Data from: How do lianas and vines influence competitive differences and niche differences among tree species? Concepts and a case study in a tropical forest

1. Lianas and other climbing plants are structural parasites of trees,
generally reducing host tree survival, growth, and reproduction, yet their
influences on the outcome of competition among tree species have remained
largely unexplored. 2. We propose that there are three distinct components
to liana-tree interactions: prevalence, defined as the proportion of
infested trees; load, defined as the mean liana cover on infested trees;
and tolerance, defined as the effect of a given level of infestation on
tree population growth rates. We introduce a new metric that integrates
these components, the liana burden, defined as the total effect of lianas
on per capita population growth rates given current prevalence, load, and
tolerance. Using these metrics, we quantify variation among 33
co-occurring tropical tree species in liana-tree interactions and its
relation with shade-tolerance. 3. The focal tree species vary strongly in
liana prevalence, load, tolerance, and burden. Interspecific variation in
tolerance is the largest contributor to interspecific variation in burden.
Species rankings of per capita population growth rates differ depending on
liana infestation levels. Thus, lianas alter competitive hierarchies to
benefit tree species that are relatively tolerant of and/or resistant to
lianas. Among tree species, shade-tolerance is positively correlated with
liana tolerance and prevalence, but largely unrelated to load and burden,
meaning shade-tolerance does not predict which species are competitively
disadvantaged by lianas. We describe a variety of mechanisms by which
lianas may potentially increase or decrease niche differences among tree
species, including interactions with spatial and temporal environmental
niche partitioning, and potential differences among tree species in
relative vulnerability to different liana species. 4. Synthesis: Lianas,
like other natural enemies, can in principle alter competitive hierarchies
and niche structure of co-occurring tree species, and our analyses suggest
such influences are substantial in our focal tropical tree community and
likely many other tree communities as well. Quantifying these effects
requires a more comprehensive approach including analyses and modeling of
dynamics of liana-tree interactions and their variation with tree and
liana species identities.