Guidelines for seed harvesting in forest seed stands

The strategic selection of seed stands represents a cost-effective and quick method in forestry for obtaining forest reproductive material of improved quality. Hence, for already more than 50 years the EU has regulated how these seed stands should be selected. The first EU-Directive on forest reproductive material was issued and the respective regulations have been implemented in the Member States accordingly. In general, forest stands are certified as basic material if a set of qualitative requirements is fulfilled. At the same time, seed stands should be well adapted to their environment and free from attacks of damaging organisms, such as pathogens. The number and spatial distribution of seed trees is of utmost importance to preserve genetic variation.

Improved technical guidelines have been prepared within FORGER to support forest practitioners in harvesting seeds in those stands. The tree species of the temperate zone, such as Norway spruce (Picea abies), oaks (Quercus spp.), beech (Fagus sylvatica) and wild cherry (Prunus avium) have been in the focus. For these species, information is provided on how many seed trees within seed stands should be harvested and what spatial arrangement they should have for seed harvests to be genetically sustainable. These recommendations may be of relevance also for other tree species that share biological similarities with the above-mentioned tree species.

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Guidelines for the choice of forest reproductive material in the face of climate change

Future performance and resilience of regenerated forest stands depends on the inherited genetic quality of the forest reproductive material (FRM) used. In the context of projected rapid climate changes, forest managers need to find ways to take decisions about the long-term management of forests without complete knowledge about what future conditions will be like. Current knowledge does not allow us to determine precisely whether a close-to-nature approach (which relies on spontaneous, natural processes) or proactive interventions in forest regeneration is better suited to fostering adaptation in forest ecosystems. An option for enhancing adaptation is human-assisted transfer of tree populations, guided by projections of future climate conditions. However, this approach has not been widely accepted in Europe, partly because of uncertainties about its results and partly because climate changes have so far affected Europe to a lower extent than other regions.

The present guidelines based on the findings of FORGER focus on issues related to the choice of FRM in the face of climate change. These are derived from knowledge generated by field studies and modelling. The objective is not to single out the most appropriate approach, valid in all conditions, but rather to present most recent research findings to support decision-making and analysis by forest managers, conservationists and field ecologists.

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