Raindrop impact exerts a force on the leaf resulting in a decaying oscillation of the leaf inclination angle. Nondestructive measurements of leaf oscillations is important for predicting changes in leaf angles in the field based on morphometric properties of leaves. The objectives of this study were to determine if a second order impulse response could describe experimentally observed changes in leaf inclination angle, to determine if field measurable, nondestructive leaf traits significantly correlate with model parameters, and to determine if the model parameters were species-specific. This study examined leaf oscillations for three common species in Colorado, USA (Acer saccharinum, Quercus gambelii, and Ulmus pumila) due to two different raindrop sizes. The drop impact was created by releasing a single drop of known size from a known height. The resulting leaf motion was recorded using a high-speed video camera. The images were then processed to measure the leaf inclination angle as a function of time, and a model was used to fit the data. The model was evaluated for quality of fit to the data. The experimental data closely fit the modeled data, indicating that the impulse response appropriately predicts leaf oscillations after raindrop impact. Strong linear relationships existed between leaf mass and maximum change in leaf inclination angle after drop impact for both the experimental and the modeled data. The model parameters were also found to be species-specific. The oscillations in leaf inclination angle are accurately described with a second order impulse response. The parameters of the impulse response correlate with field measurable leaf traits and the parameters are species-specific. The data and approach in this study provided a nondestructive tool for the prediction of changes in leaf inclination angle for many broad-leaved species with diverse leaf morphometric properties.

雨滴冲击对叶子施加力，导致叶子倾斜角的衰减振荡。叶片振动的无损测量对于根据叶片的形态测量特性预测田间叶片角度的变化非常重要。本研究的目的是确定二阶脉冲响应是否可以描述实验观察到的叶片倾角变化，确定现场可测量的非破坏性叶片特征是否与模型参数显着相关，并确定模型参数是否具有物种特异性. 本研究检查了美国科罗拉多州三种常见物种（糖精槭、Quercus gambelii和Ulmus pumila) 由于两种不同的雨滴大小。坠落冲击是通过从已知高度释放已知大小的单个坠落而产生的。使用高速摄像机记录了由此产生的叶子运动。然后处理图像以测量作为时间函数的叶片倾斜角，并使用模型来拟合数据。评估模型的数据拟合质量。实验数据与建模数据非常吻合，表明脉冲响应适当地预测了雨滴撞击后的叶片振荡。对于实验数据和建模数据，在落下撞击后，叶片质量与叶片倾角的最大变化之间存在很强的线性关系。还发现模型参数具有物种特异性。叶片倾斜角的振荡用二阶脉冲响应准确描述。脉冲响应的参数与现场可测量的叶性状相关，并且参数是物种特异性的。本研究中的数据和方法提供了一种非破坏性工具，可用于预测许多具有不同叶片形态特征的阔叶树种的叶片倾角变化。