Eucalyptus Silviculture: Fast growth, Quick Decisions

In Eucalyptus silviculture everything happens fast if your choice of species was correct to match it with site characteristics, if appropriate planting stock of known genetic background has been used and if proper establishment practices have been conducted. Deciding which is the target product to be obtained from your plantation at the end of the cultivation cycle is maybe the most important decision to take, and it should be taken even before any soil preparation operation done prior to planting. When you aim to produce fat logs suitable for sawing or veneer production it is important to keep in mind that costly silvicultural operations must be conducted from an early age and during all the cycle of production. These operations, if carried on properly and based on sound technical advice, do become investments in value adding for your trees. The motto to keep in mind along the process is not focussing in "what you have" in each moment (the number of trees, their dimensions, their form) but in "what will you have in the end" and "what you should keep doing to have that in the end". Final targets can be variable but it would not be rare that you harvested at the end of cycle only a 10 to 20% of the original planting stock. These "trees of future" can seem few, but they have different characteristics from those you would obtain at final harvest if you retained full initial stocking. Firstly they would reach bigger diameters and a noticeably higher unitary volume of timber per tree. Secondly, if pruning has been conducted properly, they would have reduced knotty cores, which are the major source of defects for lumber processing. Thirdly, most importantly, and directly related to the previous two points, they would atrract higher market values if final diameters do excel and are part of a good marketing strategy. Those few trees might easily worth as much as the whole initial trees if retained at full stocking. So, what would the difference be? Exactly in what happened to the 80 to 90% of trees that were extracted during the cultivation cycle.


So, sooner is better than later. But, what happens when we are late? It depends on how late we are. What is sure is that your eucalypt trees will not be waiting for you to take a decision. They are busy enough efficiently processing light, available water and soil resources, fixing atmospheric CO2 and putting new growth very fast to care for the wisdom of your decisions for further events.

If you are late, but not too late, it still worths it. Pruning operations done a bit later will produce a bigger knotty core diminishing the volume of high quality lumber you can obtain per tree, especially in the basal log (the one accounting for the highest percent of timber volume in each of your trees!). This means a reduction in the value of your final harvest, but not as much as to make your financial investment in tree growing unattractive. However, as we will see in next installment, the most important step is regulation of competence among trees, which should start as soon as canopy closure happens. What should your target be? Creating room enough for each "tree of future" so they do not use their available resources to compete with their neighbours for light, hence growing mostly in height. The advantage of well done thinnings will be a regulated competence and a trend towards an important growth in diameter after thinning until a new canopy closure among the remaining trees happens.

But what happens with those trees you extract? Are they marketable? It depends on their dimensions and how far away you are from suitable processing factories. But if you keep in mind the motto "what you will have in the end" it all might be easier. What is sure is that the moment to take the decision of letting your well grown sapling become a big fat pruned lumber log maker or a tall very thin lower value tree is already here. And that decission must again be better taken sooner than later.

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