Tree-related microhabitats: A comparison of managed and unmanaged oriental beech–dominated forests in Northern Iran

Abstract

Tree-related microhabitats (TreMs) provide ecological niches in features for a variety of species in forests and are suitable indicators of biodiversity for certain taxa. The study objective was to compare the abundance and occurrence of TreMs in managed versus unmanaged Oriental beech (Fagus orientalis Lipsky) forests of northern Iran to quantify the effect of forest management on biodiversity indicators. We inventoried 3,954 trees to identify the number of trees with TreMs and quantify the occurrence of different types of TreMs. Managed forests averaged 25 trees with TreMs per hectare, and unmanaged forests averaged 41 trees with TreMs per hectare. In both forests, larger-diameter trees (≥50 centimeters diameter at breast height [dbh]) had more TreMs than smaller-diameter trees. TreMs were found on trees larger than a minimum size (32 centimeters dbh) and were more common on trees in poor health, as indicated by vitality class. According to our findings, managed forests have a lower diversity of TreMs than unmanaged forests. However, if management plans in deciduous forests include the retention of large-diameter trees during harvesting events, it is possible to balance providing TreMs within the forest while maintaining growth of economically valuable timber.