In practice many young woodlands have been neglected after establishment so that trees have developed long, thin trunks and poorly developed crowns. Slower growing species have been overshaded and those which reach the canopy have such narrow crowns that they are unable to respond to subsequent thinning by filling the gaps.

Woodland owners often do not have the necessary expertise to thin their woods at the correct time. It is perceived as a costly exercise in terms of manpower with little revenue. Many woodland owners with shooting interests leave their young plantations for thirty years then, deciding that their woods need some “warmth”, plant evergreen shrubs which are doomed to fail into the gloomy interior.

Owners with conservation interests justify their lack of management as “letting nature take its course”. In so doing they are producing impoverished woodlands of little value to wildlife compared with the rich biodiversity of the mature woodland that was envisaged at the time of planting.

Encouragement and education alone will not persuade many woodland owners to thin their young woods correctly. What is needed is practical ways of managing young woodland at minimal cost to the owner and to the long-term benefit of the woodland ecosystem.
 

Thinning by Ring-barking

Trees can be quickly ring-barked by holding a chainsaw against the tree at waist height and cutting through the bark as you walk around the tree. Often, simple ring-barking is not enough to kill the tree so a suitable herbicide should be applied by brush to the cut all around the tree.

When trees are ring-barked in the winter they will usually come into leaf the following spring. Some vigorous species such as Sycamore, Acer pseudoplatanus, may produce leaves for two summers after ring-barking. As the tree slowly dies it first sheds its leaves, then the smaller twigs and branches. At this stage the stem is sound and is perfectly dry. It is ideal for felling as firewood and needs no further storage. A typical tree will remain standing for 4 years or more until root decay makes it topple.

Tree two years after ring barking

Conventional felling produces sudden large gaps in the canopy that increase the exposure of the crowns of neighbouring trees. They will be slow to fill the gaps. Ring-barking slowly opens gaps in the canopy over several years allowing the crowns of neighbouring trees to grow into the space provided. It is a natural process similar to a tree dying slowly of disease.

If firewood is not required, the ringed trees can be left to provide the valuable and scarce habitat of standing dead timber. This is a particularly rich environment for insects and fungi as well as woodpeckers and other woodland birds. When the tree eventually falls it becomes lying dead timber. It becomes moist and decay is hastened by a new assemblage of insects and fungi. Organic matter is incorporated into the soil and the woodland begins to build up its carbon storage.

At Aveland Trees we have experience in selecting trees for thinning. We can ring bark the selected trees and give advice on harvesting for firewood.

The weevil is 3 or 4 mm long and is blue-green in colour. It feeds on the leaves of young trees cutting notches in the leaf and, when present in large numbers, totally defoliating it.

Phyllobius weevils on young Alder

 I found the infestation on an old grassland site during herbicide spraying operations in the middle of May. When I returned at the end of the month the number of weevils was much lower and the trees were beginning to show fresh re-growth.

 It appears that, although an infestation of Phyllobius weevils can look very damaging at the time, the effects are generally short-lived and most young trees recover fully. The following year the infestation is rarely so heavy, the trees are better established and have many more leaves. 

 There is no pesticide approved for the control of the weevil but I found that a sharp whack with a bamboo cane dislodged most of the blighters. OK, they could easily climb back up the tree, but it made me feel better at the time.

Young Hawthorn is particularly sensitive to Glyphosate. It is very easy to catch a whole hedgerow when spraying off stubbles in the Autumn. Initially there is no sign of damage, it is only in the following Spring when the buds burst to produce distorted spiky leaves that the problem becomes apparent. 

Glyphosate is a systemic herbicide, it may take 2 or 3 years before the Hawthorn finally dies, meanwhile, in a mixed hedge, other species such as Hazel and Field Maple may recover. The only remedy is to replant the Hawthorn at great expense. 

A lot of spraying is now done by contractors who may not be aware of new hedges on a farm. They may also be in a hurry to complete the job. Please make sure that any spraying with Glyphosate upwind of a young hedge is only done under ideal spraying conditions.

Hawthorn and other “native” hedgerows should be planted at 4 plants per metre overall in 2 rows, 30cm apart. This will develop into a thick hedge with a wide “bottom”. The easiest way to do this is to measure and plant at one metre spacing (marked * below) then to return and fill in with 3 more plants (marked 0 below) between every “metre” plant:

                                    *          0          *          0          *

                                         0          0          0          0          0

Some grant schemes insist on 6 plants per metre. This will increase the cost of the hedge by 50% with no real long-term gain.

Beech and Privet hedges are usually planted at 3 plants per metre they can be planted in a double row as above or in a single row. Laurels and Leylandii should be planted in a single row at 3 plants per 2 metres. Their bushy growth will soon fill the gaps. At the other extreme, a low growing Box hedge should be planted in a single line at 20cm spacing.

I look forward to receiving your comments!