Interactions of ecological factors and natural regeneration in an altimontane Norway spruce (Picea abies (L.) Karst.) stand

In an altimontane Norway spruce stand in the Julian Alps, Slovenia, the inf luence of direct and diffuse site factors, ground vegetation, soil and myco rrhiza on natural regeneration was studied in gaps of different size. Norwa y spruce successfully germinated and survived the first years under slightl y open canopies, yet further development was possible only in the gaps. Reg eneration success varied within gaps. Microsites within small gap exposed t o direct radiation or overgrown by Polytrichum formosum were unfavourable f or regeneration. Successful regeneration was found in plots with more podzo lized soils, higher content of organic matter, sparse forest ground vegetat ion coverage and more diffuse site factor. Results support the assumption t hat in the plots with abundant direct site factor, water stress can hinder the germination and regeneration of Norway spruce during the first decade. For this reason we propose to create narrow gaps, with an east-west orienta tion of their longer axis.