Pedunculate oak decline: thinning effects on the ectomycorrhizal exploration groups

Abstract: The research was performed in a declining pedunculate oak (Q. robur L.) stand, selectingsixteen trees belonging to two declining classes and reducing the competition exerted by theneighbouring trees by thinning half of them. Their ectomycorrhizal (EM) community was monitoredover a two-year period, with regard to species abundance and soil exploration ability. Sixty-four EMspecies were measured, with relative abundances changing over time with respect to both the degree ofdecline and the thinning treatment. EMs able to explore larger soil volumes were more abundant afterthinning in both decline classes. Since oak decline was often associated with water and nutritionalstresses, this cause-effect relationship suggests that thinning could slow decline.