Biodiversity hotspots
Cavities, cracks and deadwood are home to saproxylic insects, bats, birds, lichens and fungi — many of them threatened and dependent solely on old trees.
Trees that remember centuries
Veteran trees are living history books and the richest habitats in our landscape. Discover what they are, how they form, and why we must protect them.
Definition
What is a veteran tree?
A veteran tree is one that shows the features of age — regardless of how old it actually is. These characteristics may come from years, but also from injury, management, or the conditions in which the tree has grown.
Unlike the term “ancient tree”, which refers strictly to a tree that is very old in years, a veteran can be any age. All ancient trees are veterans — but not all veterans are ancient.
Three key features give them away: a low, wide, squat shape as the crown retrenches with age, a wide trunk compared with others of the same species, and hollowing of the trunk that may not always be visible.
A hollow trunk is not a disease. It is a sign of maturity — and the beginning of one of the richest habitats in nature.
“Ancient trees link us culturally and historically to past generations of people who lived among them.”
Value
Why veteran trees are irreplaceable
A single old tree can outweigh an entire young plantation in ecological value. Here is why.
Carbon storage
Veterans have locked carbon into their mass over decades and centuries. Old trees keep storing it and regulate the microclimate around them.
Cultural heritage
Veteran trees are living links to the past — landmarks, witnesses to history, and part of the identity of landscapes and communities.
Living archives
Their growth rings and physiology record centuries of climate and environmental change, making them invaluable to science.
Morpho-physiological model
The ten life stages of a tree
Trees do not age the way we do. Across its whole life a tree passes through a recognisable sequence of morpho-physiological stages — from seed to ancient veteran — first described by Raimbault (1995) and carried into arboricultural practice by Fay and colleagues. Understanding these stages is the foundation of good care for old trees.
The stages are not strictly linear: a tree can repeat earlier developmental patterns within itself (reiteration), so an ancient tree carries both the old and the new at once. (Raimbault, 1995; Hallé, 1999.)
01 · Stages 1–7
Maturation
In the young phase the tree invests energy in height and crown surface under apical dominance, while the simple root system spreads and branches. Towards the end of Stage 4, apical dominance wanes and branches begin to act more independently.
In the mature phase the crown rounds out and reaches its largest size. Lower and inner branches are shed naturally (the “umbrella effect”), the root system becomes tiered and woody, and the first fungi begin to break down heartwood from the base of the trunk.
02 · Stages 8–9
Crown retrenchment
When the roots can no longer supply a wide crown, the tree gradually reduces it. The outer, upper branch tips die back (shown in the illustration as the ghost of the former crown), while new, more vigorous growth sprouts lower and closer to the trunk.
This is not decline but a survival strategy: a lower crown is more mechanically stable and physiologically efficient. It is precisely this natural process that arborists imitate when carrying out retrenchment pruning on old trees.
03 · Stage 9
Ageing & hollowing
Fungi break down the heartwood and ripewood, hollowing the trunk. In doing so the tree recycles its own nutrients, sheds weight and creates saproxylic habitat. This “centripetal” decay (from the centre outward) does not threaten the living, outer conductive sheath.
From dormant and adventitious buds, reiterative shoots emerge — new “mini-crowns” that renew the tree. This is its life-insurance system: a “second chance” to grow out of its own body.
04 · Stage 10
Dieback — or rebirth
In the final stage the tree may enter terminal decline. But ageing in trees is not a one-way process: senescence can be reversed by rejuvenescence — renewal from vegetative tissue (Thomas, 2013).
Adventitious roots can grow down through the hollow trunk to the soil and nourish a new crown. In this way an old tree gives rise to a “phoenix” successor — a clonal tree that carries the parent’s genetic memory and can live on (Fay, 2002).
Sources & citations
The content of this section is based on the morpho-physiological model of tree life stages as presented in Trees – a Lifespan Approach (chapter by N. Fay et al.). Cited in Harvard style.
- Witkoś-Gnach, K. & Tyszko-Chmielowiec, P. (ur.) (2016) Trees – a Lifespan Approach. Contributions to arboriculture from European practitioners. Wrocław: Fundacja EkoRozwoju. ISBN 978-83-63573-14-0.
- Raimbault, P. (1995) Physiological diagnosis and architectural analysis of trees. (Morfo-fiziološki model od 10 faza razvoja stabla.)
- Hallé, F. (1999) In Praise of Plants. Portland: Timber Press. (Arhitektura i reiteracija stabala.)
- Lonsdale, D. (ur.) (2013) Ancient and other veteran trees: further guidance on management. London: The Tree Council / Ancient Tree Forum.
- Fay, N. (2002) „Environmental arboriculture, tree ecology and veteran tree management“, Arboricultural Journal, 26(3), str. 213–238.
- Thomas, P. (2013) Trees: Their Natural History. 2. izd. Cambridge: Cambridge University Press.
Interactive timeline
Ten stages, one life
Hover or tap through the stages and watch the tree change — crown, roots and radial increment (CAI) — from seed to ancient veteran. The stages are not strictly linear; a tree can repeat them within itself (reiteration). Model after Raimbault (1995) and Fay & de Berker, Trees – a Lifespan Approach.
Threats & protection
Fragile, yet irreplaceable
Veteran trees are hard to replace — when they are gone, so are the habitats they have built over centuries.
Risks Threats
- Urbanisation and construction that cuts through or buries the root zone.
- Soil compaction around the roots from traffic, machinery and footfall.
- Inappropriate pruning and removal of deadwood out of misunderstanding.
- Changes to the water regime and raising soil levels above the roots.
Solutions How we protect them
- Root protection zone — preventing construction and compaction around the tree.
- Staged crown reduction (retrenchment pruning) that mimics natural ageing.
- Retaining deadwood and cavities as valuable habitat.
- Monitoring and expert diagnostics of stability and vitality over time.
Field guide
How to recognise a veteran tree
Six visible signs that reveal a tree's age and veteran status. None on its own is conclusive — but together they tell the story of a tree worth caring for.
Peer-reviewed science
Scientific papers on veteran trees
A carefully curated collection of peer-reviewed scientific papers dedicated to veteran and ancient trees. Each links to the original article.
Glossary
Key terms
Short definitions of the technical terms that appear on this site.
Frequently asked
Questions & answers
The most common questions about old and veteran trees — and answers that dispel widespread myths.
Interactive game
Microhabitat hunt
An old tree hides dozens of microhabitats — cavities, fungi, cracks, nests. Find them, identify who lives inside, and collect the whole set. Your score goes on the leaderboard.
Discover the hidden world of old trees
Across 10 rounds we show you illustrations of real tree-related microhabitats (TreMs) from old trees. Your task: click precisely on the microhabitat and guess which species lives in it.
- 1Click the microhabitat's location on the image — closer to the centre means more points.
- 2Speed is rewarded: the sooner you click, the better.
- 3Pick the right resident from 3 species — a correct choice doubles the round's points and unlocks its card in your collection.
Round1/10
Score0
Time0.0s
Find:
Which species lives in this microhabitat? A correct choice doubles the round's points.
Game over
Leaderboard
Microhabitat and species data are based on: Bütler R., Lachat T., Krumm F., Kraus D., Larrieu L. (2024) Field Guide to Tree-related Microhabitats. Descriptions and size limits for their inventory in temperate and Mediterranean forests. 2. izd. Birmensdorf: Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 64 str. Dostupno na: wsl.ch/fg-trems. Tipologija: Larrieu et al. (2018) Ecological Indicators 84: 194–207.
News
News on old trees
Selected news, discoveries and scientific papers on old, ancient and veteran trees from Croatia, Europe and the world.
Links
Valuable resources and initiatives
Trusted European and British initiatives for recognising, recording and protecting old and veteran trees.
European Tree of the Year
An annual award celebrating trees with a story and encouraging communities across Europe to protect them.
treeoftheyear.orgAncient Tree Forum
A professional network dedicated to the biology, conservation and management of ancient and veteran trees.
ancienttreeforum.org.ukAncient Tree Inventory
The largest database of old and veteran trees — recorded by Woodland Trust volunteers.
ati.woodlandtrust.org.ukArboricultural Association
The leading professional body for arboriculture — standards, education and good-practice guidance.
trees.org.uk
Behind the project
tree.vet is led by Arboring
tree.vet is an educational project by Arboring, an arboricultural practice specialising in the diagnostics, assessment and protection of old and veteran trees. Behind every page is hands-on fieldwork — from individual trees to urban green spaces.
Learn more about Arboring