amelioration et suivi du systeme de reboisement de paletuviers dans la region sud-ouest de madagascar (cas de la mangrove d’ambondrolava)

Abstract

In the context of the vulnerability of mangrove ecosystems to climate change as well as its
important role, which is increasingly recognized internationally in the context of reducing
global greenhouse gas emissions. A study on the improvement and monitoring of the mangrove
reforestation system was conducted. Our research took place in the southwestern part of
Madagascar, from January 2021 to January 2022. It is located in 12 km from the city of Toliara,
in the mangrove of Ambondrolava. Our objective is to assess and analyze the factors
influencing the success of mangrove plantation according to local ecological conditions and
also to determine the growth of mangrove species in order to prepare for sustainable
management of mangrove forests. Four species: Avicennia marina, Rhizophora mucronata,
Bruguiera gymnorhiza and Ceriops tagal were used to carry out this mangrove reforestation
study. The process consistsof planting seeds in nurseries and then replanting the plants in the
natural environment in Six 06 plots of 100 m2 in 4 different sites. The plantation was carried
out during the low tide spring tide where the plants are separated 1.5 m from each other.
Reforestation monitoring consisted of measuring the heights of each plant, and counting the
dead ones. The cause of the eventual mortality rate is determined within each plots. Nurseries
show a success rate of more than 97%. In the natural environment, the evaluation of the success
of plantations indicated a survival rate of 60%. The survival rate varies on average from 72.6%
(Ambotsibotsiky), 66.66% (Andalatsarety), 52.08% (Bejihy) and 38.88%, (Antsahamaty). The
survival rate of species within all sites varies from 39.23% (Avicennia marina), 42.7% (Ceriops
tagal), 71.87% (Bruguiera gymnorhiza) and 76.38% (Rhizophora mucronata). The increase in
height of individuals varies on average by 0.38 cm / month (Ceriops tagal); 3.2 cm/month
(Rhizophora mucronata); 3.46 cm/month (Avicennia marina) and 3.87 cm/month (Bruguiera
gymnorhiza). Results also showed that different parameters, such as sites and species,
significantly influence the survival and growth of reforestation. This study found that survival
and growth vary by species and site.