Utilization of standing-stored damaged spruce timber from calamity areas for the production of wood-based materials and bonded solid-wood products for the construction industry and furniture manufacture

NUKAFI – Project start / August 01, 2022

Climate change presents major challenges for the German forestry and timber industries. Extreme weather events and the mass reproduction of insect pests have caused enormous damage to the forests. In particular, spruce trees have fallen victim en masse to droughts, storms and bark beetles. The majority of the damaged or dead spruce trees cannot be harvested promptly. Some of them remain standing and lying for several years. Is the wood quality then still sufficient for the production of durable construction products or wood-based materials? Within the framework of this project, we are investigating this question in collaboration with partners from research and industry. With the creation of a guideline, we also intend to provide specific recommendations for action for forest owners and the timber industry.

Last modified: August 01, 2022

The photo shows a large forest area with dead standing spruce trees. — © Institut für Holztechnologie Dresden gemeinnützige GmbH (IHD)
Climate change leads to widespread forest damage, particularly in spruce forests (here: calamity area in the Sauerland).

The photo shows a slice of spruce wood, partially darkened, lying flat. The surface is being depressed using a sharp hand tool. — © Institut für Holztechnologie Dresden gemeinnützige GmbH (IHD)
The quality of damaged spruce wood, stored standing or lying for a long period of time, is to be investigated in the project (here exemplarily: pick test to distinguish hard/soft rot in conformity with EN 252).

The photo shows sample pieces of three different wood-based materials (OSB, particle board and MDF). — © Fraunhofer WKI | Manuela Lingnau
At the Fraunhofer WKI, various wood-based materials are being produced from damaged spruce wood and subsequently analyzed (here: example photo with OSB, particle board and MDF).

The starting point for the research work is the question of whether and how the wood quality changes if spruce trees are initially not felled following a beetle infestation or death, but either remain upright in the forest until further use (“standing storage”) or are kept for a certain period of time in dry storage outside the forest.

In order to achieve the research objective, damaged or dead spruce trees will be taken from large-scale dead-forest areas (“calamity areas”) at two locations (Harz and Sauerland). The selection of the trees will encompass both a variety of site conditions (water and nutrient supply) and differing durations of standing storage (1 to 5 years). The selected trees will be examined in order to evaluate the degradation progress of the wood in dependence on the time period. In addition, tests will be carried out on dry-stored calamity spruce wood of varying storage durations.

On the basis of these analyses, exemplary wood products will be manufactured and examined with regard to normative properties. At the Fraunhofer WKI, we produce and evaluate the following wood-based materials:

Oriented strand boards (OSB)
Particle boards
Medium-density fiberboard (MDF)

The material tests are oriented to the respective product and requirement standards (CE standard). The properties tested include wood moisture content, bulk density, thickness swelling, bending strength, and transverse tensile strength.

Within the project, sawn timber products such as boards, planks or square timber will be produced, as well as bonded solid-wood products such as cross-laminated timber (CLT) or glued laminated timber (glulam). The investigations encompass lumber grading (visual and mechanical), bonding properties, and mechanical properties. Bending, tensile, block shear and delamination tests will be performed in accordance with the standards.

The application-oriented character of the project will be complemented through the following analyses:

Technical drying of calamity wood
General risk assessment regarding the standing storage of calamity spruce trees
Analysis of consumer acceptance

On the basis of the results obtained in the project, the project team will also develop an intelligible guideline for the handling of standing-stored spruce calamity wood. Amongst other things, it will contain an overview of product-specific grading criteria. These should make it possible to obtain the best possible wood assortments from the damaged wood - with regard to the respective end product.

The guideline is intended to not only provide answers concerning the utilization of spruce calamity wood, but also to serve as a possible orientation aid or template for anticipated further calamities affecting important commercial tree species (e.g. larch, beech, or oak). The results will additionally be incorporated into standardization.

As a result of the high number of dying or already dead spruce trees, private and public forest owners are being confronted with the unusual situation of having to remove large quantities of damaged wood from the forest within a short period of time. In view of the increasing shortage of skilled workers coupled with a high level of equipment utilization, priorities must be set for harvesting. The first step is therefore to clear transport routes of trees that have been toppled or broken, and to remove from the forest any trees that are still standing but which may be relevant to safety, and to store these in piles.

However, as the majority of the storage areas near forests are already filled, the question for many forest owners is whether and for how long the dying or dead trees can remain standing in the forest, and how long this wood remains materially usable for harvesting and value-adding purposes. The same question applies to dry storage outside the forest.

Next to pine, spruce wood is the most important construction timber in Germany. It is used in large quantities for load-bearing structures and bracings in buildings - for example in roof trusses, walls and ceilings or in hall constructions. Spruce wood is, however, also utilized for window and door scantlings, wall and ceiling cladding and furniture as well as for pallets and other wooden packaging materials. Spruce wood is furthermore processed into round timber products such as masts, posts or palisades.

In order to ensure the stability and serviceability of buildings, construction products are subject to high quality requirements. Normative specifications also exist for the materials used in furniture and other products, for example with regard to product safety and surface quality. Within the scope of the project, investigations are being conducted to determine whether and how the material-specific standards can be fulfilled with damaged spruce wood that has been stored for a longer period of time.

With the research work and the creation of a guideline, the project provides an important prerequisite for enabling the greatest possible high-quality utilization of the enormous masses of damaged spruce wood under the given circumstances. This serves the protection of resources and the climate.

Economic advantages

Assuming a positive outcome of the research project, a guideline with specific recommendations for the handling of standing-stored spruce calamity wood will be available for the forestry and timber industries, including:

Forest owners
Forestry operations
Timber-logistics industry
Sawmills
Wood-based panel industry

The guideline is intended to enable a product-specific grading of standing calamity spruce with regard to the subsequent utilization of the wood. This could lead to a considerable increase in efficiency in the material utilization of spruce calamity wood and, consequently, improve the availability of raw materials for wood-based material production. This could have a positive impact on the supply availability of construction products and furniture panels made from spruce wood.

As a result, sectors that market and utilize spruce-wood products could also benefit, including:

Timber trade
Construction industry
Furniture industry

Consumers could benefit from higher material availability, faster construction times and, possibly, affordable price structuring.

Project partners

Joint project coordination: Fraunhofer WKI
Institut für Holztechnologie Dresden gemeinnützige GmbH (IHD)
Deutsche Säge- und Holzindustrie Bundesverband e.V. (DeSH)
Wald und Holz NRW, Zentrum für Wald und Holzwirtschaft (FBV)
University of Göttingen, Department of Wood Biology and Wood Products

Funding

Official project title: Stoffliche Verwertungsmöglichkeiten für stehend gelagertes Kalamitätsholz der Baumart Fichte in Abhängigkeit von Schadfortschritt und Holzqualität
(Material utilization possibilities for standing-stored calamity wood of the tree species spruce in dependence of damage progress and wood quality)

Sub-project 1 (Fraunhofer WKI): Holzwerkstoffherstellung und -evaluation, Vorhabenskoordination
(Wood-based-material production and evaluation, project coordination)
Sub-project 2 (IHD): Bestimmung biotischer Schadorganismen und mechanische Untersuchung geklebter Vollholzprodukte
(Determination of biotic harmful organisms and mechanical examination of glued solid wood products)
Sub-project 3 (DeSH): Herstellung und Evaluation geklebter Vollholzprodukte; Verbraucherakzeptanz und Leitfaden
(Production and evaluation of glued solid wood products; consumer acceptance and guidance)
Sub-project 4 (Wald und Holz NRW): Untersuchung von Dürrständern, Kalamitätsholztrockenlagern sowie Risikoanalyse
(Investigation of dead standing trees, calamity wood dry storage as well as risk analysis)
Sub-project 5 (Georg-August-Universität Göttingen): Zustandsanalyse im Bestand und die technische Trocknung von Kalamitätshölzern
(Condition analysis in the stand and the technical drying of calamity wood)

Funding body: German Federal Ministry of Food and Agriculture (BMEL) and German Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection (BMUV)

Project management: Fachagentur Nachwachsende Rohstoffe e. V. (FNR)

Funding reference: 2220WK49A3, 2220WK49B3, 2220WK49C3, 2220WK49D3, 2220WK49E3

Duration: 1.8.2022 to 31.7.2025