Resilient trees can help protect cities from climate change

Tipuana trees are emerging as a beacon of hope amidst the serious threat of climate change, which is altering weather patterns and leading to extreme conditions like heatwaves and droughts.

In São Paulo, Brazil, scientists have discovered that these remarkable trees not only survive but thrive in challenging environments, continuing to provide invaluable contributions to the ecosystem.

Drought in São Paulo’s green spaces

In a study focusing on the 2013-14 drought, scientists observed how this extreme weather event affected urban trees. The researchers studied seasonal changes, noting that usually, a rainy summer should encourage vigorous tree growth.

Surprisingly, Tipuana trees seemed to thrive despite these challenging conditions, exhibiting accelerated photosynthesis and higher growth rates, even under severe weather conditions.

Study co-author Giuliano Locosselli noted: “We need cities to be increasingly resilient in the context of global warming.”

Advocating for intentional decisions in tree planting, the argument leans towards species capable of withstanding extreme weather, thereby guaranteeing the provision of indispensable ecosystem services, like carbon capture and temperature regulation.

Focus of the research

“Cities are vulnerable to droughts and heatwaves due to the decline in permeable green spaces and the emergence of heat islands,” wrote the study authors.

“To tackle these environmental challenges, many cities adopted ambitious tree-planting initiatives. However, tree tolerance to climate extremes is overlooked even though physiological and growth limitations jeopardize ecosystem services provision.”

Notably, the researchers responsible for this vital discovery hail from the University of São Paulo’s Center for Nuclear Energy in Agriculture (CENA-USP). Their important work was supported by FAPESP through two separate projects.

Urban areas: The epicenter of climate change

As urbanization progresses, it is estimated that 68% of the global population will be residing in cities by 2050. This rapid expansion, coupled with the growing number of heat islands, increases vulnerability to droughts and other extreme events.

In an urban environment, the health of plants is often compromised by concrete structures, air pollution, and shifts in microclimates due to rising greenhouse gas emissions.

Consequently, the urgency for incorporating resilient species such as the Tipuana tree into urban landscapes becomes even more critical. The trees play a pivotal role in enhancing ecosystem services and fostering a healthy, sustainable urban environment in the face of climate change.

In response to this threat, the Brazilian government launched the Resilient Green Cities program on World Environment Day.

This forward-thinking program focuses on fostering sustainable practices and integrating policies to enhance the value of ecosystem services provided by urban green spaces, ultimately aiming to create a more resilient and thriving urban ecosystem for generations to come.

Tipuana trees: A model for resilience

The study emphasizes the need for city planning to include resilient species in the urban plant cover, ensuring that these plants can adapt and thrive under challenging environmental conditions.

The research adds significant value to urban biodiversity, with the resilient Tipuana tree standing as a prime model of adaptability and robustness.

Furthermore, the team is actively exploring other resilient native species to further diversify and enrich the city’s ecological framework.

The power of the resilient Tipuana tree

Originally from Bolivia and northern Argentina, the Tipuana tree has become a common sight in São Paulo and other parts of the world, including North America, Europe, Asia, the Middle East, and Australia.

The tree’s resilience, which has been present for over a century, is now being recognized as a significant asset in building climate resilience.

In their research, the scientists analyzed growth rings in street and park trees, focusing on stable carbon isotopes that reflect processes relating to the carbon cycle. Their findings showed an increase in these isotopes during the drought, boosting the growth of the Tipuana trees.

“Having Tipuana trees in the city is a significant advantage,” said Locosselli. However, he said it remains to be seen whether the species will be able to maintain its tolerance of water stress if a sequence of extreme events occurs.

The study opens new possibilities in our global fight against climate change, offering a promising look into nature-based solutions.

Through intentional and strategic urban planning, our cities can become resilient sanctuaries in the face of increasing weather extremities.

The full study was published in the journal Urban Climate.

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