Quality and Management of Beech

Quality and Management of Beech

The aim of beech management is to produce high value timber. However, in Austria we are far away from reaching this goal.

Producing high value timber means producing valuable logs of good quality characterised by diameter over 60 cm under bark, knot free parts of the lower stem, thin and sound knots, knotty core of 20 cm at maximum, no discolorations (redheart). Logs should also be highly resistant to abiotic damages, tending and harvesting costs should be minimised.

High-quality timber has to meet the quality criteria laid down in the Austrian Timber Trade Usances. Apart from the high standards for veneering wood beech logs with log grade A have to fulfil the following requirements: over 3 m length, average diameter over 30 cm under bark, no bumps, no distortions, knotfree wood up to 3 m, no sweeps. Red heartwood up to a maximum of 30 % of the top diameter is tolerated.

Prices of hardwood submissions show how important dimensions are; the highest dimensions achieve the highest sale price per cubic meter over bark. In general, we can say that the value increases over proportionally with increasing diameter provided the quality is good. In addition, it must be considered that logs from the lower stem (about 8 m length) are more valuable. As a rule, the following standards for mature hardwood trees apply: this part of the log corresponds to one quarter of a tree length. It accounts for half of the wood volume but only three quarters of the revenue.

Timber with log grade B may at least achieve cost coverage. Some profit can only be expected when the share of logs with grade A is high. Grade C or industrial timber will incur losses. This will not even change in case of possible increases of prices for fuelwood and pellets.

It must therefore be clear that from the economic point of view knotfree logs which achieve big dimensions within a short period of time are to be favoured. A production period which is as short as possible in order to achieve the target diameter is also important to avoid the danger of redheart formation in old beeches. Though discoloration is an optical “wood defect” not resulting in a deterioration of wood quality, it leads to less favourable grading involving price reductions. However, there are efforts to push redheart wood for furniture because of its interesting (dis-)coloration. But it cannot yet be estimated in how far this will become accepted by the market.

Unfortunately, the current situation differs considerably from the silvicultural target for beech described above, as revealed by recent surveys 2000/2002 of the Austrian Forest Inventory (ÖWI): Only a few beech logs with a diameter over 20 cm under bark achieved grade A. The ownership structure from farm forest over large-scale forest to the shareholder company "Austrian Forests" (Österreichische Bundesforste AG) shows a similar picture. Only few are high quality logs.

Grading according to dimension reveals that from around 90 million beeches over 20 cm under bark in Austria, 11 million show a harvesting dimension of over 50 cm under bark, but only 500.000 trees or 5 % show an acceptable log quality. It is necessary to significantly increase this share through targeted selection and improvement measures. It is an unbearable economic mortgage when 95 % of the stand is of unsatisfactory quality at the end of a period. This is a clear indication that tending measures were insufficient in the past stressing at the same time the urgency of improvement in the future.

Economically justifiable costs of silvicultural measures and low operational expenses can only be achieved if tending operations concentrate on single trees. Natural regeneration is to be preferred for reasons of economy. Artificial planting is useful only in a few exceptional cases and requires low levels of browsing stress.

In mixed stands the varying growth ability has to be taken into account. Single mixture is especially precarious as there are many contact points among the individual tree species. This may lead to an overriding of trees with weaker growth ability and dominant species may not achieve the targeted log quality (boundary-layer problem!)

In regeneration areas and thickets, in addition to mixture regulation, undesired bifurcations, wolf and bushy trees are removed only to the absolute necessary extent. Otherwise, it is useful to maintain a high stem number in order to secure quality logs at ground level.

As soon as the knot free tree stem length of a quarter of the final tree (at 8 m approx.), that is a stand height of 12-15 m, is achieved, future trees have to be selected. By this operation those trees will be identified which shall form the final stand with high quality trees. The optimum number i9s determined by the desired target diameter which is to be achieved within the rotation period. The desired crown size determines the space between the future trees. If the starting stand does not contain a sufficient number of high quality trees the number of possible future trees will be reduced.

If there is no future tree it is not wise to select one to ensure even distribution only for this purpose. Neither would it be useful to get so-called "reserve trees" to make up a potential mortality of future trees. Each reserve tree would compete with a future tree having a negative influence on its growth. The future trees will so often be liberated from competitors until the branches stop dying at the lower part of the crown (no dead branch stumps, callous margins and "Chinese beards"). Also, there will be no more epicormic branching. The auxiliary and secondary stands are managed only in exceptional cases.

Extremely low future tree numbers (below 100 stems/ha) as suggested by some beech management models, are only economically justified if highest quality is achieved. Therefore, they are confined to sites with extremely high performance and low risk. The production of exclusive single trees, as is the case in noble hardwood, cannot be a realistic silvicultural target in the case of beech.

The logical conclusion from the above is that though in beech management the risk is reduced the need for tending and the quality risk are much higher than in spruce. Whoever wants to be successful with beech trees, needs a clear management concept including consequent stand tending practices. Only then he can say in the moment of harvesting: it has certainly paid off.