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Background: Resource competition is an important factor affecting the invasion success of alien plants, and environmental factors influence the competition outcomes between invasive and native plants. In this study, we explore the competitive pattern between invasive Chromolaena odorata and two native plant species under different phosphorus and irradiance levels., Results: The final biomass of each plant was regulated by both morphological and physiological traits. Invasive C. odorata did not always perform better than both native plants, and the competitive pattern between C. odorata and native plants was dependent on native competitor identity and environmental conditions. With competition, invasive C. odorata showed higher biomass (over 60%) than native Xanthium sibiricum under all treatments, but only showed higher biomass (about 20%) than native Eupatorium lindleyanum in normal irradiance treatments. The effect of phosphorus on competition depended on the irradiance level. Under normal irradiance, phosphorus addition increased (almost 10 times) the competitive index of invasive C. odorata; however, under shade irradiance, phosphorus addition decreased (40%) the competitive index of C. odorata., Conclusion: These results suggest that phosphorus, irradiance and native plant competitor together influence the relative performance of invasive C. odorata. In shade environment, selecting E. lindleyanum as competitor and increasing phosphorus level is an effective method for controlling the invasion of C. odorata., (© 2024. The Author(s).)

Contents Summary 701 I. Introduction 701 II. Why we need an explicitly evolutionary perspective 702 III. A case study invasion experiment 702 IV. The way forward 703 V. Conclusions 705 Acknowledgements 706 References 706 SUMMARY: Comparing models of trait evolution might generate new insights into the role of evolutionary history in biological invasions. Assumptions underlying Darwin's naturalization conundrum suggest that close relatives are functionally similar. However, newer work is suggesting more complex relationships between phylogenetic and functional distance. We present an example in which communities of close relatives are functionally divergent in leaf traits and have greater invader biomass. Such an approach leads to new questions, such as: When might selection lead to divergence between close relatives? For example, a history of sympatry might correspond with divergence. We suggest that moving beyond a simplistic version of Darwin's naturalization conundrum as alternative hypotheses will lead to a more nuanced view on how evolution has shaped biological invasions., (© 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.)

The evolution of increased competitive ability (EICA) hypothesis and the novel weapons hypothesis (NWH) are two non-mutually exclusive mechanisms for exotic plant invasions, but few studies have simultaneously tested these hypotheses. Here we aimed to integrate them in the context of Chromolaena odorata invasion. We conducted two common garden experiments in order to test the EICA hypothesis, and two laboratory experiments in order to test the NWH. In common conditions, C. odorata plants from the nonnative range were better competitors but not larger than plants from the native range, either with or without the experimental manipulation of consumers. Chromolaena odorata plants from the nonnative range were more poorly defended against aboveground herbivores but better defended against soil-borne enemies. Chromolaena odorata plants from the nonnative range produced more odoratin (Eupatorium) (a unique compound of C. odorata with both allelopathic and defensive activities) and elicited stronger allelopathic effects on species native to China, the nonnative range of the invader, than on natives of Mexico, the native range of the invader. Our results suggest that invasive plants may evolve increased competitive ability after being introduced by increasing the production of novel allelochemicals, potentially in response to naïve competitors and new enemy regimes., (© 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.)

Invasive plants generally escape from specialist herbivores of their native ranges but may experience serious damage from generalists. As a result, invasive plants may evolve increased resistance to generalists and tolerance to damage. To test these hypotheses, we carried out a common garden experiment comparing 15 invasive populations with 13 native populations of Chromolaena odorata, including putative source populations identified with molecular methods and binary choice feeding experiments using three generalist herbivores. Plants from invasive populations of C. odorata had both higher resistance to three generalists and higher tolerance to simulated herbivory (shoot removal) than plants from native populations. The higher resistance of plants from invasive populations was associated with higher leaf C content and densities of leaf trichomes and glandular scales, and lower leaf N and water contents. Growth costs were detected for tolerance but not for resistance, and plants from invasive populations of C. odorata showed lower growth costs of tolerance. Our results suggest that invasive plants may evolve to increase both resistance to generalists and tolerance to damage in introduced ranges, especially when the defense traits have low or no fitness costs. Greater defenses in invasive populations may facilitate invasion by C. odorata by reducing generalist impacts and increasing compensatory growth after damage has occurred.

There are many non-mutually exclusive mechanisms for exotic invasions but few studies have concurrently tested more than one hypothesis for the same species. Here, we tested the evolution of increased competitive ability (EICA) hypothesis in two common garden experiments in which Chromolaena odorata plants originating from native and nonnative ranges were grown in competition with natives from each range, and the novel weapons hypothesis in laboratory experiments with leachates from C. odorata. Compared with conspecifics originating from the native range, C. odorata plants from the nonnative range were stronger competitors at high nutrient concentrations in the nonnative range in China and experienced far more herbivore damage in the native range in Mexico. In both China and Mexico, C. odorata was more suppressed by species native to Mexico than by species native to China. Species native to China were much more inhibited by leaf extracts from C. odorata than species from Mexico, and this difference in allelopathic effects may provide a possible explanation for the biogeographic differences in competitive ability. Our results indicate that EICA, innate competitive advantages, and novel biochemical weapons may act in concert to promote invasion by C. odorata, and emphasize the importance of exploring multiple, non-mutually exclusive mechanisms for invasions., (© 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.)

Native herbivory may be detrimental to plant fitness and thus can contribute a biotic resistance to exotic plant invasion. Eupatorium adenophorum , a non-native species, has formed dense monocultures in many southern Provinces of China. Because several native generalist insects feed on E. adenophorum , we evaluated whether the lower level of induced defences and greater compensatory growth contributed to successful invasion of E. adenophorum by comparison with a native congener E. heterophyllum. Early events in the jasmonic acid cascade and chlorophyll fluorescence, non-target metabolomic profiles and recovery in biomass compensation of E. adenophorum and its native congener E. heterophyllum were measured during mechanical wounding and herbivory by the generalist insect Helicoverpa armigera. Mechanical and simulated chewing damage immediately initiated defences in the two species. However, E. heterophyllum was more sensitive to tissue loss, and it produced more metabolic defensive compounds than invasive E. adenophorum. Although H. armigera feeding amplified the effects of mechanical wounding on defence induction, the biomass of E. adenophorum was only weakly affected, as its higher compensatory growth could offset the biomass loss and metabolic cost. Overall, our results suggest that H. armigera herbivory and mechanical wounding could induce different physiological responses, and are often specific to invasive E. adenophorum and native E. heterophyllum. Moreover, lower metabolic defences and higher compensation growth may contribute to the invasion success of E. adenophorum. [ABSTRACT FROM AUTHOR]

Premise: Exploring how functional traits vary and covary is important to understand plant responses to environmental change. However, we have limited understanding of the ways multiple functional traits vary and covary within invasive species. Methods: We measured 12 leaf traits of an invasive plant Chromolaena odorata, associated with plant or leaf economics, herbivore defense, and drought resistance on 10 introduced populations from Asia and 12 native populations from South and Central America, selected across a broad range of climatic conditions, and grown in a common garden. Results: Species' range and climatic conditions influenced leaf traits, but trait variation across climate space differed between the introduced and native ranges. Traits that confer defense against herbivores and drought resistance were associated with economic strategy, but the patterns differed by range. Plants from introduced populations that were at the fast‐return end of the spectrum (high photosynthetic capacity) had high physical defense traits (high trichome density), whereas plants from native populations that were at the fast‐return end of the spectrum had high drought escape traits (early leaf senescence and high percentage of withered shoots). Conclusions: Our results indicate that invasive plants can rapidly adapt to novel environmental conditions. Chromolaena odorata showed multiple different functional trait covariation patterns and clines in the native and introduced ranges. Our results emphasize that interaction between multiple traits or functions should be considered when investigating the adaptive evolution of invasive plants. [ABSTRACT FROM AUTHOR]

There is increasing evidence that climate change and nutrient fluctuations can affect the invasion of alien plants. However, most studies have been performed in pairwise experiments between alien and native species, rather than in multispecies community experiments. In southwest China, a series of artificial multispecies communities containing one invasive species, Chromolaena odorata, and three co-occurring native species were constructed to test the effects of warming and nutrient fluctuations on the invasion success of C. odorata. We found that the invasion success of C. odorata was enhanced significantly under warming but was not influenced by the nutrient fluctuation treatment. However, there was an interactive effect between the warming and nutrient fluctuation treatments on the aboveground biomass of the native plants. Further analysis revealed that the positive effect of warming on plant invasion could be explained by two factors: the enhancement of the invader and suppression of the native plants. Overall, strong warming but weak nutrient fluctuation effects on the invasion success of C. odorata were observed in this experiment. [ABSTRACT FROM AUTHOR]

• Irradiance utilization efficiency was assessed between invasive and native plants. • Invasive C. odorata has higher irradiance utilization efficiency than natives. • C. odorata possesses effective protection mechanism for high irradiance damage. High irradiance utilization efficiency is one important character for some invasive plants. Chromolaena odorata is one noxious invasive species originating from Latin America, which had spread widely in most tropical and subtropical areas. To explore why C. odorata perform better than native plants in the understory of planted forests, we compared the irradiance utilization efficiency between invasive C. odorata and three co-occurring species (Merremia vitifolia, Pueraria phaseoloides, and Litsea monopetala). We found that C. odorata had lower leaf thickness but higher specific leaf area, net photosynthetic rate per leaf thickness and photosynthetic nitrogen use efficiency than the three native species. The photosynthetic resistance to irradiance damage was stronger for C. odorata than for the three native species. These traits may have contributed to the higher performance of C. odorata than native plants, which may in turn facilitate its invasion in the understory. [ABSTRACT FROM AUTHOR]