Coppice management affects leaf traits in understory species of Mediterranean oak forests

Abstract

Coppice management is returning to be a widespread silvicultural practice across European forests. However, its effects on understorey species remain poorly understood, particularly in Mediterranean woodlands. Elucidating intraspecific trait responses of these species will help to predict the interactive effects of coppicing and climate change on a relevant aspect of forest biodiversity and ecosystem functioning. We analysed leaf trait variation in ten representative herbaceous species (specialists and generalists) and the related shifts in CSR plant strategies. We compared conspecific plants from young coppice-with-standards oak stands and next high stands, across two sites in Italy. Coppicing increased the intraspecific variability of most traits and specific leaf area while reducing that of leaf area and Mg content. Both leaf area and specific leaf area were reduced, with the latter showing a significant decrease in the generalist species. Most species exhibited increased leaf dry matter content, likely due to acclimation to dryer conditions and broader temperature variations in the coppice stands. Specialists showed a reduction in leaf K and Ca concentrations whereas generalists decreased N content, thus resulting in a higher C:N ratio. Some responses appeared species-specific or shared by closely related species. Changes in trait values resulted in shifts in the CSR space towards a reduction of competitive ability and an increase of stress tolerance. Keeping forest density and closed canopies appears relevant to support the life and functions of Mediterranean understory plants, notwithstanding that the maintenance of small coppice stands may prompt phenotypic acclimation processes to ongoing global warming.