Storage, traceability and a measurement routine

Measured volume and graded quality are only valid at a date. Logs change between the forest road and the saw line, and the contract has to say who carries that risk. This lesson covers storage thresholds, the 2018-2024 bark beetle crisis as a lesson in measurement and sorting, traceability and a routine you can run in your own yard.

What storage does to logs

The LWF Bavaria leaflet 7 "Rundholz" (Germany, November 2025) gives the biological thresholds: damaging organisms need oxygen and water, available at moisture contents of roughly 20-30% up to about 120%. Above 120% oxygen is too scarce; below 30% there is no free water. The strategy is to keep wood wet or dry it quickly below 30%, ideally below 20%.

• Dry storage in bark works only for a few weeks for winter-felled wood. Spruce must leave before the bark beetle flight (March or April) or sit at least 500 m from conifer forest, in piles at most 4 m high.
• Wet storage by sprinkling or water storage: Lutze (LWF, 2014) states 50 mm of water per day, a water-law permit, and 3-6 years for spruce, at least 2 for pine and about 2 for beech.

Worked example. The 2025 leaflet gives about 0.7 l/s per 1,000 Fm in interval operation, 1 ha per 15,000 Fm as minimum economic size and 18-20 euro per Fm per year in total. A 15,000 Fm site needs 0.7 x 15 = 10.5 l/s while running, about 37.8 m3/h, and costs 15,000 x 18 = 270,000 to 15,000 x 20 = 300,000 euro a year (own calculations). The two LWF documents use different units and reference areas, so do not compare them directly.

Wet storage has a use-by date. Engesser (WSL, Switzerland, 2003) reported that properly sprinkled wood after storm Lothar (1999) was attacked only by honey fungus, yet decay appeared sporadically after the third year in German observations, after about 3 years at Swiss sites, and in the worst case after 2. It attacks almost only sapwood, so small logs lose most value. Blue stain does not reduce strength but can rule out visual grades.

The bark beetle crisis as a measurement lesson

For Germany, Thuenen Working Paper 244 (2024) lists damaged timber harvested at 31.9 (2018), 46.2 (2019), 60.1 (2020), 50.5 (2021) and 44.7 (2022) million Efm, adding to 233.4 million, matching the 233 million quoted. It cites Moehring et al. (2021): about 177 million Efm in 2018-2020 and price losses of 3.39 billion euro; the quoted 26.31 euro per Efm does not equal 3.39 bn / 177 m (19.15), so the basis of that unit figure is unclear (own calculation).

For a buyer the lesson is operational: sort salvage by age and condition on arrival, debark early, and write explicit stain, rot and gallery limits into the contract.

Traceability

The European Commission states that the EU Deforestation Regulation, which covers wood, applies to large and medium operators from 30 December 2026 and to micro and small operators from 30 June 2027. Dates have shifted before (amendments in December 2024 and December 2025), and geolocation requirements were not covered; check the Commission page again before acting. At the mill, traceability means a chain of identifiers: lot or stack number, delivery slip, supplier or felling area, felling date, species and measured volume, carried through the sorting line and pile to the output batch. For stored wood the identifier should include felling date and sprinkling start.

A routine for your yard

1. Name the measurement rule, edition and place in every contract.
2. Check calibration of calipers, scales and scanners; keep the raw data.
3. Record rounding and allowances on the delivery slip.
4. Compare your measured volume with the seller's on a sample and look for a systematic difference.
5. Record sorting class, felling date and storage start for each lot.
6. Report yield by size class and state the baseline (stem, roadside, yard gate, saw infeed).

Limits of this course

This course is AI-drafted and based on the portal's already fact-checked articles. Several rules could not be verified in open sources: EN 1927, EN 1316 and EN 1309-3 class limits (paywalled), the Heilbronner Sortierung, Polish PN-D-95000 and WZ rules, and the Spelter (2004) recovery figures beyond the abstract. The Polish 2025 sales rules are a 2024 proposal. The MBF-to-m3 factors disagree between sources, the NA-FR-15 scaling note is unresolved, sprinkling temperatures and pile heights were not found, and harvester and photo-optical approvals may have changed since 2018. Most figures are regional (Germany, Austria, Sweden, Poland, North America) and do not transfer. Prices and economics examples are invented or dated. This is not legal or contractual advice; check figures against current standards, your contracts and your own measurements before acting.

Key points

• Storage changes quality: keep wood wet, or dry it below 30%, ideally below 20% (LWF, Germany, 2025).
• A 15,000 Fm sprinkled site needs about 10.5 l/s and costs about 270,000-300,000 euro a year (own calculation from LWF figures).
• The German salvage series (31.9 to 60.1 million Efm a year) sums to 233.4 million Efm in 2018-2022.
• Sort salvage lots by condition and write explicit limits for stain, rot and galleries.
• EUDR dates (30 December 2026 and 30 June 2027) have changed before; recheck them.
• A yard routine ties rule, calibration, allowances, sorting class, dates and yield baseline together.