Scale dependency of taxonomic and functional diversity in old-growth and secondary loess steppic grasslands.

Abstract

Widespread campaigns on forest restoration and various tree planting actions lower the awareness of the importance of grasslands for carbon sequestration or biodiversity conservation. Even lower attention is given to the conservation of biodiversity and ecosystem functioning in remnants of ancient, so called old-growth grasslands. Old-growth grasslands in general harbour high biodiversity and even small patches of these can act as important refuges for many plant and animal species in urbanised or agriculture driven landscapes. Spontaneous succession of grassland is frequently viewed as a cost-effective tool for grassland restoration, but its applicability is strongly dependent on many local to landscape-scale factors and the recovery often slow. Thus, for the assessment of the effectiveness of spontaneous succession as a restoration tool, it is essential to compare the species diversity and functional attributes of old-growth and secondary grasslands. We studied the taxonomic and functional diversity in thirteen loess steppic grasslands (8 old-growth and 5 secondary) using differently sized plots ranging from 0.01 to 100m2. Our results indicated that there are remarkable differences in taxonomic and functional diversity between old-growth grasslands and secondary ones. We also point out that during secondary succession there is a likely functional saturation of the species assembly in the first few decades of recovery, and while patterns and structure of secondary grasslands became quite similar to those of old-growth grasslands, the species richness and diversity remains still much lower. Old-growth grasslands support considerable plant diversity, and species composition is slow to recover if destroyed for agricultural land use. This underlines the priority of protecting existing old-growth grassland remnants over restoration actions and the recovery of secondary grasslands.