Early intervention locks in long term timber profit

William Merivale

July 23 2013 04:03 AM

More than 20,000 hectares of broadleaves have been planted over the last 10 years or so. Most of this was by farmers on relatively good quality land.

Despite requiring a greater investment per hectare than conifers, broadleaves actually represent a more unpredictable return, so attention to detail and good management are essential from the outset.

Unlike conifers, which tend to produce one dominant leading shoot each year, most broadleaf species are not naturally apically dominant. This is why formative shaping of young broadleaf trees is a requirement in virtually all plantations if quality timber is to be produced.

A stand of broadleaves that has been left to its own devices can all too easily end up as firewood, with little or no potential to produce quality timber, whereas early intervention, ideally with a pair of sharp secateurs to begin with, can make a substantial difference to the end product.

Unless this is done, stem quality will be seriously compromised. But when it is carried out correctly, formative shaping will help to maintain a sufficient number of trees from which to select the final crop.

Shaping is best done in mid-summer when the tree's own natural defences against disease are at their most active, and when cuts heal the quickest.

For once, it seems we are actually experiencing a summer and the current spell of fine weather is a good time to get on with this essential operation.

PLIABLE

Work should start on formative shaping of ash, sycamore and cherry in their second year after planting when 1 to 1.5 metres in height, and at the stage when the shoots are still quite pliable.

Oak and beech, on the other hand, are normally tackled a little later, perhaps from year five onwards. If shaping is delayed until defects have become lignified the trees are unlikely to straighten following pruning.

Further shaping is likely to be necessary over the next two to three years, and should certainly be done no later than three years after the first operation.

The goal must be to achieve at least three metres of straight, defect-free stem and if this pruning can't be done with a sharp pair of secateurs then it has been left a little late.

Even in very high quality stands you should expect to carry out the operation at least twice.

The aim is to remove any forks so as to encourage a single, straight stem. Also remove any competing co-dominant shoots, dead leaders, and disproportionately large side branches.

As a general rule, a side branch with a diameter of 50pc or more of the main stem should be removed. It is normally unnecessary to remove small side branches as they will die as the canopy closes and shade increases.

Broadly speaking, the young trees are classified into four different categories. Category 1 trees are those of superior form where little or no intervention is required; a category 2 tree can usually be transformed into a category 1 with a little judicious shaping; and a category 3 tree, with rather more work, can often be turned into a category 2.

Finally, category 4 covers all those of sufficiently poor form that intervention is unlikely to be worthwhile.

In short, the better trees should be concentrated on as very poorly formed examples will rarely be converted into quality stems.

They will serve their purpose in providing side shade to their more promising neighbours, and be harvested for firewood at the thinning stage.

ACCURATE

After first shaping there should be at least 60pc of the stems in Quality Categories 1 and 2; and after the second shaping at least 50pc of the stems should be in Quality Categories 1 and 2.

Trials have shown that shaping noticeably increases height growth in these categories, especially in ash and sycamore.

Some care must be taken to ensure a clean and accurate cut – see photo. The cut should be made close to the main stem, but just outside the branch collar, or branch bark ridge, a clearly discernible ridge close to where the branch meets the stem.

It is this collar which produces the callus that grows over the cut and if it's damaged the wound takes longer to heal and leaves the tree open to infection.

Likewise, if too long a peg is left this too can lead to infection, as well as a dead knot resulting in degraded timber.

Formative shaping is enjoyable work, and the hands-on nature means that the owner becomes familiar with their plantation, and even individual trees, from the outset. They will also be in a better position to deal rapidly with any problems that may arise.

William Merivale is national secretary of PEFC Ireland and a forestry consultant based in Cork. Email: william@cjandco.net