Data from: Plant communities on nitrogen‐rich soil are less sensitive to soil moisture than plant communities on nitrogen‐poor soil

1.Plant species composition and diversity are known to change across local
gradients of light, moisture, and nutrients, but ecologists still have a
relatively limited understanding of how communities respond to multiple
limiting resources. 2.We used a trait‐based approach to investigate how
the functional composition and diversity of forest understory plant
communities change along gradients in light, soil moisture and nitrogen
availability. We used a total of seven leaf, root, and whole‐plant traits
for 55‐78 species, and estimated the effects of the three resources on the
mean and dispersion of these traits in understory plant communities across
50 forest sites. 3.Soil moisture and nitrogen availability (C/N ratio)
both influenced plant community traits, but light availability (canopy
openness) did not. Generally, increases in moisture and nitrogen both
resulted in shifts towards more acquisitive resource use strategies,
including greater leaf area, specific leaf area and maximum plant height,
and lower leaf dry matter content, root dry matter content and rooting
depth. Functional diversity of most traits also increased with increasing
soil moisture and nitrogen. Although most traits varied with soil moisture
on nitrogen‐poor sites, moisture did not influence of the distribution of
any traits on nitrogen‐rich sites. 4.Synthesis: Independent co‐limitation
of soil moisture and nitrogen appeared to influence the functional
composition and diversity of understory vegetation in our study area. The
co‐occurrence of species with resource acquisitive and conservative
strategies on nitrogen‐rich sites may make plant communities relatively
resistant to changes to soil moisture. These results suggest that altered
precipitation regimes under climate change could lead to greater changes
in the composition and diversity of plant communities on nutrient‐poor
soils than on nutrient‐rich soils.