Edge influence on understorey plant communities depends on forest management

Abstract

Questions Does the influence of forest edges on plant species richness and composition depend on forest management? Do forest specialists and generalists show contrasting patterns? Location Mesic, deciduous forests across Europe. Methods Vegetation surveys were performed in forests with three management types (unthinned, thinned 5–10 years ago and recently thinned) along a macroclimatic gradient from Italy to Norway. In each of 45 forests, we established five vegetation plots along a south‐facing edge‐to‐interior gradient (n = 225). Forest specialist, generalist and total species richness, as well as evenness and proportion of specialists, were tested as a function of the management type and distance to the edge while accounting for several environmental variables (e.g. landscape composition and soil characteristics). Magnitude and distance of edge influence were estimated for species richness per management type. Results Greatest total species richness was found in thinned forests. Edge influence on generalist plant species richness was contingent on the management type, with the smallest decrease in species richness from the edge‐to‐interior in unthinned forests. In addition, generalist richness increased with the proportion of forests in the surrounding landscape and decreased in forests dominated by tree species that cast more shade. Forest specialist species richness, however, was not affected by management type or distance to the edge, and only increased with pH and increasing proportion of forests in the landscape. Conclusions Forest thinning affects the plant community composition along edge‐to‐interior transects of European forests, with richness of forest specialists and generalists responding differently. Therefore, future studies should take the forest management into account when interpreting edge‐to‐interior because both modify the microclimate, soil processes and deposition of polluting aerosols. This interaction is key to predict the effects of global change on forest plants in landscapes characterized by the mosaic of forest patches and agricultural land that is typical for Europe.

Response to Comment on “Forest microclimate dynamics drive plant responses to warming”

“…Forest ecologists are very much aware that many species benefit from canopy openings, and many of us have extensively worked on this topic (9)(10)(11). We also fully agree that at a landscape scale, biodiversity is enhanced by forest patches with deep shade and more open patches or edge habitat, as shown by many studies, including our own work (12,13). Environmental change affects forest understory plant communities in many ways, and we agree with the general remarks in Schall and Heinrichs' concluding paragraphs.…”

Small scale environmental variation modulates plant defence syndromes of understorey plants in deciduous forests of Europe

“…More details can be found in Govaert et al (2020) and Meeussen et al (2020) as we rely on the same study design.…”

“…Plant material was collected for all four study species occurring in each of the 225 plots. Sampling of plant material was conducted during early summer 2018, starting at the southernmost plots to account for differences in phenological stages across latitudes [see Govaert et al (2020) for details].…”

“…Future research addressing the inducibility of both defence and tolerance traits in response to herbivore feeding will contribute to a better understanding of the importance of induced trait responses in shaping patterns along environmental gradients. Forest edge-to-core transects can in this context act as an extremely useful study system as they are characterized by strong biotic and abiotic clines over a small spatial scale (De Frenne et al, 2019;De Smedt et al, 2019;Govaert et al, 2020;Lantman et al, 2019;Meeussen et al, 2020;Murcia, 1995;Remy et al, 2016).…”

“…The spatial scale of sampling along latitudinal or elevational gradients (partly) mismatches the spatial scale of evolutionary processes that are postulated to drive variation in defence traits (Gaston, 2000). Forest edge-to-core transects, for example, are characterized by strong abiotic clines in temperature, humidity, light and soil nutrient availability (De Frenne et al, 2019;Meeussen et al, 2020;Murcia, 1995;Remy et al, 2016), as well as biotic clines in the floral, arthropod and gastropod community composition over less than 100 m (De Smedt et al, 2019;Govaert et al, 2020;Lantman et al, 2019).…”