The Civ name is "The Merchants of Wood", so that also ties in nicely, which is cool.
Another idea would be to make wooden barrels of booze be the inter-district trade goods instead, with the various quality levels of booze creating the variation of coinage value, based on the happiness of the dwarves who would drink it. This would also work as trade-in value of decorated barrels to the Districts producing booze:
We could call it "The Booze Standard".
Just some thoughts.
1. Booze in wood barrels = currency
2. Wood barrels are "in"
3. Wood pots are a "no"? Booze in wood pots is fake currency.
4. Stone pots are "no"? except for lignite or jet because those materials pots are lighter than wood barrels. Booze in stone pots is fake currency
5. Metal barrels are "in"
6. Booze in metal barrels = currency. I'd say "more" value as metal sources is finite, but are more in quantity initially but more labor intensive to retrieve.
Wood as a resource.
1. Let's say there are 100 trees per district, x20 = 2,000 trees.
2. Average of 5 logs per cut trees = 10,000 possible "barrels" initially.
3. Depending on sapling growth rate, let's say 10 trees grow / district / year, x20 = 200 trees x 5 logs = 1,000 possible "barrels" currency added annually.
My point is that wood are a resource is abundant at first, but becomes scarce when harvested without regard, so there is a built in "keep the future" in mind investment. The re-growth rate of trees makes it an ideal source of currency. And this does not include cavern trees, or underground fungus tree farms.
Compare to metal as resource.
1. There are more metals (assume) in an embark map spanning many z-levels.
2. These metal ores are finite that once all of it are mined out, it's is all gone.
3. But it also takes time to convert the ores into multiple bars; and into barrels.
Metals to make into barrels as form of currency would be a finite source to inflate or deflate the value of wood currency.
I can see it at now when the first batch of gold barrels are introduced. "I'd trade you 10 wood barrel booze for that 1 gold barrel booze!" Then years later, then gold barrels are common, the trade will be back to 1:1 ratio.