Abstract

When mature beech forests are harvested, the new regeneration is established by natural regeneration, which is by using the seeds from the old stand to create the new generation. Most often the seed from a single mast year is used preceded by site preparation. After seed-fall, a heavy thinning in the old stand is performed, leaving a protective shelter. Sometimes an alternative, less intense regeneration method is used, which involves the use of seed from several mast years and no site preparation. These methods usually result in adequate regenerations but sometimes failures occur in old stands with a low site index, a thick humus layer, and acid soils. The occurrence of mast years and the size of the seed production in them are important factors when working with natural regeneration. The mean interval between mast years has been about five years since the end of the 17th century, but during the last 30 years this has decreased to 2.5 years. Seed production increased with increasing site index and mast years were usually preceded by a warm and dry July in the previous year. An alternative, more extensive regeneration method is currently sometimes used in southern Sweden. The method has both economic and ecological advantages. Seed from several mast years are used and instead of site preparation, several judicious cuttings are made in the old stand in order to regulate the conditions of the forest floor in a way that promotes the establishment and growth of the new seedlings. The regeneration dynamics have been studied and documented and the method has resulted in good regenerations, independent of site index. However, regeneration failures sometimes occur at old sites with low fertility and a low pH. In Europe, liming is an option to overcome these difficulties. To study the effect of liming, 12 sites in southern Sweden were limed in 1991 and 1993, and in 2007 three of these were regenerated using the traditional method, and three were regenerated with the alternative method. Neither the sizes of the seed-falls nor the height growth of new seedlings were influenced by liming. When the traditional method was used, liming improved the regeneration result in a stand of low site index, while the opposite effect was found in a stand of high site index. Seedling survival, the size of earthworm populations, and the concentrations of a potential defensive compound in seedling leaves, chlorogenic acid, all increased after liming. In the alternative regeneration method, the numbers of germinates developing in years following mast years was negatively affected by liming in the first six years after liming. Thereafter the effect was positive. Liming shortens the regeneration period and increases the number of seedlings.

Keywords

fagus sylvatica; natural regeneration; seed production; site preparation; liming; oligochaeta; sweden

Published in

Acta Universitatis Agriculturae Sueciae
2010, number: 2010:12
ISBN: 978-91-576-7489-0
Publisher: Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences

SLU Authors

• Övergaard, Rolf

  • Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Forest Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/28771