Phenology of Croton blachetianus Baill in a dry tropical forest associated with the dynamics of temporal variability of rainfall

Abstract

In the semi-arid environment, the synchronism and the magnitude of the precipitation pulses are indispensable for the ecological processes, mainly due to the availability of water in the soil for the plants and to the microbiological activity of the soil. The present study aimed to determine the vegetative and reproductive phenological behavior of Croton blachetianus Baill in areas of Caatinga. The hypothesis was that the occurrence of the phenophases is synchronized with the spatial and temporal distribution of the precipitation pulses, under semi-arid conditions. For the phenological study, 50 tree individuals were selected, marked and monitored weekly, recording the presence and absence of the phenophases of sprouting, appearance of flower buds, flowering (anthesis), fruiting and senescence, whose data were related to the water pulses and inter-pulses. The method proposed by Fournier was used to estimate the percentage of the intensity of the phenophases in each individual. The phenological data of intensity of each phenophase (sprouting, flower-bud, flowering, fruiting and senescence) were related to the distribution of rain pulses and through Spearman’s correlation coefficient, using the number of individuals under each phenophase and the daily climate data. The vegetative and reproductive phenological behavior of C. blachetianus reflected the seasonal pattern of precipitation. The intensity and duration of the phenophases depended on the extent and frequency of the rain pulses during the rainy season. Total leaf senescence happened when the precipitation inter-pulses intensified as the dry season progressed, characterizing deciduousness.