June 4, 2006

Redwood Risks

Filed under: Cypresses,Timber Growing,Trees — shem kerr @ 5:07 am

As Sequoia sempervirens, Thuja plicata and similar durable stable lightweight timber markets experience rising demand with tightened availability, small and medium forest growers are showing renewed interest. There is a tendency for promotors and enthusiasts to gloss over, downplay, ignore or dismiss the risks.FellingSequoia On optimal sites each single risk may be minimal; but several such risks put together may add up to a loss of several percent of the potential crop, or potential profit. On a less than optimal site trying to grow Sequoia may be a liability. Of 10,000 acres of Sequoia planted in New Zealand around 1% established. This post touches on the problems that I’ve personally come across, and my own photos illustrate the points.

WindthrownSequoiaWindthrow is what happens when the tree’s root system can’t continue to anchor the tree upright against the force of the wind, and the tree is blown over. Sequoia have a shallow root system that doesn’t extend far from the stem. On some soil types windthrow is more likely than on others.

On in situ soils derived from mudstone, slippage can give similar results to windthrow. The bigger and heavier the tree is the more likely it is to slip.

StemBreakageSequoia wood is relatively weak and brittle. Strong wind gusts can snap stems. It is possible that stem rot could enter through broken heads.StemRotSequoia

In general, higher than average wind run speeds or salt laden winds slow growth rates and can shape trees short or unbalanced.

SequoiaWeedcompetitionMuehlenbeckia need plenty of light. Competing vegetation can even distort growth.
Some grasses, or competing soil communities may also stunt growth.



Branch cankers can be a source of lost growth potential. So far, canker risk is minute compared to Thuja plicata, Chamaecyparis lawsoniana or Cupressus macrocarpa

Sequoia wood is brittle and the green (unseasoned) wood is quite heavy. Stem breakage SmashedStemcan occur when felling over broken ground. this is more likely on tall thin stems of lower wood strength than it is on shorter thick stems of higher strength wood.

Branches that die and then have the trunk grow around them, produce ‘black’ orBlackKnot lose knots in the milled timber. this downgrades the timber.

Market risks for Sequoia aren’t something that I’ve had personal experience of. My understanding is that once a product reaches a certain threshhold price, consumers get serious about turning to and appreciating alternative products. Wood product alternatives include Pinus radiata and P taeda timber treated either chemically or thermally to resist decay; and composites of crop fibres and minerals or resins. These alternatives take market share away from the grower, and give it to the processor and industrialist. A way to keep or grow market share is to grow Sequoia faster and more economically though silviculture: and secondly through planting fast growing clones especially selected for producing highly durable and stronger wood at a young age. This in itself may introduce another risk: lack of genetic diversity leading to disease risk.


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