EARTHWORMS AS BIOINDICATORS OF FOREST SITE QUALITY

The effectiveness of earthworm species as bio-indicators of forest sit e quality was tested by a dataset of 180 plots in temperate lowland fo rest (Flanders, Belgium). In these plots, earthworm samples were taken together with vegetation surveys and additional site quality paramete rs. Vegetation surveys were used to calculate mean humidity, acidity a nd nitrification indices and to display sites in a humus quality-soil humidity-ecogram. In this ecogram, the earthworm biomass per species, per ecological category and in total was related with timber growth in dices for ash (Fraxinus excelsior) and beech (Fagus sylvatica). The ob served parallels and discrepancies are discussed. (C) 1997 Elsevier Sc ience Ltd.