Additive effects of warming and nitrogen addition on the performance and competitiveness of invasive Solidago canadensis L.

Changes in temperature and nitrogen (N) deposition determine the growth and competitive dominance of both invasive and native plants. However, a paucity of experimental evidence limits understanding of how these changes influence plant invasion. Therefore, we conducted a greenhouse experiment in which invasive L. was planted in mixed culture with native Levl. et Van under combined conditions of warming and N addition. Our results show that due to the strong positive effect of nitrogen addition, the temperature increases and nitrogen deposition interaction resulted in greatly enhanced species performance. Most of the relative change ratios (RCR) of phenotypic traits differences between and occur in the low invasion stage, and six of eight traits had higher RCR in response to N addition and/or warming in native than in invasive . Our results also demonstrate that the effects of the warming and nitrogen interaction on growth-related traits and competitiveness of and were usually additive rather than synergistic or antagonistic. This conclusion suggests that the impact of warming and nitrogen deposition on can be inferred from single factor studies. Further, environmental changes did not modify the competitive relationship between invasive and native but the relative yield of was significantly greater than . This finding indicated that we can rule out the influence of environmental changes such as N addition and warming which makes successfully invade new habitats through competition. Correlation analysis showed that invasive may be more inclined to mobilize various characteristics to strengthen competition during the invasion process, which will facilitate becoming the superior competitor in interactions. These findings contribute to our understanding of the spreading of invasive plants such as under climate change and help identify potential precautionary measures that could prevent biological invasions.