Light pollution increased night-active but not day-active Collembola in Hulunbuir Grassland, China

Artificial light at night (ALAN) has been and is still spreading rapidly across the globe. Although many studies have demonstrated its adverse effects on the behavior and physiology of various organisms, little is known regarding its direct and indirect effects on soil animals. Therefore, the effects of ALAN and fauna exclusion and their interactions with Collembola were studied using field control experiments in the Hulunbuir Grassland, China's Erguna Forest Grassland Transition Zone Ecosystem Research Station. The Collembola were captured with pitfall traps, and their activity-density and species richness were calculated. The results showed that ALAN significantly increased the activity-density and species richness of Collembola. Fauna exclusion also increased the activity-density and richness of active Collembola at nighttime but not in the daytime. The effect of ALAN and fauna exclusion directly promoted Collembola but not through soil and plant properties. ALAN facilitated Collembola by extending their activity time, whereas fauna exclusion exerted a beneficial impact by reducing the number of predatory groups on Collembola. These two beneficial factors could collectively promote Collembola density and activity without contradicting each other.