Production and biomass of mangrove roots in relation to hydroperiod and physico-chemical properties of sediment and water in the Mecoacan Lagoon, Gulf of Mexico

Abstract

Production and biomass information of roots is valuable for understanding the ecological process within mangroves. In this study, the production, biomass, turnover rate, and longevity of underground roots of mangrove (Rhizophora mangle L., Laguncularia racemosa L. Gaertn, and Avicennia germinans L. Stearn), as well as the density and biomass of pneumatophores was evaluated in relation to hydroperiod and physico-chemical properties of substrate and water in the Mecoacan Lagoon, Gulf of Mexico. Root extraction was performed in order to measure the biomass and production of roots by in-growth core technique; whilst the hydroperiod and physico-chemical parameters in water were determined using piezometers. The study was conducted from September 2016 to August 2017. A total root biomass of 23.7 tonDw ha−1 (subterranean roots + pneumatophores) was weighing; the large roots showed the highest biomass weighing 1532 ± 254 gDw m−2; followed by the medium roots (189 ± 30 gDw m−2) and fine roots (194 ± 27 g Dw m−2). The average total production was 0.41 ± 0.05 g m−2 day−1, an average turnover rate of 0.41 ± 0.07 year−1 and longevity of 4.04 ± 0.07 years. Pneumatophores showed average heights of 17.8 ± 0.8 cm with a density of 292 ± 30 pneumatophores m−2 and average biomass of 453 ± 51 gDw m−2. In conclusion, the production and biomass of subterranean roots and pneumatophores show spatial variations controlled by environmental factors as hydroperiod, interstitial redox potential, mangrove tree density and soil moisture content.