DOI: 10.5061/dryad.sp012
title: Data from: Neighbourhood effects on plant reproduction: an experimental-analytical framework and its application to the invasive Senecio inaequidens

description: 1. Density-dependence is of fundamental importance for population and
 range dynamics. Density-dependent reproduction of plants arises from
 competitive and facilitative plant-plant interactions that can be
 pollination-independent or pollination-mediated. In small and sparse
 populations, conspecific density-dependence often turns from negative to
 positive and causes Allee effects. Reproduction may also increase with
 heterospecific density (community-level Allee effect), but the underlying
 mechanisms are poorly understood and the consequences for community
 dynamics can be complex. Allee effects have crucial consequences for the
 conservation of declining species, but also the dynamics of range edge
 populations. In invasive species, Allee effects may slow or stop range
 expansion. 2. Observational studies in natural plant communities cannot
 distinguish whether reproduction is limited by pollination-mediated
 interactions among plants or by other neighbourhood effects (e.g.
 competition for abiotic resources). Even experimental pollen supply cannot
 distinguish whether variation in reproduction is caused by direct density
 effects or by plant traits correlated with density. Finally, it is unknown
 over which spatial scales pollination-mediated interactions occur. 3. To
 circumvent these problems, we introduce a comprehensive experimental and
 analytical framework which simultaneously (1) manipulates pollen
 availability and quality by hand pollination and pollinator exclusion, (2)
 manipulates neighbourhoods by transplanting target plants, and (3)
 analyses the effects of con- and heterospecific neighbourhoods on
 reproduction with spatially-explicit trait-based neighbourhood models. 4.
 Applying this framework to Senecio inaequidens, one of Europe’s fastest
 plant invaders, we found that the seed set was strongly pollen-limited.
 Reproduction had increased by pollinator-mediated facilitation by both
 con- and heterospecific neighbours which may lead to (community-level)
 Allee effects. Pollination-independent interactions, such as amelioration
 of abiotic conditions through neighbours, contributed to additional
 positive neighbour effects. However, these pollination-independent
 interactions were weaker than the pollination-mediated interactions and
 they occurred over smaller spatial scales. Finally, the strength and
 direction of neighbourhood effects depended on neighbour traits and thus
 changed with the trait composition of the neighbourhood. 5. Synthesis. By
 manipulating both pollen availability and target plant locations within
 neighbourhoods, we can comprehensively analyse spatially-explicit
 density-dependence of plant reproduction. This experimental approach
 enhances our ability to understand the dynamics of sparse populations and
 of species’ geographical ranges.
description: Target
 DataSee readme
 file.target.data.txtSource dataSee readme file.source.data.txtNHM example R scriptFile "NHM_example.r" contains exemplary commented R code for the estimation of plant neighbourhood models for the open - pollinated treatment.NHM_example.rResults NHM exemplary runFile "nhm_out_open.rdata" contains the R object nhm.out of formal class 'NHMsample' [package "NHM"], i.e. the results of our exemplary run of plant neighbourhood models for the open - pollinated treatment. For details see the NHM_example.r script.nhm_out_open.rdataNHM_1.1.0. R packageArchive "NHM_1.1.0.tar.gz" contains an R package (NHM) for the estimation of plant neighbourhood models.NHM_1.1.0.tar.gzReadme