Many people are interested in how big a tree’s crown will grow. It can be important in planning gardens, managing street trees, forest silviculture and in assessing the health of ancient trees.

Estimating tree height is very imprecise as it is dependent on so many different factors.  However, I wrote recently about the very good relationship statistically between a tree’s stem diameter and its crown diameter (read more).  I have received several requests for more information, and for this to be presented in a way that could be used by those who care for and manage trees.

So I have reworked the graph to produce a simple plot of tree crown diameter and stem diameter for the following nine species: ash (Fraxinus excelsior), beech (Fagus sylvatica), silver birch (Betula pendula), wild cherry (Prunus avium), sweet chestnut (Castanea sativa), oak (Quercus robur & Q. petraea) poplar (Populus spp.), sycamore (Acer pseudoplatanus) and common walnut (Juglans regia).

tree crown diameter and stem diameter graph
Tree crown diameter and stem diameter for nine broadleaved species. Click to enlarge.

Here is a simple summary of the same data in a table, presented in 0.10m stem diameter (dbh) increments.

crown diameter (m)
dbh (m) walnut ash oak sweet chestnut wild cherry beech sycamore silver birch poplar
0.10 4.47 2.65 2.50 3.86 3.30 2.52 2.48 2.58 2.71
0.20 6.23 4.54 4.28 4.93 4.84 4.10 4.37 4.19 4.60
0.30 7.99 6.43 6.05 5.99 6.38 5.67 6.26 5.81 6.50
0.40 9.75 8.32 7.82 7.06 7.92 7.24 8.15 7.43 8.39
0.50 11.51 10.21 9.59 8.13 9.46 8.82 10.04 9.05 10.29
0.60 13.27 12.10 11.36 9.19 11.00 10.39 11.93 10.67 12.18
0.70 15.03 13.99 13.14 10.26 12.54 11.96 13.82 12.29 14.08

The data for this work was collected from open grown trees.  Note therefore that trees grown in forest conditions, where they will have been affected by light levels and other competition factors, will not follow closely the data presented here.

I hope that this data may prove useful for those who are interested in scoring the condition of ancient trees, in planning tree avenues, and in garden planning or landscape architecture. Remember that the results presented here are based on peer-reviewed scientific work: if you want a reference for this work you can find it in my previous post on this subject (click here).  Let me know if you find a use for this data.

Gabriel Hemery


  1. Hi Gabriel
    I was at the Farm Woodland Forum last week to consider agro-forestry projects in East Anglia. There is much more data on the ‘agro’ than the ‘forestry’, so I hope to research tree performance in open-grown conditions. These measurements you present will be very useful in planning alley widths etc. Is there any more info on open-grown trees such as volume production, or info on other species like the alders?

  2. Many thanks for this Gabriel. I have also taken the liberty of forwarding it to the Ancient Tree hunt for the rest of the volunteer verifiers to see what use they can make of it. In due course I will feedback any info I accumulate for your interest.
    Kev Coleman
    Volunteer Verifier
    Ancient Tree Hunt

    1. Author

      Thanks Kev – delighted you feel it’s worth sharing with the army of tree volunteers that do such a great job for our ancient trees.

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