Robinia forests in Romania – felling, brash windrows and root suckering

Ferdinand Terlinden

1 day ago

6 min read

Robinia series · Authority: “understanding where the timber comes from”

Three hectares at most, felling between September and March, a plot that regenerates itself by root suckering: robinia harvesting, told from the plot itself.

An earlier article explains how every Romanian tree is traced, from the ten-year plan to the lorry. This one tells the other half of the story: what happens on the plot — when trees are felled, how, with which machines, and why the forest grows back on its own. Our subject is robinia — also known as black locust, and often sold as acacia (Robinia pseudoacacia).

Because the way robinia is felled is not an operational detail: it determines both how the forest regrows and the quality of the timber you will buy.

3 hectares, not one more

the maximum area of a robinia clear-cut set by the Romanian Forest Code (Legea 46/2008, art. 29)

3-hectare coupes, never side by side

Romanian robinia is harvested by clear-cutting: on a given plot, all the trees are felled at once. But the law keeps a tight rein on the practice: 3 hectares at most in a single block, and no adjoining coupe may be opened until the previous one has closed over again as a young stand. In a forest of several hundred hectares, harvesting therefore advances through small windows that shift over the decades — never across whole swathes.

Why clear-cutting, rather than taking a tree here and there? Because robinia is a light-demanding species that regenerates by root suckering: felling the whole plot at once is precisely what triggers the most vigorous regrowth. This is the coppice system, applied for generations to species that resprout from the stump or the roots.

Aerial view of a 3-hectare robinia clear-cut in Romania, rows of brash windrows between retained stands — A robinia coupe seen from the air: the harvesting window stops sharply at the neighbouring stand, and the branches are already laid out in brash windrows.

Six months for felling: from 15 September to 15 March

Romanian regulations (OM 1540/2011) only open coppice harvesting during the dormant season, from 15 September to 31 March. At Acacia Bois, felling even stops on 15 March. For the rest of the year, the machines stay out of the forest.

For the forest. In winter, the tree’s reserves — its starch — have gone back down into the roots. Felling at that point leaves all that energy in the ground: in spring it bursts out as root suckers that grow more than a metre a year. Felling in full growth would waste those reserves and weaken regrowth — and machinery would damage soft, living soils.

For your timber. A tree felled when the sap is down contains less water and less starch — precisely what insects and blue-stain fungi thrive on. The timber dries more evenly, splits less and keeps better. Part of your stake’s longevity was decided on the day the tree was felled.

On the coupe: the harvester and sorting

On plots suitable for machinery, a harvester with a felling head works the slope: the machine grips the tree, fells it, delimbs it and cross-cuts it in a few seconds, recording the diameters as it goes. On ground that is too steep or too sensitive, felling is still done by hand, with a chainsaw. Each stem is then sorted on site: the straight logs go to our sawmill in Teiu, Hunedoara County (Romania), to become stakes, posts, boards and decking; sections that are too crooked or too thin are used as fuelwood.

Forest harvester with felling head on a robinia clear-cut in winter in Romania — The harvester on a winter coupe: grip, fell, delimb, cross-cut — and measure each stem along the way.

Brash windrows: laying out the branches to let life through

After felling, the branches remain. They are neither burnt nor left in heaps: they are laid out in brash windrows — long, regular rows aligned with the slope. Between the rows the ground stays clear: that is where the root suckers come up from the spring, unobstructed. The windrows themselves break down slowly where they lie: they return their nutrients to the soil, slow down run-off and shelter a whole range of small wildlife while the young stand closes over.

Nobody replants — and that is the best part of the story

Romanian law requires the owner to regenerate the plot within the two growing seasons following felling. With robinia there is generally nothing to plant: the roots left in the ground produce a whole new stand by root suckering. Thousands of stems per hectare spring up in the first year; within two or three seasons the plot has closed over, denser than before felling.

This overstocking is not corrected: the stand is not thinned. The stems compete with one another, grow slowly and lay down close rings — and 25 to 30 years later, a hard, dense timber is harvested, ready for a new rotation. Felling is therefore not the end of the forest: it is the first day of the next one.

Dense young robinia stand naturally regenerated by root suckering after a clear-cut in Romania — From the edge of the mature stand: the plot felled below has already closed over into a dense young stand, regenerated by root suckering.

What this means for the buyer

Timber felled when the sap is down, in a dense, slow-growing stand, then sorted stem by stem: that is the raw material for everything that leaves the sawmill. And every stage of this operation leaves an administrative trail — ten-year plan, marking, authorisation, transport — described in detail in our article on traceability, “Traceability of Romanian timber – SUMAL, APV and the EUDR”. Responsible harvesting and traceability are two sides of the same timber.

Key points

· Clear-cuts of 3 ha maximum (Romanian Forest Code, art. 29), never two adjoining coupes open at the same time.

· Harvesting only during the dormant season: legal window from 15 September to 31 March, Acacia Bois practice up to 15 March.

· Sap down = reserves in the roots (vigorous root suckers) and drier timber, less prone to attack, that dries better.

· Branches laid out in brash windrows: the ground stays clear for the suckers, and the nutrients return to the soil.

· No planting needed: the plot closes over on its own in 2–3 seasons, and is harvested again 25–30 years later.

Frequently asked questions

Why is robinia only felled between September and March?

Because that is the dormant season, imposed by Romanian regulations for coppice (OM 1540/2011). In winter, the tree’s reserves are in the roots: regrowth by root suckering will be vigorous in spring, and the felled timber contains less water and starch — it dries better and attracts fewer insects and fungi. At Acacia Bois, felling runs from 15 September to 15 March.

Is clear-cutting bad for the forest?

Not in the case of robinia, provided it is regulated: 3 hectares maximum, never two adjoining coupes, and compulsory regeneration within two growing seasons. Robinia is a light-demanding species that resprouts from its roots: clear-cutting is precisely what triggers its regrowth. The plot closes over within 2–3 years, with no planting, denser than before.

What happens to the branches after felling?

They are laid out in brash windrows, long regular rows left on the plot. Between the rows, the root suckers come up freely; the windrows break down where they lie, return their nutrients to the soil, limit run-off and provide shelter for small wildlife. Nothing is burnt on the coupe.

How long does the plot take to grow back?

The root suckers come up in the very first spring and can grow more than a metre a year: within two or three growing seasons, the plot has closed over. The stand, deliberately left unthinned, then grows tightly packed and slowly — which is what produces the fine rings and the hard timber — until the next rotation, 25 to 30 years later.

Is robinia invasive? Should you plant it in your garden?

Outside its native range, robinia is a vigorous, naturalised non-native species that spreads by root suckering — several European countries monitor it for that reason. Let’s be honest: what worries the gardener is exactly what makes the resource. That vigour allows a harvested plot to close over on its own, without planting, rotation after rotation; in a managed forest, root suckering is controlled by the forest management plan. In a small garden, on the other hand, plant it knowing what you are taking on — suckers can appear several metres from the trunk — or simply enjoy its timber.