GROWTH, ALLOMETRY AND SURVIVAL OF Avicennia germinans L. SEEDLINGS IN CARDENAS, TABASCO, MEXICO

Background. The mangrove forest is a mixture of tree and shrub species which inhabit the coastal areas of the tropics and subtropics, around estuaries and coastal lagoons, near the mouths of rivers, with another different capacities than the tolerance of salinity. Despite its ecological and social importance, it is one of the ecosystems most threatened by changes in land use and climatic variations. Objective. Evaluate the increase in total height and basal diameter in the dry and rainy period in Avicennia germinans L. seedlings, from the nursery and from natural regeneration. Methodology. In ten sampling units (SU) the total height (At), basal diameter (Db) and the survival rate (%) of the reforested individuals were recorded. In each SU, three Sub-SU (SSU) were installed where only the first two attributes were recorded for natural repopulation. The measurements were carried out in three stages during one year (M1, M2 and M3). Results. The mean annual increase in reforestation was 1.14 cm in Db and 58.8 cm in At. SU 4 was the one that reported the greatest increase in Db (1.87 cm) and At (132.6 cm), while the lowest values were presented in SU 9. The growth relationship between Db and At was statistically significant (p ≤ 0.05). Reforestation survival decreased from 73.2% to 52.7% during the evaluation period. The highest growth in Db, At and survival were in the SU´s where the water flow is greater and with a canopy gap is larger. Natural regeneration had a lower mean annual increase in both Db (0.51 cm) and At (37.2 cm). Implications. This novel information provides the basis for the planning, management and conservation of A. germinans in the southeast of Mexico. Conclusion. The time of measurement and the ecological differences between sampling units significantly influence the dasometric increase of A. germinans. The reforested individuals show a greater annual increase in Db and At compared to those of natural regeneration.