Activity of different ectomycorrhizal types studied by vital fluorescence

Ectomycorrhizal root tips were sampled in a Norway spruce (Picea abies L. Karst) stand (Höglwald, Bavaria) during one growing season and analysed by fluorescence microscopy. After staining with fluorescein-diacetate, tissue fluorescence was used as an estimate of activity of six identified ectomycorrhizal types on Picea abies (Tylospora sp.-Picea abies, Piceirhiza nigra, Piceirhiza gelatinosa, Xerocomus badius-P abies, Russula ochroleuca-P abies, Cenococcum geophilum) and two unidentified mycorrhizas. There were differences among ectomycorrhizal types in the FDA-hydrolysing activity of the various tissue layers of the mycorrhizas: outer and inner hyphal sheath, Hartig net and stele. The differential activity in tissues was judged to be an estimate of physiological activity of the fungal symbiont and of the life span of the mycorrhiza. The differences in species activity may influence the overall activity of mycorrhizas in a forest stand.