Data from: Complementary responses of morphology and physiology enhance the stand-scale production of a model invasive species under elevated CO2 and nitrogen

1. Elevated atmospheric carbon dioxide (eCO2) concentrations and nitrogen (N) enrichment are known to enhance plant productivity and invasion. However, the implications of their interactive effects for plant productivity are not well understood, especially at the stand scale, presumably because morphological and physiological responses to these global change factors are rarely studied together in the field or assessed at the stand-level. 2. We first determined how leaf-level morphological and physiological traits responded to factorial combinations of ambient and elevated CO2 and N. We collected trait data from the model invasive species Phragmites australis (common reed) that were measured over three years in a long-term global change field experiment. We then combined the trait data and additional descriptions of P. australis canopies in a simulation model of carbon assimilation to determine how morphology and physiology contribute to P. australis’ stand scale productivity. 3. At the leaf level, we found that light-saturated rates of photosynthesis were strongly stimulated by eCO2 (37%) and that this effect was enhanced by increasing salinity. N had a smaller effect (17% stimulation) on physiological responses than eCO2, but leaf morphological traits responded primarily to N; plant height increased by 27% and leaf area increased by 47%. 4. Stand scale simulations demonstrated that that morphological and physiological adjustments induced approximately additive responses when P. australis experienced both eCO2 and N enrichment. The simulations also indicated that morphological changes (which were primarily associated with canopy size) influenced stand scale carbon assimilation more than physiological changes. Moreover, 97% of the N response was due to changes in morphology, whereas 62% of the eCO2 response was caused by physiological shifts. 5. Our analysis indicates that morphological and physiological trait responses to elevated CO2 and nitrogen are likely to enhance the productivity of P. australis in complementary ways, potentially accelerating its invasion in North America. Furthermore, our data suggest that changes in morphological traits may have a greater influence on carbon gain than leaf-level physiology under near-future environmental conditions. Our study also highlights the importance of accounting for both morphological and physiological responses when attempting to infer global change responses from leaf-level data.

1. 大气二氧化碳浓度升高（eCO2）与氮（N）富集已被证实可提升植物生产力并增强植物入侵能力。然而，二者的交互效应对植物生产力的影响尚未得到充分解析，尤其是在林分尺度（stand scale）上，推测其原因在于，针对这些全球变化因子的形态与生理响应，极少在野外开展联合研究，也未在林分尺度上进行评估。
2. 本研究首先明确了叶尺度形态与生理性状对本底浓度与升高浓度CO2及N的因子组合的响应规律。我们从入侵模式物种普通芦苇（Phragmites australis, common reed）中采集了性状数据，该数据于一项长期全球变化野外试验中历时三年测定完成。随后我们将性状数据与普通芦苇冠层的额外描述参数整合至碳同化模拟模型中，以阐明形态与生理过程如何影响普通芦苇的林分尺度生产力。
3. 在叶尺度上，我们发现eCO2可显著促进光饱和光合速率（增幅达37%），且该效应会随盐度升高进一步增强。N对生理响应的促进幅度（17%）弱于eCO2，但叶形态性状主要响应N处理：植株株高提升27%，叶面积增加47%。
4. 林分尺度模拟结果显示，当普通芦苇同时遭遇eCO2升高与N富集时，形态与生理调整会产生近似加性的响应。模拟结果还表明，（主要与冠层大小相关的）形态变化对林分尺度碳同化的影响强于生理变化。此外，N响应的97%源于形态变化，而eCO2响应的62%由生理转变所导致。
5. 本研究分析表明，针对CO2升高与N富集的形态与生理性状响应，可能以互补方式提升普通芦苇的生产力，进而可能加速其在北美地区的入侵进程。此外，我们的数据显示，在近未来的环境条件下，形态性状变化对碳获取的影响可能强于叶尺度生理过程。本研究还强调，若试图从叶尺度数据推演全球变化响应，需同时考虑形态与生理响应的重要性。