| Summary: | Structural and functional characteristics of mangrove forests are primarily governedby the interaction of environmental characteristics, that act in global, regional or local 102Anuário do Instituto de Geociências - UFRJ Volume 26 / 2003scales. However, in areas submitted to strong influence of human activities, disturbanceshould be considered seriously. In this way, the structural characteristics of mangroves ofGuanabara bay were studied during three years (2000-2002). The studied forests presenteda high structural diversity, reflecting the action of disturbances, that determine differentdegradation levels and regeneration status (different phases of secondary succession) of thestands. The stems density varied from zero (gaps) to 52,800 stems.ha-1. The mean diameterat breast height varied from 1.33 cm to 7.83 cm and the medium tree height varied from1.80 m to 7.27 m. Several structural and dynamics patterns of the studied plants communitieswere identified, as follow: (a) reverse " j " shaped, (b) "normal" distribution, (c) massmortality, (d) overlap of "events", (e) recolonization/gaps, (f) regeneration failure, (g)gaps and, (h) invasion by Acrostichum aureum. The high structural diversity observed inthe studied forests, identified through the use of phytosociological parameters and speciescomposition, which determines a structural mosaic, is due to the overlapping of the followingcharacteristics: (1) variable nature of disturbances, (2) disturbances characteristics (chronicor acute), (3) spatial variability in disturbances action, (4) temporal variability in disturbancesaction, (5) variation in the frequency of disturbances occurrence and (6) capacity of thesystem to recover after a disturbance.
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