Restoration of montane heathlands – Early- and mid-successional stages promote phytodiversity

Abstract

Heathlands are highly threatened ecosystems with high conservation value. Montane heathlands have suffered from widespread habitat loss due to land-use abandonment and afforestation. The aim of our study was to analyse the long-term effects of montane heathland restoration, nine to ten years after restoration, on vegetation in the Rothaar Mountains (Central Germany). We compared vegetation composition in four vegetation types: (i) early-successional heathland stages on sod cut sites or ski pistes (hereafter referred to as EARLY), (ii) late-successional (old-growth) heathland stages (LATE), (iii) restored heathlands on former spruce forests where seed transfer by hydroseeding or the application of chopper material (crushed aboveground biomass from donor heathland site including seeds) had been applied (RESTORED) and (iv) windthrows with salvage logging (WIND). In every vegetation type, ten vegetation relevés were carried out and the cover of all vascular plant, bryophyte and terricolous lichen species were analysed. Furthermore, soil samples were taken in every relevé and measured with respect to soil acidity as well as carbon, nitrogen, phosphate and potassium contents.Our study demonstrated that the restoration plots were characterised by chemical soil conditions comparable to those of existing heathland communities. RESTORED was the hotspot of phytodiversity. Species richness of vascular plants, threatened vascular plants and target species peaked on RESTORED, followed by EARLY. Additionally, EARLY was characterised by the highest number of terricolous lichen species and threatened bryophyte species.The applied restoration measures were successful in establishing montane-heathland and acidic-grassland vegetation on former spruce forests. However, two usually dominant species of montane heathlands, Vaccinium myrtillus and Vaccinium vitis-idaea, had hardly established. Both species are slow colonisers and require specific microsites characterised by high moisture and organic content of the soil for generative reproduction. Additionally, the study demonstrated that early- to mid-successional stages of montane heathlands play a vital role for the conservation of cryptogams and low-competitive plant species.