Temporal complementarity in activity-density of two arthropod macro-detritivore taxa

1. Macro-detritivores are important fragmenters performing a first step in the ecosystem process of nutrient cycling. Woodlice and millipedes are important representatives of this group and their ecology and niche requirements are often regarded as very similar. However, it is unclear whether there is a difference in temporal activity throughout the year between both groups, possibly leading to temporal complementarity for leaf litter breakdown, and whether patterns of temporal variation in activity are consistent across different habitat types. 2. We studied year-round pitfall-trap data of woodlice and millipedes from an old sand quarry with a high habitat heterogeneity. 3. Our results indicate that there is high temporal complementarity between both detritivore taxa, with millipede activity-density peaking in spring, while woodlice showing a peak in summer. Interestingly, timing of activity depended on habitat openness. Millipedes peak first in open habitat and later in closed habitat, while woodlice showed the opposite pattern. 4. Temporal turnover in community composition was high and of similar magnitude as spatial turnover in community composition across this relatively small scale of our study area. 5. We conclude that, although woodlice and millipedes show comparable habitat preferences, their temporal activity patterns show the potential for temporal complementarity for litter breakdown