Data and R code from: Pollination interactions reveal direct costs and indirect benefits of plant–plant facilitation for ecosystem engineers

Ecosystem engineers substantially modify the environment via their impact
on abiotic conditions and the biota, resulting in facilitation of
associated species that would not otherwise grow. Yet, reciprocal effects
are poorly understood as studies of plant–plant interactions usually
estimate only benefits for associated species while hardly considering how
another trophic level may mediate direct and indirect effects for
ecosystem engineers. We run a field experiment with ecosystem engineers
blooming either alone or with associated plants to decompose net effects
and to test the hypothesis that pollinator-mediated interactions provide
benefits which balance costs of facilitation by ecosystem engineers. We
found that net costs of facilitation are accompanied by
pollinator-mediated benefits. Despite ecosystem engineers producing less
flowers per plant, they were visited by more and more diverse pollinators
per flower when blooming with associated plants than when blooming alone.
However, fruit set was unaffected by the presence of associated plants and
seed production per plant was higher when ecosystem engineers bloomed
alone. Our findings suggest that besides experiencing direct costs,
ecosystem engineers can also benefit from facilitating other species via
increasing their own visibility to pollinators. This study illuminates how
the outcome of direct plant–plant interactions might be mediated by
indirect interactions including third players.