European beech is a significant woody plant with a large number of competing abilities which can be applied in forest ecosystems. The altitude gradient is associated with some changes of ecological factors that affect in different ways occurrence plant species. Our research focused on the observation of vegetation changes along altitude gradient in beech forests and is part of the SAV project - The species richness of the understory plant species of higher plants of beech forests along the altitude gradient. The volcanic mountain range Javorie, on which the research is carried out, extends in the southern part of central Slovakia and is part of the Slovenské stredohorie. The choice of mountain range was conditioned by a uniform geological bedrock and a height range. The selected height steps along the gradient have a range of 100 meters. In each of the scale height, data is collected through phytosociological records and dendrological data. Editing data is done in Turboveg for Windows (Hennekens & Schaminée 2001), Juice Analysis (Tichý 2002) and the results are presented in graphs in Microsoft Excel. The processed results point to the minimum of plant species in the middle altitudes and the maximum species count is recorded at the edges of the altitude gradient. These results confirmed significant research of Hrivnák et al. (2013), which took place in several mountains with volcanic bedrock. As the altitude rises, we to see a drop in temperature and a slight increase in moisture through herbal indicators. From the dendrometric data we have shown a relationship in which the abundance of understory plant species decreases as the number of trees in the area increases. Conversely, as tree thickness increases, plant abundance increases. The premise who mentioned Hrivnák et al. (2013) that the cause of the decline in species at medium altitudes is due to the massive competency of the European beech, we have confirmed in our work.