Resilient giants: How the world’s oldest trees stand tall against climate change (commentary)

Have you ever stood beneath a towering tree and gazed up at its expansive canopy? As you tilt your head back, have you considered the profound history embedded in its branches?

Picture the countless individuals and animals that have sought refuge under its branches over the centuries. Think of the storms it has braved, the fires it has withstood, and the droughts it has endured to stand resolute through the ages.

Each of these ancient giants has witnessed centuries of environmental change that have shaped their resilience. As climate change intensifies, these trees offer vital lessons in endurance and adaptation. How are these remarkable trees standing tall against the pressures of a changing climate? Their stories provide insight and hope into forest conservation and climate adaptation.

Australian eucalyptus: Adapting to fire

In Australia’s arid and fire-prone landscape, eucalyptus (Eucalyptus spp.) trees reign supreme, making up about three-quarters of the country’s forests . Some species live up to 500 years, having evolved remarkable survival strategies.

Among the most remarkable is their capacity for rapid regeneration following the bushfires that periodically sweep through Australia during the dry season. Their thick, fire-resistant bark acts as a shield  against the flames, while their seeds – which lie dormant until awakened by the heat of a fire – ensure swift regeneration. This ingenious adaptation not only allows eucalyptus trees to withstand periodic fires but also plays a crucial role in maintaining the delicate ecological balance of their habitats.

Eucalyptus forests provide essential habitats for many unique species. Their resilience underscores the importance of sustainable management practices, including controlled burns and preserving fire-adapted species, to sustain these ecosystems amid climate change.

Scots pine: Northern resilience

In the vast taiga of northern Europe and Asia, the Scots pine (Pinus sylvestris) stands as a symbol of endurance amid rugged climate conditions. Capable of living up to 500 years, this remarkable tree, with its rugged, knotted bark, has adapted to thrive in a variety of soil types and climate conditions – cold-adapted, acidic soils – the Scots pine flourishes where other trees cannot. Its leathery needles are frost-resistant and evergreen, allowing it to photosynthesize in winter  when deciduous trees have shed their foliage.

This resilience and adaptability have made it the most widely distributed pine species in the world, from Scotland to Siberia, Scandinavia to Spain. Withstanding disturbances like fire and logging, the Scots Pine boasts remarkable regenerative abilities. Its seeds, lying dormant for years, await the perfect moment to sprout, allowing forests to rise anew after disruptions.

These forests, teeming with life and complexity, rely on thoughtful management to maintain their health. By supporting practices that encourage natural regeneration and preserve the intricate web of habitats, we can help the Scots pine continue its story of adaptation and survival.

Western red cedar: A cooling effect

In the temperate rainforests of the Pacific Northwest coast of North America, the western red cedar (Thuja plicata) stands as a venerable giant, capable of living for over 1,500 years. These trees are celebrated for their remarkable durability and resistance to rot, qualities that have made them invaluable in traditional Indigenous cultures for centuries. They’ve been labeled the ‘Tree of Life’ by many Indigenous peoples, who used the trees for houses, clothes, weapons, tools, medicines, art and canoes. Today cedar wood continues to be very coveted in the forestry industry.

These moisture-loving giants have become an indicator of climate stress to come, often demonstrating signs before other species. Recent back-to-back drought conditions have caused a significant dieback among western red cedars which has sparked increased concern over temperate rainforests in the face of a warming climate. A recent study of this dieback however, found that it is only the younger trees that are dying  due to drought intolerance. Trees older than 150 years have survived.

This is likely due to the remarkable ability of old-growth cedars to create cooler, wetter microclimates – up to 2.5 degrees Celsius (4.5 degrees Fahrenheit) cooler than surrounding areas. The shade they provide allows for a rich understory and soil composition to develop which acts as a sponge – absorbing and releasing water slowly throughout the year – mitigating against both drought and flood conditions. This remarkable cooling effect underscores the critical role of old-growth forests in mitigating climate change impacts.

Baobab trees: Africa’s watering hole

Standing majestically in the arid landscapes of Africa, the baobabs, also referred to as the “Tree of Life” by local people are icons of resilience and longevity. Among them, the Grandmother Baobab in Madagascar, locally known as ‘Tsitakakoike,’ is a living testament to the endurance of these ancient trees. Estimated to be over 1,000 years old with a trunk circumference of about 28 meters (92 feet), this giant tree has become an anchor for the ecosystem and communities around it.

Baobabs (Adansonia spp.) possess a remarkable ability to store water in their massive trunks, which swell to hold thousands of liters during the rainy season. This adaptation not only ensures their survival through prolonged droughts but also provides a crucial water source for the surrounding flora and fauna. The trees’ hollow trunks often become habitats for bats, birds, and small mammals, offering shelter and protection in an otherwise harsh environment.

However, the survival of baobab trees is increasingly threatened. Many young baobabs do not reach maturity due to overgrazing. Mature baobabs, though resistant to grazing, are susceptible to bark stripping by elephants that attempt to access the water stored within during extremely dry conditions.

The Grandmother Baobab, like many of its kind, acts as a mother tree, providing resources and stability to the ecosystem. As climate change intensifies and drought conditions become more severe, the role of these trees as reservoirs of water and biodiversity becomes even more critical. Their ability to withstand extreme conditions and support life around them underscores their importance in maintaining ecological balance and resilience.

Sumaúma Tree: The Amazon’s water pump

The sumaúma tree (Ceiba pentandra) is found across Central America, northern South America, West Africa, and Southeast Asia. Known by various names such as sumaúma and árvore-da-seda, ceiba tree, and kapok tree, the sumaúma has ancient populations in the tropical Americas and Africa that significantly predate human presence in these regions.

Perhaps the largest of all Amazonian trees, the sumaúma is unparalleled in the diameter of its crown and roots. Its canopy can stretch up to 50 meters across, with roots spreading 20 meters in diameter to support the tree’s massive structure. These roots extend over a radius of nearly 152 meters underground, providing stability in flooded soils and muddy floodplains, though the tree can also thrive on firm soil in various continents.

With the breadth of its roots spread out along the rainforest floor, it effectively acts as a giant water pump, soaking up to a thousand liters of water daily into its crown, before releasing it back into the atmosphere – helping to reduce the planet’s temperature. This remarkable ability not only supports the local water cycle but also serves as a vital water source for surrounding populations.

The tree is understood by some to be the supreme spirit or chief of the forest. It is considered to be the rain tree, and rituals are held near it to beg for rain, further reinforcing the link between Ceiba and water. The morphology of its trunk gives the occasional tree a swollen shape reminiscent of a pregnant belly. The sumaúma plays a critical role in its ecosystem. Its massive, buttressed trunk and expansive canopy provide habitat for a diverse array of species.

The sumaúma’s adaptability to the rainforest’s dynamic environment illustrates the importance of preserving these giant trees and their delicate ecosystems. Conservation efforts must focus on protecting the Amazon rainforest from deforestation and climate change to maintain the ecological functions provided by trees like the sumaúma.

View all of Mongabay’s coverage of forest here.

Giant sequoias: Lungs of the planet

Giant sequoias (Sequoiadendron giganteum), native to California, are among the longest-living trees, with some reaching over 3,000 years. These colossal trees can grow between 75 and 90 meters (250 and 300 feet) tall. Even more impressive, these trees can have diameters of nine meters (30 feet).

Like the eucalyptus, they too have evolved to thrive in fire-prone environments, with thick, fire-resistant bark that protects them from high-intensity fires. Their seeds germinate in the nutrient-rich ash created by wildfires, promoting forest regeneration.

Not only this, but as the largest living organisms on earth by volume, they have an amazing ability to pull and store carbon dioxide from the atmosphere. One of the largest sequoia trees, The General Sherman, has a volume of about 1,486 cubic meters  (52,500 cubic feet, or), and contains over one million kilograms  (or over 2.2 million pounds) of stored carbon. This volume of stored carbon pulled over 1,400 metric tons of carbon dioxide out of the atmosphere. The General Sherman sequoia is so large that as a single tree it has stored about 86 years worth of an average American’s carbon emissions.

This incredible ability to store carbon highlights the integral role these ancient trees play in combating climate change.

Bristlecone pines: Lessons from the oldest living trees

In the rugged White Mountains of California, the ancient bristlecone pine forest is home to the oldest trees on earth. Bristlecone pines (Pinus longaeva) have thrived here for nearly 5,000 years – since before the pyramids in Egypt – enduring extreme temperatures and scarce resources on these barren mountains. Their survival is a testament to their ability to adapt to severe conditions.

These ancient trees appear to thrive on barren, lifeless mountainsides that receive very little rainfall, have little-to-no soil for nutrients, and have excruciatingly long and cold winters. The secret to their long life is their ability to adapt to this desolate and often unforgiving environment.  A study of bristlecone rings, which vary in width year to year, reveal that the trees are able to endure significant stress through achieving a dormant state where their nutrient and water needs are low.  Their extraordinary longevity and adaptability provide insights into historical climate patterns. Protecting bristlecone Pines is crucial for understanding the long-term impacts of climate change and preserving the unique biodiversity of their harsh environments.

Conclusion

From the fire-resistant eucalyptus of Australia to the ancient bristlecone pines of California, each of these trees offers valuable lessons in resilience and adaptation. Their ability to withstand and adapt to climate change underscores the importance of preserving our ancient forests and the ecosystems they support. These trees are not just survivors; they are living testaments to the strength of nature and our responsibility to protect it. As we navigate the challenges of climate change, the stories of these remarkable trees provide hope and guidance for a more resilient future.

Meg Severide is the Manager of Visuals and Storytelling at the International League of Conservation Photographers (iLCP), a global community of professional photographers and filmmakers driving conservation impact through ethical visual storytelling. She curates impactful visual content captured by iLCP photographers and creates compelling conservation stories that raise awareness about pressing environmental concerns to inspire positive change.