DOI: 10.5061/dryad.8gs3n
title: Data from: Consensus RDA across dissimilarity coefficients for canonical ordination of community composition data

description: Understanding how habitat structures species assemblages in a community is
 one of the main goals of community ecology. To relate community patterns
 to particular factors defining habitat conditions, ecologists often use
 canonical ordinations such as canonical redundancy analysis (RDA). It is a
 common practice to use dissimilarity coefficients to perform canonical
 ordinations through distance-based RDA (db-RDA) or transformation-based
 RDA (tb-RDA). Dissimilarity coefficients are measures of resemblance where
 the information about species communities is condensed into a symmetric
 square matrix of dissimilarities among sites. In this paper we compared 16
 of the most commonly used dissimilarity coefficients to evaluate if the
 species abundance distribution (SAD) of a community can be used to select
 an appropriate coefficient. Of these, 11 are designed to be used primarily
 with abundance data although they can also be used with presence-absence
 data, whereas five can only be applied to presence-absence data. Using
 simulations, we compared the explained variance of RDAs differing only by
 their coefficients to evaluate how the abundance patterns of communities
 influence coefficient choice. We found that coefficients are largely
 equivalent, independently of the community SAD. In light of these
 findings, we propose the consensus RDA method, a new canonical ordination
 procedure that performs a consensus of RDAs across several coefficients.
 This new method focuses on the common relations found by independent RDAs
 differing only by their dissimilarity coefficients; this ensures the
 absence of a coefficient-related bias when interpreting the canonical
 ordination result. Also, because in our simulations the presence-absence
 data were directly derived from the abundance data, we were able to
 evaluate if the information in presence-absence data was equivalent to
 that in abundance data. We found that although some information was lost
 by converting abundance data into presence-absence, both data formats may
 be complementary. When applying consensus RDA to abundance and
 presence-absence data independently, a more complete understanding and
 interpretation of the ecological patterns is obtained. An ecological
 example illustrating consensus RDA and the conclusions of our simulations
 is presented, using Carabidae data collected at the Ecosystem Management
 Emulating Natural Disturbances (EMEND) project in northwestern Alberta,
 Canada.
description: Standardized abundances
 of carabid species caught in every sitesThis table contains the
 standardized abundances of each carabid species captured in each of the
 192 sites. Carabids were collected using three pitfall traps in each site
 and beetle abundances were divided by the number of days each trap was
 active to remove the effect of trap disturbance. The code for each species
 is available in table E1 of the associated publication (Blanchet et al.
 Consensus RDA across dissimilarity coefficients for canonical ordination
 of community composition data, Ecological Monographs) as well as the
 detailed description of sampling protocol. More details about sampling and
 analysis of this data may be found in: Blanchet FG, JAC Bergeron, JR
 Spence, F He, 2013. Landscape effects of disturbance, habitat
 heterogeneity and spatial autocorrelation for a ground beetle (Carabidae)
 assemblage in mature boreal forest. Ecography, 36(5): 636-647; Bergeron
 JAC, GF Blanchet, JR Spence, WJA Volney, 2012. Ecosystem classification
 and inventory maps as surrogates for ground-beetle assemblages in boreal
 forest, Journal of Plant Ecology, 5(1): 97-108; and Bergeron JAC, JR
 Spence, WJA Volney, 2011. Landscape patterns of species-level association
 between ground-beetles (Coleoptera: Carabidae) and overstory trees in
 boreal forests of western Canada, Zookeys, 147: 577-600. This data and the
 analysis procedures associated with this paper are also available in the R
 package ordiconsensus
 (https://r-forge.r-project.org/R/?group_id=68).beetles.txtRelative basal area for each tree species recorded in every sitesThis table contains the relative basal area for each tree species sampled at each site. In each of the 192 sites, the diameter at breast height (dbh) and species of the 25 trees closest to the centre of the plot and over 5 cm bdh were recorded. Total basal area was calculated for each species in each site and divided by the total basal area of all species in each site to produce the relative basal area. Refer to the associated publication (Blanchet et al. Consensus RDA across dissimilarity coefficients for canonical ordination of community composition data, Ecological Monograph) for more details on sampling protocol and table E2 of this same publication for the abbreviation of the tree species. More details about sampling and analysis of this data may be found in: Blanchet FG, JAC Bergeron, JR Spence, F He, 2013. Landscape effects of disturbance, habitat heterogeneity and spatial autocorrelation for a ground beetle (Carabidae) assemblage in mature boreal forest. Ecography, 36(5): 636-647; Bergeron JAC, GF Blanchet, JR Spence, WJA Volney, 2012. Ecosystem classification and inventory maps as surrogates for ground-beetle assemblages in boreal forest, Journal of Plant Ecology, 5(1): 97-108; and Bergeron JAC, JR Spence, WJA Volney, 2011. Landscape patterns of species-level association between ground-beetles (Coleoptera: Carabidae) and overstory trees in boreal forests of western Canada, Zookeys, 147: 577-600. This data and the analysis procedures associated with this paper are also available in the R package ordiconsensus (https://r-forge.r-project.org/R/?group_id=68).beetle_expl.txt