BACKGROUND AND AIMS Andropogon gerardii is a highly productive C4 grass species with a large geographic range throughout the North American Great Plains, a biome characterized by a variable temperate climate. Plant traits are often invoked to explain growth rates and competitive abilities within broad climate gradients. For example, plant competition models typically predict that species with large geographic ranges benefit from variation in traits underlying high growth potential. Here, we examined the relationship between climate variability and leaf-level traits in A. gerardii, emphasizing how leaf-level microanatomical traits serve as a mechanism that may underlie variation in commonly measured traits, such as SLA. METHODS A. gerardii leaves were collected in August of 2017 from Cedar Creek Ecosystem Science Reserve (MN), Konza Prairie Biological Station (KS), Platte River Prairie (NE), and Rocky Mountain Research Station (SD). Leaves from ten individuals from each site were trimmed, stained, and prepped for fluorescent confocal microscopy to analyze internal leaf anatomy. Leaf microanatomical data was compared with historical and growing season climate data which was extracted from PRISM spatial climate models. KEY RESULTS Microanatomical traits displayed large variation within and across sites. According to AICc selection scores, the interaction of mean precipitation and temperature for the 2017 growing season was the best predictor of variability for the anatomical and morphological traits measured here. Mesophyll area and bundle sheath thickness were directly correlated with mean temperature (annual and growing season). Tissues related to water-use strategies, such as bulliform cell and xylem area, were significantly correlated with one another. CONCLUSIONS The results indicate (1) microanatomical trait variation exists within this broadly distributed grass species (2) microanatomical trait variability appears likely to impact leaf-level carbon and water use strategies, and (3) microanatomical trait values vary across climate gradients, and may underlie variation in traits measured at larger ecological scales.

中文翻译：

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微观解剖学特征跟踪美国大平原主要 C4 草种的气候梯度

背景和目标 Andropogon gerardii 是一种高产的 C4 草种，地理范围广泛，遍及北美大平原，该生物群落的特点是温带气候多变。植物性状经常被用来解释宽气候梯度内的生长率和竞争能力。例如，植物竞争模型通常预测具有较大地理范围的物种受益于潜在高增长潜力的性状变化。在这里，我们研究了 A. gerardii 中气候变异性与叶片级特征之间的关系，强调了叶片级微观解剖学特征如何作为一种机制，可能是常见测量性状（如 SLA）变异的基础。方法 A. gerardii 叶子于 2017 年 8 月从雪松溪生态系统科学保护区 (MN) 采集，孔扎草原生物站 (KS)、普拉特河草原 (NE) 和落基山研究站 (SD)。来自每个站点的 10 个个体的叶子被修剪、染色并准备用于荧光共聚焦显微镜以分析内部叶子解剖结构。将叶片显微解剖数据与从 PRISM 空间气候模型中提取的历史和生长季节气候数据进行比较。主要结果 显微解剖学特征在站点内和站点间显示出很大的差异。根据 AICc 选择分数，2017 年生长季节的平均降水量和温度的相互作用是此处测量的解剖学和形态学特征变异性的最佳预测指标。叶肉面积和束鞘厚度与平均温度（年度和生长季节）直接相关。与用水策略相关的组织，如大泡状细胞和木质部区域，彼此显着相关。结论 结果表明 (1) 这种广泛分布的草种中存在显微解剖学特征变异 (2) 显微解剖学特征变异似乎可能影响叶片水平的碳和水分利用策略，以及 (3) 显微解剖学特征值随气候梯度而变化，并且可能在更大的生态尺度上测量的性状变异的基础。