Short-term effect of removing tree competition on the ectomycorrhizal status of a declining pedunculate oak forest (Quercus robur L.)

The effects of a sylvicultural treatment (thinning) on the ectomycorrhizal community structure and diversity were studied each season for 2 years in a declining Quercus robur woodland in northern Italy. Sixteen dominant oak trees were chosen as representative of two decline classes (eight per class). Fine root status, ectomycorrhizal community composition and structure were analysed before and after drastically altering tree density by felling all the neighbouring trees of four selected trees in each decline class. The ectomycorrhizal community was found to be extremely rich, with numerous infrequent species: of the 64 anatomotypes found, only 23 were present both before and after the thinning treatment, demonstrating that community structure changes rapidly after disturbance. Following an initial reduction, 10 months after removing competition and independently of health status, the biodiversity had recovered its previous level, demonstrating the high resilience of the ectomycorrhizal community to disturbance.