Retention of trees at final harvest - evaluation of a conservation technique using epiphytic bryophyte and lichen transplants

Some trees are commonly retained as a conservation measure during forest ha rvest. However, their actual contribution to maintaining biodiversity is po orly known. In Swedish forests, aspen Populus tremula supports a rich epiph ytic flora. The bryophyte Antitrichia curtipendula and the lichen Lobaria p ulmonaria, used in forest inventories as indicators of long forest continui ty and presence of red-listed species, were used in a transplantation exper iment. Transplants on groups of retained aspen trees in clearcuts were comp ared with transplants on scattered trees in clearcuts and on aspens in uncu t mature forests. The survival and 'vitality' of a total of 2240 transplant s were recorded 20-25 months after transplantation, where 89% of the lichen transplants remained, as compared with 99% for the bryophyte. Both species had high vitality in clearcuts, although the bryophyte was most vital in t he forest. The lichen had significantly higher vitality on groups of trees as compared with scattered ones. Vitality was significantly higher on the n orth than on the south sides of retained trees for both species. The result s indicate that retained trees can form biodiversity links during forest su ccession after final harvest and that they are beneficial to at least some species considered to be sensitive to forest operations. (C) 1999 Elsevier Science Ltd. All rights reserved.