Salces-Castellano A., T. Kasprzyk, B. Goffinet, T. Kiebacher, N. Patel, Y. Liu, S. Dong, A. Guisan, F. Collart & A. Vanderpoorten. 2026. Strong elevation-dependence of cross-taxon diversity patterns in plants. Ecological Indicators 193: 115833. pdf.

Abstract reads: Cross-taxon congruence, the degree of similarity in the diversity patterns across taxonomic groups, raises fundamental questions on the processes shaping biodiversity, with substantial implications for conservation. Here, we determine the extent to which (i) the correlation of taxonomic and phylogenetic α and β diversity between bryophytes and spermatophytes vary depending on ecological conditions, and (ii) the congruence of the diversity patterns among taxa is explained by their common response to environmental factors. Bryophyte and spermatophyte community composition of 413 plots of 4m2 in the western Alps was coupled with novel phylogenomic data and 68 abiotic variables. Spatial error simultaneous autoregressive models and generalized dissimilarity models were employed to measure how diversity patterns among taxa co-vary along an elevation gradient. Cross-taxon congruence was much higher for taxonomic than phylogenetic diversity and substantially varied with elevation, evidencing that, even at fine resolution, the dependence of bryophytes to micro-habitats does not prevent a macro-ecological signal of elevation to emerge. In particular, a strong correlation for species richness emerged in the alpine belt while cross-taxon correlations for taxonomic turnover peaked at mid-elevation. These correlations substantially dropped when controlling for environmental variation, suggesting that cross-taxon congruence largely depends on the similarity of the response of different taxa to the same factors, especially in the alpine belt where the size difference between bryophytes and spermatophytes is minimal. In practice, the usefulness of spermatophytes as surrogates for bryophytes strongly depends on the environmental context and diversity metrics.

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