Quantifying how biodiversity affects ecosystem functions through time over large spatial extents is needed for meeting global biodiversity goals yet is infeasible with field-based approaches alone. Imaging spectroscopy is a tool with potential to help address this challenge. Here, we demonstrate a spectral approach to assess biodiversity effects in young forests that provides insight into its underlying drivers. Using airborne imaging of a tree-diversity experiment, spectral differences among stands enabled us to quantify net biodiversity effects on stem biomass and canopy nitrogen. By subsequently partitioning these effects, we reveal how distinct processes contribute to diversity-induced differences in stand-level spectra, chemistry and biomass. Across stands, biomass overyielding was best explained by species with greater leaf nitrogen dominating upper canopies in mixtures, rather than intraspecific shifts in canopy structure or chemistry. Remote imaging spectroscopy may help to detect the form and drivers of biodiversity–ecosystem function relationships across space and time, advancing the capacity to monitor and manage Earth’s ecosystems.

量化生物多样性如何在大空间范围内随时间影响生态系统功能是实现全球生物多样性目标所必需的，但仅使用基于实地的方法是不可行的。成像光谱是一种有潜力帮助应对这一挑战的工具。在这里，我们展示了一种光谱方法来评估年轻森林中的生物多样性影响，从而深入了解其潜在驱动因素。使用树木多样性实验的空中成像，林分之间的光谱差异使我们能够量化对茎生物量和冠层氮的净生物多样性影响。通过随后对这些影响进行划分，我们揭示了不同的过程如何导致植物水平光谱、化学和生物量的多样性引起的差异。跨过看台，生物量超产的最佳解释是在混合物中叶氮含量较高的物种在上部冠层中占主导地位，而不是冠层结构或化学的种内变化。远程成像光谱可能有助于检测跨空间和时间的生物多样性-生态系统功能关系的形式和驱动因素，从而提高监测和管理地球生态系统的能力。