Physical characteristics of the soil environment suitable for Tuber magnatum production in fluvial landscapes

Abstract

Tuber spp. are ectomycorrizal fungi that produce edible ascocarps termed truffles. The most valuable species, T. magnatum, is perhaps the most selective among these for soil environment. Since T. magnatum is often found in fluvial plains, the present study focused on the characterization of the soil physical characteristics suitable for this ectomycorrhizal fungus, and the relationship of these characteristics with fluvial landforms. The investigation was carried out in a truffle-producing area which encompassed the most representative landforms of a fluvial landscape characterized by the presence of Populus deltoides symbionts in both productive and unproductive locations. Soil physical characteristics were determined in productive and unproductive transects according to a stratified random design. Truffle-producing locations displayed a coarser texture, smaller aggregates, a less stable aggregation and a larger volume of soil occupied by highly interconnected macropores. The spatial distribution of this combination of characteristics was then investigated by using a geostatistical approach utilizing clay content and a soil structure indicator as markers. Spatial analysis connected T. magnatum habitats with the soil environment present in river levees, where scattered and chaotic redeposition of solid particles creates very porous, highly aerated surface strata.