Scaling functional traits to ecosystem processes: towards a mechanistic understanding in peat mosses

1. The role of trait trade-offs and environmental filtering in explaining the variability of functional traits and ecosystem processes has received considerable attention for vascular plants but less so for bryophytes. Thus, we do not know whether the same forces also shape the phenotypic variability of bryophytes. Here we assess how environmental gradients and trade-offs shape functional traits and subsequently ecosystem processes for peat mosses (Sphagnum), a globally important plant genus for carbon accumulation. We used piecewise Structural Equation Modeling (SEM) to understand how environmental gradients influence vital processes across levels of biological organization. 2. We gathered data on functional traits for 15 globally important Sphagnum species covering a wide range of ecological preferences. Phenotypes lie along well-established axes of the plant economic spectrum characterizing trade-offs between vital physiological functions. Using SEM we clarified the mechanisms of tra...