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The Root Cause: Why Protecting Existing Trees Matters More Than Planting New
08 September 2025
David Fisher
Head of Geosynthetics Sales Our Root Cause campaign, highlights the importance of protecting existing trees in new developments. The evidence is clear: established trees deliver immediate, proven benefits that replacement planting cannot replicate, either in the short or long term. Why Established Trees MatterAn established tree is a living piece of infrastructure. It provides cooling, water management, slope protection and biodiversity all at once. And these benefits arrive instantly, no waiting decades for them to take root. Cooling the EnvironmentOn a summer’s day, a single mature tree can reduce air temperature around it by 2–8°C. This cooling effect happens in two ways:
The results are significant:
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Managing RainfallMature trees also manage water in ways that new saplings cannot. On average:
This matters because in urban areas, impermeable surfaces like tarmac and concrete absorb almost no water. Instead, rain rushes into drains, overwhelming systems and increasing flood risk. Trees slow this process down, reducing runoff by 20–60% in urban SuDS designs. In Manchester, engineered tree pits captured almost 60% of rainfall from surrounding pavements, a performance figure no new planting could match in its early years. The Reality on New Build DevelopmentsDespite their value, most established trees don’t survive development.
Planning conditions often require planting two or three new trees for every one removed. While it sounds good on paper, the survival rate of these new trees is poor. Often only 25–50% survive without proper aftercare. Those that do survive will take decades to match the ecological, cooling and water management benefits of the trees they replace. Put simply: planting is no substitute for retention. 
Why Planting Alone Doesn’t WorkDevelopers often rely on planting to demonstrate biodiversity net gain or sustainability commitments. But planting strategies face two major problems:
For example: a whip planted today may not reach a meaningful canopy for 20–30 years. In the meantime, the site has lost the very functions that manage surface water and heat from day one. 
The Root CauseThrough The Root Cause, we want to start a conversation across the industry about the hidden but critical role of tree root protection. By highlighting buyer expectations alongside practical solutions, our aim is to support new build developers in creating schemes that deliver for both people and the planet. ProtectaWeb is just one part of this, but it is a vital tool for ensuring that the trees which give character, beauty and biodiversity to our communities are safeguarded for generations to come. A Better Approach: Protect(aWeb) First, Plant LaterThe solution is not to abandon planting altogether, but to change the order of priorities.
New planting should then complement, not replace, the retained stock. This approach secures immediate benefits while also planning for long-term succession. 
How Geoworks Supports DevelopersWe understand the pressures developers face. Space is tight, margins are tight, and planning targets are demanding. That’s why The Root Cause campaign doesn’t set nature and engineering against each other, it brings them together. At Geoworks, we provide geosynthetic solutions that complement green infrastructure:
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