover, there was a significant correlation between density of vegetation and elevation/subsurface changes (r = 0.763, p < 0.05; r = 0.714, p < 0.05 respectively), and there were no significant correlations between accretion and vegetation characteristics. The results indicate that mangrove vegetation has a positive effect on the increase of surface elevation, and vegetation density may be a key factor because of the high biomass and carbon storage rate in high density areas. This study provides additional data with which to explore the elevation variation in mangroves and a scientific basis and technical support for strengthening wetland protection.