Open karst habitats promote the diversity of ground-dwelling orthopterans and cockroaches (Insecta: Orthoptera, Blattodea) along a temporary river

Abstract

Temporary rivers are dynamic freshwater ecosystems, supporting unique and often highly diverse terrestrial communities in the riparian habitats during the flowing phase. However, studies investigating the differences in orthopteran and cockroach (Insecta: Orthoptera, Blattodea) assemblages between riparian and adjacent upland habitats are scarce, despite their abundance and functional importance in terrestrial ecosystems. Orthopterans and cockroaches were sampled in 2014 at 72 sites along the temporary Krcic River (SE Croatia) in two habitat types—riparian and karst, using pitfall traps. Abundance, taxa richness, true diversity and conservation value of ground-dwelling orthopterans and cockroaches were significantly higher in the karst than in the riparian habitat. This result can be ascribed to significant differences in environmental factors: soil temperature, air humidity and vegetation structure, namely tree, shrub and herb layer abundances. Most assemblage parameters and spatial distribution of ground-dwelling orthopteran and cockroach taxa were driven by higher soil temperature and less developed tree layer in the karst, both groups preferring open habitats. Karst sites with a well-developed shrub layer and herb layer had the highest conservation value for rare ground-dwelling orthopterans (e.g. Paramogoplistes novaki) and locally rare cockroaches (e.g. Ectobius balcani), respectively. Nevertheless, densely vegetated riparian sites also harboured some locally valuable species (e.g. Troglophilus cavicola). This study highlights the importance of open karst habitats in promoting the diversity of ground-dwelling orthopterans and cockroaches, and contributes to the understanding of key environmental factors driving their habitat choice, as a prerequisite for efficient conservation and monitoring.