Oak often needs to be promoted in mixed beech-oak stands - the structural processes behind competition and silvicultural management in mixed stands of European beech and sessile oak

Abstract

Biogeosciences and Forestry Biogeosciences and Forestry Oak often needs to be promoted in mixed beech-oak standsthe structural processes behind competition and silvicultural management in mixed stands of European beech and sessile oak Kobra Maleki (1) , Laura Zeller (2) , Hans Pretzsch (2) Forest ecosystems nowadays provide multiple ecosystem goods and services at a time and throughout all development phases. Species mixing is considered an effective measure to gain benefits beyond purely additive effects. However, the complex structural processes behind interspecific competition and temporal and spatial facilitative effects through mixing are still far from being understood and predictable. In particular the mixture of European beech (Fagus sylvatica L.) and sessile oak (Quercus petraea [Matt.] Liebl.) is gaining even more importance due to the fact that forests from these species are considered more tolerant to climatic effects and are expected to expand their natural range to the north due to global warming. The 30 long-term experimental plots analysed in this study reveal the structural processes in mixed beech-oak stands based on data at the tree and stand level. Using spatial and non-spatial structural indices, we can show an increasing dominance of beech over oak in unmanaged stands and the effectiveness of thinning operations to support oak. Those processes are representative for other light-demanding tree species in mixtures with shade-tolerant species. Improving the knowledge on the structural processes in mixed-species stands is particularly relevant when trying to modify forest structure in order to adapt forest management to shifting environmental conditions and the increasing demand for ecosystem services.

Beech and hornbeam dominate oak 20 years after the creation of storm-induced gaps

“…Since beech and hornbeam are more sensitive to drought than oak (Bréda et al, 2006;Friedrichs et al, 2009), their future remains uncertain in the context of more intense and/or more frequent spring and summer droughts (Jump et al, 2006;Geßler et al, 2007). However, beech and hornbeam are strong competitors for oak, especially during the regeneration stage (Ligot et al, 2013;Petritan et al, 2012;Van Couwenberghe et al, 2013), and have strong negative impacts on the survival, height and diameter growth of young oaks (Jensen and Löf, 2017;De Groote et al, 2018;Maleki et al, 2020). In this context, it is crucial to identify which environmental and silvicultural conditions would favour the regeneration of oak compared to that of hornbeam and beech in order to define management options that would facilitate oak regeneration and eventually promote oak in European forests in the next century.…”

Leaf Phenological Responses of Juvenile Beech and Oak Provenances to Elevated Phosphorus

“…This is likely since oaks are more tolerant to cold temperatures, which allows them to begin their growing cycle earlier than beeches. Research considering comparison of leaf phenological responses to various environmental factors between these forest species are lacking, although they often form valuable mixed stands all over Europe [39,40]. Due to differences in their genetics and physiological processes, they may respond differently to elevated P, as well.…”

Chances and Limitations of Mixed Oak Regeneration under Continuous Canopy Cover—Evidence from Long-Term Observations

“…These principles can be implemented in practice, especially by using single-tree selection, group selection, or shelterwood systems [28]. However, the utilization of natural processes, as a core element of close-to-nature silviculture in particular, puts native oaks at an additional disadvantage compared to their mostly more shade-tolerant admixed tree species [18,23,31,32]. This appears to further weaken oaks in their relative competitive strength on many sites, often resulting in a decline in vitality or loss of oaks in young and mature stands.…”