Étude des potentialités forestières pour l'épicéa commun dans l'est de la France à partir des données de l'IFN

Abstract

Norway spruce growth was investigated on the scale of eastern France to examine the feasibility of using the National Forest Inventory (NFI) data for establishing fertility indices as a function of various environmental parameters. The methodology used calls on a combination of several different data sources: the NFI dendrometric and ecological data (2087 NFI plots were studied), climate data collected with the Météo France AURELHY method, a digital model for the field and indicator values for species derived from ENGREF's EcoPlant base of phytoecological data. The predictive model for the fertility index considers elevation, 3 variables connected with soil water availability and 2 trophic variables that are bioindicated by vegetation. Elevation is the most powerful variable as regards the fertility index of spruce - at low elevations, dominant height of spruce is fairly stable and tends to drop as elevation increases. The positive effect of soil and the balance between incoming and outgoing water deriving from the topographic position of the plot confirm previously recorded results. We ascertained that limestone outcrop negatively affects height growth of spruce. This is even more marked in the case of poorly investigated sites where the pH and C/N ratio are high. Finally, the NFI data, supplemented with climate and trophic information, provide an effective tool for explaining spruce growth.