Regeneration practices

Regeneration refers to the silvicultural operation of establishing forest stands. There is a range of methods that can be applied in the regeneration process of a forest:

Silvicultural practices for regeneration of a forest

Type of regeneration

Natural regeneration

Natural regeneration is the establishment of forests stand through natural seeding or coppice

Natural seeding is largely determined by the availability of seeds from nearby stands. This method relies to a large extent on the composition with regards to tree species and genotypes of the previous generation.

Coppice is the stimulation of the development of new shoots from stumps and roots of cut trees. The feasibility of this method relies mainly on the capability of trees species to coppice, which is far more common on broadleaves.

Artificial regeneration

Artificial regeneration encompasses planting and artificial seeding activities, allowing the selection of tree species. It is guided by the environmental site conditions that ultimately determine whether a species will survive and remain healthy, as well as its growth rate [5]. Artificial regeneration provides more direct control over the tree species, genotypes and placement of trees in the new stand [5].

Combination of natural and artificial regeneration

Combination of natural and artificial regeneration are also possible. The choice of a regeneration method is guided by the management goal (e.g., timber production, biodiversity protection), the preferred tree species , and the availability and cost of reproductive material (such as seeds and seedlings). Furthermore, the choice of a regeneration method is closely linked to the harvest regimes that are applied.

Main regeneration types

Over 60% of forests in the EU originate from natural regeneration. Coppicing has been more widespread in the past, but nowadays only about 4% of the total forest area are originated by this method, mainly in South-East European countries.

Forest area (Mha) and share of forest area (%) by regeneration type in the EU27 in 2015

 

Regeneration type by country over time

Regeneration origin distribution by country

 

Annual regeneration by country and type in 2000

 

Annual regeneration by country and type in 2010

 

Annual regeneration by country and type in 1990

 

Annual regeneration by country and type in 2005

 

Annual regeneration by country and type in 2015

 

Overall, planting is the most common artificial regeneration method in Europe. Regeneration by sowing is limited to regenerating stands of light demanding conifers on sites that have been clear-felled in North and Central-East Europe.

Forest reproductive material

The choice of forest reproductive material refers to the decision by a forest manager on the material (i.e., seeds or seedlings produced from seeds, cuttings, or other propagating parts of a tree) to be used during the regeneration stage. The choice is closely related to the choice of the tree species composition and regeneration method (mainly artificial regeneration). The choice of breeding material is also important in the context of afforestation.

When applying artificial regeneration, a forest manager can choose whether to use seeds (or seedlings produced from seeds) that have been collected in registered seed stands, or to use improved forest reproductive material developed from seed orchards. Improved forest reproductive material relates to material that has been selected and/or tested to obtain benefits, such as increased productivity, improved timber quality, better resilience to climatic conditions, pests and diseases. Another option is to use forest reproductive material that has been genetically modified, but genetically modified trees are currently not used in European forestry due to regulatory restrictions and limited public acceptance.

Use of forest reproductive material

Information on the use of tree breeding material in forest management is limited and can only be inferred from statistics on production and trade of seedlings and seeds, as well as information on tree breeding programmes. In the period 2004–2014, on average 30 M plants and 400,000 kg seeds were traded annually. Coniferous reproductive material trade is dominated by Scandinavian and Baltic countries, while about 15% of traded seedlings were of hardwood tree species, especially in Central Europe [7].

Trade of seedlings in the EU27, %

 

Annual trade of seedlings within the European Union, including data on Spain, France, Belgium, Austria, Czech Republic, Slovakia, Poland, U.K, Netherlands, Germany, Denmark, Latvia, Lithuania, Estonia, Finland, and Sweden [7].

Tending operations

Tending operations are carried out to benefit a forest crop at any stage of its life between the seedling and the mature stages: weeding, cleaning, thinning, pruning, climber cutting and girdling. The primary purpose is to produce higher quality timber and maximise income.