Data from: Plant functional traits and environmental conditions shape community assembly and ecosystem functioning during restoration

Recovering biological diversity and ecosystem functioning are primary
objectives of ecological restoration, yet these outcomes are often
unpredictable. Assessments based on functional traits may help with
interpreting variability in both community composition and ecosystem
functioning because of their mechanistic and generalizable nature. This
promise remains poorly realized, however, because tests linking
environmental conditions, functional traits, and ecosystem functioning in
restoration are rare. Here, we provide such a test through what is to our
knowledge the first empirical application of the ‘response–effect trait
framework’ to restoration. This framework provides a trait-based bridge
between community assembly and ecosystem functioning by describing how
species respond to environmental conditions based on traits and how the
traits of species affect ecosystem functioning. Our study took place
across 29 prairies restored from former agricultural fields in
southwestern Michigan. We considered how environmental conditions affect
ecosystem functioning through and independently of measured functional
traits. To do so, we paired field-collected trait data with data on plant
community composition and measures of ecosystem functioning and used
structural equation modelling to determine relationships between
environmental conditions, community-weighted means of functional traits
and ecosystem functioning. Environmental conditions were predictive of
trait composition. Sites restored directly from tillage (as opposed to
those allowed to fallow) supported taller species with larger seeds and
higher specific leaf area (SLA). Site age and fire frequency were both
negatively related to SLA. We also found a positive relationship between
soil moisture and SLA. Both trait composition and environmental conditions
predicted ecosystem functioning, but these relationships varied among the
measured functions. Pollination mode (animal pollination) increased and
fire frequency decreased floral resource availability, seed mass had a
negative effect on below-ground biomass production, and vegetative height
increased decomposition rate. Soil moisture and fire frequency both
increased while site age decreased above-ground biomass production, and
site age and soil moisture both increased decomposition rate. Synthesis
and applications. Our results suggest that both trait composition and
environmental conditions play a role in shaping ecosystem function during
restoration, and the importance of each is dependent on the function of
interest. Because of this, environmental heterogeneity will be necessary
to promote multiple ecosystem functions across restored landscapes. A
trait-based approach to restoration can aid interpretation of variable
outcomes through insights into community assembly and ecosystem
functioning.