Soil organic nitrogen endows invasive Solidago canadensis with greater advantages in low‐phosphorus conditions

Abstract

AbstractAlthough the importance of soil nitrogen (N) and phosphorus (P) has long been recognized in plant nutrition, no study has addressed how soil organic N and P contribute to the success of invasive plants. To do so, we conducted two experiments in which invasive Solidago canadensis and native S. decurrens were either subjected to five amino acids or subjected to organic and inorganic N treatments (i.e., five amino acids and five ratios of nitrate to ammonium) under two P levels. In the first experiment, S. canadensis and S. decurrens grew taller when five amino acids were supplied than when no N was supplied, suggesting both species can use soil amino acids as N sources. In a second experiment, S. canadensis grew larger and taller than S. decurrens in the presence of organic and inorganic N, and organic N exhibited greater positive effects on the growth advantage of S. canadensis relative to S. decurrens than inorganic N; P levels influenced the effects of organic N on plant growth through changing biomass allocation and leaf chlorophyll. These results suggest that organic N and inorganic N may differentially contribute to the growth advantage of invasive species. Considering plant organic N economy is necessary to elucidate invasion mechanisms and expand plant strategies.