Fig. 2. Phenology of plant and soil processes in response to plant diversity treatments in the Jena Experiment. The phenology of (A) plant height, (B) greenness, (C) root production, and (D) detritivore feeding activity from March 2021 to September 2021 for aboveground activity, and to February 2022 for belowground activity. The lines show the average monthly value for each species-richness level, with darker shades of green (aboveground) and brown (belowground) indicating higher plant species richness. The blue transparent stripes indicate the two mowing periods (14-25.06 and 13-24.09).

Plant diversity effects on the synchrony of aboveground-belowground phenology

Plant species richness affected the phenological synchrony of several response variables (Fig. 3), especially during the early growing season in spring (pre-mowing, Fig. 3a, b). Plant species richness increased phenological synchrony between plant community height and greenness, plant community height and root production, and greenness and root production. In contrast, plant functional group richness reduced phenological synchrony between greenness and root production and plant community height and detritivore feeding activity. This can be seen as a shift from negative r values to r values around zero. During summer (post-mowing period, Fig. 3b, e), increasing species richness shifted the synchrony between plant community height and greenness from a light asynchrony to a light-positive synchronous pattern. However, increasing plant functional group richness decoupled greenness and detritivore feeding activity (i.e. shift toward no correlation between response variables) (Fig. 3e). No significant plant diversity effects on phenological synchrony were observed over winter (Fig. 3c, f).