Lasting legacies: Relicts of historical plant communities in Central European grasslands amid a century of biodiversity loss

Central European grasslands have undergone significant transformations due to anthropogenic pressures such as land-use change, nitrogen deposition, and climate change. The persistence of historical grassland communities in the face of environmental change offers a unique opportunity for restoration initiatives. This study evaluates the availability of such remnant grasslands in Switzerland, by identifying patches that retained species composition and richness similar to the status of grasslands a century ago, and which can thus serve as nuclei for restoration. We resurveyed 73 sites selected from historical records, previously recorded around 1900, across a range of elevations and moisture regimes. Two plot types were sampled at each site: randomly positioned plots to assess average changes in species composition and targeted plots to assess the most similar remnants of the historical community. Species richness in the current most similar plots remained remarkably comparable to historical levels across all elevations and moisture levels, whereas current average plots exhibited a decline in dry and mesic grasslands. Ecological indicator values revealed significant increases in nutrient levels in dry and wet grasslands, likely driven by nitrogen deposition and land-use intensification. These changes were accompanied by shifts in species composition and increased tolerance to grazing and mowing. The analysis of CSR strategies highlighted a growing dominance of competitive species in wet and dry grasslands, along with a notable decline in stress-tolerant specialists. Our findings demonstrate the potential of remnant grasslands for restoration while emphasizing a large influence of environmental change.