Invasive plants and their roots lead to more similar soil microbial communities

What is it about?

Using the first dataset of its kind, we conducted a continental-scale assessment of how invasive plants, particularly their roots, affect soil microbial communities across 377 plots in the United States. This dataset, the most comprehensive to date, integrates a wealth of information, including data on invasive and native plants, soil properties, root traits, and microbial communities. With it, we were able to address critical questions: (1) Do the roots of invasive plants differ significantly from those of native species? (2) How do microbial communities in invaded plots compare to those in uninvaded plots? (3) To what extent do root traits drive the effects of invasive plants on microbial communities? We found that invasive and native plants exhibit distinct root traits, with invasive species typically having more fine roots, while native plants possess higher root tissue density. Additionally, we discovered that soil microbial communities in heavily invaded ecosystems were more homogeneous in composition across different ecosystem types and geographical regions compared to those in areas dominated by native plants, which exhibited highly variable microbial communities across the continent. Notably, in highly invaded plots, the root traits of invasive plants had twice the influence on structuring soil microbial communities as the root traits of native plants.

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Photo by Mario Heller on Unsplash

Photo by Mario Heller on Unsplash

Why is it important?

One of the most pressing environmental challenges of the 21st century is the spread of aggressive non-native species, known as invasive plants, into native ecosystems. These invaders cause over $3 billion in economic damages annually in the United States, often driving species extinctions and disrupting ecosystem functions. As a result, a key objective in ecological research is to understand the effects of invasive plants on native ecosystems. However, while most studies have concentrated on their aboveground impacts, there is surprisingly little knowledge about their influence belowground. This is particularly striking, given that plant roots account for roughly half of plant biomass and play a crucial role in shaping ecosystems. To fully comprehend the impact of invasive plants and provide informed management strategies, it is essential to investigate their belowground effects. This study marks a significant advancement in understanding large-scale and cross-scale patterns in the relationship between plant invasions, root traits, and soil microbial composition. Our findings highlight how invasive plants may influence ecosystem functioning on a macroscale by homogenizing microbial communities, offering new insights into the broader ecological impacts of plant invasions.