Forest Focus : test de nouvelles méthodes d'échantillonnage et de cartographie des formes d'humus forestier et des propriétés du sol - Rapport scientifique, Juin 2007 | Forest Focus: Testing new methods for mapping and sampling forest humus forms and soil properties - Scientific report, June 2007

Maintenance and monitoring of soil quality has recently become a major issue of conservation since worldwide dramatic changes in soil fertility occurred. The assessment of soil quality requires the definition of synthetic indicators, quick and easy to sample using, if possible, non-destructive methods. In forests, numerous indicators exist among which humus forms appear to be interesting because of their sensitivity to changes in climate and management and their link with other soil properties only accessible through costly physico-chemical analyses. Among the in situ study methods of soil properties, electrical resistivity stands as a non-invasive method that allows precise delineation of soil properties within the field. This method has been widely used in agriculture to design experiments and adapt management methods to site specific properties but scarcely used in forests. The aim of our study was to test the efficiency of the electrical resistivity method to delineate properties of forest soils. In particular, we focused on the potential correlation between electrical resistivity and humus form as a specific property of forest soil. Our results showed contrasted results between the 5 RENECOFOR plots we studied. On some plots, we obtained significant correlations between soil properties, humus forms and electrical resistivity. On the contrary, some other plots showed lesser levels of significance or no response at all. The possible explanations for these differences are discussed in the present report, but further data analyses are necessary to better understand drivers of electrical resistivity in forest soils. All in all, the electrical resistivity method has an interesting potential in terms of monitoring and mapping soil properties but further researches are necessary before applying it at a wider range.