The Relationship Between Abundance and Actual Spatial Distribution of Terrestrial Isopods (Oniscidea)

(1) Studying the spatial distribution of wingless arthropods restricted to the Earth’s surface presents numerous challenges. In this study, we focused on the spatial distribution of terrestrial isopods (Oniscidea) within a managed forest ecosystem, examining relationships among abundance, variance, occupancy, and clumpiness (i.e., aggregation) to highlight their significant roles in the observed phenomena. (2) Terrestrial isopods were collected using pitfall traps along a gradient spanning deforested and forested areas. For analysis, we employed summary statistics to describe the community using 18 different coefficients. Abundance–variance and abundance–occupancy models, together with Taylor’s power law and ordination symbol plots were performed. (3) Nearly 1000 individuals representing 8 species were identified and analyzed. All species exhibited a clumped distribution; however, Ligidium hypnorum displayed the highest degree of clumpiness, which resulted in notably low frequency and constancy despite its high overall abundance. Shrubs were the habitat with the highest rate of aggregation. Most species concentrated their individuals in just up to 5 of the 75 pitfall traps, with the remaining traps typically containing fewer or no individuals. (4) Species that are highly abundant on a local scale can be surprisingly limited in their spatial distribution, making their assumed dominance questionable and causing them to deviate from established trends. Awareness of species-specific traits and attention to such details can progressively improve the interpretation of observed ecological patterns.