Data from: Cyclic population dynamics and density-dependent intransitivity as pathways to coexistence between co-occurring annual plants

1. Recent studies have brought renewed attention to the importance of
complex species interactions - notably intransitive interactions - to
patterns of plant community diversity. One underappreciated avenue through
which intransitivity can occur is through cyclic population dynamics.
Though such cyclic intransitive relationships have been extensively
studied in predator-prey systems, evidence of their importance in
competitive communities, notably plant communities, is more limited. Most
studies of coexistence in plant communities assume fixed-point coexistence
even while utilizing models that allow for cyclic population dynamics. 2.
In this paper, we explore the potential for density-dependent, cyclic
population dynamics and intransitivity in a model for annual plants. We
then examine how these density-dependent cycles impact mutual invasibility
and ultimately stable coexistence between plant species pairs. We do this
using data collected from four co-occurring annual plant species living in
natural wildflower communities in SW Western Australia. To maximize the
number of biologically plausible pathways by which coexistence mediated by
density-dependent cyclic intransitivity can occur, we use an annual plant
model that allows for competitive direct interactions, facilitative direct
interactions, and higher-order interactions between species. 3. Results
from our empirically-parameterized model suggest that monocultures of all
four focal species can have cyclic solutions with periodicity greater than
1 under sunny ("open") or shaded field conditions. Cyclic
patterns drive variation in annual abundance patterns, with stable
solutions for persistent monocultures and invasibility potential (the
capacity of one population to invade another) common. Mutual invasibility
in the face of cyclic population dynamics was found for just one of six
species pairs, only under open environmental conditions. Our results
illustrate the potential for cyclic intransitivity to both drive and
prevent stable coexistence in environmentally heterogeneous biological
communities. 4. Synthesis. We provide analytical and empirical evidence
that coexistence in competitive communities (annual plants) can be
achieved under non-equilibrium circumstances, through density-dependent
cyclic intransitivity. Our results suggest that cyclic population dynamics
may be common and important for coexistence dynamics in some types of
communities. In such communities, the exploration of stable coexistence
should therefore include consideration of cyclic as well as fixed-point
equilibria for maximal accuracy.