Turf transplants for restoration of alpine vegetation: does size matter?
Turfs transplanted from native vegetation can be used to restore diverse plant communities on disturbed sites. There is, however, limited understanding of optimal turf size and the tolerance of different plant communities and species to transplanting. The effects of turf size in restoration of alpine plant communities were studied in SW-Iceland. Treatments tested in 2-m2 plots were as follows: planting of sixteen 5×5 cm turfs, four 10×10 cm turfs, one 20×20 cm turf or one 30×30 cm turf; a 20×20 cm turf shredded and spread over the plot and controls without turfs. The 10-cm thick turfs were extracted from nearby heath and grassland vegetation and planted in mineral soil and road verges at 260-410 m elevation. Species composition, cover and colonization were monitored for three growing seasons. Grassland vegetation tolerated division into small turfs better than heath vegetation, but responses varied by functional groups. Cover of dwarf-shrubs decreased with decreasing turf size; grass cover was highest in plots with 5×5 cm turfs and lowest in plots with shredded turfs, while moss cover increased most rapidly in plots with shredded turfs. Synthesis and applications. Optimum turf size for the restoration of native species varied among functional groups of plants and decreased as follows: evergreen dwarf-shrubs > deciduous dwarf-shrubs > sedges > grasses > mosses. Turfs that are at least 20-30 cm in diameter may be needed for the transplantation of dwarf-shrubs, while turfs as small as 5 cm in diameter can be used to establish many grass species. Even smaller units can be used to facilitate moss colonization. Turfs that are salvaged from development projects can be a valuable source of native species for use in restoration schemes. Turf size for transplanting should be selected with regard to donor vegetation, growth form and abundance of the target species.