Tidal wetlands worldwide are undergoing rapid invasions by tall‐growing clonal grasses. Prominent examples are invasions by species of the genera Spartina, Phragmites and Elymus. The responsible physiological and ecological drivers of these invasions are poorly understood. Physiological integration (PI) is a key trait of clonal plants, which enables the exchange of resources among ramets. We investigated PI in Elymus athericus, which has been rapidly spreading from high‐marsh into low‐marsh environments of European salt marshes during the last decades. We applied a nitrogen stable‐isotope approach to trace nutrient translocation between ramets in a factorial mesocosm experiment. The experiment was set up to mimic an invasion pattern commonly found in tidal wetlands, i.e. from high‐elevated and rarely flooded into low‐elevated and frequently flooded microenvironments. We tested for intraspecific variability in PI by including two genotypes of Elymus that naturally occur at different elevations within the tidal frame, a high‐marsh (HM) and a low‐marsh (LM) genotype. PI strongly increased offspring ramet aboveground and belowground biomass by 62 and 81%, respectively. Offspring ramets under drained conditions had 95% greater belowground biomass than those under flooded conditions. LM genotype offspring ramets produced 27% more aboveground biomass than HM genotypes. Offspring ramets were clearly more enriched in ¹⁵N under flooded versus drained conditions; however, this positive effect of flooding on δ¹⁵N was only significant in the LM genotype. Our findings demonstrate the importance of PI for the growth of Elymus offspring ramets and thereby for the species' capacity for fast vegetative spread. We show that offspring ramets under stressful flooded conditions are more dependent on nutrient supply from parent ramets than those under drained conditions. Our data furthermore suggest a higher degree of adaptation to flooding via PI in the LM versus HM genotype. In conclusion, we highlight the importance of assessing PI and intraspecific trait variability to understand invasion processes within ecosystems.

中文翻译：

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在我的朋友的帮助下：生理整合促进湿地草Elymus athericus入侵淹没的土壤

世界范围内的潮汐湿地正迅速生长着高高的无性草。最著名的例子是斯巴迪娜（Spartina），芦苇（Phragmites）和披碱草（Elymus）属的入侵。人们对这些入侵的负责任的生理和生态驱动因素知之甚少。生理整合（PI）是克隆植物的关键特征，它可以使分株之间进行资源交换。我们调查了Elymus athericus中的PI在过去的几十年中，欧洲盐沼已从高沼地迅速扩散到低沼地环境。在阶乘介观实验中，我们应用了氮稳定同位素方法来追踪分株之间的营养素转运。进行该实验的目的是模仿潮汐湿地中常见的入侵模式，即从高海拔且很少被淹没到低海拔且经常被淹没的微环境中。我们通过包括两种披碱草属基因型来测试PI的种内变异性自然发生在潮汐框架内高海拔（HM）和低沼泽（LM）基因型的不同高度。PI分别使后代的地上和地下生物量大大增加了62％和81％。排水条件下的后代分株的地下生物量比洪水条件下的高95％。LM基因型后代分株的地上生物量比HM基因型多27％。在水淹和排水条件下，后代分株显然富含^15N。然而，充斥于δ这种积极作用¹⁵ n为只在LM基因型显著。我们的发现证明了PI对Elymus生长的重要性后代分株，从而提高该物种快速营养传播的能力。我们显示，在压力淹没条件下的子代分株比在排水条件下的子株更依赖于来自母体分株的营养供应。我们的数据进一步表明，LM基因型与HM基因型相比，通过PI对洪水泛滥的适应性更高。总之，我们强调评估PI和种内性状变异性以了解生态系统内入侵过程的重要性。