Data from: 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 trait
covariation and scaling to ecosystem processes. We tested whether peat
mosses, like vascular plants, constrain trait variability between a fast
turnover strategy based on resource acquisition via fast traits and
processes, and a strategy of resource conservation, via slow traits and
processes. 3. We parameterized a process-based model estimating ecosystem
processes linking environmental drivers with architectural and functional
traits. In our SEM approach the amount of variance explained varied
substantially (0.29 ≤ R2 ≤ 0.82) among traits and processes in Sphagnum,
and the model could predict some of them with high to intermediate
accuracy for an independent dataset. R2 variability was mainly explained
by traits and species identity, and poorly by environmental filtering. 4.
Some Sphagnum species avoid the stress caused by periodic desiccation in
hollows via resource acquisition based on fast photosynthesis and growth,
while other species are adapted to grow high above the water table on
hummocks by slow physiological traits and processes to conserve resources.
5. Synthesis. We contribute to a unified theory generating individual
fitness, canopy dynamics and ecosystem processes from trait variation. As
for vascular plants, the functional traits in the Sphagnum economic
spectrum are linked into an integrated phenotypic network partly filtered
by the environment and shaped by trade-offs in resource acquisition and
conservation.