Citizen-Led Passive Restoration of a Cork Oak Stand Following the Cessation of Mowing: A Study of the Effects on the Herbaceous Plants

The cessation of recurrent anthropogenic activities can promote vegetation succession. In this paper, we report a case study of passive restoration of the herbaceous plant vegetation associated with cork oaks carried out by citizens in collaboration with local farmers in a suburban area of Rome (Italy). A sampling design has been carried out in two comparable patches using replicated plots: (i) a first patch corresponding to the passive restored area, evolving from an uncultivated field towards a cork oak forest, where the mowing activity was stopped in 2017, and (ii) a second patch corresponding to an uncultivated land periodically mowed as a control. We recorded 24 plant species in the restored patch and 9 in the control patch. The Shannon-Wiener diversity index was significantly higher in the restored patch when compared to the control. Whittaker diagrams, graphically representing evenness, showed significant differences among plotted values. The Chao 2 richness estimators evidence the differences between patches (52.17 species vs. 9), graphically observed in the sample rarefaction curves. An analysis in the 2017–2025 period showed a substantial increase in NDVI values in the restored patch (from 0.18 in 2017 to 0.28 in 2025; approximately +54% relative to 2017; mean NDVI increased from 0.181 in 2017 to 0.29 in 2025), indicating an increase in cover/biomass associated with the post-2017 restoration of the area. Suspending mowing, both humidity (due to the reduction in grass cover) and nutrients increase, and the pH is reduced (Ellenberg indices): it is possible that the young oak trees are comparatively more effective cation exchangers. Therefore, only a few years after mowing was suspended, we observed a marked recovery not only of the dominant cork oak component but also of the herbaceous species (Vulpio-Dasypyretum villosi association). Even young, isolated cork oak trees can act as nurse plants (or keystone structures), supporting many species and creating microhabitats for shade-tolerant plants. This passive restoration began when local citizens and a school asked landowners to stop mowing in an area where cork oaks were naturally regenerating, making it an example of autonomous citizen-led environmental management.