Effects of Warming, Phosphorous Deposition, and Both Treatments on the Growth and Physiology of Invasive Solidago canadensis and Native Artemisia argyi

Invasive-plant traits, native-plant traits, and their divergences as invasion factors

Invasive plants exert significant ecological impacts on native plants, communities, and ecosystems. However, consistent conclusions regarding how traits of invasive plants, native plants, and their divergences affect invasion dynamics are still lacking. Here, we conducted a pairwise common garden experiment to investigate how invasion was influenced not only by invasive plants but also by native plants, aiming to elucidate the role of invasive-plant traits, native-plant traits, and their divergences in invasion processes. Our findings revealed variations in invasive stage depending on the combinations of invasive and native plants. Specifically, native plants such as A. argyi, A. lavandulifolia, and C. album exhibited competitive superiority when co-occurring with the three invasive plants. S. viridis, A. vestita, and A. annua had competitive superiority when they co-occurred with E. canadensis, G. quadriradiata, and E. annuus respectively. Furthermore, our results demonstrated that the competitive abilities of invasive plants were primarily influenced by factors such as height, diameter, and biomass allocation, while native plants' competitive abilities were mainly affected by diameter, biomass allocation, and function group differences. Moreover, our analysis revealed that invasive-plant traits, native-plant traits, their divergences, and their interactions together explained 36.88% of the variation in invasion dynamics, with invasive-plant traits and the native-plant traits explaining 10.19% and 6.88%, respectively. In conclusion, the traits of invasive and native plants, along with their divergences, significantly influence interspecific relationships, and influencing the invasive stages. Divergences in competitive strategies between the native plants and invasive plants facilitated invasion processes. Our study not only contributes to understanding the mechanisms underlying invasion, but also provides a scientific foundation for predicting and managing the negative effects of invasive plants.

Two Growing-Season Warming Partly Promoted Growth but Decreased Reproduction and Ornamental Value of Impatiens oxyanthera

Climate warming profoundly affects the vegetative growth, flowering phenology and sexual reproduction of plants; therefore, it affects the ornamental value of wild flowers. Despite this, the extent and mechanism of the impact remain unclear. Here, we conducted a warming experiment for two growing seasons (increases of 1.89 °C in 2017 and 2.37 °C in 2018) with infrared heaters to examine the effects of warming on the ornamental value of the wild flower Impatiens oxyanthera, endemic to China, in Mount Emei. We evaluated the comprehensive ornamental value based on plant morphology and flowering characteristics using the analytic hierarchy process (AHP) and disentangled the impact of the two traits on ornamental value using principal component analysis (PCA) and the partial least squares structural equation model (PLS-SEM) under ambient and warming treatments. We hypothesized that warming would reduce the ornamental value of I. oxyanthera in terms of plant morphology and flowering traits. Our results showed that warming significantly decreased plant height and crown width and increased branch number and single-leaf area. Warming also decreased vexillum length, corolla tube length, nectar spur length and pedicel length. In addition, warming shortened flowering duration per plant and reduced flower number, while there was no significant effect on flower longevity and flower color at full-bloom stage between the control and warming treatment. Therefore, the comprehensive ornamental value under warming was lower than that under the control. Pedicel length, flower color, flower longevity and flowering duration per plant were the main factors affecting the comprehensive ornamental value. The PLS-SEM showed that warming had an indirect negative effect on ornamental value via direct negative effects on flowering traits. Collectively, these results indicate that, although promoting vegetative growth, short-term warming significantly decreased the ornamental value of I. oxyanthera due to warming-caused smaller flowers and shorter flowering duration.

Nitrogen Deposition Amplifies the Legacy Effects of Plant Invasion

The legacy effects of invasive plant species can hinder the recovery of native communities, especially under nitrogen deposition conditions, where invasive species show growth advantages and trigger secondary invasions in controlled areas. Therefore, it is crucial to thoroughly investigate the effects of nitrogen deposition on the legacy effects of plant invasions and their mechanisms. The hypotheses of this study are as follows: (1) Nitrogen deposition amplifies the legacy effects of plant invasion. This phenomenon was investigated by analysing four potential mechanisms covering community system structure, nitrogen metabolism, geochemical cycles, and microbial mechanisms. The results suggest that microorganisms drive plant-soil feedback processes, even regulating or limiting other factors. (2) The impact of nitrogen deposition on the legacy effects of plant invasions may be intensified primarily through enhanced nitrogen metabolism via microbial anaerobes bacteria. Essential insights into invasion ecology and ecological management have been provided by analysing how nitrogen-fixing bacteria improve nitrogen metabolism and establish sustainable methods for controlling invasive plant species. This in-depth study contributes to our better understanding of the lasting effects of plant invasions on ecosystems and provides valuable guidance for future ecological management.