Dynamics of herbaceous vegetation during four years of experimental coppice introduction
Understanding the effects of coppicing on forest ecosystems is important for progress towards sustainable forest management. A newly established coppicing experiment in a secondary temperate deciduous forest in the SE Czech Republic provides a rather unique insight into succession driven by canopy thinning in a forest still lacking species typical for forests established since long time ago. Herbaceous layer vegetation was monitored for four subsequent years in 2012-2015. We focused on the influence of canopy thinning intensity in two different forest types defined by dominant tree species (oak and lime). Our results showed that the opening of the canopy had immediate effects on herbaceous vegetation. Coverage, species richness and compositional patterns followed the coppicing intensity gradient. The dominant tree species had contrasting effects. Under oak, the reaction to coppicing was weak. Under lime, strong reaction both related to coppicing intensity and temporal development was observed. Herbs with short life cycle had the greatest contribution, but perennial grasses also began to increase their coverage after coppicing. Several invasive species, mostly short-lived herbs, emerged but are supposed to retreat as the succession will proceed. We conclude that coppice introduction to a secondary forest led to contrasting patterns related to dominant tree species. The marked difference was probably due to the slow sucession towards a future forest community saturated by species. This process may be now further diversified by coppicing management.
Patterns of functional diversity of two trophic groups after canopy thinning in an abandoned coppice
Coppice abandonment had negative consequences for biodiversity of forest vegetation and several groups of invertebrates. Most coppicing restoration studies have focused only on a single trophic level despite the fact that ecosystems are characterized by interactions between trophic levels represented by various groups of organisms. To address the patterns of functional diversity in the perspective of coppicing restoration, we studied the short-term effects of conservation-motivated tree canopy thinning in an abandoned coppice-with-standards in Central Europe, a region where such attempts have been rare so far. The functional diversity of vascular plants and spiders, chosen as two model trophic groups within a forest ecosystem, was compared between thinned and control forest patches. To characterize functional patterns, we examined several functional traits. These traits were assigned into two contrasting categories: response traits reflecting a change of environment (for both vascular plants and spiders) and effect traits influencing the ecosystem properties (only for vascular plants). Functional diversity was analysed by CCA using two measures: community-weighted means (CWM) and Rao's quadratic diversity (RaoQ). CCA models revealed that the canopy thinning had a positive effect on diversity of the response traits of both trophic groups and negatively influenced the diversity of effect traits. In addition, we found distinct seasonal dynamics in functional diversity of the spider communities, which was probably linked to leaf phenology of deciduous trees and therefore an effect trait not directly examined in this study. We conclude that canopy thinning affected functional diversity across trophic groups during the initial phase of coppicing restoration. With necessary precautions, careful canopy thinning can be effectively applied in the restoration of functional diversity in abandoned coppices.
Habitat requirements of endangered species in a former coppice of high conservation value
Transformation of coppices to high forests has caused fundamental changes in site conditions and a decline of many species across Central Europe. Nevertheless, some formerly coppiced forests still harbour a number of the declining species and have become biodiversity hotspots in the changing landscape. We focused on the best preserved remnant of formerly grazed and coppiced subcontinental oak forest in the Czech Republic - Dúbrava forest near Hodonín. To improve our understanding of the ecology of the declining species, we studied local habitat requirements of vascular plants most endangered at the national level. We recorded vegetation composition and sampled important site variables in plots with the largest populations of endangered species and in additional plots placed randomly across all major forest habitats. We demonstrated that sites with endangered species have a highly uneven distribution in ecological space and their species composition is often similar to open-canopy oak forests. Within this habitat, the endangered species are concentrated in places with a high light availability and high soil pH. Light-demanding species characteristic of subcontinental oak forests are the best indicators of these sites, while broadly distributed shade-tolerant and nutrient-demanding species avoid them. These results support the view that the occurrence of many endangered species in Dúbrava forest is a legacy of the long history of traditional management that kept the canopies open. The light-demanding species are now threatened by ongoing successional changes. Therefore, active conservation measures are recommended, including opening up the canopies, early thinning of young stands, control of expansive and invasive species and understorey grazing or mowing.