Posts tagged ‘beech’
On a recent trip to a woodland in southern England I came across a beech tree that had been rent asunder by winter gales. The tree had a large fork and one of its stems had broken causing the entire trunk to split open, all the way to the ground. What caught my eye from afar was the shocking vibrancy of the freshly exposed wood inside the stem. It was almost an iridescent orange and contrasted beautifully with the bright green smooth bark.
- Beech tree rent asunder
On closer inspection, it became clear that damage some distance further up along the limb had allowed rot to set in, causing a structural weakness in the forked stem. Unusually though, the stem had then split halfway through and its weight had then pulled the entire forked stem away from the main stem, rather than simply splitting near to the original weakness.
- Beech tree rent asunder – wider view
Discussing this with the woodland owner I learnt that they have no intention to manage the tree as it is not accessible by the general public and therefore of low risk. I’m not an arboriculturist but I would be interested if any readers have some experience of this type of split. I’ve no idea either how a forester/arboriculturist would go about dealing with this if it was necessary. The amount of tension present would present a tremendous (sorry couldn’t resist it) hazard, and the partially hung limb a further complication.
Gabriel Hemery
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In the early 1990s, when I was a student at the University of Wales Aberystwyth, I used to visit the town dump. Not to scavenge because I was flat broke (well not quite) but because it was the best, and actually one of the few, places in the UK where it was still possible to see red kites in the wild.
I captured this photo of a captive Red Kite on a compact camera (Panasonic Lumix TZ8) during a falconry show in France. It took about 50 shots to capture the shot I wanted with another bird of prey flying in the background of this perching kite.
Red kites were once common throughout England and Wales; being one of the main scavengers in the streets of London. Even Shakespeare referred to London as “The city of kites and crows.” By the by the end of the 19th Century however they were driven to extinction in England by humans, while only a tiny population survived in the woodlands and valleys of Wales.
What are you thinking, my wild friend
As you claim supremacy of the summer sky?
What magic holds you there without a single flap
Of your gorgeous wings?Who dressed you today wondrous one,
In a rust coloured waistcoat and a starched white shirt?
Your taloned wings outstretched, embrace the sky
You truly are God’s work.Who are you nagging with that fishwife song?
They can hear you from Garreg Dan to Caban Coch.
Keep on calling my brave beloved, someone will come,
You cannot be the last Red Kite.
Written by Allen Williams
Between 1989 and 1994, red kites were imported from Spain and released into the Chilterns: a stunning protected landscape of rolling hills and beech woodlands only a few miles north of London. The introduction project was run by English Nature and the RSPB. The birds started breeding in the Chilterns woodlands in 1992 and the population has expanded massively to the surprise and delight of both naturalists and local people. Today there are over 300 breeding pairs in the area. I frequently enjoy walking in the beech woodlands of the Chilterns where large gathering of red kites provide a spectacular display.
So successful has been the introduction that since 1999, chicks have been taken from the Chilterns and used to re-introduce the red kite to other parts of the UK including Scotland and various locations in England (The Midlands, Yorkshire, Newcastle). In January 2006, the first wild red kite for about 150 years was seen on the streets of London (read more). The reintroduction of the red kite must be one of the greatest conservation success stories of the 20th Century.
Gabriel Hemery
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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 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
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I co-authored an academic paper in 2005 that summarised research undertaken to explore the relationship between a tree’s stem diameter and its crown (or canopy) diameter 1. Out of my 60 or so publications, it has been one of the most popular among forest scientists (e.g. Google Scholar citations).
It was fascinating to discover that statistically there was a very good relationship (scientists would refer to a correlation from a regression analysis) between stem diameter and crown diameter. We decided to explore this further by calculating the ratio between the two, we called it the z ratio (= crown diameter ÷ stem diameter). We then plotted this z ratio against stem size. You can see the result on the graph below for nine common European broadleaved trees.
Crown diameter: stem diameter relationship for nine broadleaved tree species. The z ratio (y axis) is crown diameter divided by stem diameter; the dbh (x axis) is stem diameter at breast height (measured at 1.3m). Click to enlarge graph
The graph highlights some very interesting growth patterns and difference between different species:
- Common walnut (Juglans regia) has the largest crown diameter at any given stage in its stem size. When a walnut stem is 15 cm in diameter its crown can be estimated to be 5m wide. Foresters can use that knowledge to design walnut plantations: e.g. if they plant their walnut trees 5m apart, their crowns will not compete until their stem diameter is 15 cm (which will take about 15 years from planting in the UK).
- Sweet chestnut (Castanea sativa), like walnut, has a very large crown while it is young (with a small stem size). Unlike walnut however, as its stem size increases, the ratio with its crown diameter decreases rapidly to the point after 35cm in diameter, when it has the smallest crown diameter for any of the nine tree species assessed.
- Sycamore (Acer pseudoplatanus) has the most consistent crown to stem ratio while it grows.
The data can be used to plan tree spacings and to calculate basal area. For example: for walnut with a stem diameter of 0.60m, its crown diameter is 13.27m, and its z ratio is 22.12. Using the equation (left) for estimating basal area per hectare (G, m2 ha-1) tells us that there would be 57 trees per hectare with a basal area of 16.1 m2 ha-1.
These findings can be used beyond tree spacings and calculating basal area; they can also be used to help in:
- planning thinning regimes (how many trees to remove in a growing plantation and when)
- planning stand density (how many trees to retain in a forest stand at any given size)
- assisting in managing mixed conifer-broadleaved stands
- estimating branchwood and woodfuel volumes
- maintaining free-growth silvicultural systems, and
- in urban tree planning by arboriculturists and landscape gardeners (e.g. designing and managing tree avenues).
Gabriel Hemery
Reference
1 Hemery, G.E., Savill, P. & Pryor, S.N. (2005). Applications of the crown diameter – stem diameter relationship for different species of broadleaved trees. Forest Ecology and Management 215, 285-294. View abstract
