Changes to biodiversity, driven by an increasing consumption of natural resources, and associated alterations to ecosystem processes and functions pose critical challenges to humanity in the 21st century. Functional, genetic and phylogenetic diversity of plant species influence not only the provisioning of food and raw materials, but also the disturbance resistance and resilience of ecosystems, protective functions of the soil, the pool of genetic resources and other ecosystem services landscapes provide. Monitoring and understanding the effects of different levels of plant diversity requires spatial and temporal continuity, as well as standardized assessment schemes. Approaches for acquiring these datasets using traditional field techniques across large spatial scales will necessarily be incomplete, due to time and financial limitations, and lack of accessibility, especially in remote, protected or sensitive areas. Imaging spectroscopy offers promise to overcome these limitations, because spectral data, which depend on chemical, structural, metabolic and phenological differences among leaves, plants and canopies are linked to different ecophysiological strategies. These data can be acquired continuously over large areas at high spatial detail. However, the methods and evidence for linking spectral data to biodiversity and ecosystem functions at multiple scales are still in their early stages. The proposed organized session will bring together experts from leaf spectroscopy, remote sensing, plant functional ecology, plant physiology, genetics, phylogenetics and soil sciences to provide a synthetic overview on how spectroscopic data can be used to assess functional, genetic and phylogenetic plant diversity above ground, and soil processes, including microbial diversity below ground. The contributed talks will present approaches and case studies examining biodiversity and ecosystem functions at multiple scales and levels of organization spanning leaves, canopies, and communities, monitored using proximal, airborne and spaceborne techniques. In particular, the linkages between above- and below-ground diversity and physiological functions will be explored in manipulated biodiversity experiments in grasslands and forests. Additionally, the session will illustrate current methodological and technical challenges including merging datasets from different sensors operated across multiple spatial scales and providing easily accessible global portals for data sharing and exchange.