ACTIVITY OF DIFFERENT ECTOMYCORRHIZAL TYPES STUDIED BY VITAL FLUORESCENCE

Ectomycorrhizal root tips were sampled in a Norway spruce (Picea abies L. Karat) stand (Hoglwald, Bavaria) during one growing season and ana lysed by fluorescence microscopy. After staining with fluorescein-diac etate, tissue fluorescence was used as an estimate of activity of six identified ectomycorrhizal types on Picea abies (Tylospora sp.-Picea a bies, Piceirhiza nigra, Piceirhiza gelatinosa, Xerocomus badius-P. abi es, Russula ochroleuca-P. abies, Cenococcum geophilum) and two unident ified mycorrhizas. There were differences among ectomycorrhizal types in the FDA-hydrolysing activity of the various tissue layers of the my corrhizas: outer and inner hyphal sheath, Hartig net and stele. The di fferential activity in tissues was judged to be an estimate of physiol ogical activity of the fungal symbiont and of the life span of the myc orrhiza. The differences in species activity may influence the overall activity of mycorrhizas in a forest stand.