Project: Genetic testing of oak in Sweden

This project was concluded in 2022.

Project information

Project manager
Johan Kroon
Participating organizations
Linnaeus University, Skogforsk
Financiers
Föreningen Skogsträdsförädling/Stiftelsen konsul Faxes donation, Erik Stenströms stiftelse för ekskogsbrukets främjande, Erik och Ebba Larssons samt Thure Rignells stiftelse, Stiftelsen Petersson-Grebbe, Stiftelsen Extensus
Timetable
2018–2022
Subject
Forestry and wood technology (Department of Forestry and Wood Technology, Faculty of Technology)

More about the project

The aim of the project is to give guidelines of the genetic material of oak for use in operational forestry. The project will genetically test oak of different origin. Special attention is given to sessile oak (Quercus petraea) which is also included in the testing. In general, the project will provide improved knowledge about the genetics of oak in Sweden. In this project, we have collected acorns from individual trees and grown plants for continued testing in offspring trials in southern Sweden for long-term studies of vitality (climate adaptation), growth and stem quality. Early tree characteristics will be evaluated within the project period.

When cultivating noble deciduous trees, it is often the question of long generation times and the economic outcome is very strongly dependent on the timber quality obtained from the final product. For a forest owner, it is also important and extra satisfactory if a young forest can be established quickly. This is favoured by oak that is vital (climatically well adapted) and exhibits rapid youth growth and has consistently straight stem.

It is therefore essential to start from well tested genetic material. Besides the genetic material itself having a high production potential and producing good quality wood, it is of the utmost importance that the material is well adapted to the climate in which it is to be grown. For example, the conditions for oak to cope with the now-so-known "oak death", which is considered to be a very complex problem caused by various stress factors, should be considerably greater if the trees are climatically well adapted. Knowledge and access to good genetic material for different species of trees also increases the freedom of action when new forests are established.

There are only two native oaks in Scandinavia, pedunculate oak (Quercus robur) and sessile oak (Q. petraea). So far in forest cultivation of oak in Sweden, the interest has been concentrated to pedunculate oak. Therefore, the value of the closely related sessile oak in forest production is pretty much unknown. Today there are also no comparative field trials for systematic evaluation of sessile and pedunculate oak in Swedish conditions, which means that there is no scientific basis for assessing differences linked to growth and survival.

There is a shortage of indigenous genetic cultivation material for many deciduous species, which is compensated by the import of both seeds and plants from the continent. However, we do not know whether such material is suitable for use in Sweden. Using a genetic material that has been moved far from the planting site is a risk-taking. Since southern Sweden constitutes the northern boundary of the natural range of the noble deciduous trees, it is probably extra important to have control of genetic traits linked to climatic adaptation.

Knowledge about the importance of provenance and the different value of seed sources in oak in Sweden is very lacking today. In an ambitious study to gather research results on oak in Europe, there is no reference to Swedish studies (Eriksson 2015). Although the state of knowledge for Swedish oak is limited, there are results from oak in the continent where clear differences in growth rhythm and growth have been shown to be dependent on differences in the origin of the material.

For two years, Skogforsk has collected acorns and grown seedlings to test oak offsprings in genetic field trials, with an additional purpose to include sessile oak. Acorns from individual trees were sown in seed boxes with the goal of retraining about 200 cover root plants per variety after retraining. Two trials will be planted in the coming spring with offspring (families) from about 50 sessile oaks and 80 pedunculate oaks originating from Swedish populations, as well as reference families of sessile oaks from Denmark, Germany and Croatia. Acorn was sown in autumn 2018, and today there are enough plants for two planned field trials with about 6,000 plants each. The plants are labeled and should be packed for freezing storage during the winter. Planting in field trials is scheduled for spring 2020.

The project is part of the research in the Forest Ecology and Ecophysiology research group.