Background and Objective

Reproductive material with high genetic diversity and growth potential is required to establish forest regeneration with the ability to adapt to the changing climate. Currently, the management of forest seed stands is typically not focused on high-quality seeds, but rather on timber yield. Best growing trees are removed, while individuals with lower productivity and quality remain for seed production. This problem could be ameliorated by a selective thinning that will retain the most suitable trees to produce seeds for the next generation.
We will study the consequences of a selective reduction of population size and density in an approved seed stand of beech in comparison to a reference population by analysing the mating system and genetic diversity across two generations with DNA markers.
The Thünen Institute of Forest Genetics will carry out the project together with the forest district Oerrel in Lower Saxony (fsb Oerrel). The Northwest German Forest Research Institute (Department Forest Growth) will contribute an economic evaluation. The proposed project aims at the development of policy recommendations to manage approved forest seed stands for the production of high-quality seeds.

Approach

Working package 1 comprises all field work in the approved seed stand, including selection of trees for seed harvest, seed collection, collection of samples for genotyping, selective thinning. The working package 2 covers all genetic analyses, including the characterisations of parent and progeny generation with DNA markers, and the population genetic data evaluation and modelling of mating systems. Working package 3 is focused on progeny testing in the nursery and the evaluation of phenotypic traits. Working package 4 will contribute economic estimates of different management variants. Working package 5 aims to comprehensively summarize all gained results and to drive conclusions for forest management.

Data and Methods

Results

The management of forest seed stands is usually focused on timber yield rather than high-quality seeds. Under target-diameter harvesting regimes the best trees are harvested, leaving those individuals with lower productivity and quality for seed production. The Thünen-Institute of Forest genetics studied the genetic consequences of a selective thinning regime favoring the best trees within a seed stand, leading to a strong reduction of population size and density. The study was conducted in cooperation with the Forest Service of Lower Saxony (fsb Oerrel) and the Northwest German Forest Research Institute (NW-FVA). The study provides recommendations for the management of forest seed stands that enable the production of seeds of high genetic quality as well as high genetic diversity. To produce high quality seeds of beech within the category “Selected”, it is necessary to focus more strongly on quality, growth performance and genetic diversity in addition to current minimum requirements.