Abstract :
The study examines humus profile development during a chronosequence consisting of four beech forest growth stages, and particularly the role of some components of soil fauna (lumbricid oligochaetes) on humus morphogenesis. An experimental site was set up in a lowland beech forest (Fougères state forest, eastern Brittany, France) to carry out a chronosequence analysis. This lowland beech forest is acidophilous, managed as an even-aged beech stand. The dominant tree species is beech (Fagus sylvatica L.). Samples were taken twice a year, from autumn 1997 to spring 2000 inclusive. Earthworms were caught after watering with formalin solutions. Only five species were found: three epigeic (litter-dwellers): Dendrobaena octaedra, D. rubida tenuis, Eisenia eiseni; one epi-anecic (litter/soil-dweller): Lumbricus rubellus; one endogeic (soil-dweller): Allolobophora caliginosa. D. octaedra is dominant in the four plots at densities ranging from 41 ind•m–2 (88 % of total earthworm population) to 12.4 ind•m–2 (99 % of total). Species richness and abundance are low in accordance with a moder humus form typical of acid soil conditions. Results are discussed according to plot heterogeneity, stand age, seasonal variations and functional diversity.
