Retention trees can benefit biodiversity without significant long-term reduction in stand regeneration in Estonian mixed forests

Retention forestry is regarded as an efficient approach for conserving ecosystem functions and biodiversity in production forests, but its long-term impacts on forest ecosystem goods and services are poorly documented. We investigated the functioning of solitary retention trees in regenerated young forest as refuges or dispersal centres for shade-preferring species and explored the potential cost on future timber supply due to suppressed tree regeneration. We described land snail assemblages, soil characteristics, vegetation structure and stand regeneration along 50-m transects radially away from 34 deciduous retention trees in young stands (15-16years post-harvest, passed the pre-commercial thinning) in Estonia. General linear modelling revealed that the abundance and species richness of snails were higher in close proximity of the retention trees. Neither stand regeneration density nor its basal area varied systematically along the distance gradient. Thus, contrary to our hypothesis, the positive impact of retention trees on shade-preferring and hygrophilous species group in young production stands had no clear trade-off with stand regeneration. The development of both these functions should be studied further in maturing forests.