August 20th 2025
A recent study published in Science (June 2025) provides compelling genetic evidence that natural selection is beginning to favor ash trees with some resistance to ash dieback. Saplings that have survived early exposure to the fungus Hymenoscyphus fraxineus exhibit greater resistance genetically than older generations. This represents Darwinian evolution in action and offers real hope for future resilience—although experts caution that this process may be too slow on its own, and that human support (e.g., selective breeding) may still be necessary The GuardianThe Times.
Complementary research found that healthy trees contribute disproportionately more to the next generation of ash through both seed and pollen dispersal across substantial distances. This will help spread resistance genes through the population BioMed Central.
Non-Intervention vs Active Management
Forest Research modeled various management approaches and found that:
- Non-intervention (i.e., letting ash regenerate naturally, without felling) combined with natural regeneration ranked among the best scenarios for minimizing immediate biodiversity loss.
- Alternatives such as felling (even with replanting) sometimes performed worse for associated species in the short term (1–10 years). However, over the long term (50–100 years), most scenarios predicted >95% ash loss regardless Forest Research.
On-the-Ground Practice and Guidelines
Guidance from the Forestry Commission (as of January 2025) advises:
- Do not fell infected ash trees unless they pose a safety risk or are needed for timber. A small proportion may tolerate the disease and serve as sources for future recovery.
- Instead, monitor tree safety and consider pollarding or other pruning techniques where appropriate.
- Avoid unnecessary removal to preserve genetically valuable individuals Ash Dieback in DevonGOV.UK.
Broader Ecological Context & Challenges
Despite some encouraging signs, regeneration is struggling in many woodlands. A long-term study (2000–2022) across ancient UK woodlands showed sharply rising sapling mortality and steep declines in 5-year survival rates—from 41% to just 16%. In locations like the New Forest and Dartmoor, no saplings survive in some areas. Climate change, drought, dieback and overgrazing by deer are all compounding the problem The Guardian.
Summary Table: Can Ash Dieback Trees Recover If Left Alone?
| Aspect | Findings |
|---|---|
| Genetic evolution | Resistant saplings are emerging; natural selection is working—but progress is gradual |
| Reproductive dynamics | Healthy trees disproportionately propagate, boosting spread of resistance |
| Management outcomes | Natural regeneration (non-intervention) is often best short-term strategy |
| Practical advice | Don’t fell unless necessary; monitor and use pruning instead |
| Regeneration trends | Sapling survival is deteriorating in many areas, threatening forest resilience |
| Intervention importance | Human actions (selective breeding, planting resistant stock) may help accelerate recovery |
Bottom Line
Yes—some ash trees can recover or reproduce resistance if left to natural selection. There is real, genetic evidence of evolving resilience among saplings. Natural regeneration (non-intervention) remains one of the best short-term strategies for biodiversity and ecosystem health.
However, the recovery is slow and hampered by high sapling mortality, climate stress, and grazing. Without human support—e.g., identifying and promoting tolerant individuals, selective breeding, or managing deer impacts—the pace of recovery may not outstrip the decline.
Further reading on ash dieback news
‘New hope’: ash trees rapidly evolving resistance to dieback, study reveals
In some UK woodlands, every young tree has died. What’s going wrong?
