From the Ground Up: Can Root Traits Help Understand Invasion Dynamics?

Trait-based comparisons of invasive and native plants have advanced our understanding of invasion mechanisms, but most focus on aboveground traits, overlooking the influence of root traits. In this mini-review, we synthesize existing research to evaluate the often-neglected role of root traits in plant invasions across different levels of disturbance and nutrient availability. We then propose a new Root Trait-Environment-Invasion (RTEI) framework that accounts for how environmental context interacts with root traits to mediate invasion success. Our review suggests that there is no single root trait that correlates with invasion. However, we did identify emerging patterns that varied with the level of disturbance and nutrient availability. For example, in low-disturbance, high-nutrient environments, we found that plant invaders often display root traits associated with enhanced resource acquisition, such as higher root biomass. In contrast, invasive plants generally exhibited more fine root traits, such as increased specific root length than native plants in high-disturbance, low-nutrient environments. From the synthesized literature, we derived the RTEI framework, which predicts that acquisitive root traits associated with enhanced nutrient uptake will promote invasion success under high-nutrient, low-disturbance conditions. In high-disturbance environments with abundant nutrients, invaders are expected to exhibit traits enabling rapid root turnover or clonal regeneration. In low-nutrient environments, traits that foster microbial mutualisms or resource conservation may enhance invasiveness.