Assessing restoration success by predicting time to recovery—But by which metric?

Pine savanna restoration on agricultural landscapes: The path back to native savanna ecosystem services

Restoration of savanna ecosystems within their historic range is expected to increase provision of ecosystem services to resident human populations. However, the benefits of restoration depend on the degree to which ecosystems and their services can be restored, the rate of restoration of particular services, and tradeoffs in services between restored ecosystems and other common land uses. We use a chronosequence approach to infer multi-decadal changes in ecosystem services under management aimed at restoring fire-dependent pine savannas, including the use of frequent prescribed fire, following abandonment of row-crop agriculture in the southeastern U.S. We compare ecosystem services between restored pine savannas of different ages and reference pine savannas as well as other common land uses (row-crop agriculture, improved pasture, pine plantation, unmanaged forest). Our results suggest that restoring pine savannas results in many improvements to ecosystem services, including increases in plant species richness, perennial grass cover, tree biomass, total ecosystem carbon, soil carbon and C:N, reductions in soil bulk density and predicted erosion and sedimentation, shifts from soil fungal pathogens to fungal symbionts, and changes in soil chemistry toward reference pine savanna conditions. However, the rate of improvement varies widely among services from a few years to decades. Compared to row-crop agriculture and improved pasture, restored savannas have lower erosion, soil bulk density, and soil pathogens and a higher percentage of mycorrhizal fungi and ecosystem carbon storage. Compared to pine plantations and unmanaged forests, restored pine savannas have lower fire-prone fuel loads and higher water yield and bee pollinator abundance. Our results indicate that restoration of pine savanna using frequent fire provides a broad suite of ecosystem services that increase the landscape's overall resilience to climate change. These results are likely relevant to other savannas dominated by perennial vegetation and maintained with frequent fire.

Hay transfer is a nature-based and sustainable solution for restoring grassland biodiversity

As we enter the United Nations Decade on Ecosystem Restoration, there is an increasing need for finding nature-based solutions for the restoration of grasslands across the globe. Besides seed sowing, alternative restoration methods that build on locally available propagule sources, such as hay transfer, should also be considered and given high priority. The transfer of hay from a donor site to the restoration site serves a double aim by introducing target species and suppressing weeds. We tested the applicability of hay transfer in restoring species-rich grassland in a former cropland in Hungary, over six years of post-restoration monitoring from 2015 to 2020. We sampled the plant species composition of the three donor sites (target state of restoration) and the area surrounding the restoration site. We found that six year after restoration, a species-rich grassland developed with 42 successfully established specialist species that had a cover of 45%. Most specialist species became established from the hay from the second to the sixth year, but the surrounding areas also provided additional propagule sources. Among the eight analysed functional traits, seed mass of the transferred species was the best predictor of the establishment of specialists, and we found that small-seeded species had an establishment advantage in the first years after restoration. Our results suggest that hay transfer can be a suitable nature-based solution for local grassland restoration projects and its potential should be utilized especially in regions where suitable donor sites are present in sufficient quantity and quality.