Be that as it may, the ancient world definitely went through a lot of trees, when they were the principle source of energy.

To put that in some perspective, a Roman legion (roughly 5,000 men) in the Late Republic might have carried into battle around 44,000kg (c. 48.5 tons) of iron – not counting pots, fittings, picks, shovels and other tools we know they used. That iron equipment in turn might represent the mining of around 541,200kg (c. 600 tons) of ore, smelted with 642,400kg (c. 710 tons) of charcoal, made from 4,620,000kg (c. 5,100 tons) of wood. Cutting the wood and making the charcoal alone, from our figures above, might represent something like (I am assuming our charcoal-burners are working in teams) 80,000 man-days of labor. For one legion. https://acoup.blog/2020/09/25/collections-iron-how-did-they-...

I think his point was that in Europe, most deforestation happened much earlier than the industrial revolution, and he wanted to clear the relatively common misconception that everything was green until the industrial revolution.

Right! But as I understand it, most of this wood was from managed forest, which allowed for much more efficient harvesting and also allowed for controlling various qualities of the wood.

Lindybeige has a good video on the topic. It doesn't quite go back to Roman times though.

https://www.youtube.com/watch?v=zVPUFMwm73Y

From same blog, who sourced, the impression I got was that medieval-period industrial activity featured more forest management, as it was private property / a resource.

In Roman times... We know, for instance, that Elba was almost totally deforested during the Roman period to fuel the bloomeries smelting the ore and Pliny notes in his Natural History that smelting (not always of iron) had substantially reduced forest-stocks in parts of Gaul and Campagnia. Roman iron production in the eastern High Weald of England may have deforested something like 500km2 over the course of three centuries and there is reason to believe that Roman-period iron production in this area stopped because of scarcity of fuel, rather than ore. Iron-working was hardly the only factor in the steady deforestation of Europe, but it was a major factor.

So apparently Roman-era metal production was sufficient to deforest isolated large islands, but probably not for mainland areas better able to reforest themselves.

As with most of the forest in the UK, it was cut down for timber and then did not regrow because of deer. This has been happening for thousands of years.

No surprise there, the bear became extinct in the British Isles by the 10th century.