Data from: Resources alter the structure and increase stochasticity in bromeliad microfauna communities

Our approach combined natural gradients in environmental conditions with experimental manipulations of bottom-up interactions (resources), top-down interactions (predators) and dispersal at two spatial scales in the field. We found that resource addition strongly increased the abundance and reduced the richness of microfauna communities. Community composition shifted in a predictable way towards assemblages dominated by flagellates and ciliates but with lower abundance and richness of algae and amoebae.

While all functional groups responded strongly and predictably to resource addition, similarity among communities at the species level decreased, suggesting a role of stochasticity in species-level assembly processes. Dispersal limitation did not affect the communities. Since our design excluded potential priority effects we can attribute the differences in community similarity to increased demographic stochasticity of resource-enriched communities related to erratic changes in population sizes of some species.

In contrast to resources, predators and environmental conditions had negligible effects on community structure. Our results demonstrate that bromeliad microfauna communities are strongly controlled by bottom-up forces. They further suggest that the relative importance of stochasticity may change with productivity and with the organizational level at which communities are examined.

Usage notes protozoa_data.tsv This file contains a tab-delimited dataset of all protozoa morphospecies counts, as well as sample and treatment information. protozoa_enviro_data This file contains a tab-delimited dataset of all environtmental data taken for all samples, including treatment and sampling identification information. This dataset can be merged with protozoa_data.tsv to reproduce the analyses in Petermann et al. protozoa_variables_explanation.rtf This is a text document (rich text format) which contains metadata regarding all the variables in both .tsv files.