Temporal rainfall variability as inductor of the phenology of Brazilian semiarid species

Abstract

Usually, in the Brazilian semiarid region where dry and humid periods are well determined, phenological events are mainly affected by seasonal rainfall and availability of water in the soil. The studies in these regions have importance especially to understand the dynamics of dry forests. Thus, the objective of this work was to characterize the phenophases of trees P. pyramidalis, C. blachetianus, A. pyrifolium and J. mollissima, and their relationship with the temporal distribution of rainfall, which occurs in the form of pulses. Furthermore, the effect of goat grazing was evaluated. The experimental areas presented different caprine stockings, where first had ten and the second five. The third stocking remained without goats during the experimental period. For the phenological follow-up, 50 tree individuals of each species were selected, tagged and monitored weekly, at Experimental Station, in the municipality of São João do Cariri-PB. In order to quantify the phenological events, the percentage of Fournier intensity was used, registering the presence and absence of the phenophases: sprouting, flowering, fruiting and senescence, whose data were related to the water pulses and inter-pulses. The phenological events presented annual patterns, with interannual variations in intensity. We observed that the phenophases occur in synchrony with the temporal distribution of the rainfall pulses in the area of its occurrence. As the dry season progresses, reduction in sprouting, flowering and fruiting occurs when the inter-pulses of rainfall was intensified. The presence of goats did not influence the phenological development of the species.