DOI: 10.5061/dryad.1c59zw45m
title: Differences in species composition between calcareous and siliceous herbaceous communities are primarily explained by competition in favourable climates

description: Differences in vegetation composition between communities from calcareous
 and siliceous soils might be due to high competition on siliceous soils
 for species from calcareous origin, and high rock-induced drought stress
 on calcareous soils for species from siliceous origin. We tested the
 hypothesis that, with increasing climate stress, competition should
 decrease on siliceous rock for species of calcareous origin and drought
 stress increase on calcareous rock for species of siliceous origin because
 of decreasing community biomass with increasing cold or drought stress.
 This question is of high interest for predicting changes in species
 distribution with climate change since bedrock type and climate change are
 both complex factors that are likely to interact with climate. We set up a
 transplant removal experiment in contrasting climate conditions of the
 south of France, warm and wet temperate, warm and dry Mediterranean, and
 cold temperate in the Alps and the Pyrenees. In each climate condition,
 three targets (two species and one population from a third species) from
 each origin were transplanted with and without neighbours on the two rock
 types and for two years with different levels of drought stress. Variation
 in the effects of neighbours and rock-induced drought stress on transplant
 survival with and without neighbours were analysed with linear modelling
 at each site, separately, and with ANCOVA in the whole design. The
 competition was the highest on siliceous rock in the more favourable
 climate conditions but for species of siliceous origin. The lower
 competition found for species of calcareous origin was likely due to the
 occurrence of allelopathic effects that decreased the negative effect of
 neighbours as measured with the removal method. The rock-induced drought
 stress was the highest on calcareous rock, in particular for species of
 siliceous origin. Thus, the decrease in competition intensity on siliceous
 rocks with increasing climate stress was more important for species of
 siliceous than calcareous origin. Additionally, the importance of the
 rock-induced drought stress was relatively low in the most stressful
 climate conditions as compared to the overwhelming importance of climate
 drought stress over the two years of our experiment, which likely induced
 a collapse of the positive effect of growing on a siliceous rock.
description: # Differences in species composition between calcareous and siliceous
 herbaceous communities are primarily explained by competition in
 favourable climates
 [https://doi.org/10.5061/dryad.1c59zw45m](https://doi.org/10.5061/dryad.1c59zw45m) The dataset was collected in a cross-transplantation experiment conducted over two years at four different sites in France (Bordeaux, Toulon, Pyrenees, and Alps) on two bedrock types. ## Description of the data and file structure Collection of survival data of transplanted targets during two years at four sites and on two bedrocks. ### Files and variables #### File: Michalet\_et\_al.\_Data.xlsx **Description:**  ##### Variables * Climatic site (effect variable): the four experimental sites. * PCA1 score (effect variable): the positions of the sites on the first axis of a PCA conducted on climate variables. * Year (effect variable): 2022 or 2023. * Rock (effect variable): calcareous or siliceous. * Species origin (effect variable): calcareous or siliceous. * Neighbours (effect variable): With or without neighbours * Survival% (response variable): Target survival. ## Access information NA