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Previous issue date: 2017-02-14 === Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) === Manguezais s?o ecossistemas costeiros e estuarinos que pertencem a climas quentes e temperados ou tropicais ?midos, s?o dominados por esp?cies lenhosas, fornecem importantes bens e servi?os ecossist?micos e possuem valor socioecon?mico. Os manguezais s?o sens?veis a dist?rbios e est?o em constante processo de degrada??o devido ? carcinicultura e ao desenvolvimento urbano. Intera??es entre indiv?duos vegetais podem resultar em competi??o e facilita??o interferindo no crescimento, no padr?o de distribui??o e na sobreviv?ncia das plantas, al?m de modificar caracter?sticas f?sico-qu?micas do ambiente. Vari?veis abi?ticas e bi?ticas interagem permitindo an?lise da adapta??o das esp?cies em diferentes condi??es ambientais, podendo tamb?m inferir sobre a intensidade de degrada??o. O objetivo geral do estudo foi identificar os principais fatores limitantes no crescimento e na sobreviv?ncia de plantas de Rhizophora mangle L. (Rhizophoraceae) em dois ambientes dominados pela esp?cie e localizados em ?rea de carcinicultura, sendo um com presen?a de ?rvores e copa fechada, e outro aberto com plantas jovens e subarbustivas. Foram realizados dois monitoramentos com sele??o de parcelas e plantas em cada ambiente, totalizando 90 indiv?duos, para quantificar o crescimento ao longo do tempo atrav?s de medidas da altura, n?mero de ramos e di?metro a 30 cm do solo. Para as vari?veis abi?ticas foram feitas medidas da temperatura e pH do solo, luminosidade, salinidade, velocidade do vento, temperatura do ar e penetrabilidade do solo nas parcelas de cada ambiente aberto e fechado por 12 meses. Indiv?duos adultos de R. mangle foram competidores interferindo no crescimento de plantas jovens da mesma esp?cie atrav?s da limita??o de luz e do estresse advindo do ac?mulo de sedimentos. Em ambiente aberto, com plantas jovens apresentando mesma idade e distribu?das de forma agregada, ocorreu facilita??o com redu??o de condi??es estressantes devido ? maior incid?ncia de radia??o solar e temperatura desse ambiente, e tamb?m competi??o atrav?s de alta densidade de plantas. Devido a essas intera??es positivas e negativas agindo simultaneamente, o efeito final da densidade-depend?ncia no crescimento de plantas do ambiente aberto foi neutro. Al?m disso, temperaturas m?dias de 30?C, pH do solo com valores entre 5,5 e 6,5 e salinidade com cerca de 35 ppm foram fatores que beneficiaram o crescimento das plantas ao longo do tempo em ambiente aberto atrav?s da fotoss?ntese, de adapta??es fisiol?gicas e poss?vel melhor assimila??o de nutrientes do solo. Esses resultados ajudaram a entender as caracter?sticas ambientais que facilitam e interferem na recupera??o de ?reas degradadas pela carcinicultura. === Mangroves are ecosystems coastal and estuarine belonging to warm and temperate climates and wet tropics, mangroves are dominated by woody species, provide important ecosystem goods and services and have socioeconomic value. Mangroves are sensitive to disturbances and are constantly being degraded due to shrimp farming and to urban development. Interactions between plant individuals may result in competition and facilitation by interfering on the plant growth, pattern of distribution and plant survival, besides modifying physical-chemical characteristics of the environment. Abiotic and biotic variables interact allowing the analysis of the adaptation of the species in different environmental conditions and also about the intensity of degradation. The main objective of the study was to identify the main limiting factors on the growth and survival of Rhizophora mangle L. (Rhizophoraceae) plants in two environments dominated by this specie and located in the shrimp farming area, one with trees and closed canopy, and another open with young and sub-shrub plants. Two monitoring were carried out with selection of plots and plants in each environment, totaling 90 individuals, to quantify the growth over time by means of measures of height, number of branches and diameter at 30 cm. For the abiotic variables, measurements of soil temperature and pH, luminosity, salinity, wind velocity, air temperature and soil penetrability were taken in the plots of each open and closed environment for 12 months. Adult individuals of R. mangle were competitors interfering in the growth of young plants of the same species through the limitation of light and of the stress coming from the accumulation of sediments. In the open environment, with young plants presenting the same age and distributed in an aggregated way, facilitation occurred with reduction of stressful conditions due to the higher incidence of solar radiation and temperature of this environment, and also competition through high density of plants. Due to these positive and negative interactions acting simultaneously, the final effect of density dependence on plant growth of the open environment was neutral. However, mean temperatures of 30?C, soil pH values between 5.5 and 6.5 and salinity with about 35 ppm were factors that benefited the growth of the plants over time in open environment through photosynthesis, of physiological adaptations and possible better assimilation of soil nutrients. These results helped to understand the environmental characteristics that facilitate and interfere the recovery of areas degraded by shrimp farming.
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