Building resilience into Sitka spruce (Picea sitchensis [Bong.] Carr.) forests in Scotland in response to the threat of climate change

It is expected that a warming climate will have an impact on the future productivity of European spruce forests. In Scotland, Sitka spruce (Picea sitchensis (Bong.) Carr.) dominates the commercial forestry sector and there is growing pressure to develop alternative management strategies to limit potential economic losses through climate change. This review considers management options to increase the resilience of Sitka spruce dominated forests in Scotland. Given the considerable uncertainty over the potential long-term impacts of climate change, it is recommended that Sitka spruce should continue to be planted where it already grows well. However, new planting and restocking should be established in mixtures where silviculturally practicable, even if no-thin regimes are adopted, to spread future risks of damage. Three potentially compatible species with Sitka spruce are western hemlock (Tsuga heterophylla (Raf.) Sarg.), grand fir (Abies grandis (Lamb.) Lindl.) and Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and all form natural mixtures in its native range in North America. The predicted windier climate will require a range of management inputs, such as early cutting of extraction racks and early selective thinning, to improve stability. The potential to improve resilience to particularly
abiotic damage through transforming even-aged stands into irregular structures and limiting the overall size of the growing stock is discussed.