Effect of microsites on the survival, density, and ectomycorrhizal status of shade-tolerant Abies alba regeneration attacked by fungal pathogens

Abstract

An increased incidence of fungal pathogens has been recognized as one of the most important causes for insufficient natural regeneration in pure Abies alba Mill. forests in the Western Carpathians (central Europe). We investigated the spatial distribution of A. alba seedlings in seven stands in which severe symptoms of fungal pathogen infections were observable and compared microsite variables and ectomycorrhizal status of seedlings in locations with abundant or poor regeneration. We also tested the effect of local stand density, seedbed, and vegetation control on seed germination and the survival of 1-year seedlings. The study provided evidence that gap environment may increase the mortality of 1-year seedlings caused by fungal pathogens. That pattern was consistent with the spatial distribution of older seedlings: locations with abundant older regeneration were characterized by a greater local stand density, lower canopy openness, and lower mineral topsoil moisture than poorly regenerated locations. Yet, despite considerable spatial differentiation in ectomycorrhizal types, the mycorrhizal status of 2-year seedlings in abundantly regenerated areas did not differ from that in poorly regenerated areas.