基于野外调查和同质种植园实验的芦苇植物功能性状变异研究

研究表型可塑性和遗传变异在植物表型分化中的相对作用，有助于预测全球环境变化下的植物群落组成和生态系统功能的变化。芦苇（Phragmites australis）是全球性广布的草本植物，种内变异丰富，在我国西北和东部均存在多个分化稳定的生态型，但中国芦苇在更大尺度上的表型研究还非常匮乏。将位于黄河上游的宁夏平原和黄河下游的黄河三角洲作为研究区域，通过野外调查和同质种植园实验对芦苇自然种群的植物功能性状变异进行观测。结果表明，无论在野外还是同质种植园，黄河三角洲芦苇的基径、叶长和叶宽均显著大于宁夏平原芦苇，说明两个地区的芦苇种群之间存在着受遗传决定的表型分化，这可能与两个地区间的降水等气候差异有关。在野外，宁夏芦苇的株高和叶厚显著大于黄河三角洲芦苇，但在同质园中差异消失或相反，说明株高、叶厚受环境影响较大，表型可塑性也是芦苇适应环境变化的重要机制。在同质种植园中，宁夏平原芦苇的叶片氮磷含量较低，但株数却显著多于黄河三角洲芦苇，反映了不同地区芦苇之间存在不同的适应策略，宁夏平原芦苇更偏向于高扩散率的杂草策略，而黄河三角洲芦苇更偏向于竞争策略。此外，宁夏平原芦苇的株高、叶长两个性状以及基径-比叶面积相关性在野外和同质园两个环境中存在一致性，表明了性状变异和权衡策略的遗传稳定性。综上，位于黄河上下游的芦苇种群间存在着适应性分化，这是表型可塑性和遗传变异共同作用的结果，不同来源芦苇对全球变化下的多重环境因子的响应还需要进一步研究。

Variation in plant functional traits of Phragmites australis based on field investigation and common garden experiment

Study on the relative contributions of phenotypic plasticity and genetic variation to plant phenotypic differentiation can facilitate the predictions of community composition and ecosystem functioning under global environmental changes. As a cosmopolitan grass, common reed (Phragmites australis) has a high intraspecific diversity and has several ecotypes in northwest and east China. However, few studies focused on the phenotypic variation of common reed at a larger scale in China. Here, we investigated the intraspecific variation in plant functional traits of P. australis from Ningxia Plain, an upstream wetland, and the Yellow River Delta, a downstream wetland, via field investigation and common garden experiment. The results showed that the shoot diameter, leaf length and leaf width of P. australis from the Yellow River Delta were significantly larger than those from the Ningxia Plain in both the field and the common garden, suggesting a stable phenotypic differentiation controlled by genetic variation between the two regions. The phenotypic differentiation could be explained by the adaptation to local climatic conditions such as precipitation. In the field, the shoot height and the leaf thickness of P. australis from Ningxia Plain were significantly higher than those from the Yellow River Delta, but the difference disappeared or reversed in the common garden, which suggests that these traits are regulated directly by the current environment and phenotypic plasticity is also an important mechanism for P. australis to adapt to environmental changes. In the common garden, the content of nitrogen and phosphorus in leaves of P. australis from Ningxia Plain was lower, while the plant density was significantly larger than that from the Yellow River Delta. Which reflects different adaptive strategies that P. australis from Ningxia Plain prefers a ruderal strategy with a high reproduction rate, while P. australis from the Yellow River Delta favors a competitive strategy. Moreover, there were correlations between the field and the common garden observations in shoot height, leaf length and relationship between shoot diameter and specific leaf area, which indicates the genetic inheritance of trait variation and trade-off strategy. In conclusion, there is an adaptive differentiation between the upstream and downstream populations of P. australis in the Yellow River basin due to phenotypic plasticity and genetic variation. Further studies are needed to reveal the responses of plant from different provenances to future changes of the multiple environmental factors.