Site conditions and functional traits affect regeneration dynamics of European hornbeam ( Carpinus betulus L.) in forest canopy gaps


Abstract: European hornbeam is a deciduous tree in mixed forest ecosystems, making a valuable contribution to species richness at a community level. We investigated early-phase regeneration of saplings in canopy gaps under contrasting ecological conditions by analyzing relationships between site parameters, leaf nutrients, and light-regulated carbon and water exchange functions at ecosystem and forest levels. Using plant response variables, we also detected functional soft traits and trade-offs. Species abundance proved to be affected by the elevation and slope of the sites, air humidity, precipitation during the growing period, as well as light-dependent and light-saturated rate of the assimilation function. Relationship between leaf potassium and transpiration proved to be the most effective plant functional trait across the sites. Under seasonally fluctuating, warm-dry and cold-semidry climate conditions with limited light availability, nutrient-gas exchange trade-offs modulated sapling development. Specifically during autumn, we detected extended leaf phenology in gas exchange functions under light-amplified warm and humid climate conditions. Our results suggest that natural regeneration of European hornbeam can be improved by lower and higher irradiation adjusted by plant functional traits, depending on site-specific and climate-related ecological parameters. These conclusions can provide a scientific basis for decision-making and practical implementations in forest management.

Keywords: Canopy gap dynamics, light response, gas exchange function, soft trait, extended leaf phenology

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