Current models predict that the frequency of extreme weather events will increase with global climate change. Knowledge on the responses of natural communities to extreme weather helps us to envision and understand future changes in biodiversity expected in a changed climate. However, we know little on the resistance and resilience of restored communities, which knowledge should be fundamental in ecological restoration.
We studied the resistance and resilience of restored insect (Orthoptera) communities to extreme weather in a natural experiment using data collected before, during and after a year of extreme weather (“YEW”, 80% more rainfall than average). Orthoptera communities were monitored in the largest active grassland restoration in Europe (Hortobágy National Park, E Hungary), where restored communities approached natural communities in abundance, species richness and composition. We characterised resistance as the ability of the community to tolerate disturbance and resilience as the ability of the community to bounce back after disturbance. We analyzed the effects of (i) local and landscape-scale factors of restoration, (ii) community integrity (similarity to natural communities), and (iii) functional and taxonomic diversity on resistance and resilience of the restored communities.
Results/Conclusions
Over the years, abundance and species richness varied more in restored than in natural communities. In restored grasslands, Orthopteran abundance and richness decreased by c. 40% and species composition homogenized during the YEW but communities approached pre-collapse levels after it. Resistance was positively influenced by community integrity, functional diversity of life forms and distance to target vegetation, and negatively by restoration age and functional diversity of ecotypes. In contrast, resilience was negatively influenced by community integrity and restoration age, and was higher on former cereal than on sunflower fields. Community structure differed between restored and natural grasslands before the YEW because common species were underrepresented and one large predator was overrepresented in restored compared to natural grasslands. After the YEW, species less common in natural grasslands bounced back more in restored grasslands. These changes were associated with changes in the diversity of life forms, trophic roles and habitat preferences.
In summary, these results suggest that resistance and resilience in restored communities should be interpreted differently than in natural communities. Community structure integrity appeared generally important for resistance and resilience. However, its effect on resilience, along with that of restoration age, was different from those expected, thus further studies are warranted.