Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013, Bern, Switzerland.
Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, 72076, Tübingen, Germany.
Oecologia. 2019 Oct;191(2):389-396. doi: 10.1007/s00442-019-04490-1. Epub 2019 Aug 22.
Habitats with fluctuating resource conditions pose specific challenges to plants, and they often favor a small subset of species that includes exotic invaders. These species must possess a superior ability to capitalize on resource pulses through faster resource uptake or greater resource-use efficiency. We addressed this question in an experiment with invasive knotweed, a noxious invader of temperate ecosystems that is known to benefit from nutrient fluctuations. We used stable isotopes to track the uptake and use efficiency of a nitrogen pulse in competition pairs between knotweed and five native competitors. We found that nitrogen pulses indeed promoted knotweed invasion and that this is explained by a superior efficiency in turning the taken-up extra nitrogen into biomass, rather than capturing an overproportional share of the nitrogen. Thus, temporary increases in nutrient availability might help knotweed to invade natural environments, such as river banks or nitrogen-polluted margins and wastelands, where nutrient fluctuations occur. Our experiment shows that resource-use efficiency can drive invasion under fluctuating resource conditions, and that stable isotopes help to understand these processes.
生境资源条件波动会给植物带来特殊挑战，而这些生境通常有利于一小部分物种，其中包括外来入侵物种。这些物种必须具备通过更快地吸收资源或更高的资源利用效率来利用资源脉冲的卓越能力。我们在一项关于入侵性葛藤的实验中解决了这个问题，葛藤是一种有害的温带生态系统入侵物种，已知它会受益于养分波动。我们使用稳定同位素来追踪葛藤和五种本地竞争者之间竞争对中氮脉冲的吸收和利用效率。我们发现，氮脉冲确实促进了葛藤的入侵，这可以通过将吸收的额外氮转化为生物量的更高效率来解释，而不是捕获不成比例的氮份额。因此，营养物质可用性的暂时增加可能有助于葛藤入侵自然环境，如河岸或氮污染的边缘和荒地，这些地方会发生养分波动。我们的实验表明，在资源波动条件下，资源利用效率可以推动入侵，而稳定同位素有助于理解这些过程。
