Harvest regimes

Harvesting regimes relate to the extent that a forest area is cleared – or to which the forest canopy is opened – by a (final) harvest operation. This intervention allows the opening of canopies, permitting the regeneration and development of new trees. There are numerous harvest regimes and they can broadly be separated by the extent to which the canopy layer is removed and the distribution of harvest over the forest area [22].

The extent to which the canopy layer is removed relates to the choice of harvest regimes. In clearcuts, the canopy layer is (almost) entirely removed, resulting in an even-aged forest. In other systems, the canopy may be removed in two or more successive fellings, which results in the future stand developing under the shelter of the old stand. Multiple consecutive small scale cuttings promote continuous forest cover [22].

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Clear cutting

In a clear-cutting regime, the forest stands are completely cleared and then regenerated.

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Shelterwood regime

Shelterwood regime can encompass a wide variety of systems, not all trees are harvested on the stand, creating a more than one forest layer.

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Single tree selection

In single tree and group selection systems, scattered single trees or small groups of trees are selected over the whole area and removed.

The choice of the harvesting system is made by forest management. There is limited information on applied harvesting systems across Europe.

Interactive overview of forest management systems common in Europe.

Note: The darker shading, the more common management system in Europe. Source: [23]

Madurity

Maturity in forest management refers to the felling age within the potential lifespan of a given tree species.

The potential lifespan of tree species is affected by climate, soil quality, abiotic and biotic events, and competition, among other factors. Some species, often labelled as pioneer species, are characterised by fast, early growth rates, limited shade tolerance and short life expectancy. Other species are late-successional species that need shade to regenerate and have slow, early growth rates and longer lifespans.

In actively managed forests, the felling age (or rotation length) is typically significantly shorter than the potential lifespan of a tree species. The felling age is often based on the growth period required to derive a maximum value from a forest stand. The calculation of this period is specific to the forest considered and the management goals. Such goals may be to maximise the economic return from wood production, conserve biodiversity, provide protective functions.

Potential lifespan and typical felling age of economically significant and widespread tree species in Europe

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SCOTS PINE

Potential lifespan: >200 years

Common fellling age: 80-100 years

PEDUNCULATE OR SESSILE OAK

Potential lifespan: >400 years

Common felling age: 110-150 years

NORWAY SPRUCE

Potential lifespan: >200 years

Common felling age: 80-100 years

EUROPEAN BEECH

Potential lifespan: >400 years

Common felling age: 100-130 years

Note. The information is indicative as felling ages vary across Europe and maximum tree age is rarely systematically measured or reported. Also, the reported longevity refers to trees inside forests as individual trees outside of forests trees may get much older.

Source: Common felling age: EFISCEN database. Potential lifespan: [24]

Wood removals

Wood removal is one of the main interventions carried out during the management of forest areas. Wood removal refers to the extraction of tree’s wood components (mainly stem wood but also logging residues) during the tending, thinning, and harvesting operations from the forest. The motivation to remove wood is to produce raw materials for products. In addition to planned wood removals, wood may also be removed (or salvaged) after a catastrophic event.

The tree stems are the main part of the tree that is removed from the forest during harvest operations. Stemwood is still mostly used to produce solid wood products and pulp and paper or fuelwood.

The amount of wood removals in the EU has steadily increased over recent decades. The production of roundwood increased from about 300 M m3 in the early 1990s to more than 500 M m3 (without bark) in recent years [25].

Development of roundwood production in Europe

 


Distribution of roundwood production in Europe, m3/ha

Sources:
1. Camia, A., Giuntoli, J., Jonsson, K., Robert, N., Cazzaniga, N., Jasinevičius, G., Avitabile, V., Grassi, G., Barredo Cano, J.I. and Mubareka, S., The use of woody biomass for energy production in the EU, EUR 30548 EN, Publications Office of the European Union, Luxembourg, 2020, ISBN 978-92-76-27867-2 (online),978-92-76-27866-5 (print), doi:10.2760/831621 (online),10.2760/428400 (print), JRC1227192. Extracted from State of Europe’s Forests 2020 Report - Forest Europe published by Ministerial Conference on the Protection of Forests in Europe3.. Camia A., Robert N., Jonsson R., Pilli R., García-Condado S., López-Lozano R., van der Velde M., Ronzon T., Gurría P., M’Barek R., Tamosiunas S., Fiore G., Araujo R., Hoepffner N., Marelli L., Giuntoli J., (2018). Biomass production, supply, uses and flows in the European Union. First results from an integrated assessment. Publications Office of the European Union. doi:10.2760/5395204. Scarlat, N., Dallemand, J., Taylor, N. and Banja, M., Brief on biomass for energy in the European Union, Sanchez Lopez, J. and Avraamides, M. editor(s), Publications Office of the European Union, Luxembourg, 2019, ISBN 978-92-79-77235-1 (online),978-92-79-77234-4 (print), doi:10.2760/546943 (online),10.2760/49052 (print), JRC109354.

Statistics on wood removals and fellings may not be directly comparable because of differences in reporting methodologies and definitions. Typically, more wood is felled than what is removed from the forest. The difference is due to harvest losses in the form of stem tops, stem parts near the stump of a tree or larger branches. Some smaller or crooked trees may also be felled but not removed from the forest.

Logging residues typically include stem tops, branches and small trees that are felled during harvest activities but which are not removed commercially as roundwood. These logging residues and stumps are often left in the forest to decompose. They may be collected as firewood or extracted during site preparation. In recent years, the interest in using these residues as feedstock for bioenergy production has increased. However, limited information exists on how logging residues are currently extracted in Europe.