Variabilidade temporal das fenofases de Mimosa ophthalmocentra Mrt. ex Benth. em sistema ecológico de caatinga no cariri paraibano.

Abstract

The study of phenology is important because it allows to understand how ecosystems work, and the interactions between the biotic and abiotic components, and the reproductive and vegetative phases of the plants. Thus, the research aimed to study the temporal variation of the phenophases of Mimosa ophthalmocentra Mart. ex Benth. in an area of Caatinga in the semiarid region of Paraíba. The work was developed in an area reserved for studies of ecology and dynamics of the caatinga divided into 96 contiguous plots of 10 X 10 m. For the monitoring of the phenophases of M. ophthalmocentra, one individual was selected per plot. Observations were made monthly, from July 2016 to July 2017, with flowering, fruiting, sprouting, leaf fall, flower fall, dispersal and fruit fall data. The percentage of individuals expressing the phenophasis and percentage of Fournier intensity for each plant were estimated. For the monitoring period, the occurrence of almost exclusively vegetative phenological events (leaf sprouting and leaf fall) was recorded, and in two months of the reproductive flowering event. The only phenomena that occurred during the entire monitoring period was leaf fall, with a peak in June 2017. Fournier intensity index showed that leaf fall despite being continuous showed a temporal variation in the intensity of occurrence. Sprouting started with the rainy season, peaking in March 2017, when the precipitation peak also occurred. For the sprouting event, the intensity was low and accompanied the decrease of the percentage of individuals presenting the phenophasis. During the monitoring period, the only reproductive event observed was flowering, which began in June 2017, with a peak of 11% in July. As for flowering intensity, there were also low indices with values of 2.1% (June) and 2.7% (July). In general, the occurrence of the temporal variability of the events, mainly the reproductive ones, was verified, expressing the dependence of the phenophases with the low precipitation and the long period of drought that is occurring in the region.