Chuva de sementes em área de mata ciliar degradada de um riacho intermitente no Semiárido Paraibano.

Abstract

This paper aimed to study the seed rain in degraded riparian area of an intermittent riverside system in the city of Serra Branca, in the region of Cariri, in Paraíba. The sample period was from July 2019 to June 2020 and covered the degraded riparian area of the creek Lagoa da Serra (7°30’04.32’’ S and 36°42’13.12’’ W, with 511 meters high), belonging to Rio Taperoá sub-basin. In this riparian area, 50 contiguous plots of 10 x 20 m, being placed in the center of each one, a collector with a dimension of 0.5 m x 0.5 m (0.25 m²), totaling 12.5 m² of sample area. Collections were made every month. The screening of the material was carried out at Laboratório de Ecologia e Botânica – LAEB/CDSA/UFCG and weighed on a scale with an accuracy of 0.001g, considering the fractions: leaves, branches, flowers, fruits, seeds, bark and miscellaneous. For the species registered in the seed rain, parameters of relative density and relative frequency were calculated. Shannon's diversity index (H’) and Pielou’s equability index were also determined. Considering the fractions of the material deposited in the seed rain collectors, a total mass of 2,365.4222 g was obtained, with emphasis on leaf fraction with greater mass, representing 68.98% of the total. In the seed rain 34 species were raised, with all the growth habits, with predominance of families consisting of herbaceous species, followed by lianas, shrubs and trees. A total of 42,270 seeds was registered in the area. Regarding the number of seeds deposited per family, the highlights were Poaceae (21,252), Asteraceae (10,030) and Malvaceae (4,894) and Fabaceae (2,406). Related to the number of seeds deposited by species, Chloris virgata Sw. (13,788), Blainvillea acmella (L.) Philipson (9,795), Urochloa decumbens (Stapf) R.D.Webster. (3,609), Sida cordifolia L. (3,402) and Morphospecies 4 (2,500) stood out. Considering the density and relative frequency data, temporal variability of values by species was observed. The Shannon diversity index for seed rain was 2.116 and the equability was 0.600. Therefore, considering the record of seasonal variation in seed rain, the importance of studying the temporal variability of precipitation has been ratified, with the responses of the dynamics of seed rain in degraded riparian areas in the context of the Brazilian semiarid. The dissertation aligns with the items 6 and 15 of the 2030 agenda. Item 6 - Potable water and sanitation; Item 15 - Earth life.