Posts tagged ‘damage’
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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It has been the warmest Spring for 60 years in the UK but it’s the time of year again when most gardeners will be watching out for a late Spring frost, hoping that they can protect their tender plants. Horticulturists are well aware of the terrible financial impact of frost on the flowering of apples and pears, where a whole year’s potential crop can be killed off. In forestry we’ve taken longer to get serious about frost.
Study of the timing of events in plants is known as phenology. For several years I undertook research into the flushing (the phenology of spring leaf burst) for two of our most sensitive tree species: ash Fraxinus excelsior and common walnut Juglans regia.
Unlike the plants in a garden that can be moved to a greenhouse or protected with fleece material, the trees in a forest cannot be protected so immediately. However the forester is not powerless. There are practical silvicultural steps that can be taken to match carefully a species to its site; such as altitude, aspect, and micro features (e.g. avoiding frost hollows). Perhaps the greatest potential advantage can be realised through genetic selection: using planting stock that have been selected to be late flushing – reducing the likelihood of frost damage as their buds will break later in the Spring.
Walnut phenology and a flushing score
I made these drawings to illustrate scientific scoring systems that I had developed for use in the field to assess the phenological development of different trees (progenies or provenances) in trials.
Ash phenology and a flushing score
Foresters have ignored phenology at great cost in the past. Southern beech Nothofagus species were introduced to Britain in the 1950s with some excitement due to their fast growth and useful timber. Field trials and some commercial plantations of roble beech and rauli beech looked promising for a number of years until several cold periods devastated hundreds of hectares. Why? The seed collectors for these plantations had gone to the wrong places in Chile to collect seed. Had they considered better the phenological aspects, these promising species may by now have been more widely adopted.
Ignorance of phenology was also prevalent for several decades when the cheapest tree seed was sourced from Eastern Europe and imported into the UK. These origins were often not appropriate for the UK and I have seen numerous plantations of ash with multiple forks, established during the 1980s and 1990s. The impact is significant as these trees will never produce a valuable crop unless the owner repeatedly visits the trees to apply corrective pruning – and this costs time and money.
Gabriel Hemery
