Winter Storage of Douglas Fir: Effects of Storage Method and Origin

Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) has the potential to become an important complementary tree species in southern Sweden under a changing climate. The species has high growth potential and valuable timber properties, but successful establishment depends partly on appropriate nursery cultivation and storage of seedlings.

Douglas fir shows substantial differences among origins in autumn hardening, cold hardiness and bud burst. Inland origins generally develop winter hardiness earlier, whereas coastal origins may have a longer growing period and later hardening. Consequently, seedlings from different origins may respond differently to winter storage. Storage before sufficient hardiness has developed may cause damage, while unsuitable storage conditions may lead to desiccation or reduced vitality.

The project investigates how different storage methods affect seedling vitality and whether the response varies among inland and coastal origins. Particular attention is given to the relationships between storage timing, cold hardiness, accumulated chilling hours and subsequent seedling vitality.

The aim of the project is to improve knowledge of how winter storage affects Douglas fir seedlings from different origins and to identify suitable storage practices for different types of planting material. The results will provide practical guidance for nursery handling and support more reliable production and establishment of Douglas fir in southern Sweden.

Contacts: Michal Kibitlewski, SLU och Karin Hjelm, Skogforsk

Partner: Andrew Nelson,University of Idaho