Biogeochemical Niche building of Invasive Fallopia japonica: Insights from Stable Isotope Probing

Abstract

Exploring invasive plant species, in this case the infamous Fallopia japonica, has become pivotal in understanding their impact on biogeochemical processes within ecosystems. Building upon the work of Girardi et al., who investigated how F. japonica uses polyphenols to inhibit nitrification, our study employs stable isotope analysis to delve into the biogeochemical niche-building mechanisms of this invasive species. Following Girardi et al.’s findings, which highlighted the inhibitory effects of resveratrol on potential nitrification rates in F. japonica invaded riparian ecosystems, our research takes a step further to investigate the broader implications of the success of F. japonica. We employed stable isotopes, ¹³C-CO2 and ¹⁵N-NO3 and -NH4, to shed light upon the biogeochemical dynamics associated with the invasive prowess of F. japonica and find whether Fallopia japonica exhibits a higher affinity for ammonium than nitrate when compared to the native species Urtica dioica, and whether it allocates resources predominantly to root growth.   Contrary to previous hypotheses, our results challenge the belief that F. japonica exhibits a higher affinity for ammonium than nitrate compared to native species. Through our labelling experiments on young F. japonica and Urtica dioica (native) plants, we discovered that F. japonica displays a lower affinity for ammonium than U. dioica. Additionally, F. japonica demonstrated higher nitrogen-use efficiency and a pronounced preference for allocating resources to root biomass, underlining its ability to efficiently utilize nitrogen resources. These findings shed light on the intricate mechanisms behind the ability of F. japonica to disrupt ecosystems, emphasizing the importance of stable isotopes in unraveling such complexities. Through the integration of stable isotope probing techniques and a comprehensive understanding of rhizosphere processes, our work contributes to the ongoing efforts to foster sustainable and efficient agricultural systems in the face of global change. Moving forward, our research trajectory aims to explore the impact of phenols on nitrification in soils. Specifically, we plan to apply phenols to soil and investigate their effects on nitrification, with potential implications for denitrification processes. This endeavor aligns with the broader goal of understanding the multifaceted interactions between invasive plant species and biogeochemical processes, contributing to the development of effective strategies for invasive species management.   Keywords:                      Fallopia japonica, Urtica dioica, invasive species, native species, nitrogen cycle, nitrogen use efficiency, ammonium, 15N labelling, 13C labelling, biogeochemical niche, stable isotopes