Estudo fenologico de especies arboreas de uma floresta tropical em Linhares, ES

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

This paper aims at describing the periodicity of reproductive and vegetative phenologica1 events of canopy trees in a tropical lowland seasonal moist forest at Línhares, northeaster ES, and relating them to climatic seasonality. Every mo weeks, five individuals of 41 species, distributed withín 15.000 ha of forest, were observed for the occurrence of flower OOds, flowering, fruiting, propagules dispersal, leaf shedding, flushing, and periods of canopy dominance by either new leaves and mature leaves, from May 1982 to December 1992. At the same time, climatic data were gathered for the same area. While at least 15% of the species were observed in flower and 10% in fruit at any time of the year, these events predominated in certain defined periods of the year. Bi-modal curves for flowering were observed: one group of trees produced flower buds in the rainy season (January and February) and flowered at the transition to the dry season (April); another produced flower OOds in the dry season (June- Ju1y) and flowered at the beginning of rainy season (October). Fruiting predominated during the dry season (June and Ju1y), mainly as a consequence of strong fruiting seasonality of dry-fruited anemochoric species. Seed dispersal predominated in the transition between the dry and rainy seasons (September), Out from April to May only 1% of the species dispersed their seeds. In spite of the strong rain seasonality , the majority ofthe species (49,7%) were classified as evergreen, 34% were brevideciduous and 18,3% were deciduous. Leaf shedding predominated from September to October, and the new leaf canopy followed this phenophase, from November to December. The flushing of evergreen species occurred during the rainy season, from December to February. Climatic variables were correlated to community phenodynamics. Photoperiod was positively correlated with flowering, flushing and new leaf canopy, and negatively with fruiting and mature canopy. Insolation was positively correlated with fruiting and the mature leaf canopy phases, and negatively correlated with leaf shedding and new leaf phases. Evaporation was positively correlated with leaf shedding and negatively correlated with fruiting, flushing and mature canopy. Actua1 evapotranspiration correlated positively with flushing and negatively with leaf shedding. Average air temperature correlated positively with flowering and negatively with flushing. Water deficit, showed positive correlatino with flushíng and negative with leaf shedding. All phenophases showed a high seasonality considering the whole set of species, and two ,phenorythms were distinguished; semestral cycles (flowering) and annual cycles (other phenophases). Although the majority of the species (65%) have flowered and fruited annua1ly, only less than the half had regular cycles with a well defined timing. Continuous (1 species), supra-annual (4 species) and infra-annual (9 species) flowering cycles were detected, the latter groups in the majority being very irregular. The amplitude of the cycles was much variable between years, mainly for the fruiting and mature leaf phases. In some years the influence of climatic abnonnalities resulted in irregularity of reproduction in many species, altering the patterns of the community. It was observed an increase of the reproductive activity at the community from 1990 to 1992, similar to gregarious flowering and massive fruiting episodes, following an increase in the absolute minimum air temperature and decrease in the soil water deficit. The percentage of species and individuals with leafless trees increased in the drier years, influenced mainly by an increase in evaporation and not direct1y by the soil water deficit. After 1990, the proportion of trees and species with mature canopy leaves increased considerably, following an increase in absolute air temperature, insolation and relative humidity. The results indicated that short tenn studies do not yield a clear picture of phenological rhythms in tropical forests, especially when the objective is to understand the relationship between phenodynamics and a biotic factors in tropical forests with different degrees of climatic seasonality. Many questions are sti1l open to discussion, among them those related to the importance of the biotic factors on the observed patters

ASSUNTO(S)

mata atlantica essencias florestais fenologia

ACESSO AO ARTIGO

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