Ectomycorrhizal communities within beech (Fagus sylvatica L.) forests that naturally regenerate from clear-cutting in northern Spain

The objectives of the work described here were to evaluate the diversity of ectomycorrhizal (ECM) fungi within Spanish beech (Fagus sylvatica L.) forests subjected to clear-cutting and natural regeneration and to elucidate the extent to which the carbohydrate concentration in roots of trees of different ages and sizes is related to ECM colonization. The study concerned an unmanaged forest, a stand clear-cut in 1996 and another clear-cut in 2001. ECM colonization of beech roots showed seasonal dynamics in the disturbed areas, but the percentage of roots colonized by ECM was not always related to the accumulation of non-structural carbohydrates. The composition of ECM communities differed between different stands and 40% of ECM morphotypes only occurred in disturbed ecosystems. However, comparable numbers of different ECM morphotypes (24, 25) were found in the three beech stands. This finding indicates that ECM diversity was quite high and similar within disturbed and unmanaged areas. This finding suggests that (1) ECM diversity was not affected by the size and age of trees and (2) the potential of ECM inocula remained high within clear-cut areas. Consequently, the introduction of ECM inocula by silvicultural practices would not be needed to improve the regeneration of clear-cut areas described in our study.