How big will this tree grow?

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).

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