Monitoring damage to forest trees (crown "thinning") in Croatia since 1987 indicates that in all forests and for all tree species, young and old stands combined, 26%44% have deteriorated. The intensity of this phenomenon is not identical over whole Croatia. The greatest damage being on the territory of Forest Enterprise units of Zagreb and Delnice. Its impact on the quality of fir (Abies alba Mill.) and Norway spruce (Picea abies Karst.) seed has been monitored on the territory of the Forest Enterprise unit of Delnice. For this purpose we selected and marked fir and spruce trees of different crown-damage classes (O, 1, 2 and 3 with 3 indicating the heavieat damage) in different ecological-management forest types. Cone samples were collected from marked trees. Seed quality (germination capacity, germination rate, seed weight) was investigated in the laboratory. Both germination capacity and germination rate were found to be slightly higher in crown-damage-class "3" than in class "0" on several plots. The phenomenon was simultaneously monitored on the territory of the Forest Enterprise unit of Split where forest damage is of much lesser intensity. Although the data are preliminary, they strongly suggest that there has been a significant effect of crown "thinning", particularly in the case of fir.
Key words: forest damage, qualitative seed properties, Abies alba, Picea abies.