In Nitrate-Rich Soil, Fallopia x bohemica Modifies Functioning of N Cycle Compared to Native Monocultures

Amélie A M Cantarel,Charline Creuzé Des Châtelliers,Soraya Rouifed,Jonathan Gervaix,Laurent Simon,Julien Bourg,Florence Piola,Sophie Poussineau,Leslie Blazère

doi:10.3390/d12040156

Abstract

The effects of invasive species at the ecosystem level remain an important component required to assess their impacts. Here, we conducted an experimental study with labeled nitrogen in two types of soil (low and high nitrate conditions), investigating the effects of (1) the presence of Fallopia x bohemica on the traits of three native species (Humulus lupulus, Sambucus ebulus, and Urtica dioica) and (2) interspecific competition (monoculture of the invasive species, monoculture of the native species, and a mixture of invasive/native species) on nitrification, denitrification, and related microbial communities (i.e., functional gene abundances). We found that the species with the higher nitrate assimilation rate (U. dioica) was affected differently by the invasive species, with no effect or even an increase in aboveground biomass and number of leaves. F. x bohemica also decreased denitrification, but only in the soil with high nitrate concentrations. The impacts of the invasive species on nitrification and soil microorganisms depended on the native species and the soil type, suggesting that competition for nitrogen between plants and between plants and microorganisms is highly dependent on species traits and environmental conditions. This research highlights that studies looking at the impacts of invasive species on ecosystems should consider the plant–soil–microorganism complex as a whole.

Highlights

IntroductionBecause an invasive species is a new element in a system, it has an impact (positive or negative) on this system by being present [1]
Because an invasive species is a new element in a system, it has an impact on this system by being present [1]
We found significant negative effects on the Denitrification Enzyme Activity (DEA) of invasive species monocultures or mixtures compared to the significant negative effects on the DEA of invasive species monocultures or mixtures compared to native species monocultures (Figure 4B) but only in soil with high NO3- − concentrations (X2 = 16.9; the native species monocultures (Figure 4B) but only in soil with high NO3 concentrations (Χ2 = 16.9; p = 0.0002)

Summary

Introduction

Because an invasive species is a new element in a system, it has an impact (positive or negative) on this system by being present [1]. It has been shown that some of these invasive plants might play a role in denitrification (NO3 − reduction into gaseous forms [10,11]). All of these studies suggest that invasive plants might have positive or negative feedbacks on soil microorganism functioning, facilitating their establishment in invaded ecosystems, and impacting plant–plant competition for N-substrates [12]

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Conclusion