Análise da chuva de sementes em área de caatinga no Cariri Paraibano.

Abstract

The work aimed to analyze the dynamics of seed rain in an ecological system in the Caatinga area in the semiarid region of Paraíba. The sample period of the study was from January to December 2019, where it was carried out in the Experimental Space Reserved for Studies of Ecology and Dynamics of Caatinga - Area I of the Laboratory of Ecology and Botany - LAEB/CDSA/UFCG (7°39'38.8'' S and 36°53'42.4'' W; 538 m altitude). The study area has an extension of 1.05 ha and 96 plots of 10 x 10 were arranged in it, and 48 plots were defined for the study of seed rain. In these reserved plots, collectors with dimensions of 0.25 m² (0.5 x 0.5 m) were arranged, totaling 12 m² of sample area. The material was collected monthly and sorted at the Ecology and Botany Laboratory. Then the material was weighed on a precision analytical balance of 0.001g. The total mass of the fractions was 3,521.3651 g in 12.0 m², corresponding to 2,934.47 kg/ha1 of total material. The leaf fraction represented the highest deposition in most months, showing its highest expression in the month of September when there was no precipitation. Regarding the percentage of mass per fraction, the leaf component represented the highest annual contribution, followed by branches and fruits, with bark having the lowest deposition. In the percentage of seeds deposited, it was observed that there were seasonal variations in the seed rain, because in the rainy season it obtained the highest deposition of seeds and in the dry season there was a drop in the contribution. Relating species richness and precipitation, it was observed that the highest species richness was in the month of June, when precipitation values were low. Regarding the percentage of seeds and contribution of species richness, May had the highest presence of seeds, but the seed richness exceeded every month in June. Therefore, seed rain is an extremely important mechanism for reversing degraded areas and studies aimed at natural regeneration.