Influência de Batis maritima l. (Bataceae) no recrutamento e crescimento de Avicennia SPP. l. (Avicenniacea) em uma área degradada do rio Pacoti, Ceará

Abstract

Knowledge of the processes that contribute to the initial establishment and growth of mangrove species in degraded areas is fundamental for the understanding of the organization of herbaceous and woody communities as well as for the improvement of mangrove recovery protocols. The present study aims to understand the processes that facilitate the recruitment and growth of mangroves carried out by pioneer plants of the Batis maritima species. For this purpose, from December 2017 to April 2018, the height and stem diameter of mangrove plants with height greater than or equal 15 cm were measured from 10 plots of 4m² each (2m x 2m) randomly established, being 5 plots in a patch of B. maritima and 5 plots in an adjacent control area. The height was measured with a measuring tape from the soil to the apical meristem and the diameter of the stem was measured with a caliper rule at a height of 10 cm from the soil. The relative growth rate (RGR) was calculated by subtracting the final height (Hf) from the initial height (Hi) and dividing by the number of days elapsed between the first and last samplings (d) [TCR = (Hf - Hi) / d)]. Temperature and salinity data were measuredwith thermometer and salinometer, respectively. Sedimentological analysis were performed to determine the granulometry, as well as moisture and organic matter contents of the experimental areas. A total of 1954 individuals of Avicennia spp. were counted in the B. maritima area, which had a mean height of 49.37 ± 25.64 cm and a mean stem diameter of 6.85 ± 2.38 mm. In the control area, 994 Avicennia spp. individuals were recorded, which presented a mean height of 59.73 ± 29.63 cm and a mean diameter of 9.12 ± 4.15 mm. The mangrove population of the genus Avicennia in the B. maritima spot had an average density of 8.14 plants/m². In the control area, the mangrove population had an average density of 4.15 plants/m². The amount, height and stem diameter of the mangrove plants differed significantly between the areas (T test, p <0.0001). The RGR, in height, of the mangrove plants in the Batis maritima patch was 0.018 cm/day, while in the control area it was 0.047 cm/day. The data suggest that B. maritima facilitates the recruitment and establishment of Avicennia spp., which causes the mangrove populations to reach high densities and compete with each other and with the nurse species, which would explain the smaller stem diameter and plant growth rate when compared to control.