Data from: Experimental assessment of biotic and abiotic filters driving community composition

Species occurrence in a site can be limited by both the abiotic
environment and biotic interactions. These two factors operate in concert,
but their relative importance is often unclear. By experimentally
introducing seeds or plants into competition-free gaps or into the intact
vegetation, we can disentangle the biotic and abiotic effects on plant
establishment. We established a seed sowing/transplant experiment in three
different meadows. Species were introduced, as seeds and pre-grown
transplants, into competition-free gaps and the intact vegetation. They
included 12 resident plants from the locality and 18 species typical for
different habitats. Last two years, gaps were overgrown with vegetation
from surrounding plants and we observed the competitive exclusion of our
focal plants. We compared plant survival with the expected occurrence in
target locality (Beals index). Many of the species with habitat
preferences different from our localities were able to successfully
establish from seeds and grow in the focal habitat if competition was
removed. They included species typical for much drier conditions. These
species were thus not limited by the abiotic conditions, but by
competition. Pre-grown transplants were less sensitive to competition,
when compared to seedlings germinated from seeds. Beals index
significantly predicted both species success in gaps and the ability to
withstand competition. Survival in a community is dependent on the
adaptation to both the abiotic environment and biotic interactions.
Statistically significant correlation coefficients of the ratio of
seedling survival in vegetation and gaps with Beals index suggest the
importance of biotic interactions as a determinant of plant community
composition. To disentangle the importance of abiotic and biotic effect on
plant establishment, it is important to distinguish between species pool
as a set of species typically found in given community type (determined by
Beals index) and a set of species for which the abiotic conditions are
suitable.