Composition and community structure of mangroves distributed on the east coast of Marajó Island, Brazil

Abstract

Mangroves in the Amazon are in uenced by several environmental conditions that determine the composition and structural development of the arboreal ora, which results in different distribution patterns. In this study, we sought to answer two questions: (1) what is the composition and structure of the mangroves near the mouth of the Amazon River in Marajó Island? (2) Are the fringe and inland mangroves more similar or dissimilar in terms of oristic composition? For this, we delimited a fringe zone and an inland zone about 1 km apart from each other. In each zone, we distributed ve 400-m 2 plots. The individuals were grouped into diameter and height classes and structural and phytosociological parameters were calculated. Ten species were recorded in the mangroves, of which seven are typical of white-water (várzea) and black-water (igapó) ooded forest ecosystems. We believed the adjacent ecosystems and the hydrological network are inducing the establishment of such species. The composition and structure of mangroves did not differ statistically between zones, and the degree of similarity may be a result of similar environmental factors in these zones such as low relief and high frequency of macrotides. We conclude that the vegetation of the studied mangroves has a major in uence of the uvial-marine system of the great rivers of the Amazon associated with a diversity of ecosystems that, together, generate greater oristic richness when compared to mangroves in other regions.

Spatial Distribution and Substrate Preferences of Bryophyte Species in Mangrove Ecosystems of the East Coast of Marajó Island, Brazil

“…The greatest similarity between the bryophyte floras of the municipalities of Ilha do Marajó (Soure, Salvaterra and Cachoeira do Arari) can be attributed to the configuration of the studied areas, which have a similar floristic composition (Lisboa et al 1993; Carvalho & Jardim 2017; De Oliveira Faro et al 2023) and are also influenced by tributaries of Baía do Marajó (Gregório & Mendes 2009). These mangroves have a low richness of bryophytes when compared to the mangroves on the coast of São Paulo, which can be attributed mainly to the pressures of degradation and deforestation in this ecosystem.…”

“…1). In this study, four locations (Table 1) were selected to access eight mangrove forests with tree coverage described by De Oliveira Faro et al (2023). The mangrove complex of the Marajó Island can be observed between streams and on the banks of the Tocantins and Amazon rivers that drain the island and that flow into the bays and the Atlantic Ocean (Schaeffer-Novelli 2018).…”