Impact of spacing and pruning on quantity, quality and economics of Douglas-fir sawn timber

Impact of spacing and pruning on quantity, quality and economics of Douglas-fir sawn timber: scenario and sensitivity analysis

Rais, Andreas (Technische Universität München)
Poschenrieder, Werner (Technische Universität München)
van de Kuilen, J.W.G. (TU Delft Bio-based Structures & Materials; Holzforschung München)
Pretzsch, Hans (Technische Universität München)

2020

Controlling the long-term effect of management on the quantity and properties of individual boards is a fundamental challenge for silviculture. Within this basic study on Douglas-fir, we have investigated the sensitivity of the net present value (NPV) to three most common planting densities and a prominent pruning strategy. We therefore have applied an individual tree growth model, which represents intrinsic stem structure as a result of crown competition. The model extrapolated board strength development to the rotational age of 70 years, starting from real and comprehensive data recorded from experimental Douglas-fir plots at the age of 20 years. Total volume production increased from about 1600 m³ ha⁻¹ for 1000 and 2000 trees ha⁻¹ to 1800 m³ ha⁻¹ for 4000 trees ha⁻¹. The economic superiority of the lowest density stands increased considering the NPV at inflation-adjusted interest rates of 0%, 2% and 4%: Given an interest rate of 2% and no pruning, the NPV at 2000 was at about 50% of the one at 1000 trees ha⁻¹. The NPV at 4000 trees ha⁻¹ was even negative. Generally, artificial pruning was not effective. The revealed financial trade-off between growth and timber quality in young stands underlines the importance of silvicultural guidelines, which quantify the effect of management on yield per strength class and financial outcome.

Management tool
Processing chain
Strength grading
Timber quality

http://resolver.tudelft.nl/uuid:aa2e1449-2479-4486-b839-33123f4c4c3d

https://doi.org/10.1007/s10342-020-01282-8

1612-4669

European Journal of Forest Research, 139 (5), 747-758

Institutional Repository

journal article

© 2020 Andreas Rais, Werner Poschenrieder, J.W.G. van de Kuilen, Hans Pretzsch