Research on the natural regeneration of Rhizophora apiculata Blum at different forest ages in Ben Tre province

Abstract

Research on the natural regeneration ability of mangroves (Rhizophora apiculata)
was carried out from June to Decmber 2020 at the Management Board of
Special - Protection Forests of Ben Tre province. The objectives of the study
are (i) to determine some characteristics growth of tall tree layer affecting
forest regeneration, (ii) to determine the quantity, quality and potential trees
and (iii) to propose restore forests. The project has conducted to establish 15
standard plots with an area of 500 m
2
to determine the density, diameter,
height, canopy diameter of tall trees. Establish 60 standards sample plots with
an area of 4 m
2
(4 corners for each plots) to determine the composition of
regenerated trees, measure and count regenerated trees according to height
levels (grade 1: < 0.5 m, grade 2: 0.5 - 1.0 m, grade 1. 3; 1.0 - 1.5 m, level 4:
1.5 - 2.0 m, level 5: 2.0 - 3.0 m, level 6: 3.0 - 5.0 m and level 7 > 5.0 m). As a
result, have determined that the growth characteristics of tall trees layer as
diameter, height, stem volume and forest volume increase as forest age
increases; while density decreases as forest age increases. The percentage of
trees at the height level decreased gradually as the height of the regenerated
trees increased. Potential trees have got 32.5% with (trees with a heig ht greater
than 1.0 m) with 11,422 trees/ha. Density had a marked effect on the number
of regenerated and potential regenerated trees in the direction of inversely
proportional to the increase in density and canopy cover of the high tree layer.
Forest age has a clear influence on the regeneration ability of mangroves, with
the highest percentage of promising trees at the age of V, VIa, and VIb.