From Trees to Data: A Standardised Approach to Forest Monitoring

Forest ecosystems provide a wide range of services, including timber production, biodiversity conservation, protection against natural hazards, and human recreation. However, they are increasingly under pressure from direct human interventions and climate change. Strengthening forest resilience to changing environmental conditions requires appropriate adaptation measures, which in turn depend on a deep understanding of near-natural forest structures and functions. High-resolution in situ data, both temporally and spatially, are essential for understanding and effective planning and management. This presentation introduces a potential eLTER service offering standardised terrestrial data collection, good practice guides and white papers to assess high resolution 3D structural forest ecosystem properties. Recent advances in proximate sensing like LiDAR and photogrammetry enable high-precision, three-dimensional forest reconstructions at unprecedented levels of detail. Among these, terrestrial laser scanning (TLS) has become the gold standard for generating very high-resolution, accurate 3D point clouds in forest environments. With improvements in portability and usability, TLS technology is now more accessible for widespread application. Mobile laser scanning (MLS), including handheld or backpack-mounted personal laser scanning (PLS) systems, has recently emerged as a much faster alternative, capable of mapping a view hectares per day. However, this speed comes at the expense of reduced precision compared to TLS. For even larger-scale mapping, unmanned aerial vehicle laser scanning (UAVLS) is increasingly used to assess high resolution 3D forest structures across entire landscapes. Additionally, UAV-based and terrestrial photogrammetry based on spectral data provide detailed 3D structural information from overlapping images, while also enabling functional trait assessment through spectral data analysis. A variety of sensors and methods are now available to capture detailed structural and functional information on trees and forests. These data acquisition techniques, along with their derived products, can significantly enhance eLTER standard observations by improving information on e.g. vegetation structure, biomass, energy flows and light availability. Furthermore, such standardised and scalable approaches can add value to various satellite missions by supporting the calibration and validation of satellite-derived data products. In this presentation, we will outline the potential data products, documents and guidelines of this proposed service, discuss the benefits for different eLTER user groups, and explore its role in improving satellite data calibration and validation.