London boasts one of the largest urban forests globally, featuring over 8 million trees across both public and private spaces. However, this summer, these trees are experiencing significant strain due to three heatwaves coupled with insufficient rainfall.

A local council in London has alerted residents to avoid sitting or gathering beneath large trees following a rise in incidences of falling branches.

Harrow Council reports an uptick in cases of sudden branch drop syndrome, which has been exacerbated by the recent heatwaves.

Experts from the charity Trees for Cities anticipate an increase in tree mortality and branch shedding as climate conditions worsen.

So, what strategies can be implemented to alleviate these issues?

With projections indicating that London will face higher temperatures in the coming years due to climate change, trees are increasingly recognized for their essential role in reducing carbon emissions and pollution, as well as for cooling urban areas.

The Mayor of London has pledged to expand the city’s tree canopy by 10% by 2050 to address rising temperatures.

However, certain native tree species are finding it increasingly difficult to survive.

Trees for Cities is an organization dedicated to planting and caring for trees. Recently, the team participated in watering young trees in Greenford, located in west London.

Seb Herst, the senior urban forest coordinator, emphasizes that proper tree maintenance will become crucial.

“We certainly don’t want to abandon the native trees that thrive in the UK. They support a great deal of local wildlife, and non-native species may not provide the same benefits.

“So, it’s important to ensure our native species are well-maintained, while also considering variants that are better suited to changing climates. For instance, sourcing oak trees from southern France that are better adapted to anticipated climate conditions here.”

He continues, “Maintaining our trees is essential. London has quite small tree pits; expanding these could help. We also have compacted soils, so how do we enhance soil aeration to retain moisture and manage heavy rainfalls?

“As we observe the climate shifting, we need to adapt our tree care practices accordingly.”

Mete Coban, the Deputy Mayor of Environment for London, asserts that climate change is currently impacting the city.

“We recognize that heatwaves are significantly affecting tree species.

“Our goal must be to plant more trees to bolster our resilience against extreme heat and climate change effects.

“Additionally, we must select the appropriate species and ensure we have the right infrastructure to safeguard our trees, as we can expect increasingly higher temperatures in the future.”

Georgie Power, a senior urban forest coordinator at Trees for Cities, participated in the watering effort in Greenford, where she also spread bark mulch around tree roots to retain moisture.

She warns that rising temperatures will likely put additional stress on trees.

“It seems that sudden branch drop syndrome occurs when trees endure extreme heat and drought, akin to a process of self-amputation. The trees, lacking sufficient water for their branches, will sever some to preserve the remainder.

“This summer—especially in April, May, and June—has been incredibly hot. The trees have faced immense stress.”

Georgie notes, “As climate change progresses, we can expect overall temperature increases, leading to more instances of tree deaths and conditions like sudden branch drop syndrome.

“We already need to choose different tree species to adapt to climate change. For instance, Trees for Cities is increasingly planting Italian Alder because it is more resilient to drought and flooding than the common Alder.

“This demonstrates our proactive approach in selecting species that will better fit our future climate conditions.”