DOI: 10.5061/dryad.510dt0g
title: Data from: The association between a nurse cushion plant and a cluster-root bearing tree species alters the plant community structure

description: 1.Several plant species have the potential to facilitate the presence of
 other plant species in the community, and yet most of our knowledge on
 this phenomenon comes from studies considering only one facilitator
 species. What happens when there are two facilitator species in the
 community? Are the facilitation effects by one species being altered by
 the presence of a potentially second facilitator species and vice‐versa
 (i.e. bidirectional facilitation)?. 2.Knowing that cushion plants
 ameliorate stress and improve soil fertility and that cluster‐root bearing
 species mobilise soil phosphorus (P), we investigated the potential
 occurrence of bidirectional facilitation via stress amelioration and
 nutrient exchange in the cushion plant Acaena integerrima (Rosaceae) and
 the cluster‐root bearing tree species Embothrium coccineum (Proteaceae).
 3.In southern Chile, where both species naturally occur, we compared
 aspects of the vegetative and reproductive performance of each species
 growing in association or not. We also determined if Embothrium alters the
 nurse effects of Acaena cushions on other species by evaluating species
 richness, frequency, and abundance in cushion plants with and without
 Embothrium. To infer the existence of nutrient exchange, we determined
 soil and leaf nutrient levels of both species. 4.Species richness,
 frequency, and abundance were higher within than outside Acaena cushions.
 Although the presence of Embothrium did not enhance the overall positive
 effects of Acaena on species composition, nine species occurred more
 frequently when Embothrium was present. Embothrium occurred more
 frequently and had a higher survival and leaf nitrogen (N) concentration
 when growing with Acaena than without it, although its growth and leaf P
 concentration were lower. In contrast, Acaena had a lower number of and
 mass of fruits per inflorescence and a higher leaf P concentration when
 growing with versus growing without Embothrium. 5.Synthesis. The cushion
 plant Acaena integerrima facilitates the occurrence of many species in the
 community, including the cluster‐root bearing species Embothrium
 coccineum, which in turn enhances the facilitation effect of Acaena on
 certain species. When Embothrium and Acaena occur together, the latter
 improves its nutritional status but reduces its fitness, implying a lack
 of bidirectional facilitation.
description: Acaena observational
 reproductive outputarea, plant identit,
 shoot identity, number of reproductive shoots per area, individual mean
 fruit mass, number of fruits per shoot, and total fruit mass per shoot of
 the cushion plant Acaena integerrima in presence and absence of the
 species Embothrium coccineumobservational reproductive
 output Dryad.xlsxsoil temperature
 Dryadhourly soil temperature
 inside Acaena integerrima cushion plants and in bare ground, during spring
 and summersoil
 chemistrySoil pH, Organic Matter
 Content (OMC, %), nitrate (NO3, %), Olsen P (mg. Kg-1), Available K (mg.
 g-1), exchangeable K (cmol. Kg-1), total N (%), C:N ratio, Fixed P (%),
 and extractable Al (mg. Kg-1) in cushion plants of Acaena integerrima with
 and without Embothrium (Acaena + Embothrium and Acaena - Embothrium,
 respectively), barge ground, and bare gorund sorrounding Embohrium
 seedlings.soil
 humiditySoil gravimetric water
 content (%) measured at a single point of time in Acaena cushion with and
 without Embothrium (Acaena + Embothrium and Acaena - Embothrium,
 respectively), Embothrium in bare ground, and bare
 ground.Effect of Acaena on
 Embothrium survival and growthsurvival (0 and 1 for
 alive and dead, respectively), relative growth rate in height, and number
 of new leaves relative to the number of previous leaves in Embothrium
 seeedlings within and outside Acaena cushions.survival and RGR
 Embothrium.xlsxEffects of the presence
 versus experimental removal of Embothrium on the reproductive output
 Acaenaarea (m2), Number of
 fruits per reproductive shoot, total fruit mass per shoot (g) and mean
 mass of a fruit (g) in cushion plants of Acaena integerrima in presence of
 Embothrium (control) and after removal (clipped) of
 Embothriumexperimental reproductive
 output Acaena.xlsxSpecies richness,
 frequency and abundanceNumber of individuals
 per species sampled in cushion plants of Acaena integerrrima with and
 without Embothrium, and in bare ground plots.frec-abundce-Rqza-Acaena-notro
 con area de BG.xls