Diversity of Beetles Captured in Pitfall Traps in the Șinca Old-Growth Forest, Brașov County, Romania: Forest Reserve versus Managed Forest

Abstract

Natural forests have unique, very stable structures and host a large number of endemic species, making them of high conservation value. The Șinca Old-Growth Forest in Brasov County (Romania) is no exception, being a flagship natural forest of mixed beech and silver fir among European mountain forests. Knowledge of the diversity of beetles living in this ecosystem and of the conservation degree of the species can be obtained by comparing it with the diversity existing in a managed forest, similar in composition and structure. Thus, the present study allowed a first analysis of the terrestrial coleopteran communities captured in pitfall traps both in a forest reserve and in a managed forest. The abundance of captured beetles was about 17% higher in the forest reserve (16,393 individuals) than in the managed forest (14,008 individuals), while species richness was higher in the managed forest (44 species), where 19.1% more taxa were identified than in the forest reserve (37 species). There were significant differences between the two beetle communities indicated via a PERMANOVA test; these differences are most likely due to the presence of certain beetle species only in a certain stand type, but also due to large differences between populations of common insect species. Analyses of the Shannon, Simpson, Evenness, and Berger–Parker diversity indices showed a similar diversity between the two terrestrial beetle communities. The presence of rare species such as Carabus variolosus (Fabricius, 1787), Ceruchus chrysomelinus (Hochenwarth, 1785), and Rhysodes sulcatus (Fabricius, 1787) indicates the high value of this ecosystem and illustrates the importance of its conservation. A more in-depth analysis of beetle diversity in the Șinca forest may only be possible after further research based on additional beetle sampling methods capable of capturing dead wood-dependent insects in particular.