Análise temporal do papel das herbáceas facilitadoras Sesuvium portulacastrum (Aizoacea) e Batis maritima (Batacea) no recrutamento e desenvolvimento de Avicennia Germinans(Acanthaceae) em uma área de manguezal em recuperação no Estuário do Rio Pacoti, Ceará

Abstract

Facilitation, also known as "nurse effect", occurs when one plant attenuates unfavorable conditions and improves the environment for the establishment of another. This effect has been observed in pioneer herbaceous plants in the mangrove ecosystem and, as much as it is shown to develop a crucial role in ecosystems with environmentally stressful conditions, scientific studies are still scarce. In the mangrove, facilitation occurs in a physical way, which would be the recruitment, trapping/retention of mangrove propagules and seedlings from the physical complexity of the herbaceous, acting as a support. The other form of facilitation is the improvement in the physicochemical conditions of the soil through its physiology, changing the composition of the sediment, allowing the growth and survival of the mangrove propagules and seedlings. For the experiment, treatments were divided, in the Pacoti River Estuary - Ceará, with individuals of A. germinans with the presence of patches of each halophyte species and a control area adjacent to the patches, without the presence of halophytes. Fifteen 4 m2 plots were randomly established in the study area, with 5 plots for patches of each facilitator species, S. portulacastrum and B. maritima, and 5 plots in the control area. During the study period, from Dec/21 until Aug/22, the individuals of the mangrove species were counted. From Feb/19 the juvenile individuals of A. germinans were tagged with numbered seals to be measured in each plot. With this, height measurements of the labeled individuals were taken, for monitoring growth, were taken with a tape measure, from the soil to the apical bud in plants taller than 15 cm. The growth rate was calculated monthly for each individual by subtracting the final height (Hf) from the initial height (Hi), dividing by the number of days elapsed between one sampling and another (d). Sampling of environmental parameters such as salinity, temperature, and sediment samples was also carried out. In the APA of the Pacoti River estuary, an area under recovery, we observed higher densities of A. germinans in patches with S. portulacastrum with (19.62 ± 13.78 plants/m2) (med±dev.p), followed by Batis maritima values with (15.08 ± 12.50 plants/m2) and, lastly, the Control values (8.65 ± 8.36 plants/m2). Regarding growth rates, the plots showed similar values among treatments, B. maritima with (3.94 ± 3.95 cm/month cm/month), Control with (3.76 ± 4.84 cm/month) and S. portulacastrum (2.54 ± 2.92 cm/month). Salinity averages were highest in S, portulacastrum (31.38 ± 26.98); followed by Control with (29.65 ± 26.43) and B. maritima with (28.57 ± 26.43). Surface temperature averages were lowest in the B. maritima treatment (32.21 ± 3.04°C); then the Control area (32.45 ± 3.19°C) and lastly the S. portulacastrum treatment (32.41 ± 2.89°C). These results describe how the environment behaves with the action of herbaceous plants and allow us to follow the phases of its ecological succession. With this, we can show the importance of studies like this one in restoration projects of mangrove ecosystems, such study can serve as a basis for the management of degraded areas and future ecological studies of this dynamic environment.