Variation in irradiance, soil features and regeneration patterns in experimental forest canopy gaps

Abstract

Key message Natural regeneration of beech, maple and fir was investigated in relation to irradiance, ground vegetation and soil features. Seedling establishment may be favoured by creating small and irregular gaps and by successive extension of gaps along the sun-exposed gap edge. Context To successfully manage natural regeneration, it is important to understand the interactions of forest gap micro-climates and soil features. Aim The aim of this study was to identify conditions for successful natural regeneration of European beech, sycamore maple and silver fir in mixed forests. Methods Seedling growth and survival were recorded within and around two artificial gaps, and the relationships to irradiance, ground vegetation and soil features were examined. A simple conceptual model was applied to identify optimal micro-sites for regeneration. Results Ground vegetation hindered the establishment of natural regeneration in the centre of the gaps. Small seedlings of maple and beech were more abundant within the small gap and along gap edges; beech had the highest density on sun-exposed edges and maple on shaded gap edges. Tall beech and maple seedlings were more abundant along sun-exposed gap edges. Greater variability of irradiance in the larger gap contributed to greater micro-site heterogeneity relative to the small gap. Conclusions Seedling establishment may be favoured by creating small and irregular gaps and by successive extension of gaps along the sun-exposed gap edge. Circular gaps with diameters greater than stand height contribute to increased ground vegetation coverage and hinder tree regeneration, including semi-shade tolerant maple and spruce.

Comparison of drought stress indices in beech forests: a modelling study

“…), and lime (Tiliacordata Mill.) make up less than 1% of the total stem volume (Vilhar et al 2015). The bedrock consists of Cretaceous limestone, and the soil depth varies from 10 to 40 cm depending on the highly variable karstic micro-relief.…”

“…Drought stress would be more likely to occur in shal- low soils such as those in this study. There have been several studies on water supply in canopy gaps (Ritter & Vesterdal 2006, Dalsgaard 2007, Vilhar & Simončič 2012 in which soil water availability influences forest regeneration and establishment (Gray & Spies 1996, Madsen & Hahn 2008, Vilhar et al 2015. However, drought stress studies are scarce in old-growth forests, and some studies indicate differences in water supply stress between managed and oldgrowth forests at similar sites (Ritter 2004, Vilhar et al 2005, Vilhar & Simončič 2012.…”

“…We also investigated whether the water supply stress differed between the four sites. This was performed to demonstrate the effect of gap creation as a forest management practice on forest regeneration water supply stress (Vilhar et al 2015). The comparison of selected drought stress indices should aid in the development of an efficient tool for field water supply diagnosis (Bergès & Balandier 2010).…”

Black Pine Afforestations in Abruzzo (Central Italy): Perspectives and Management

“…In temperate forests [30][31][32][33]; in several tropical rain forests [34,35]; in the coniferous forest of the Pacific Northwest USA [36,37]; in long-leaf pine ecosystems of south-eastern USA [38][39][40] and in Australian eucalyptus natural forests [24,41].…”

Do composition and richness of woody plants vary between gaps and closed canopy patches in subtropical forests?

“…As a consequence, gaps and closed canopy areas are expected to support germination and growth of different suites of species, resulting in different composition and richness between them (Denslow ; Swaine & Whitmore ; Vilhar et al. ).…”