Facilitation in mangrove ecosystem: the role of herbaceous species in seedling recruitment and growth patterns of Avicennia germinans in a recovering mangrove in Northeastern Brazil.

Abstract

The restoration of mangroves is crucial for preserving their vital role as ecosystems. Facilitation could assist in the restoration of degraded ecosystems, especially during the first life stages. This study investigated how herbaceous species can facilitate the recruitment and growth of Avicennia germinans in a degraded mangrove area undergoing restoration during extremely dry and rainy seasons typical of northeastern Brazil. The research assessed the densities and growth of A. germinans in the presence of Batis maritima and Sesuvium portulacastrum, and without any other plant species as control during the rainy and dry seasons from 2017 to 2019. The area had been previously disturbed by the salt pond industry abandoned since the late 1980s. The results revealed different facilitation mechanisms. S. portulacastrum and B. maritima promoted 2.6 and 1.7 times higher densities of A. germinans than control plots. While B. maritima had significantly faster growth of A. germinans than S. portulacastrum plots, associated with a capacity of decreasing salinity levels, facilitating mangrove seedlings during dry seasons, S. portulacastrum surpassed B. maritima and control plots in terms of density, which can be profitable for mangrove seedlings during extreme rainy seasons of floods.