Avaliação dos jovens regenerantes e da rebrota de Prosopis juliflora (Sw) DC. Em área degradada de mata ciliar no Semiárido Paraibano.

Abstract

The objective of this work was to evaluate the phytosociological parameters of the young regenerating and the dynamics of the regrowth of Prosopis juliflora (Sw.) DC. in a degraded riparian area of an intermittent river system in the city of Serra Branca, Cariri, Paraíba. The sampling period was from February to July 2021 and covered the degraded riparian area of the Lagoa da Serra stream (7°30'04.32'' S and 36°42'13.12'' W, with 511 m of altitude) belonging to the sub-basin of the Taperoá River. In this stretch of riparian forest, 50 contiguous plots measuring 10 x 20 m were demarcated for the study. Basal area values and absolute parameters of density (DA) and frequency (AF) were calculated. Individuals were classified into diameter and height classes. Considering the survey of young regenerators, 285 individuals were identified. The density was 285 individuals.ha-1. Young individuals of P. juliflora were recorded in 29 plots representing 58% of the total sampled. The average height recorded for the young regenerating was 1.54 m and average diameter of 1.65 cm. Considering the phytosociological parameters of absolute density and absolute frequency by size classes of natural regeneration, the highest values were found in class 4 (h > 1.51 m and DNS < 3.0 cm), 136 ind./ha and 50%. In the percentage distribution of the number of individuals by size class of natural regeneration, an increase in the number of young individuals was observed, with the increase of classes, CT1 (8.43%), CT2 (14.03%), CT3 (29, 82%) and CT4 (47.72%). For the dynamics of regrowth, 106 individuals with regrowth were identified. The density was 106 individuals.ha-1. The total basal area of regrowth was 2.12 m2.ha-1. Individuals with regrowth were identified in 23 plots, representing 46% of the total sampled. The mean height recorded for regrowth was 4.69 m and mean diameter of 20.18 cm. The height class that presented the largest number of individuals was class IV (4.1-5.0 m), where 29.24% of the sampled individuals were present. For the diameter classes, the largest number of individuals was identified in class IV (12.1-15.0 cm) and 15.09% of the total number of individuals sampled were present in this class. Considering the individuals that did not show regrowth, 130 stumps were recorded. Relating to the absolute frequency, of the 50 plots, the stumps were recorded in 32 plots, representing 64% of the sampled plots. The average height recorded for the stumps was 14.85 cm and the average diameter recorded was 16.88 cm. For the stumps height classes that did not showed regrowth, inverted J formation was observed in the classes in the intervals from 5.0-10.0 cm to 60.1-65.0 cm. In the stump diameter classes that did not showed regrowth, class IV (12.1-15.0 cm) was the one with the highest number in the sampled intervals. Therefore, the data recorded in this study are relevant for the knowledge about the natural regeneration and regrowth dynamics of P. juliflora, allowing the direction of strategies for its management in degraded riparian forests along intermittent streams in Caatinga areas, aiming at the conservation of water resources associated with these ecosystems, thus being in compliance with goals 6 and 15 of the SDGs 2030.