Modelling the effects of forest management on the wood properties and branch characteristics of UK-grown Scots pine

Scots pine (Pinus sylvestris L.) represents around 16% of the area of commercial conifer plantations in Great Britain, but around 30% in north and north-eastern Scotland. Most of the timber produced from these forests goes into lower-value markets such as fencing and panel products, and only a small proportion is converted into high-value structural timber. In order to maximise financial returns from this resource in the medium and long term, it will be necessary to increase the outturn of structural timber. However, this requires knowledge of the variation in those wood properties that influence structural timber performance and of the effects of silviculture on wood quality. Changes in silvicultural practices in recent decades—wider initial spacings, a preference for artificial regeneration, and an increased use of mechanised thinnings, have led to concerns about the suitability of Scots pine timber for use in structural applications due to potentially poorer stem form, a greater proportion of juvenile wood and larger, more numerous knots. As part of the research presented here, novel predictive equations were developed for the key physical, mechanical and branching properties that determine structural timber quality in Scots pine, namely: microfibril angle, wood density, clearwood bending strength and stiffness, and branch number, size, insertion angle and status (alive or dead). Simulations were carried out using these equations to examine the effects of different silvicultural regimes on each wood and branch property of interest. Based on these simulations it is recommended that in order to produce high quality Scots pine timber, trees are planted at narrower initial spacings and grown on longer rotations than currently prescribed, and, where appropriate, thinnings should be delayed. Together, these measures will restrict final branch size and the amount of mechanically inferior juvenile wood in the final crop.EThOS - Electronic Theses Online ServiceGBUnited Kingdo