LiDAR for Green Infrastructure: monitoring vertical greening with wooden support structures

Green infrastructures (GI) are key elements in urban areas for heat mitigation, carbon capture and providing of aesthetic reasons. However, there is currently limited knowledge about the effects of various plant compositions, arrangements and varying density of plant cover, because traditional measuring methods are expensive / labour-intensive, imprecise, and tall buildings pose accessibility challenges. The presented study proposes applying LiDAR measurements on GI to gain in-depth understanding of plant growth, inventory of vegetation cover and thereby providing a useful tool for sustainable urban hazard management.

The use of LiDAR (Light Detection and Ranging) technology has revolutionised forest monitoring by offering precise, efficient, and highly detailed spatial data for creating comprehensive 3D reconstructions of forest structures. The ability to capture fine details on both vegetation and structural surfaces is particularly advantageous for studying complex, vertical environments such as green façades. This study used static ground-based LiDAR (RIEGL VZ-600i) to capture the 3D structure of a vertical greenery with wooden support structures before and after harvesting. Defined squares of 1 m² were fully harvested, the biomass collected and dry weight was obtained. Reference measurements for vegetation height (distance from wall to the outermost part of the plant) were recorded on a grid for 40 measurement points. The reference measurements were related to LiDAR alpha-hull volumetric analysis and predictions of growing biomass could be derived.

By integrating point cloud analysis developed for forest monitoring into urban contexts, LiDAR facilitates a holistic analysis of natural and built environments. By analysis of LiDAR intensity and mapping further reference measurements for plant vitality and structural integrity, green wall health can be evaluated. Already established practices like alpha-hulling provide a successful tool to document green façades comprehensively. Combining LiDAR with traditional measures enhances our understanding of the interactions between vegetation and architectural surfaces, enabling improved design and maintenance of GI and NBS to enable better planning and maintaining of NBS to reduce the effect of urban heat islands.