How to record tree form
Trees can come in a wide variety of shapes, and this often depends on their age and how they’ve been used or managed. Here are the tree forms which you can record with the Ancient Tree Inventory.
What can we learn from the form of a tree?
- Describes how the tree has grown
- Indicates past or present management
- Helps identify historic treescapes e.g. pollard and coppice, wood pasture
- Dictates where girth is measured (for consistency in recording)
- Clarifies girth measurements (validates unexpected sizes e.g. multi stem trees)
- Can confirm historical evidence of former site management (e.g. boundaries and woodbanks)
- Helps others analyse the data and provides useful evidence
The tree form option that you select is an assessment based on what you can see at the time of recording and local knowledge of how the tree may have been managed. Tree form can change over time too.
The most frequently encountered tree forms include:
But you should also look out for:
The tree has a single trunk to at least 1 m above the ground; it may continue with or without branching or divides into two or sometimes more stems.
There is no evidence of historic management. One or more branches may have been cut, but usually not all at the same height (see Pollard for comparison).
An ancient maiden may be retrenching naturally and may have lost most of its primary crown or its crown may be ‘stag-headed’.
Naturally open grown maiden trees will often have a short trunk forking at a low height with many large branches radiating from this point.
Pollarding is an ancient form of tree management. A pollard was cut as a ‘working’ tree.
All or most branches, limbs or stems of the tree were (probably) cut at approximately one height above the ground in the past, leading to new growth of branches.
Branches, limbs or stems of the tree were cut at a minimum height of 1.8 m (average 2.5 m), below which it is or was a single stem.
Trees that have been frequently cut have a very distinct hour-glass figure to the stem with a large, often knobbly, ‘knuckle’ or ‘bolling’.
The pollard options that are on the ATI are listed below:
- Pollard (lapsed)
- Pollard (managed)
- Pollard Form (natural)
A tree which has been pollarded in the past but has not been re-pollarded will develop a large crown with heavy branches.
Cuts may have happened long ago, the tree may have been cut just once or repeatedly, but evidence of it should be seen. Today many pollards we find will be lapsed pollards e.g. if they are former 'working trees' that were cut frequently in the past, but have not been managed in the same way for a long time.
A historically managed pollard with evidence that it is still being cut on a regular rotation.
Note: This does not include lapsed pollards that have their crowns reduced at a higher height for safety reasons or maiden trees that have had some infrequent crown reduction.
Pollard form (natural)
Trees that grow in a pollard form either naturally or following injury.
For example, a maiden tree that has lost its primary crown, often from storm damage, or gradual dieback of stem and limbs (retrenchment) resulting in new growth of branches, limbs or stems forming a replacement crown.
Note: Look for other pollards in the area as this may help you to consider whether the tree is an open-grown maiden or a pollard.
A historically managed tree usually cut lower than 0.5m above ground, creating a “stool” of many new stems. Ancient coppice will have been re-cut many times and the stump of the original tree may no longer be present.
What should I do if i am unsure whether the tree is a coppice?
Identifying ancient coppice can sometimes be tricky, depending on what is visible from the remaining coppice stool. If in doubt then record as 'multi stem' and in the comments field explain that the tree may be a potential coppice. Also look for other neighbouring coppice trees, as this will help you to judge whether the wider area was subject to coppicing in the past. See the following examples below.
Coppice (high stump)
A variation of a coppice form where branches, limbs or stems were cut between 0.5m and 1.5m above the ground, creating a high stump from which new growth has sprouted.
The tree divides into two or more stems less than 1m above the ground, usually from near ground level.
Some species may have stems that are fused to much higher than 1m but the individual stems are clearly defined.
The basal footprint is generally oval if the tree is twin-stemmed and may be more irregular than a maiden or pollard. Many trees will naturally grow with co-dominant stems.
Note: Record as a multi stem tree if the girth measurement is exaggerated by the inclusion of more than one individual stem.
Multi stem (boundary)
This is a tree which is multi stemmed and forming part of a land boundary (whether that be in a woodland or other land boundary) but that has NOT been obviously managed as a ‘laid hedgerow’ (see below).
Trees of this form may be found along woodland rides. It may be planted on top of a man-made earth bank or wall.
Erosion over time may create an exposed root system above ground level.
They will often be difficult to measure the girth with any accuracy due to their irregular and elongated form. The tree may have similarities to being a laid hedgerow but must relate to a historic boundary e.g. a ‘historic wood-bank’.
A tree that has originated by natural vegetative reproduction from a fallen or decaying tree, or survived as a fragment of the original stem.
Note: if a tree has fallen but some of its roots are still intact, then the tree may regenerate naturally, although this process can take a long time to develop.
There must be evidence that the tree was part of an older tree which will either be a standing dead tree, a stump, or collapsed and re-growing from the horizontal stem or as a layered branch.
A stump is less than 4m in height and usually less than 1m.
Occurs as either a cut stump from a felled tree or as the remains of a collapsed or decayed stem.
Stumps are usually dead.
Stump (high >4m)
This has a stem taller than 4m in height without any branches.
Usually originally a maiden and usually dead.
It may be the result of a natural break and fractured or deliberately cut high up and retained for its wildlife habitat.
Note: A live tree with a high shattered stump that is regrowing can be categorised as a Maiden or if short as a Pollard form – natural
A tree that has been part-cut near its base and its stem laid at an angle as part of the historic management of hedge-laying.
May also be later pollarded at a convenient hedge height creating an irregular and complex form.
Usually difficult to measure due to its shape. The girth measured is rarely comparable with another. Take plenty of photos and record the girth close to the base if the tree has many stems.
It is often difficult to identify individual trees – Laid (hedgerow) suggests a “complicated” tree form which may involve more than one tree.
These are trees that are generally growing out from the face of a vertical cliff.
Often they do not have a clearly defined single stem.
And the girth measurement is frequently estimated for safety reasons!
If you are unsure which option to select, please record as 'unknown'.
Tree form may change over time. And it may be that a tree has grown, been managed or been damaged in such a way, and over a long period of time, that its tree form can not be allocated with confidence to any of the above types.
It is therefore reasonable to allocate “Unknown” in these circumstances.