Caracterisation edaphique et bioclimatique du massif forestier du jbel outka (rif central, maroc)
Institution:
Université Louis Pasteur (Strasbourg) (1971-2008)Disciplines:
Directors:
Abstract EN:
Following an analysis of the components of the natural vegetation upon which are based the methodological choice and orientation of the sampling programme of this study, the edaphic and bioclimatic characteristics of plant groups in the j. Outka massif are individualized through correspondence analysis. The properties and altitudinal range of each landform, together with other secondary topographic variables, are considered as factors of individualization. The various plant groups occur as distinct levels and their organization is properties of their substrate brings out the links between soil and morphogenetic characteristics and the plant groups. However, the factors brought out by this analysis are partly of a general order and partly of a pedological nature and are basically of interest in soil sciences. Plant distribution depends essentially on soil hydric and trophic properties which are function of the nature of each deposit. Clay, bulk density and organic matter are the variables that explain edaphic properties. By intoducing soil volume, the water and mineral reserves at the disposal of plants can be estimated. Correlations are established between these properties and plant groups.
Abstract FR:
L'etude edaphique et bioclimatique du j. Outka a permis une individualisation des groupements vegetaux par l'analyse des correspondances. A petite echelle, l'altitude et le type de formations superficielles interviennent dans la repartition des groupements vegetaux. Le facteur altitudinal, qui reflete les variations climatiques, determine aussi des etages de vegetation. A grand echelle, les proprietes trophiques et hydriques, qui dependent du type de depot, regissent la repartition de la vegetation. Les caracteristiques pedologiques n'interessant que la pedogenese. L'argile, la densite apparente et la matiere organique, degagees par l'analyse en composantes principales, sont les variables explicatives des proprietes edaphiques. En faisant intervenir le volume du sol, on arrive a estimer les reserves hydriques et minerales disponibles pour la vegetation. L'analyse factorielle des correspondances degagent des rapports entre les proprietes hydriques et les groupements vegetaux d'une part et les proprietes trophiques et ces memes groupements vegetaux d'autre part. L'effet guttman traduit un gradient altitudinal des reserves hydriques et minerales. L'etude edaphique completee par une analyse multidimensionnelle, apparait comme une approche fiable dans la typologie des milieux forestiers.