Epigeic Carabids (Coleoptera, Carabidae) as Bioindicators in Different Variants of Scots Pine Regeneration: Implication for Forest Landscape Management

Maintaining biodiversity is one of the factors determining the proper functioning of ecosystems, especially those with high human impact. Ground beetles, as bioindicators, are particularly valuable in understanding ecosystem responses and sustainability in forest and landscape management. Focusing on the regeneration of pine forests, this study aimed to describe ground beetle assemblages on Scots pine natural and artificial regeneration in northeastern Poland. This study was conducted between 2016 and 2018. Pitfall traps were set up for catching epigeic carabids on previously prepared research plots designated for natural and artificial pine regeneration. The research areas included three variants: N-natural pine regeneration, plots without soil preparation; NP-natural pine regeneration with traditional soil preparation by ploughing; and A-artificial pine regeneration with ploughing. Four plots as replicants were selected in each experimental variant, with six pitfall traps in the transects running through the centre of each study plot. In each year of the study, 11 samples were collected from each plot; overall, 33 samples per plot were collected during the three years. As a result of this study, 26,654 ground beetle individuals belonging to 89 species were caught during the three-year observation. Natural regeneration without soil preparation (N) was the most favourable in terms of the occurrence of stabilised assemblages of ground beetles. However, the remaining methods of pine regeneration, on a multi-annual scale (2016-2018), contributed to the increase in the number of ground beetles but also provided high variability in assemblage composition, diversity indices, and life-history traits. Thus, in the early stage of pine regeneration, each of the examined variants of pine regeneration can be used without fear of causing damage to carabid populations. However, further studies are required to investigate the effect of different pine regeneration types on carabid beetle assemblages over a longer period.