Simulated nitrogen deposition induces shifts in growth and resource-use strategies during range expansion of an invasive plant

An appropriate resource-use strategy contributes to the invasion success of exotic plants. During range expansion, population density and resource availability are two important factors that exert significant influences on resource-use-associated traits. As population density decreases and resource availability increases towards range edges, invasive species are likely driven to become increasingly quicker in energy return. In addition, nitrogen (N) deposition has accelerated at both regional and global scales due to anthropogenic activities. However, little is known about how resource-use-associated traits shift in response to simultaneous changes in population density and N deposition. <i>Mikania micrantha</i>, one of the worst invasive weeds in South China, was examined in this study. We investigated the effect of simulated N deposition on the growth and leaf physiology of <i>M. micrantha</i> and the relationship between these traits and population density across N gradients. The results showed that N deposition greatly increased the growth and leaf physiological parameters of <i>M. micrantha</i>, and the decrease in population density and increase in resource availability jointly drove the resource-use strategy of this plant to be more acquisitive during range expansion. In addition, both growth and leaf physiology have evolved to perpetuate the range expansion process, they may not necessarily be associated with each other. These results suggest that the resource-use strategy of invasive plants is highly context dependent. The evolution of resource-use strategies in the face of changes in nutrient availability due to N deposition may facilitate the spread of <i>M. micrantha </i>under various conditions. This work reveals the patterns of resource-use strategies in long-term plant invasion and provides insights into how invasive species will fare in the context of nitrogen deposition.