A signal of competitive dominance in mid-latitude herbaceous plant communities

TL;DR

This study reveals that plant height clustering signals competitive dominance in mid-latitude herbaceous communities, influenced by environmental factors like evapotranspiration and productivity, highlighting the scale-dependent nature of biotic interactions.

Contribution

It introduces a novel approach linking competition theory with large-scale plant distribution data to identify signals of competitive dominance across environmental gradients.

Findings

Plant height clustering correlates with evapotranspiration and productivity.

Competitive signals are strongest in mid-latitude regions with optimal growth conditions.

Climate severity diminishes the impact of competition away from optimal conditions.

Abstract

Understanding the main determinants of species coexistence across space and time is a central question in ecology. However, ecologists still know little about the scales and conditions at which biotic interactions matter and how these interact with the environment to structure species assemblages. Here we use recent theory developments to analyze plant distribution and trait data across Europe and find that plant height clustering is related to both evapotranspiration and gross primary productivity. This clustering is a signal of interspecies competition between plants, which is most evident in mid-latitude ecoregions, where conditions for growth (reflected in actual evapotranspiration rates and gross primary productivities) are optimal. Away from this optimum, climate severity likely overrides the effect of competition, or other interactions become increasingly important. Our approach bridges the gap between species-rich competition theories and large-scale species distribution data analysis.