Inadequate pruning turns greenery into a headache in São Paulo every storm and contributes to power outages

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Tree pruning is one of the main demands of São Paulo residents to the city hall. According to open data from the SP156 platform analyzed by O GLOBO, in 2024, 77,625 tree management requests were opened by residents of the capital, the highest rate since 2018. This year, until September, there were 52,428, a number 7.5% lower than that recorded during the same period last year.

Management has become a pressure game between the town hall of Ricardo Nunes (MDB) and Enel, with contradictory figures. The town hall declares having carried out 162 thousand tree prunings in 2025, in addition to 13.3 thousand preventive removals. It also says the number of teams working on the streets to provide management has increased from 122 to 182, and that it has started a digitized inventory of the city’s vegetation. Nunes accuses Enel of having carried out only 31,945 sizes during the year. According to the town hall, the company was committed to pruning 282,271 trees. Enel refutes this assertion and affirms that in 2025 alone it carried out 232,000 prunings and responds that the figure available to the municipal authorities is exceeded due to a “flaw in the municipal system, of which the town hall has been aware since the beginning of the year”.

In any case, volume is not synonymous with quality, warns professor and doctor of botany at the University of São Paulo, Giuliano Locosselli. He is one of the authors of a study, published in 2024 in the journal Urban forestry and urban greeningin which researchers from several universities analyzed town hall data on 456 trees that fell between 2016 and 2018.

Thanks to artificial intelligence, it was possible to detect the main causes of falls, such as inadequate pruning, such as that practiced by energy companies – the so-called “V” pruning, in which the branches in the middle of the tree are cut to allow cables to pass through, causing an imbalance.

— That’s not to say they’re all low quality, but many are designed with cabling in mind. Pruning is an important management technique, but if not done correctly, it is actually very harmful, says Locosselli. — We see in the streets that numerous prunings unbalance the trees, reduce the canopy, the quantity of leaves necessary for their nourishment, carry out photosynthesis and all this compromises the functioning and balance

Identifying if a tree has fallen due to improper pruning is relatively simple. The professor explains that poor management can affect the stem of the plant, that is, the trunk.

— We often see a tree breaking in two or opening. This type of failure is directly associated with pruning, particularly V-shaped pruning, and what is called drastic pruning, explains the botanist.

Bad guys also include root-strangling sidewalks, building “walls” around roots, and planting unsuitable specimens.

— All relevant sectors of society must plan management and planting. In the end, everyone loses. It is necessary to involve the town hall, the concessionaire and public awareness — notes Locosselli.

Another constant complaint from the mayor concerns Enel’s allegedly lower-than-projected investment in electricity infrastructure. Nunes, in an interview with the program Roda Viva Last Monday, he said the company should have invested 3.9 billion reais last year in the Greater São Paulo region, but it should have spent less, 3 billion reais. The company, however, declares that it has approved an investment plan for the period 2025-2027 of 10.4 billion reais.

During last week’s storm, at least 231 trees fell in the city. Asked about City Hall’s role in preventing power outages, Nunes said in the Roda Viva that only “10%” of power outages were caused by vegetation problems.

This figure, however, contrasts with the data communicated by Enel to the National Electric Energy Agency (Aneel), analyzed by O GLOBO. On October 11, 2024, another major storm swept through the city, with high winds recorded. At the time, more than 3 million properties were left in the dark in the city of São Paulo and, like this year, restoration was also slow: Enel took an average of 41.5 hours to respond to incidents.