# Depth effects of trail development on herbaceous plant diversity and stress responses through flavonoid accumulation

## TL;DR

This study explores how trail development affects plant diversity and stress responses in natural ecosystems by analyzing flavonoid accumulation in plants at different distances from trails.

## Contribution

The study reveals depth effects of trail development on herbaceous plant diversity and flavonoid accumulation patterns as stress responses.

## Key findings

- Plant diversity was lowest near trails and highest in intermediate plots.
- Flavonoid concentrations varied significantly with trail proximity, showing higher isoorientin and myricetin near trails.
- Quercetin was higher in intermediate plots, while vitexin and kaempferol were higher away from trails.

## Abstract

Trail development is more prevalent as tourism develops globally. The depth effect of trail development on plant diversity and native species’ stress response via tuning flavonoids in natural ecosystems remain relatively poorly understood. We investigated the depth effects by comparing plant species diversity and flavonoid contents (of six common native species) in sampling plots plots (Rabbit Mountain Open Space, Boulder County, CO, USA) with varying distances away from trail. We found plant diversity to be lowest in plots immediately proximal to trails and highest in intermediate plots. We also found the concentrations of total flavonoids to vary significantly between plots closer and away from trails. Specifically, we found the concentrations of isoorientin and myricetin higher in plots closer to trails. On the contrary, the concentrations of vitexin and kaempferol were higher in plots away from trails. Quercetin was higher in the intermediate plots. Overall, trail development negatively impacted herbaceous plant diversity, which was evident as depth effects. The plant species responded to environmental stresses imposed by trail development through fine-tuned flavonoid accumulation.

The online version contains supplementary material available at 10.1007/s44154-025-00227-8.