Stem growth and phenology of three subtropical mangrove tree species

The present study aimed to investigate the relationships among stem circumference growth, phenology and abiotic variables, of three mangrove tree species of southern Brazil. Species circumference growth, measured using dendrometer bands, and phenological events were followed for 12 months. Data were correlated with day length, temperature and precipitation using a model based on the method of least squares, taking into account temporal autocorrelation of the data. During the study period, temperature influenced the fruiting of Avicennia schaueriana Stapf and Leechm. ex Moldenke, while it was strongly related to the production of leaves and flowering in Laguncularia racemosa (L.) Gaertn and Rhizophora mangle L., respectively. Monthly precipitation was related to the flowering of only R. mangle. No abiotic variable (day length, temperature and rainfall) was correlated with stem growth for the L. racemosa and R. mangle during the period. However, the highest rate of increase in stem circumference for all three species occurred during the period of highest temperature and rainfall. Our results demonstrate that the reproductive phenophases are more intense in wetter and hotter conditions. Combined with endogenous factors, these abiotic variables influence vegetative and reproductive phenophases and stem circumference growth. Stem growth rates were different for each studied species, but they all exhibited high peaks of stem growth concomitant with periods of higher temperature and precipitation. Phenological events, and how they correlate with the analysed abiotic variables, differed among the three species and stem growth showed a direct relationship with phenophases during the study period only for A. schaueriana.