STOMATAL PATCHINESS IN CONIFERS - EXPERIMENTS WITH PICEA-ABIES (L) KARST AND ABIES-ALBA MILL

Strong evidence for the occurrence of pronounced stomatal patchiness i n needles of Picea abies (L.) Karst. and Abies alba Mill. was found us ing various indirect methods. Anatomical investigations revealed a sep tate leaf anatomy for both species, a phenomenon expected if a patchy distribution of stomatal aperture is present. Calculation of some phot osynthetic characteristics (e.g. carboxylation efficiency) from gas ex change measurements is shown to be markedly affected by the patchy dis tribution of stomatal apertures on the needles. The importance of stom atal patchiness in connection with air pollution related forest declin e symptoms as well as an hypothesis suggesting a possible role of the phenomenon as a protective mechanism against photoinhibition are discu ssed.