Preliminary Study on Hourly Dynamics of a Ground-Dwelling Invertebrate Community in a Farmland Vineyard

Simple Summary Understanding diel variations in ground-dwelling invertebrates is an important issue for agricultural ecology, which has been extensively studied at the population level. However, contemporary studies on hourly variations in the field are scarce at the community level owing to the lack of an effective method for collecting hourly data. Therefore, this study used a novel, automatic method using infrared camera traps to photograph a ground-dwelling invertebrate community at 5 min intervals from 31 July to 29 September in farmland in Ningbo City, China. In total, 9 taxa and 1147 individuals were identified across 42 d in 217,728 photographs. The taxonomic richness and abundance of the ground-dwelling invertebrate community did not show significant hourly variations within each day nor significantly preferred active hours. Only millipedes had significant hourly variations within each day, with a significant preference for activity between 1:00 and 4:00. Additionally, slugs, beetles, and grasshoppers showed preferred active hours around sunset and midnight. This study provides a useful method for monitoring hourly changes in ground-dwelling invertebrate communities in farmlands as well as fine temporal resolution data to understand the responses of ground-dwelling invertebrate communities to climate change and human management.Abstract We evaluated the hourly dynamics of ground-dwelling invertebrate communities in farmland using infrared camera traps between August and September 2022. No significant variations within 24 h nor between any two time points of each day were observed in the taxonomic richness and abundance of the entire community. However, the periods from 4:00 to 7:00 and 13:00 to 20:00 showed relatively high taxonomic richness, while those from 2:00 to 6:00 and 16:00 to 21:00 showed relatively high abundance. Millipede abundance varied significantly in a 24 h period, with higher abundance from 3:00 to 4:00 and 1:00 to 2:00. Additionally, slug, beetle, and grasshopper abundances were significantly higher from 22:00 to 23:00, 17:00 to 18:00, and 23:00 to 24:00, respectively. The abundance of other taxa did not show significant variations between any two time points of a day. Predominant generalist predators showed positive correlation in their activity times. These results suggest that significant variations within each 24 h period are uncommon at either community or taxa (except for millipedes) levels in farmland ground-dwelling invertebrates. Further, while most taxa had significantly preferred active hours, the total community did not. Therefore, hourly dynamics should be considered to understand biodiversity maintenance.