Ground beetle community in suburban Satoyama — A case study on wing type and body size under small scale management

• We applied small scale management in suburban Satoyama secondary forest (Japan).
• We analyzed carabid species wing type and body size before and after management.
• Carabid assemblages were classified according to the vegetation type.
• Wing type (brachyptery and macroptery) was linked to vegetation structural stability.
• In some species, decline in abundance was accompanied with decrease in body size.

A Satoyama landscape is an important reservoir of biodiversity; however, in post-industrial era traditional Satoyama management became economically unfeasible.To maintain Satoyama, labor-saving management styles have begun to be implemented. In contrast to the traditional styles based on labor-intensive practices such as rotational tree clear-cutting, the labor-saving styles consist mainly in tree thinning and ground vegetation cutting within a small spatial range. The consequences of this new approach are unclear, and our study aimed at filling this gap in our knowledge by analyzing the effects of small scale management on ground beetle community in suburban Satoyama (Kashiwa city, central Japan). We applied labor-saving management at limited spatial range, and sampled and analyzed ground beetles both before and after management. Cluster analysis revealed three groups of beetle assemblages, corresponding to three habitats: forest, bamboo stand and grassland. Comparison of wing traits showed that, before management, brachypterous beetles dominated forest plots and macropterous beetles were more prominent in the grassland plot, while in the bamboo stand both types of wing morphology were evenly represented. This trend can be linked to habitat structural stability driven by vegetation regeneration cycles which reflect dominant plant longevity. After management, macroptery increased in all three habitats. Probably, habitat disturbance created by vegetation management gave advantage to macropterous beetles over brachypterous beetles. These results suggest that wing type can be linked to vegetation structural stability. In some species, decline in abundance was accompanied with decline in body size. Our study shows that small scale Satoyama management can have pronounced effects on beetle assemblages.

The analysis of wing traits showed that, before management, brachypterous beetles dominated forest plots and macropterous beetles were more abundant in the grassland plot, while in the bamboo stand both types of wing morphology were evenly distributed. After management, macroptery increased in all three habitats. Probably, management disturbed the habitats by creating gaps in the vegetation and hence gave advantage to macropterous beetles. These results suggest that wing type can be linked to the habitat structure and its stability.Wing type distribution across three habitat types (1) before management (2011), and (2) after management (2012).Letters above the bars (a, b and c in 2011, a′ and b′ in 2012) show significantly different proportions (by multiple comparison proportion test at P < 0.05). The numbers on the bars show the numbers of beetle individuals caught per plot.The proportion of macroptery of 2012 became significantly higher in all three habitats compared to 2011 (by a multiple comparison proportion test at P < 0.05).Figure optionsDownload as PowerPoint slide