Data from: Competition and coexistence in plant communities: intraspecific competition is stronger than interspecific competition

Theory predicts that intraspecific competition should be stronger than
interspecific competition for any pair of stably coexisting species, yet
previous literature reviews found little support for this pattern. We
screened over 5400 publications and identified 39 studies that quantified
phenomenological intraspecific and interspecific interactions in
terrestrial plant communities. Of the 67% of species pairs in which both
intra- and interspecific effects were negative (competition),
intraspecific competition was, on average, four to five-fold stronger than
interspecific competition. Of the remaining pairs, 93% featured
intraspecific competition and interspecific facilitation, a situation that
stabilizes coexistence. The difference between intra- and interspecific
effects tended to be larger in observational than experimental data sets,
in field than greenhouse studies, and in studies that quantified
population growth over the full life cycle rather than single fitness
components. Our results imply that processes promoting stable coexistence
at local scales are common and consequential across terrestrial plant
communities.