DOI: 10.5061/dryad.66t1g1k37
title: Changes in community-weighted trait mean, functional diversity, soil chemical properties and temperature along an elevational gradient in Tenerife, Canary Islands

description: This dataset comprises community-weighted trait means and functional
 diversity of leaf traits, chemical soil properties
 and temperature recorded in roadside (disturbed) and interior
 (less disturbed) plots, along an elevational gradient of 2,300 m
 in Tenerife, Canary Islands. The leaf traits measured were specific leaf
 area (SLA), nitrogen, nitrogen to phosphorus ratio, leaf dry
 matter content (LDMC) and carbon to phosphorus ratio.
 The soil chemical properties measured were pH, nitrogen, nitrogen to
 phosphorus ratio, carbon to phosphorus ratio, calcium,
 potassium, magnesium and cation exchange capacity. Also the
 scores of the three first axes derived from a PCA
 analysis including the soil chemical properties are included. The
 temperature variables consist of bioclimatic variables Bio10 (mean
 temperature of the warmest quarter) and Bio11 (mean temperature of the
 coldest quarter). This dataset has been used for the analysis presented in
 Ratier Backes et al. (2021).
description: Data
 collection took place in April and May 2018. All data and samples were
 retrieved from permanent plots established in 2008, following the design
 of the standardized mountain road survey of the Mountain Invasion Research
 Network (MIREN). Three roads on the island’s southern slopes were
 selected, spanning from the coast to the crater of Mt. Teide. On each
 road, twenty sampling locations were distributed evenly over the ascent of
 approximately 2,300 m. At each sampling location, two plots with 2 m x 50
 m each were established, one directly adjacent and with the long side
 parallel to the road, and a second one perpendicular to the roadside plot,
 at 50-100 m away from the road. Steep topography and private property
 prevented sampling in some locations, resulting in a total of 111
 plots. <strong>Temperature
 data</strong> Near-surface soil temperature was
 measured using miniature loggers (HOBO 64K Pendant, with 0.53 °C accuracy,
 Bourne, MA, USA). They were installed in the center of the roadside plot
 and 50 m away from it, at the start of the distant plot, at a depth of 3
 cm below the soil surface. They were programmed to log at 1.5 h intervals
 from May 2018 until April 2019. After data quality control, the
 bioclimatic variables Bio10 (mean temperature of the warmest quarter) and
 Bio11 (mean temperature of the coldest quarter) were
 calculated following the definitions of WorldClim. <strong>Soil sampling and
 soil analysis</strong> From three
 locations in each plot, we collected a bulked soil sample from the upper
 10 cm of the mineral soil layer. The samples were sieved (&lt;2 mm)
 and remaining, visible plant particles were removed. Soil pH was measured
 in 1 molar KCl. For gas-chromatographically measuring total soil carbon
 and nitrogen concentrations, fresh soil was dried for 72 hours at 105 °C
 and then milled to fine powder. To determine the concentrations of the
 base cations calcium, magnesium and potassium, fresh soil was percolated
 in a solution of 0.1 molar barium chloride. Afterwards, the cation
 concentrations were measured by atomic absorption spectrometry (ContrAA
 300 AAS, Analytik Jena, Jena, Germany). The concentration of hydrogen ions
 was measured by determining the pH of the percolates, and the cation
 exchange capacity (CEC) was calculated as the sum of ion equivalents of
 all measured exchangeable cations (Ca, K, Mg and H). For the determination
 of bioavailable phosphorus, the soil samples were analyzed using the
 method proposed by Olsen (1954). The ratios of N:P and of C:P were
 calculated based on the results for N, C and P. <strong>Species richness, community-weighted trait means and functional diversity</strong> Species richness, community-weighted trait means and functional diversity were calculated based on vegetation surveys and leaf samples collected on the plots. See Ratier Backes et al. (2021) for more details. Species richness was defined as the total number of species recorded per plot. Community-weighted trait means (CWMs) were calculated for each of the five leaf traits (SLA, LDMC, leaf N, leaf N:P ratio, leaf C:P ratio) and for each plot, as follows: CWM = <sub><i>i</i><i>=1</i></sub><sup><i>N</i></sup><i>p</i><sub><i>i</i></sub><i>trait</i><sub><i>i</i></sub>      (1) where <i>p<sub>i</sub> </i>is the relative cover of species <i>i</i> in the community, and <i>trait<sub>i</sub></i> is the trait value of species <i>i</i>. To quantify functional diversity (FD), we calculated Rao’s quadratic entropy for each plot: Rao’s Q = <sub><i>i</i><i>=1</i></sub><sup><i>N</i><i>-1</i></sup><sub><i>j</i><i>=</i><i>i</i><i>+1</i></sub><sup><i>N</i></sup><i>p</i><sub><i>i</i></sub><i>p</i><sub><i>j</i></sub><i>d</i><sub><i>ij</i></sub>   (2) where the species’ trait distances are weighted by their relative abundance in the community. N is the number of species in the plot, <i>p<sub>i</sub></i><sub> </sub>and <i>p<sub>j</sub></i> are the relative cover of species <i>i</i> and <i>j</i>, and <i>d<sub>ij</sub></i> is the trait distance between species <i>i </i>and<i> j</i>. Thus, Rao’s Q gives the mean functional distance between any two species in a plot. We included all five leaf traits in the calculation of Rao’s Q (multi-trait functional diversity).
description: Missing values in the bioclimatic variables bio10 and bio11
 correspond to plots where the loggers could not be installed, were lost or
 damaged. For the soil samples, missing values correspond to plots where
 samples could not be taken (e.g., on purely rocky areas) or samples
 for which phosphorus measurement failed. For CWMs, NAs represent plots
 with no species, and for Rao's Q they correspond to plots with less
 than 2 species. Please refer to the ReadMe file for more
 information.