Data from: Relationships between plant traits, soil properties and carbon fluxes differ between monocultures and mixed communities in temperate grassland

1. The use of plant traits to predict ecosystem functions has been gaining
growing attention. Aboveground plant traits, such as leaf nitrogen (N)
content and specific leaf area (SLA), have been shown to strongly relate
to ecosystem productivity, respiration, and nutrient cycling. Further,
increasing plant functional trait diversity has been suggested as a
possible mechanism to increase ecosystem carbon (C) storage. However, it
is uncertain whether belowground plant traits can be predicted by
aboveground traits, and if both above- and belowground traits can be used
to predict soil properties and ecosystem-level functions. 2. Here, we used
two adjacent field experiments in temperate grassland to investigate if
above- and belowground plant traits are related, and whether relationships
between plant traits, soil properties and ecosystem C fluxes (i.e.,
ecosystem respiration and net ecosystem exchange) measured in potted
monocultures could be detected in mixed field communities. 3. We found
that certain shoot traits (e.g., shoot N and C, and leaf dry matter
content) were related to root traits (e.g., root N, root C:N, and root dry
matter content) in monocultures, but such relationships were either weak
or not detected in mixed communities. Some relationships between plant
traits (i.e., shoot N, root N and/or shoot C:N) and soil properties (i.e.,
inorganic N availability and microbial community structure) were similar
in monocultures and mixed communities, but they were more strongly linked
to shoot traits in monocultures and root traits in mixed communities.
Structural equation modelling showed that above- and belowground traits
and soil properties improved predictions of ecosystem C fluxes in
monocultures, but not in mixed communities on the basis of
community-weighted mean traits. 4. Synthesis: Our results from a single
grassland habitat detected relationships in monocultures between above-
and belowground plant traits, and between plant traits, soil properties
and ecosystem C fluxes. However, these relationships were generally weaker
or different in mixed communities. Our results demonstrate that while
plant traits can be used to predict certain soil properties and ecosystem
functions in monocultures, they are less effective for predicting how
changes in plant species composition influence ecosystem functions in
mixed communities.