It didn't help that the King used them all up in the war with England a couple hundred years after Cervantes. A lot of Europe is trying to reforest now and hopefully that process continues.

We don't have the spectacular red Maple or Ponderosa pine forests that America has, this is true, but if this helps, some places in the North and Center of Spain (and many more in the rest of Europe) still look pretty much like Lothlorien. You just need to know where to go. Check Muniellos (oak), Tejera de Tosande (ancient yews and beech) or Irati forest (beech) for example.

The inner center and hot south can be more dusty and discouraging, but you can still be surprised by a few, not well known, jewels like Cabañeros, Valsain's pine forest, Alto Tajo, or Grazalema and the last relict Mediterranean -humid- forests in Cadiz. Plenty also of lagoons, marshes and aquatic ecosystems to visit, like Doñana or Daimiel. The biosphere reserve Hayedo de Montejo is located in Don Quixote's land.