Soil toxicity and species dominance rather than nutrient availability drive plant species richness in swamp forests of Central Europe

Aim: A resource-based conceptual model of plant diversity (RBCM) assumes direct relationships between resource supply and the diversity of a local plant assembly. However, the RBCM largely ignores variation imposed by soil toxicity due to climatic effects. Both soil-limiting resources and soil toxicity vary along climatic gradients but their net and interactive effects on plant species diversity remain unknown. We asked how climatic gradients shape resource availability, soil toxicity and dominance of herb-layer graminoids, and how these predictors control local species diversity of herbs and bryophytes.
Location: Swamp forests, Central Europe
Taxon: Vascular plants, bryophytes
Methods: Alpha taxonomic diversity of vascular plants and bryophytes was counted for 101 vegetation plots sampled in temperate swamp forests distributed along an 800-km geographical gradient across the Continental, Alpine and Pannonian biogeographical regions. Path analysis (structural equation modelling) was use..., , , # Soil toxicity and species dominance rather than nutrient availability drive plant species richness in swamp forests of Central Europe

Vegetation and ecological data were retrieved from original field research of authors conducted in three biogeographical regions (Continental, Alpine and Pannonian) of Central Europe. We sampled 101 vegetation plots in stands of the *Alnus* swamp forests during the period of 2010–2019 using the traditional European phytosociological approach. A list of all vascular plants and ground-dwelling bryophytes was created in each plot. The dataset includes species richness for herb-layer plants (referred to as herbs) and bryophytes. Alpha diversity values are accompanied by a set of explanatory variables associated with the resource based conceptual model of plant diversity. We measured and/or calculated climatic (large-scale) variables and several site productivity variables (i.e. soil fertility measures, light and water conditions), environmental harshness...