Wood is still an important resource whose production and consumption has only grown, and yes, we've made it sustainable.

As an example, Finnish forests today have 2400 Mm^3 of wood, which is nearly twice as much as they had in the beginning of the 20th century, we cut ~70 Mm^3 per year, but the amount keeps growing because the yearly growth is greater than 100 Mm^3.

The reason for this is that most forests have essentially been turned into monoculture tree farms, and carefully managed for maximum productivity.

I'm not an expert in forestry, but I don't get the correlation between mono-cultures and the overall forest area. If there was one, then the forests should be smaller now due to higher yield per area.

Mind you, I'm not saying that it is not sustainable, just that we did not necessarily make it so. It just happens to play out.

Modern tree farms are sparser than natural growth forest. The quantity they are optimized for is yearly increase of new wood per area as opposed to maximum amount of wood that will eventually grow once trees are mature and planting trees as densely as possible is not ideal for this. (That is, trees planted somewhat sparser grow faster and mature quicker.)

> Mind you, I'm not saying that it is not sustainable, just that we did not necessarily make it so. It just happens to play out.

Again in Finland, it didn't just play out this way, the current state of affairs is result of intensive government-led research into sustainable and effective forestry methods started in the 1920s. Back then, the forests were the most important export resource of the recently independent nation, we needed a lot of imports and therefore ensuring that there will be new trees to cut down was a national priority.