Survival and vitality of a macrolichen 14 years after transplantation on aspen trees retained at clearcutting

Abstract

Industrial forestry has caused large biodiversity changes in European boreal forests. One recently introduced conservation measure in production forestry is retention of trees at clearcutting to benefit flora and fauna. Aspen Populus tremula is often retained for conservation purposes since it is a key tree species for biodiversity with many associated species, a number of which are red-listed. Still, the importance to biodiversity of aspen trees retained at harvest is largely unknown. In 1994, a transplantation experiment with the old-growth forest indicator lichen Lobaria pulmonaria was set up on 280 aspens at 35 sites in east-central Sweden with a total of 1120 transplants, with the aim to assess the habitat suitability of retained aspens following harvest. After 14years 23% of L. pulmonaria transplants remained, with a significantly higher survival on retained aspens than on aspens in the surrounding forest, especially on the northern side of stems. Transplants were also more vital on northern than on southern sides of stems. There was no difference in survival or vitality of transplants between dispersed aspens and aspens in groups. Results largely agreed with a re-inventory made already after two years but the importance of the north side of retention trees became evident for species survival only after 14years, indicating that to gain deeper insights longer time-spans may be necessary. This study, which is the longest lichen transplantation time-series from a well replicated experiment so far published, shows that retention of trees at harvest may be an efficient conservation action.