Application de la modélisation spatiale multifactorielle pour l'évaluation de la dynamique et la vulnérabilité des écosystèmes forestiers face aux changements globaux: cas de la forêt de Maà¢mora
par Koffi Dodji NOUMONVI
Ecole Nationale Forestière dà¢â‚¬â„¢Ingénieurs (ENFI) de Salé - Ingénieur des Eaux et Forêts spécialisé en Géomatique des ressources naturelles 2015
Once completely covered with cork oak, half of Maâmora forest has been reforested with other species, mainly Acacia, Eucalyptus and Pine. This is the result of many management strategies that have been called upon since 1951.
Assuming that the consideration of the vulnerability of forest ecosystems to climate change would bring more in the future management strategies, this work started with an analysis of the dynamics (classification of satellite images and changes study between 1987 and 2000 as well as between 2000 and 2014) of forest ecosystems with regards to Maâmora forest, after which we identified a number of factors including the changing biophysical, climatic, anthropogenic and silvicultural factors. These 4 groups of factors helped assess, by weighting and integration (using weights determined by AHP), the synthetic vulnerability of forest ecosystems to climate change initially in 2010 then in 2045 and 2070 after the projection of changing factors and considering the RCP scenarios 4.5 (1) said optimist and 8.5 (2) said pessimist.
This study shows that Maâmora forest has experienced great dynamics. The surface areas of the main forest species in 1987 were as follows: 64 461 ha, 44 719 ha, 5 770 ha and 3 850 ha for cork oak, eucalyptus, pine and acacia respectively. The changes between 1987 and 2000 and then from 2000 to 2014 vary from a species to species. These include a decrease of 11.6% followed by a 4.6% increase in cork oak surface area; an increase of 73% between 1987 and 2014 in the area reforested with pine trees, an increase of 7.5% of the area covered with Eucalyptus followed by an 11% decrease to the year 2014 and an increase of 34% in the surface area of Acacia followed by a decrease of 41% to the year 2014.
Regarding the vulnerability of forest ecosystems, it's evident that the most continental forest ecosystems are the most vulnerable to climate changes, thus justifying why cork oak almost disappeared in the cantons D and E. The vulnerability also becomes more significant when we project further into the future. It should be noted that the synthetic vulnerability of no group of the forest is null. The groups with low vulnerability accounted for 53% of the forest surface area in 2010 compared with only 11% in 2045 with the first scenario. Every group would become moderately or highly vulnerable to climate change with the second scenario in 2045 as well as in 2070 regardless of the scenario.
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