## 1 Introduction
In the context of this work, both sets of pixels provide critical information about functional diversity, ecosystem and geomorphic processes in landslides, and more broadly the dynamics of mountainous. The second set of challenges to investigating functional traits and functional diversity is associated with the sources of remotely sensed data and the distinctive trade-offs among spatial, spectral, and temporal resolutions [40; 41; 42]. First, landslides vary greatly in size [43; 44] thus, sensor spatial resolution can strongly influence landslide detection [45]. Second, downscaling of spaceborne multi-, e.g., [5; 46; 47; 48], and hyperspectral [49; 50; 51; 52] data may be necessary to characterize functional diversity and habitat diversity derived from functional traits and functional types and substrates, respectively. Used methods include band-sharpening or bilinear interpolation to match the smallest field sampling unit and modeling fractional cover using spectral mixture analyses (SMA). In both instances, subsequent upscaling using environmental data allows examination of diversity patterns at landscape and regional scales. Third, upscaling of functional traits derived from airborne, hyperspectral data may be necessary to characterize functional diversity from image scenes to regions; this may require modeling upscaled functional traits with environmental data [12; 53; 54]. Finally, an improvement of the temporal resolution of data offered by the new generation of spaceborne hyperspectral missions (Files S1 and S2: Table S1) can be extremely valuable not only to capture landslide populations triggered by precipitation or earthquake events but also the development of individual landslides within any population or assemblage. Leveraging studies that have overcome some of the challenges outlined above, this review brings together spectroscopy work conducted in different fields to develop the ecosystem \"centered\" view of landslides outlined in Figure 1. This view recognizes the critical influence of biodiversity both on slope resistance and susceptibility to failure and landslide recovery and, more broadly, of interactions between ecosystem and geomorphic processes driving the dynamics of mountainscapes mediated by landslides at multiple scales. More specifically, this review aims to (1) synthesize broad established methods to retrieve functional traits from remotely sensed data, (2) summarize approaches to characterize functional diversity derived from remotely sensed functional traits, (3) review work addressing functional diversity, ecosystem functioning, and dynamics of mountainscapes, and (4) elaborate on how these methods and approaches can help develop a needed holistic view of landslides. On the one hand, (1) and (2) hinge on the selection of relevant functional traits at leaf and plant levels, developing models associating these traits with their optical properties, scaling functional traits with air- and spaceborne data, and assessing functional groups and functional diversity at multiple scales ([15; 55; 56; 16; 53]). On the other hand, (3) acknowledges the need to integrate diverse approaches and fields, and (4) the importance of landslide size and scale to understand interactions between ecosystem and geomorphic processes from individual landslides and sites to entire landslide populations, assemblages, and landscapes (Figure 1).