Restoration of southern hemisphere beech (Nothofagaceae) forests: a meta-analysis

Nothofagus (southern beech) species form a major component of southern hemisphere forests, and in many regions are becoming an important focus for restoration efforts. However, restoration projects are predominantly carried out at small, local scales using a wide range of different techniques that have produced mixed results. In order to improve outcomes and develop general strategies for southern beech restoration, we review and compare data from previous trials to determine what techniques have been scientifically tested, identify the most effective methods, and pinpoint gaps in current practices. We assessed the effects of restoration techniques, applied in 91 trials from 22 publications across the southern hemisphere, on seedling survival and growth. Providing shelter improved both seedling survival and growth, controlling weeds improved survival, and protecting from herbivores improved seedling growth. Despite being one of the most commonly applied techniques, fertilizer application only marginally improved seedling survival and did not significantly influence seedling growth. Other techniques, such as increasing glasshouse container size or growth time or manipulating soil before planting, showed mixed results. Surprisingly, no trials examined the use of ectomycorrhizal fungal inoculum as a restoration technique. We discuss the outcomes of this review in the context of our current understanding of southern beech regeneration ecology, to inform future Nothofagus restoration practices and suggest where future research should be directed.