Plant traits are useful for predicting how species may respond to environmental change and/or influence ecosystem properties. Understanding the extent to which traits vary within species and across climatic gradients is particularly important for understanding how species may respond to climate change. We explored whether climate drives spatial patterns of intraspecific trait variation for three traits (specific leaf area (SLA), plant height, and leaf nitrogen content (Nmass)) across 122 grass species (family: Poaceae) with a combined distribution across six continents. We tested the hypothesis that the sensitivity (i.e. slope) of intraspecific trait responses to climate across space would be related to the species' typical form and function (e.g. leaf economics, stature and lifespan). We observed both positive and negative intraspecific trait responses to climate with the distribution of slope coefficients across species straddling zero for precipitation, temperature and climate seasonality. As hypothesized, variation in slope coefficients across species was partially explained by leaf economics and lifespan. For example, acquisitive species with nitrogen-rich leaves grew taller and produced leaves with higher SLA in warmer regions compared to species with low Nmass. Compared to perennials, annual grasses invested in leaves with higher SLA yet decreased height and Nmass in regions with high precipitation seasonality (PS). Thus, while the influence of climate on trait expression may at first appear idiosyncratic, variation in trait–climate slope coefficients is at least partially explained by the species' typical form and function. Overall, our results suggest that a species' mean location along one axis of trait variation (e.g. leaf economics) could influence how traits along a separate axis of variation (e.g. plant size) respond to spatial variation in climate.

中文翻译：

---

草类的全球种内性状与气候关系与物种的典型形态和功能有关

植物性状可用于预测物种如何响应环境变化和/或影响生态系统特性。了解物种内和气候梯度之间性状变化的程度对于了解物种如何应对气候变化尤为重要。我们探讨了气候是否驱动 122 种草类（禾本科）三个性状（比叶面积 (SLA)、株高和叶氮含量 (Nmass)）的种内性状变异的空间模式，这些草种综合分布在六大洲。我们测试了这样的假设：种内性状对跨空间气候的敏感性（即斜率）与物种的典型形态和功能（例如叶子经济、身材和寿命）有关。我们观察到了种内性状对气候的正向和负向反应，不同物种的降水量、温度和气候季节性的斜率系数分布为零。正如假设的那样，不同物种的斜率系数的变化部分是由叶片经济和寿命来解释的。例如，与具有低 Nmass 的物种相比，具有富氮叶子的获取性物种在温暖地区长得更高并且产生具有更高 SLA 的叶子。与多年生植物相比，一年生草本植物的叶子具有较高的 SLA，但在降水季节性 (PS) 高的地区却降低了高度和 Nmass。因此，虽然气候对性状表达的影响乍一看可能显得特殊，性状-气候斜率系数的变化至少可以部分地由物种的典型形态和功能来解释。总体而言，我们的结果表明，一个物种沿一个性状变异轴（例如叶子经济学）的平均位置可能会影响沿单独变异轴（例如植物大小）的性状如何响应气候的空间变化。