三种增温情景对入侵植物紫茎泽兰种子出苗的影响

Three warming scenarios differentially affect the seed emergence of an invasive forb Eupatorium adenophorum

全球气候变暖影响外来植物的入侵风险,不同增温情景可影响入侵植物的生长和其他表型。种子出苗是种群生活史的重要阶段,但是目前还不了解不同增温情景对入侵植物种子出苗的影响。设置三种增温情景(白天增温、晚上增温、全天增温),通过同属近缘种比较,研究不同增温对入侵植物紫茎泽兰(Eupatorium adenophorum)和本地植物异叶泽兰(Eupatorium heterophyllum)种子出苗的影响。与对照(不增温)相比,三种增温方式都不同程度地降低异叶泽兰的出苗率,白天增温时出苗率最低,其次是全天增温;对于紫茎泽兰而言,晚上增温提高其出苗率,白天增温降低其出苗率,在全天增温条件下紫茎泽兰没有出苗。增温对紫茎泽兰的影响比对异叶泽兰的影响更明显。此外,异叶泽兰与紫茎泽兰种子出苗率与积温基本呈线性关系,且不同增温方式对各线性关系影响存在差异。这些结果初步表明,如果未来的气候变暖发生在夜间,则有利于提高紫茎泽兰的入侵风险;如果发生在白天、尤其是全天,则可能极大降低其入侵风险。

Global climate warming commonly affects the invasion risk of exotic plants, and diverse different warming scenarios can affect their growth and other traits. Although seed emergence is among the key stages of life cycle of plant populations, little is known about how different climate warming affects the seed emergence of invasive plants. We conducted a simulated climate warming experiment at Chengdu, in which the invasive forb Eupatorium adenophorum and its native congener E. heterophyllum were subjected to three warming treatments： day-warming, night-warming, daily warming. We recorded the seed emergence every day and then analyzed how different warming scenarios affected it of the two species. Compared with the controls, three warming ways reduced the emergence rate of E. heterophyllum, and the emergence followed the order： day-warming 〈 daily warming 〈 night-warming. For Eupatorium adenophorum, night-warming increased its seed emergence, day-warming decreased it, and no emergence was found in the daily warming. Overall, simulated warming had greater effects on Eupatorium adenophorum than on E. heterophyllum. Additionally, there were linear relationships between the emergence rate of these two species and accumulated air temperatures, and the effects of different warming ways on these linear relationships were variable. Our findings suggest that the nighttime-based climate warming may be advantageous for E. adenophorum to enhance its invasion risk, and the opposite may be true in the day-warming, particularly in the daily warming.