Fig. 4 Competitive interactions drive non-linear
responses to ambient and added N. Estimated steady-state abundance
distributions (relative plot proportions) for each species group across
the observed gradients of ambient (left) and added (right) N deposition
(zero centered +/- two standard deviations) in NW and W global change
plots (See Fig S9 for all treatments). Points show simulated equilibrium
abundances (100 at each value of x). Dotted lines show best model fit
from a general additive model in the geom_smooth function in
ggplot2 (Wickham 2009)..