The Role of Retention Trees in Providing a Habitat for Bryophytes and Lichens in Young Forest Stands: A Mid-Term Perspective

Abstract

Retention of trees from the previous generation is one of the most widespread conservation practices in forests used for timber production. Despite the comparatively long history of this approach in Europe, there is a lack of long-term studies on the effectiveness of retention trees in preserving epiphyte communities. We compared the diversity of bryophyte and lichen species on retention trees in 20 young forest stands in Latvia in two assessments, 11 years and 18 years after clearfelling. Linear mixed-effects models showed that richness of both lichens and bryophytes remained stable during the assessment years, while bryophyte cover and diversity on retention trees increased over time. The main indicator of higher species richness, cover and diversity on retention trees in managed forests in hemi-boreal vegetation zone was the tree species, with deciduous trees playing the key role. They also provided essential habitat for rare species. Regarding bryophytes, ash, elm, and aspen can be suggested as more efficient retention trees, thus aiding the continuity of bryophyte succession in young forest stands. For lichens, lime could also be prioritised.