Table 1 Some examples of evolution-oriented forestry practice, including re-orientation of usual interventions (no supplementary cost) and additional interventions
From: Considering evolutionary processes in adaptive forestry
Forestry practice | Expected benefits | Associated costs and risks |
|---|---|---|
N e-oriented regulation of the density and spatial distribution to equalize reproductive success between trees in small populations | Reduce the variance in reproductive success to reduce genetic drift | No supplementary cost |
Reduce spatial genetic structure in the seedlings and inbreeding in next generation | Risk to slow down the elimination of detrimental genes, prefer equalization of mating success per patch (compatible with the next line) | |
In heterogeneous environment, dissociate areas of production and areas of evolution (selection patches in harsh areas) and allow gene flow between these entities | Increase the reproductive contribution of the trees that have survived to drastic selection pressure | Limited supplementary cost |
Requires preliminary simulation studies to estimate benefits in various contexts (strength and spatial structure of the environmental heterogeneity) | ||
Save the lone tree, which cumulates long distance dispersal (in allo-pollinated seeds) and can be adapted to marginal conditions; collect seeds for local assisted regeneration | Diversify the mating pairs to favour the emergence of new genotypic combinations | Limited supplementary cost |
Requires a protocol for assisted regeneration | ||
Promote adaptation to marginal conditions | ||
Risk of inbreeding if self-pollinated seeds are not purged at a very early stage (e.g. seed abortion) | ||
Assisted local seed dispersal (e.g. collecting, possibly over several years, mixing and replanting seeds within the stand) or pollen dispersal (e.g. air flow used in seed orchards) | Enhance local gene flow to diversify the mating pairs and favour the emergence of new genotypic combinations | Potentially significant supplementary cost |
Requires preliminary studies to estimate benefits in various contexts (genetic diversity and spatial structure) | ||
Reduce inbreeding | ||
Requires a protocol for assisted regeneration | ||
Enhance local migration capacity by favouring seed dispersal and germination at distance from the main stand | Speed-up colonisation of locally favourable habitats in an environmental gradient | Potentially significant supplementary cost |
Genetic enrichment by introduction of a limited amount of seeds or pollen from presumably pre-adapted allochthonous origins | Introduce pre-adapted genotypes | Potentially significant supplementary cost |
Increase local genetic diversity | Risk of gene swamping and reduction of effective population size (N e) if local population is small and if introduced material has low genetic diversity | |
Risk of unforeseen local maladaptation | ||
Marker-assisted selective thinning (futurist) | Increase selection intensity on target major genes while retaining genetic diversity in the rest of the genome | High supplementary cost |
Requires accurate genetic knowledge and high-throughput genotyping capacities |