Mulch types

[j]

I've got a bit of landscaping needing a little mulching. I've laid down 4 or 5 layers of news print and topped it with some dyed mostly pine bark mulch. I can see this is going to take a lot more bags.

There seems to be a few common mulches: pine bark, wood shreds, shredded cypress and pine straw.

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

[Billy]

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 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, 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.

[j]

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

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

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

Jeff