Softwood quality in times of climate change

FutureWood – Project start / October 01, 2018

Climate change presents major challenges for the forestry sector. In particular, the supply of high-quality softwood is becoming increasingly problematic. In the FutureWood project, we are investigating the raw material quality produced by differing silvicultural systems, taking into account the climatic and ecological aspects. We are applying the gained knowledge in the conception of optimized silvicultural systems and manufacturing procedures for the forestry and timber industries in order to safeguard the sustainable production of high-quality coniferous-wood products.

Last modified: October 01, 2018

The timber tree species spruce forms a flat root system in many locations. This and its winter vegetation result in a high susceptibility to windthrow and windbreakage. The stability of the Douglas fir, which has deeper roots, has not yet been fully researched. Whilst it can withstand more extreme drought than spruce, climate change means that the risk of long dry periods and severe storms is increasing. Through the rise in temperature and shorter periods of frost, the living conditions of many tree pests are improving, enabling them to produce a further generation each year. Solely adapted, healthy forest stands will be able to continue to survive under the intensified environmental conditions.

In recent years, silvicultural measures have therefore been undertaken in many places in order to increase the overall stability of forest stands: Increasing the proportion of deciduous trees, converting to mixed forest and, therefore, single-tree cultivation - also for conifers. This leads to the formation of large tree crowns and wider annual rings. The knot frequency increases whilst the wood density decreases. The result is reduced strength, as a consequence of which the harvested raw wood no longer fulfills the sorting criteria which currently apply for high-quality wood products such as construction timber with a high static load-bearing capacity.

So how can the supply of construction timber and other high-quality softwood products be safeguarded in times of climate change? An interdisciplinary research team from the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut WKI, the HAWK Hochschule für angewandte Wissenschaft und Kunst Hildesheim/Holzminden/Göttingen (university for applied sciences and arts) and the Georg-August-Universität Göttingen (University of Göttingen) is addressing this question in detail.

The scientists are thereby pursuing two approaches: Firstly, they are developing a silviculture concept for conifers which is adapted to climate change in order to ensure the highest possible raw-timber quality in the future. Secondly, they are trying to optimize the sorting processes in such a way that even low-grade raw wood can be used for sophisticated wood-based products.

Waldbestand nach 80 Jahren Niederdurchforstung — © Fraunhofer WKI | Tobias Krenn
Forest stand following 80 years of low thinning

Waldbestand nach 40 Jahre Hochdurchforstung — © Fraunhofer WKI | Tobias Krenn
Forest stand following 40 years of crown thinning: In comparison to the forest stand following 80 years of low thinning, the final crop trees have achieved similar diameters in half the lifetime.

Optimization of the silviculture system

The researchers perform a representative comparison of the silvicultural systems “crown thinning” and “low thinning” using spruce and Douglas fir, which originate from experimental areas of both silvicultural systems. These areas are made available by project partners. The crown thinning method is based on single-tree cultivation through clearing around vigorously growing “final crop trees”. In this way, the forestry industry is able to generate the desired target strengths more quickly within a stand which can withstand wind and weather. The consequence, however, can be the inferior wood quality described above. During low thinning, an entire tree stand is allowed to grow in a densely packed manner. Due to the strong competition for the crown space, the trees strive to grow upwards and have a smaller diameter. Whilst this results in better wood quality, these trees are, however, generally weaker and therefore more susceptible to windthrow and windbreakage, drought and tree pests.

The project team will examine the two silvicultural systems from a yield, technological, economic and ecological perspective in order to conceive a silvicultural concept for coniferous trees which is adapted to climate change. A value-creation chain for construction timber production modelled on the basis of the investigated silvicultural systems ensures economic comparability of the management concepts. In order to safeguard environmentally friendly and sustainable forestry management, an ecological assessment is performed simultaneously. Scientists from the University of Göttingen record the structural characteristics of the investigated stands by means of terrestrial laser scanning and carry out detailed vegetation surveys on species diversity and location quality.

Optimization of the wood-based material production

The application possibilities for inferior-quality wood stocks in wood-based materials with a high degree of digestion, such as particle board and fiberboard, are well documented. For plywood, laminated veneer lumber (LVL) and glued laminated timber (glulam), however, high-quality raw wood with high strength is required. Within the framework of the project, at the Fraunhofer WKI we are therefore producing more sophisticated wood-based products using the spruce and Douglas fir trees from the differently managed experimental areas. With a view to increasing the efficiency of coniferous raw timber utilization, we are striving to optimize the sorting of lumber and veneer. In this section of the project, in cooperation with a wood-based materials manufacturer, we compare visual strength grading for sawn timber with modern mechanical grading methods. The aim is to use the material properties which we have determined as a basis for the re-evaluation and adaptation of the sorting criteria applied up until now. From the knowledge gained in this way, concrete conclusions can be drawn regarding the suitability of the utilized stocks for the various intended applications and requirements for future silvicultural management.

With this project, we are making a contribution towards a forestry and timber industry adapted to climate change and towards the promotion of wood as a climate-friendly CO₂ storage medium. This is important, as high-quality wood products, such as construction timber, have a long usage lifespan and can be further processed to create other products, such as particle board or paper, once this initial period of use has expired (“cascade utilization”). The retention time for the CO₂ is thereby increased.

Project results

The investigation of softwood from differing silvicultural systems has shown that application-oriented sorting based on product requirements – and, consequently, more efficient use of wood resources – is possible in dependence on silvicultural parameters. A re-evaluation of various visual criteria can be advantageous. The project team also found that Douglas fir in particular is an interesting tree species in terms of silviculture under the current climatic conditions.

Project partners

Research partners:

HAWK Hochschule für angewandte Wissenschaft und Kunst Hildesheim/Holzminden/Göttingen
Georg-August-Universität Göttingen

Partners for experimental areas:

Niedersächsischen Landesforsten (State forest in Lower Saxony)
Landesbetrieb Hessenforst (Land office, Hesse)
Department for Sustainable Development and the Environment, Federal State Government for Agriculture and Environment of Mecklenburg-Vorpommern
Private forest owners, represented through the Oldershausen HOFOS GmbH

Industrial partners:

EGGER Holzwerkstoffe Brilon GmbH & Co. KG

Funding

Official project title:
Optimierung von Waldbewirtschaftungssystemen unter veränderten klimatischen Bedingungen im Hinblick auf die Verbesserung der Festigkeitseigenschaften von Nadelbauholz

(Optimization of forest management systems under changing climatic conditions with regard to improving the strength properties of softwood timber)

Funding body:
German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU)

Project management:
Fachagentur Nachwachsende Rohstoffe e. V. (Agency for Renewable Resources, FNR)

Funding reference:
28W-K-3-149-02

Duration:
01.10.2018 to 30.09.2022

(Forest Climate Funds)

Research project

Softwood quality in times of climate change

Optimization of the silviculture system

Optimization of the wood-based material production

Project results

More information

Project partners

Funding

Contact Press / Media

Dr. Dirk Berthold

Contact Press / Media

Tobias Krenn