Plant interactions as biotic drivers of plasticity in leaf litter traits and decomposability of Quercus petraea

The importance of plant litter traits and decomposability for nutrient cycling processes and plant community dynamics through plant-litter-soil feedbacks has been largely emphasized. However, the role of biotic interactions as drivers of intraspecific variability in litter traits remains surprisingly little studied. In this study, we used a large-scale, multi-site network of long-term tree removal experiments manipulating the abundance of a foundation tree species, i.e. Quercus petraea, to assess how plant interactions control intraspecific variation in oak leaf litter traits and decomposability. We studied 19 plots across eight experimental sites covering a large gradient of oak abundance, stand age and local abiotic context. Oak leaf litter quality strongly declined with tree removal in early forest successional stage. Litter became poorer in nutrients such as N and Mg and richer in secondary metabolites such as lignin and condensed tannins. This in turn slowed its decomposition. Impo...