Sitka Spruce

FIM Summary of Sitka Spruce Plant Research

There is a continuing programme of research into the characteristics of Sitka spruce with the long term aim of improving the genetic quality of planting stock. FIM actively monitor the latest developments in crop improvements to ensure our clients forests are maximising productivity and return on investment through biological growth and crop quality.

The research is being led by the Sitka spruce Breeding Co-operative which is a collaboration between Forest Research (the research agency of the Forestry Commission) and senior members of the forestry industry. The key objectives are:

  • To improve the economic return of key coniferous species by ensuring they are well adapted;
  • To grow faster and straighter than unimproved stock;
  • To possess better internal wood qualities which are able to satisfy the construction timber market.

Target Characteristics of Sitka spruce

In analysing tree form the following characteristics are assessed, all of which are important factors to end users and thus affect commercial value. Research is actively focused on improving these specific traits of Sitka spruce:

  • Diameter Increase
  • Wood Density
  • Stem straightness
  • Minimal branching
  • Acoustic Velocity

Improved Sitka spruce

Superior characteristics are being demonstrated by Seed Orchard plants and MOO cuttings when compared with the original ‘unimproved’ Queen Charlotte Island (QCI) provenance trees planted in the UK during the 20th Century.

Seed Orchard Sitka

Seed Orchard Sitka spruce (also known as ‘improved’ or ‘elite’ Sitka) are selected plants grown in a seed orchard from parents specifically chosen for genetically superior characteristics. These are known as ‘half-sibling’ plants, as each seed is produced from different parents. Due to the range of parents these crops do display genetic variation however to a much lesser extent than unimproved stock. Seed Orchard seedlings are robust plants suitable for planting in a range of conditions.

VP (MOO) Sitka

Vegetatively propagated (MOO) Sitka is the most genetically advanced Sitka seedling currently available. These are full-sibling cuttings (where both parents are known) grown from tip cuttings taken from selected improved mother plants. The similarity in genetic traits is expected to increase the uniformity of the crop compared with Seed Orchard and QCI stock. These plants are estimated to show a 20% improvement in diameter increase, straightness and branching without compromising timber density. The seedlings can be more fragile during the first phase of establishment. Accordingly, FIM typically plant these only on the best soils at lower altitudes to minimise the increased costs which can occur from failed plants.