The aim of the study was 1) to identify whether the gradient of alkaline dust pollution originating from magnesite plants – SLOVMAG, a. s. Lubenik a SMZ, a. s. Jelšava (Slovenske rudohorie Mts., Western Carpathians) induces changes in alpha diversity of oak-hornbeam forests, and 2) to compare sensitivity of selected components of local biodiversity including cryptogams and flowering plants. Altogether 24 plots were sampled along four visually distinguishable degradation stages: A – poorly developed vegetation on the magnesite crust, B – dense grassland vegetation almost without tree-layer, C – degraded woodland with opened canopy, and D – visually not-affected original closed-canopy woodland. For each plot we sampled phytocoenological releves including terrestrial cryptogams, and presence records for epiphytic lichens and bryophytes, macromycetes and slime molds. We also recorded soil chemistry parameters – concentrations of C, Ca, Mg, S, N, P, K, light conditions, bark pH and the distance from the emission sources (ES). Increased alkaline dust, corresponding to smaller distance to the emission source correlated with higher concentrations of Mg, Ca, Fe, S, C/N in soil samples, and with significant changes in species composition as well as vertical and horizontal vegetation structure. Following regressive succession oak-hornbeam woodland (alliance Carpinion betulis; assoc. Carici pilosae-Carpinetum) was converted to woodland steppe, further to ruderal grasslands (alliance Atropion), then to halophilous procoenoses of Agrostis stolonifera and Puccinelia distans on degraded soils with eroded magnesite crust (and with biological soil crust – cyanobacteria Microcoleus steenstrupii, Nostoc microscopicum and Schizothrix arenaria; moss Desmatodon cernuus; pioneer terrestrial lichen Thelidium zwackhii) and finally habitat with no vegetation (magnesite crust). Stage with highly alkaline soils with halophilous procoenoses represent habitats of early successional stages and do not occur in any other habitats in the Western Carpathians. Magnesium content in topsoil, light conditions, and the herblayer cover proved to be the most significant factors influencing the presence of macromycetes. We also recorded significant changes in species richness and the species pools of terrestrial fungi (mostly saprotrophic species and symbiotic), woody species (phanerophytes), and epiphytes (both lichens and bryophytes) along the gradient. Overall species diversity decreased. Terrestrial cyanobacteria formed visible layer only in the stage A. The degradation stages are characterized by low representation of symbiotic macromycetes and by high proportion of saprotrophic fungi. The highest species richness of vascular plants was recorded in degradation stages B and C, the highest herb-layer cover in stage B. The highest species richness of terrestrial mosses is also in dense grassland vegetation. Occurrence of nitrophilous epiphytic lichens differentiates unaffected oak-hornbeam woodlands from the plots covered by the emission source.