Kew Gardens, a UNESCO World Heritage site known for its lush greenery, faces a concerning future as climate change impacts its iconic tree collection. The gardens, located on the outskirts of London, experienced a severe drought in 2022, the hottest year on record in the UK, with temperatures exceeding 40 degrees Celsius. This extreme weather event led to the loss of approximately 400 trees, as water levels deep beneath the soil dried out, forcing some trees, accustomed to temperate climates, to shed their leaves.
Scientists at Kew, spurred by this loss, have been studying the long-term impact of climate change on the gardens’ 11,000 trees. Using new climate models, they have projected that up to 50% of the trees could be vulnerable to climate change by 2090. With rising mean annual temperatures, some of the 2,000 species present in Kew Gardens could be pushed beyond their natural range.
While the annual rainfall may not decrease significantly, its pattern could become erratic. The predictable wet seasons of the past could be replaced with unpredictable dry spells, potentially putting the trees at risk throughout the year.
In their report, ‘Planting the Future,’ Kew scientists highlight that precipitation levels might mitigate the effects of temperature rise, but they still predict that up to one-third of the trees could become unsuitable for the gardens by the end of the century. This includes some of Britain’s most cherished species like the oak, beech, birch, and holly. The English oak, in particular, is known to be drought-sensitive and could face significant challenges.
The report urges the horticulture industry and urban planners to increase the diversity of trees and shrubs. They emphasize the need for new plant varieties to ensure the continued greenery of Kew Gardens and South East England. Kew Gardens is actively identifying trees that can withstand hotter temperatures and less predictable rainfall.
One example is a hybrid sapling from the Steppe region, a cross between the common beech and the Oriental beech. This hybridization demonstrates the potential for creating resilient trees that can thrive in the changing climate.
The urgency of the situation is underscored by the fact that botanic gardens globally hold 30% of the world’s known plants, including 41% of known tree species. Kew Gardens serves as a microcosm of this global challenge, showcasing the need for proactive measures to safeguard plant diversity in the face of climate change.
