Using LiDAR to Enhance Urban Tree Safety and Stability
Researchers at the University of São Paulo are applying LiDAR technology to assess and enhance the stability of urban trees, aiming to reduce fall risks.
Addressing Urban Tree Safety with Technology
As cities grow, the risk posed by urban trees becoming hazardous is a pressing concern. A research collaboration at the University of São Paulo (USP) in Brazil has innovatively applied LiDAR (Light Detection and Ranging) technology to evaluate tree health and optimize pruning methods. The objective is to minimize the risk of trees failing, especially in urban environments prone to strong winds.
The team has developed a comprehensive approach using LiDAR, which generates a 3D digital representation—or "point cloud"—of a tree’s architecture. This technology collects millions of data points to create an accurate model of the tree, allowing researchers to analyze its structure with precision.
Tree Health Assessment Components
| Assessment Method | Description | Purpose |
|---|---|---|
| LiDAR Scanning | Creates a detailed 3D model of the tree | Assess tree structure and health |
| Pruning Algorithm | Based on topological optimization | Identify branches to cut for structural balance |
| Finite Element Method (FEM) | Simulates wind effects on tree stability | Predict vulnerabilities and assess response to stress |
In this project, the team aimed to develop a pruning app leveraging these findings, enhancing the durability of trees against wind stress. A well-known incident occurred in December 2025, when winds exceeding 90 km/h (56 mph) resulted in 1,327 fallen trees in the São Paulo Metropolitan Area, leaving over two million residents without power and highlighting the urgency of this research.
Understanding Wind Vulnerabilities
Improper pruning techniques can significantly increase a tree's exposure to wind forces, leading to breakage or uprooting, especially in isolated trees. Marcos Silveira Buckeridge, a co-author of the related study, notes that many trees in urban settings face additional challenges due to wind tunnels created by surrounding buildings that amplify gusts of wind, increasing the likelihood of falls during storms.
The researchers partnered to create a simulation that evaluates a tree's balance and determines optimal pruning techniques by studying the mechanical vulnerabilities of different regions of the plant. This collaboration brought together biologists and engineers aiming to integrate their expertise in life sciences and technology.
Laser Scanning Process
The team conducted extensive laser scans on a rosewood tree (Tipuana tipu) within the USP Butantã campus. The scanning process, which requires favorable weather conditions, involves positioning the LiDAR scanner at various heights and angles around the tree to gather sufficient data. This specific scan resulted in a "point cloud" composed of over 30 million data points.
Once the scanning is complete, the model accurately depicts the tree's structure without its foliage. Researchers then simulate wind from multiple directions to evaluate the tree's sensitivity and potential points of failure. This method also utilizes FEM simulations to predict how the tree interacts with environmental stresses, further validating the effectiveness of the optimization approach.
Evaluating Pruning Techniques
The findings of this research indicate that pruning branches can inadvertently create asymmetry in a tree’s structure, which may render it more vulnerable to strong winds. The pruning algorithm derived through their studies is intended to maintain balance within the tree while prioritizing the removal of less structurally important branches.
Buckeridge emphasizes that their goal is to encourage an approach where no more than 20% of the tree's mass is removed during any pruning session, thus maintaining enough natural resilience against environmental factors.
Moreover, this algorithm is designed primarily for eudicotyledonous angiosperms—flowering plants with a distinctive branching structure—while acknowledging that palm trees require a different approach due to their unique growth patterns.
Expanding Applications of LiDAR
Currently, the LiDAR technology is utilized for tree monitoring and cataloging within São Paulo's urban landscape. The researchers aim to extend this technique to scan all 650,000 street trees, enabling them to assess overall tree health more effectively across the city. Buckeridge describes using a mobile scanning device equipped with suction cups to facilitate the mapping of trees at higher speeds, significantly increasing the data collection efficiency.
In addition to assessing tree structure and strength, researchers are employing LiDAR technology on Avenida Professor Mello Moraes to identify potentially infected trees. Using an ultrasound device, they can determine if cavities exist within the trunk, which can compromise the tree's overall stability. This combined approach promises improved diagnostics of tree health and longevity.
Addressing Tree Roots and Environmental Factors
While the current research focuses on tree structure and pruning, Buckeridge acknowledges that the roots are also a critical aspect of tree health, as approximately 30% of tree falls in São Paulo are attributed to root instability. The team is developing ways to incorporate root data using ground-penetrating radar technology, which helps visualize the root structure beneath the surface.
The importance of environmental factors such as temperature variations and moisture levels is central to understanding tree risk. After exposure to heavy rain, for instance, the weight of the wood increases significantly, raising the likelihood of structural failure. To tackle this challenge, researchers are integrating dendrometers to measure expansion and contraction in wood, which is a key indicator of tree stability. Buckeridge and his team plan to train their models to encompass multiple factors that contribute to a tree's overall health and potential risk.
Future Directions and Challenges
The integration of LiDAR technology in urban forestry presents exciting opportunities for enhancing tree safety and sustainability. Moving forward, the researchers hope to develop a comprehensive app that incorporates various environmental and structural factors using LiDAR data. However, Buckeridge notes that the computational complexity of such models remains a significant hurdle.
Additionally, studies into the biochemistry of trees may yield insights into universal markers that signify vulnerability to environmental threats. Understanding these markers could help create better management practices across various tree species, enhancing resilience against the challenges posed by urban environments.
Key Takeaways
- LiDAR technology enhances the study of urban tree health by creating detailed 3D models.
- In December 2025, winds over 90 km/h led to thousands of fallen trees in São Paulo, emphasizing the urgency of this research.
- The pruning algorithm aims to maintain structural balance while ensuring less than 20% of a tree's mass is cut during pruning.
- Approximately 30% of tree falls relate to root issues, with ongoing studies addressing this component.
- A comprehensive app is planned to integrate multiple factors affecting tree stability and health.
The ongoing research at USP signifies an innovative step in urban forestry, showcasing how technology can transform our approach to tree management. As these methods develop, they hold the potential not only to prevent accidents but also to sustain urban green spaces efficiently, ultimately enhancing the well-being of urban environments.
Frequently Asked Questions