Effets de la densité des tiges des pessières de substitution sur la diversité et la productivité des macromycètes d'une forêt du plateau suisse

Abstract

We were encouraged to conduct this study by the replacement of a deciduous forest by a single-species spruce plantation. We explored the influence of the various spruce stem densities on the diversity and productivity of macromycetes. We extended our investigations to two small deciduous forest plots that had remained intact so as to assess the substitution effect. The silvicultural interventions implemented to replace the deciduous forest with spruce are described. From 2000 to 2003, we made weekly recordings of the macromycetes from May to November over a total surface area of 3,000 m2. The results demonstrate that the substitution spruce plantation allows for excellent fungal diversity and good productivity. Of the three spruce stem densities, the medium one was the most conducive to diversity and productivity. The number of species of mycorrhizal and saprophytic humicolous fungi is practically identical for both types of stands. In contrast, there are more saproxylophagous species beneath spruce while the biomass of edible mushrooms is significantly higher in the deciduous plots. Ectomycorrhizal macromycetes common to both spruce and the surviving deciduous trees from the old forest can be considered as potential colonisers for the root systems of the new spruce plantation. The connection between climate and the very great variability in the fungal fruiting times observed is briefly commented upon.