Application of a simple and effective method for mangrove afforestation in semiarid regions combining nonlinear models and constructed platforms

The strength and frequency of local tides in coastal lagoons plays a crucial role in providing suitable locations for the establishment of mangrove seedlings. Hence, the purpose of this investigation was to assess the hydrodynamics of a meandering tidal channel in order to select optimal locations for the construction of platforms, and thus improve the recruitment of white mangrove (Laguncularia racemosa) and red mangrove (Rhizophora mangle) propagules. The study was conducted within a coastal lagoon located along the semiarid coast of the Gulf of California. Current velocities and vorticity were simulated during flood and ebb tides using nonlinear numerical models. We tested three platforms of 3 × 3 × 0.5 m and measured the velocity and vorticity again. Once the model predicted locations where the ratio between friction and advective terms were greater, we proceeded with the construction of platforms in such suitable locations. The platforms presented a wooden perimeter filled with sediment at a similar height of the nearby mangroves (i.e., + 0.5 m Mean Sea Level). One platform was afforested with 50 red mangrove propagules, while the remaining two platforms were left without plants. Results indicated that the platforms without plants were quickly invaded by white mangrove propagules. Contrary to the aforementioned, the platform with red mangrove propagules was not invaded or replaced by other mangrove species. After nine years, the two platforms with white mangroves present 60 and 40 trees with a height of 3.5 ± 0.5  m, while the red mangrove platform presents 25 trees with a height of 3 ± 0.5 m. Our study showed the feasibility of combining numerical models and constructed platforms in order to create mangrove islands in semiarid coastlines.