Fluorometrische Beurteilung der relativen SOrResistenz von Fichte (Picea abies [L.] Karst.) 57 Rc'stime Evaluation par fluorometrie de la resistance relative au SO; de l'epicea (Picca abies [L.] Karst.) liee aux metabolites a jaible poids moleculairc des extraits d'aiguilles La resistance relative de I'epicc'a eommun {Picca abies) au SO; est caracterisee par un contenu specifique de metabolites fluorescents dans les ti.ssus de I'aiguille. Ceci a ete demontrc par I'etude fluoromctrique de chromatogrammes en couchc mince d'extraits d'aiguilles contenant des metabolites fluorescents (par exemple des composes phenoliques). Chez pres de 90 "/> des clones testes, le individus relativement resistants (itaieni caracterisiis par des valeurs-tests (cf. chapitre 3-3) de I'ordre de 0,42 a 0,88. Les elones relativement peu resistants ont toujours niontre des valeurs inferieures.Ainsi, la methode telle qu'elle est decrite, apparait comme un outil valabic pour verifier les qualitcs de resistance de l'epicea au SO;.

Summary. This study addresses the question of whether gaseous air pollutants are capable of damaging spruce foliage. For this purpose, several twig pairs of an adult tree in a natural stand from the western part of the Bavarian Forest were supplied with pure and ambient air and gas exchange was monitored. With the exception of insignificant and unexplained differences during winter, the gas exchange of the twigs showed no negative deviation due to the influence of gaseous air pollutants. Because visible damage arises only in older needles, the duration of measurement is not sufficient to exclude a long-term influence of gaseous air pollutants.

The present study comprises comparative investigations of transpiration, photosynthesis and osmotic p0tenti.1l of varioti.s twigs of a health)' and a di.seased fir. Pos.sible cntise.s for the regi.stered differences are discussed.