June 5, 2006

Irregular precision spacing close-close-wide

Filed under: Forestry Research,Timber Growing — shem kerr @ 3:45 am

A very attractive option for growers is to aim to grow timber crops as fast as is possible: to lessen biological, climatic and financial risk. Historically, forestry has taken the hunter-gatherer approach of an extractive industry; it has dragged its heels on progressing into cropping concepts. Even the most basic task of planting a tree has taken the path of minimal mental input. Species such as Pinus radiata and Pseudotsuga menziesii are relatively easy to establish. Species such as the cypresses can be quite site specific, or even micro-site specific. This post is about spacing regimes for such alternative or less mainstream timber species.

Genetics are often seen as the most likely factor for improved performance.There is a point in site quality below which even improved genetics can’t improve the quality of the crop Careful selection of seedlots or clones can just be the starting point for a proper and complete stuff up via blindly following regular grid patterns over land that is uneven in both topography (ie for wind exposure) and nutrient status or suitablity to grow a demanding crop. It’s as if forest management think that microsites come prearranged on a regular grid. On some soils on some sites it’ll be OK to plant that way. By doing so on other sites the grid will miss out some of the best micro-sites and thus lose site and tree potential.TightlyPackedSequoia Better would be to just grow the fussy trees on those micro-sites on whichTightfastigata they’ll grow fastest and healthiest; Plant a governess component between; and disregard regularity. When or if the governess trees are removed, the stand is left with various sized micro-groups of one to several crop trees planted quite close together ( say down to 1.2m apart) back to back, and relatively wide spaces of various widths between the groups.

OGfir This concept works readily with softwoods of the like of Cupressus or Sequoia. IOGfastigata have also seen it done with hardwoods like Eucalyptus. However, greater care may be needed to ensure no productivity loss from leaning or lopsided trees [ A clarification: the groups aren’t planted out in the open, but rather amongst a goveness component of the forest that exists taller than the crop at least until the butt log is established and pruned. Therefore there is little if any tendency for anEccentricLog eccentric log to be produced. However, it may be more productive to leave the governess trees to continue the job and as a worthwhile crop component in themselves. ]


The down side of this planting pattern is that greater skill will be required to determine the best micro-sites; and there is potential to have some quite large branches on the upper logs onthe outside of the group.
The upside is that:

branches on the inside of the group will be smaller or absent compared to those on trees in a regularly spaced stand with the same stems per hectare, there may be additional value in the partially clear top logs;

pruning ladder movement labour loads will be minimized;

(any) initial high pruning climb (say to 20m) need only be done once for each group, with the climber being able to swing across (rather than raw climb each tree) to access the next one in the group;

there is a better choice of which tree to or not to climb;

the crop and governess components have a degree of seperation that facilitates thinning with less likelyhood of crop damage;

not only will the crop be planted on only the most favourable micro-sites, but also,their roots and soil communities will have access to soil which isn’t littered and fouled with their own allelopathic chemicals. This will give something of a health cushion, as more growers try to establish high quality solid timber crops on sites that are less than optimal.


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