Estrutura vegetal e grau de perturbação dos manguezais da Lagoa da Tijuca, Rio de Janeiro, RJ, Brasil

Abstract

Structure and degree of perturbation of mangroves at Tijuca Lagoon, Rio de Janeiro, RJ, BrazilThe Tijuca Lagoon is located south of Rio de Janeiro City. It is bordered by a discontinued and narrow belt of mangrove trees. Mangrove forests have a high structural variability. Of the eighteen stands studied there are monospecifics stands of Laguncularia racemosa with dbh between 3.4 and 7.7 cm and height between 4.5 and 7.7 m, dominated by trees with dbh less than 10.0 cm. At the other stands, occur mixed forests, structuraly more developed, sometimes dominated by Laguncularia racemosa, sometimes by Rhizophora mangle (dbh between 7.8 and 16.7 cm; height between 6.8 and 16.1 m, prevailing trees with dbh greater than 10.0 cm). There are also mixed stands dominated by Avicennia schaueriana (dbh of 7.1 cm and 5.3 m high, predominating individuals over 10.0 cm in dbh). The structural variability observed, is strong evidence of an altered landscape. Observations on mangrove forests at southeastern Brazil show that stands dominated by Laguncularia racemosa with low dbh are typical of degraded sites in process of restoration. The structure that is quite close to that of the original forest is represented by the most developed stands (high dbh and height). One of the studied stands, with mature forest of Rhizophora mangle, high developed for the structural patterns of mangrove at the southeastern Brazil is jeopardized by the invasion of Acrostichum sp., wich is preventing the development of R.mangle saplings. This invasion is related to a high deposition of mud, wich rose the substrate, reducing tide inundation.

Absence Of Zonation In A Mangrove Forest In Southeastern Brazil

“…According to several authors (TOMLINSON, 1986;SOARES, 1999), L. racemosa is a typical species of degraded stands undergoing a process of regeneration, characterized as a pioneer species in a process of secondary succession.…”

THE RECOVERY OF A DEGRADED MANGROVE IN CEARÁ THROUGH THE PRODUCTION OF Laguncularia racemosa (L.) C.F. Gaertn. (Combretaceae) AND Avicennia sp. Stapf ex Ridl (Acanthaceae) SEEDLINGS

“…Several studies indicate that this species is typical of degraded forests in the process of regeneration, and characterize it as a pioneer species in the process of secondary succession (PERIA et al, 1990;SOARES, 1999;SAMPAIO, 2001;SOARES et al, 2003;RESENDE, 2010). According to Smith III (1992), mangrove forests subjected to more frequent disturbances have lower numbers of Rhizophoraceae species compared to species such as Laguncularia racemosa.…”

“…The vegetation structure of mangroves directly influences the conditions and functioning of mangrove forests, and therefore, its characterization is an important tool to indicate the ecosystem's responses to existing environmental conditions and to assist studies that aim at conservation (SOARES, 1999;CAVALCANTI et al, 2009;BLANCO-LIBREROS et al, 2013).…”

Heterogeneity of elemental composition and natural abundance of stables isotopes of C and N in soils and leaves of mangroves at their southernmost West Atlantic range

“…Within their geographical distribution mangrove structural development is limited by salinity, correlated with climatic aridity, and nutrients, associated with fresh water runoff (Boto, 1983;Feller, 1995;Duke et al, 1998;Medina and Francisco, 1997;Rivera-Monroy et al, 2004), and may be also modified by anthropogenic influences, particularly sediment deposition (Soares, 1999). At their latitudinal limits of occurrence frost is added to the environmental constraints for mangrove establishment, survival, and structural development (Lugo and Zucca, 1977;McMillan and Sherrod, 1986;Lovelock et al, 2007;Soares et al, 2012).…”