Plant traits of grass and legume species for flood resilience and N2O mitigation

Flooding threatens the functioning of managed grasslands by decreasing primary productivity and increasing nitrogen losses, notably as the potent greenhouse gas nitrous oxide (N2O). Sowing species with traits that promote flood resilience and mitigate flood-induced N2O emissions within these grasslands could safeguard their productivity while mitigating nitrogen losses.

We tested how plant traits and resource acquisition strategies could predict flood resilience and N2O emissions of 12 common grassland species (eight grasses and four legumes) grown in field soil in monocultures in a 14-week greenhouse experiment.

We found that grasses were more resistant to flooding, while legumes recovered better. Resource-conservative grass species had higher resistance, while resource-acquisitive grasses species recovered better. Resilient grass and legume species lowered cumulative N2O emissions. Grasses with lower inherent leaf and root δ13C (and legumes with lower root δ13C) lowered cumulative N2O emissions during and after the flood.

Our results highlight the differing responses of grasses with contrasting resource acquisition strategies, and of legumes to flooding. Combining grasses and legumes based on their traits and resource acquisition strategies could increase the flood-resilience of managed grasslands, and their capability to mitigate flood-induced N2O emissions.

Methods
See Materials and Methods

洪涝通过降低人工管理草地的初级生产力、增加氮素流失（尤以强效温室气体一氧化二氮（N2O）的形式最为显著），威胁其生态系统功能。在这类草地中播种具备提升洪涝耐受能力、缓解洪涝诱导的N2O排放性状的物种，可在保障草地生产力的同时减少氮素流失。

本研究通过一项为期14周的温室试验，以田间土壤为栽培基质，对12种常见草地物种（8种禾本科植物与4种豆科植物）进行单作栽培，探究植物性状与资源获取策略如何预测其洪涝耐受能力及N2O排放水平。

研究结果显示，禾本科植物的洪涝抗性更强，而豆科植物的灾后恢复能力更佳。资源保守型禾本科植物的洪涝抗性更高，资源获取型禾本科植物的灾后恢复能力更强。具备良好耐受恢复能力的禾本科与豆科植物可降低累积N2O排放量。固有叶片与根系δ¹³C值较低的禾本科植物（以及根系δ¹³C值较低的豆科植物），可在洪涝发生期间及灾后降低累积N2O排放量。

本研究结果凸显了资源获取策略迥异的禾本科植物，以及豆科植物对洪涝的不同响应模式。基于物种性状与资源获取策略合理搭配禾本科与豆科植物，可提升人工管理草地的洪涝耐受能力，并增强其缓解洪涝诱导的N2O排放的能力。

方法
详见材料与方法