The photo below is from a boat sitting on blocks in the harbour in Reykjavik. What it represents is a metaphor for most things on the planet – there is very little humans make that does not eventually deteriorate (well most things – glass doesn’t decay, but wears away once broken, and plastic, well some say a plastic bottle may take 500 years to break down). Marine environments may be the worse, but the biggest culprit is water. Wood will eventually rot away, and metal rusts. For wood to rot of course you need the presence of warmth, oxygen, and moisture. Take one of these away, and the process slows immeasurably. Same for metals really. That’s why logs underwater, and even wrecks in cold climes for 100+ years survive – no oxygen.
Check out this post which describes centuries worth of shipwrecks in the Black Sea. Below 150m, there is next to no oxygen, so the wood on some of the wrecks was so well preserved there were visible chisel and tool marks. On some wrecks, even coils of ropes were preserved. It’s also why underwater logging has become such an industry, reclaiming logs that sunk during logging 100+ years ago. Above water though, its another matter altogether. That’s the problem with oxygen… it plays together with moisture and warmth to rot things. Wood decays, because the moisture and temperature conditions allow fungi to grow in the wood tissue.
Ironically the woods that are most resistant to decay are also those which are hardest to work with. Black locust is a good example, or tropical woods such as ipe, or lignum vitae. Ipe can be cut (but not by hand), but challenging to glue, and impossible to shape. Old growth redwood was exceptional for decay resistance because it came from large trees with a good portion of heartwood. Newer growth trees have larger bands of sap wood, which offers less resistance. That’s why newer wood shingles won’t last as long, despite coming from the same species.
What we need is a fast-growing, CO2 absorbing, workable, highly rot-resistent wood. Think, the workability of beech/birch, the growth speed of the hybrid poplar, the rot resistance/strength of ipe, and the CO2 absorption ability of the silver maple (like who knew).