On 7/8/2011 8:37 PM, Billy wrote:
In , wrote:



I seem to remember there was some disadvantage to the cypress, is it
that it lasts too long? Is there anything to recommend one type over
another? Appearance is important also, I've got a good bit done in pine
straw but it has an "undone" sort of appearance (which ordinarily I
like), but not for the main street view.

Jeff

You're thinking of cedar.

In terms of both its physical and chemical properties, wood is an
exceptionally difficult substrate to degrade. One of the principal
reasons is that wood contains very low levels of nitrogen, which is
needed to produce the enzymes

I happen to be obsessed with compost piles and yard trimmings at the
moment, much more than I wish.

Is there some microbe that "eats" the nitrogen and apparently some
phosphorus and cranks out enzymes that helps some other organism break
down the wood? Or am I twisted around? Compost piles aren't a
particularly close mix of higher N and low N, at least not on a
microbial scale. How much mixing do you really need?


that degrade the main structural polmers
of wood - cellulose (about 40-50% of the dry weight of wood),
hemicelluloses (25-40%) and lignin (20-35%). The lignin component also
presents a barrier to wood decay because lignin is a complex aromatic
polymer that encrusts the cell walls,

How does that break down, or does it evaporate out eventually?

What role does water play in all this? It seems like it may transport
the enzymes to where they can work, I would imagine it is also key to
the organism breaking down the cellulose. Stuff lingers in the desert.


preventing access of enzymes to
the more easily degradable cellulose and hemicelluloses. In addition to
these points, wood often contains potentially fungitoxic compounds,
which are deposited in the heartwood. In broad-leaved trees the toxic
compounds are usually tannins, well know for their ability to cross-link
proteins, making animal skins resistant to decay. In contrast, conifers
contain a range of phenolic compounds such as terpenes, stilbenes,
flavonoids and tropolones. The most toxic of the tropolones are the
thujaplicins which act as uncouplers of oxidative phosphorylation; they
are particularly abundant in cedarwood, making this a naturally
decay-resistant wood for high-quality garden furnishings, etc.

I note also that animals have a C/N ratio of about 9 to 1 and
certainly no tropolenes to prevent spoilage!

Jeff