The Future Tree
The climate is changing, and its effects are already being felt across our landscapes. Rising temperatures, changing rainfall patterns, prolonged drought and more frequent extreme weather are altering the conditions on which ecosystems depend.
Trees have a vital role to play. They cool our streets, store carbon, intercept rainfall and support biodiversity. But there is a problem: the trees we rely on to help us adapt to climate change must themselves be able to withstand it.
So, what makes a tree resilient enough to thrive in the future?
What will the future ask of our trees?
A tree planted today may take decades to reach maturity, and the climate it experiences then will not be the climate we know today. Across the UK, projections point towards hotter, drier summers and milder, wetter winters, varying from place to place.
Resilient planting decisions therefore need to look ahead, towards 2050 and 2090, account for a range of possible futures, and consider the specific place where a tree is planted.
A central question for trees is water. As temperatures rise, so does the amount of water lost to the atmosphere. The Climatic Moisture Index (CMI) captures this balance between supply and demand, particularly during the April to October growing season, when trees are actively growing.
Different trees respond differently to the same climate
Climate only tells half the story. Species have evolved different functional traits: measurable characteristics that explain how they cope with stress.
One example is the turgor loss point, the point at which a leaf can no longer maintain its usual cell pressure. A more negative value generally means greater drought tolerance.
Other traits, such as wood density, add further insight. But no single measure tells the whole story. Resilience depends on how a tree's characteristics interact with its future climate and its site: soil, rooting space, drainage and, in cities, paved surfaces and urban heat.
Diversity and biosecurity
Resilience doesn't end with the individual tree. The losses from ash dieback and concerns around oak processionary moth show the risks of relying on a narrow range of species. A diverse planting palette help to manage that risk and builds resilience at the landscape scale.
The future tree is not one species. It is part of a diverse population of trees, each suited to its place.
Palette: from the science to decisions
Bringing all this evidence together is not straightforward. That's exactly what Palette was designed for.
Developed by Kew Reach with resilience researchers at the Royal Botanic Gardens, Kew, Palette combines future climate projections, species' natural climatic ranges and functional traits with practical site considerations, ecosystem services and biosecurity. Users can start with a place and explore which species may suit its future conditions.
Palette isn't a replacement for professional judgement. It makes a complex evidence base more accessible, transparent and traceable at the point where decisions are made.
Because the trees we plant today will live in the future climate, not the one we know now.
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