The bachelor thesis is focused on the dynamics of the structure and quantification of lighting conditions in the spruce natural forest. The research took place in the spruce natural forest of the NNR Zadná Poľana. The first part of the work is focused on clarifying the theoretical basis of the issue and defining the terms forest, features and attributes of the forest, the development cycle and stages of the forest, the historical development and the current state of forests in Slovakia. In other subchapters, the work deals with the general characteristics of Norway spruce (Picea abies), defines its area and the demands on the environment and the impact of solar energy on the course of individual processes in the forest stand. The complete research was carried out by the Department of Forestry in the years 2013 to 2019. The measured data were provided to me for the elaboration of a bachelor's thesis. 20 research plots were established in the research facility, in which the positions of trees were captured using Field-Map technology. The dominant tree species is Norway spruce. During two years of research, it was equally represented. On the measured number of trees with a thickness d1,3˃ 8.0 cm, its representation was up to 88.2%. All trees with a thickness of d1,3˃ 8.0 cm were measured in the stands. In 2013, the number of spruce individuals, which reached a minimum thickness of 8.0 cm, ranged from 140 to 510 pieces per hectare and their total supply was 231.0 m3 ha − 1. In 2018, repeated measurements were performed but the range of tree thicknesses was already extended from 2.0 cm. In addition, an inventory of the necromass was carried out this year. In 2018, a greater variability in abundance from 110 to 500 pieces per ha was found. However, the total average number decreased to 223.5 ± 19.9 pcs. ha−1 and the supply increased to 363.04 cubic meters per hectare.In 2019, the last year of research, the measurement of the intensity of solar radiation was made with the help of the analysis of hemispherical images. The lighting conditions in different developmental stages of the spruce forest were evaluated. Images were taken on all twenty research plots. The maximum measured values of solar radiation ranged from 60 to 70 percent.