On a quiet corner of the University of São Paulo campus stands a rosewood tree that might help save countless others. Scientists there have developed a new way to figure out exactly which branches to cut to keep city trees from toppling in storms — and it all starts with a laser.
The researchers, a team of biologists and engineers from USP, used a technology called LiDAR to scan the tree. LiDAR shoots out laser beams and measures how long they take to bounce back, creating a detailed 3D map. For this single tree, the laser captured 30 million points of data, essentially building a perfect digital twin inside a computer.
"We asked: could we develop a better pruning method by studying how trees balance?" said Marcos Silveira Buckeridge, who coordinated the project at USP's Institute of Biosciences. His collaborator, engineer Emílio Carlos Nelli Silva, had a simple answer: "We can develop a set of equations for that."
The team ran the digital tree through wind simulations using a technique called finite element analysis. By applying force from different directions, they could see exactly where the tree felt most stress — the spots most likely to snap or blow over. Then a pruning algorithm calculated which branches should go. The goal was not just appearance, but physics: cut here, and the tree can redistribute its weight and actually become stronger.
The scientists tested this on a Tipuana tipu, a species common in cities across Brazil. The tree sits exposed in what they call a "wind tunnel" — open space on all sides, battered directly by every gust.
The work comes after a harsh reminder of why it matters. In December 2025, winds exceeding 90 kilometers per hour slammed into São Paulo and surrounding areas. The damage was staggering: 1,327 trees fell across the metropolitan region, some injuring people. More than 2 million residents lost electricity.
"Improper pruning leaves trees vulnerable," Buckeridge explained. "Wind tunnels between buildings make it worse. Rain, heat, and temperature swings all add stress."
One surprising finding: not every cut helps. The research showed that pruning can sometimes create imbalance, making a tree more vulnerable rather than less. The trick is knowing exactly where and how much to trim — which is what their algorithm aims to do.
Currently, scanning a single tree with enough detail takes 40 minutes. That is too slow for city-wide use. But the team hopes to shrink the process and eventually build a smartphone app that city workers could use to decide on the safest cuts for any urban tree. The research was published in the journal Trees: Structure and Function.
"We proved it's possible with mathematics and lasers," Buckeridge said. "The next step is making it fast enough to help real cities."