Search

Seed stratification can substantially improve germinability. In glasshouse settings, knowledge of stratification requirements is critical for allowing effective control of germination. In addition, for species that seed irregularly, understanding how to break dormancy of aged seeds is important. This study tests whether moisture is required as well as cold conditions to stratify Nothofagus cliffortioides (Hook.f.) Oerst. (mountain beech) seeds, and whether shading during the germination period improves germination and survival. The seeds tested had been collected during a heavy mast year and stored dry for c. 2 years at −20°C. Dry cold stratification failed to break dormancy, with average germination (3.3%) not significantly different from unstratified controls (5.3%). In contrast, average germination of moist cold stratified seeds was at least four times higher (21.7%), with most germination occurring within 30 days. Hessian covers on trays had no impact on germination or survival. These results provide useful information for growing N. cliffortioides from seed and raise the possibility that lengthened drought periods under future climate regimes could affect natural Nothofagus regeneration by reducing the effectiveness of natural winter conditions for breaking seed dormancy. [ABSTRACT FROM AUTHOR]

Tree seedling establishment outside forest boundaries is controlled by many interacting factors. Understanding the relative importance of different pressures is essential for improving techniques for forest restoration and for understanding the potential of forest boundaries to shift and adapt to changing climate conditions.We investigated constraints on the spread of a key southern hemisphere forest type into grasslands by undertaking a multifactorial experiment sowing Nothofagus cliffortioides (Nothofagaceae) in a historically deforested retired pasture. We manipulated factors to determine the relative effects of sheltered microsites, competition with pasture species, availability of ectomycorrhizal fungi, soil nutrients and rabbit herbivory, on seedling emergence and survival.Overall survival was low (11.7% after 6 months and 1.5% after 10 months), but there were strong treatment effects on both seedling establishment and survival. The availability of shelter and competition with pasture species had strongest effects, with the presence of pasture species initially aiding seedling emergence due to a sheltering effect, but negatively affecting survival at later stages. Most remaining seedlings at the conclusion of the experiment had formed ectomycorrhizae regardless of whether inoculum was supplied, and seedling survival and health was positively related to ectomycorrhizal colonization. Fertilizing had less of an effect than other factors, and results regarding rabbit herbivory were inconclusive.Synthesis and applications. This study provides new insights into how factors interact to limit tree seedling establishment in grasslands and forest expansion into neighbouring ecosystems. This improves understanding of the ability of an ectomycorrhizal keystone forest species to migrate and adapt to climate change. This study also assists restoration practitioners in selecting techniques that will enhance seedling establishment, and highlights that direct seeding approaches in open grasslands are unlikely to result in high rates of Nothofagus establishment. [ABSTRACT FROM AUTHOR]