Biodiversity refers to genetic, species and ecosystems varieties within an area. Two main characteristics that should be investigated when considering biodiversity are richness and evenness. Richness is related to the number of different species in the analyzed area, while evenness corresponds to the homogeneity of the abundance of species. For quantifying these features, many indices have been defined, and this paper offers an overview of the most commonly used biodiversity indices, such as Shannon, Simpson, Margalef and Berger-Parker. The paper explains the process of calculating these indices on the case study example of four forest communities and discusses the results obtained. The Jaccard index analysis is used to discover a similarity between the analyzed forest communities. Results from this part of the research are visualized by creating appropriate dendrograms for making the interpretation easier. Calculating and analyzing these indices is useful not only for forest ecosystems, but for the other types of ecosystems as well, including agro-ecosystems. Biodiversity indices can be obtained in thespecialized software, for instance in EstimateS (Statistical Estimation of Species Richness and Shared Species from Samples), or by programming in the statistical package R, as it was done in this research.