DOI: 10.5061/dryad.wpzgmsbw8
title: Contrasting changes in diversity

description: Questions: Climate change may have different effects on species richness
 depending on regional climates, soil types and the functional composition
 of local communities.   Location: Subalpine belt of the Grandes
 Rousses (Alps) and Sancy mountain ranges (The Massif Central), France.
 Methods: We compared changes in species richness in response to recent
 climate change in communities from two mountain ranges subjected to
 contrasting environmental conditions, with a more continental climate and
 drier soils in the Alps than in the Massif Central. Vegetation composition
 of 189 and 157 plots were assessed in 1997 and 2017-2018 in the Alps and
 1988-1989 and 2022 in the Massif Central, respectively. Five species
 traits (height, lateral spread, leaf area, specific leaf area and leaf dry
 matter content) were measured on 108 and 144 species, respectively.
 Changes in vegetation composition and species richness along spatial
 environmental gradients were analysed with correspondence analyses at the
 Sancy site and canonical correspondence analysis at the Alpe d’Huez site.
 Changes in functional composition across sites with were analysed with
 principal component analysis. Changes in species richness with climate
 change were analysed with repeated-measure ANOVAs. Results: In both
 mountain ranges summer temperatures increased and the hydric balance
 decreased over the past three decades, but snow cover duration decreased
 in the Alps only, whereas irradiance strongly increased in the Massif
 Central only. Functional composition was characterized by shorter and more
 conservative species in the Alps than in the Massif Central dominated by
 tall exploitative species. Species richness overall decreased with climate
 change by ca 10% in the Alps but overall increased by ca 10% in the Massif
 Central. Species richness decreased in the Alps likely because of
 increasing competition induced by dwarf shrub encroachment due to
 decreasing snow cover duration, whereas species richness increased in the
 Massif Central likely due to increasing irradiance in a very nebulous
 climate. Conclusion: The opposite changes in species richness observed at
 the two mountain ranges with recent climate change were likely to be
 explained by their contrasting climate and soil conditions driving
 different functional compositions and diversity-environment relationships.
description: Vegetation releves at two dates in two mountain ranges. ANOVAs
 and PCA were used to analyze the data.
description: # Contrasting change in diversity **Principal investigator (or person
 responsible for collecting the data):** Richard Michalet, University of
 Bordeaux, France,
 [richard.michalet@u-bordeaux.fr](mailto:richard.michalet@u-bordeaux.fr)
 **Date of data collection:** 1988, 1989, 1997, 2017, 2018, 2022
 **Information about the geographic location of data collection:** Isère
 and Puy-de-Dôme departments, France **The file, created in 2024, includes
 3 sheets :** 1.     Plant traits:  PCA on plant traits (Fig. 3). 2.    
 Richness Alps: Vegetation composition at Alpe d’Huez (Fig. 4 & 5).
 3.     Richness Sancy: Vegetation composition at Sancy (Fig. 5 & 6).
 **There are no restrictions on the data.** **Description of methods for
 data collection or generation**: Vegetation composition was sampled using
 quadrat sampling (Michalet et al. 2002, Arctic, Antarctic & Alpine
 Research) in the Alps and Braun-Blanquet’s method at Sancy. Plant traits
 measurements were done following Michalet et al. (2023, Ecology).
 **Description of methods used for data processing:** We used PCA for plant
 traits and regressions to assess the relationships between CA scores and
 species richness, both followed by ANOVAs. **Variable list, units of
 measurement**, **Sheet 1 (plant traits):** Massif: the two massifs, Alps
 and Sancy Species (information): species names. Height: extended height
 (cm). Width: lateral extension (cm). LA: Leaf Area (cm2). SLA: Specific
 Leaf Area (cm2.g-1). LDMC: Leaf Dry Mass content (percentage). **Sheet 2
 (Richness Alps):** N° (information): plot number. Year (effect variable):
 year of sampling. CA1 scores: Scores of the plots in a CA on species
 composition. Richness: Number of species per plots. **Sheet 3 (Richness
 Sancy):** N° (information): plot number. Year (effect variable): year of
 sampling. CA2: Scores of the plots on the second axis of a CA on species
 composition. Richness: Number of species per plots. **Definitions for
 codes or symbols used to record missing data:** n/a.