Phenol-Driven Changes in Root Exudation and Nutrient Cycling

Invasive plant species often alter soil chemistry through root exudates, including phenolic compounds, which can inhibit native plant growth. Understanding how these compounds influence soil-plant interactions is crucial for predicting the ecological impacts of invasive species. This study focuses on the effects of phenolic compounds, particularly coumaric acid, a widely occurring phenol in invasive plant species, on biomass production, nitrogen cycling, and exudation dynamics of a native plant grown in soil affected by contrasting water regimes (regularly flooded and non-flooded). To test the hypothesis that phenols affect nitrogen cycling and impact plant growth, initial experiments evaluated the effects of four phenols in inhibiting nitrification. Subsequent experiments focused on coumaric acid, as it was the phenol with the strongest reduction of nitrification rates in soil, measuring its influence on biomass production of the native plant Persicaria lapathifolia as well as their exudation patterns under flooded and non-flooded soil conditions. Preliminary findings suggest that phenolic compounds reduce biomass production, primarily above ground, supporting the hypothesis of growth inhibition. Exudation patterns showed high variability, with phenols disrupting established exudation trends. In flooded soil conditions, plants exposed to phenols exhibited increased nitrogen uptake, potentially as an adaptive response to altered nutrient dynamics. These findings highlight the complex interactions between phenols, root exudation, and nitrogen dynamics in riparian soil that underwent varying flooding patterns. The results suggest that invasive species may leverage phenolic compounds to inhibit native plant growth and alter nutrient cycling, providing insight into invasion strategies and their potential implications under climate change.