Data from: Lianas reduce community-level canopy tree reproduction in a Panamanian forest

Lianas are a key component of tropical forests, where they compete
intensely with trees, reducing tree recruitment, growth and survival. One
of the most important potential outcomes of liana competition is the
reduction of tree reproduction; however, no previous study has
experimentally determined the effects of lianas on tree reproduction
beyond a single tree species. We used a large-scale liana removal
experiment to quantify the effect of lianas on community-level canopy and
understorey tree and palm reproduction. In 2011, we removed lianas from
eight 6,400-m2 plots (eight plots served as controls) and surveyed
understorey tree reproduction in 2012, canopy tree and palm reproduction
in 2013, and a second census of all plants in 2016. We found that lianas
significantly reduced canopy tree community flowering and fruiting after
liana removal. Two years after liana removal, the number of canopy trees
with fruits was 173% higher, fruiting individuals had 50% more of their
canopy covered by fruits and the number of tree species with fruits was
169% higher than in control plots where lianas were present. Five years
after liana removal, the number of canopy trees with fruits was 150%
higher, fruiting individuals had 31% more of their canopy covered by
fruits and the number of tree species with fruits was 109% higher than in
unmanipulated control plots. Liana removal had only a slight positive
effect on palms and on understorey tree flower and fruit production, even
though understorey light levels had increased 20% following liana cutting.
Synthesis. Our findings provide the first experimental demonstration that
competition from lianas significantly reduces community-level canopy tree
reproduction. Reduced reproduction increases canopy tree seed and
dispersal limitations, and may interfere with deterministic mechanisms
thought to maintain tropical canopy tree species diversity, as well as
reduce food availability to many animal species. Because lianas are
increasing in abundance in many neotropical forests, the effects of lianas
on tree reproduction will likely increase, and if the effects of lianas on
tree reproduction vary with tree species identity, lianas ultimately could
have a destabilizing effect on both tree and animal population dynamics.