Pollard

Images "grabbed" from this video at about the 7:10-to-8:00 mark

Same grove, different angle.

These trees are approximately 50km west-southwest of downtown Santander, Spain.

This is what ancient trees that have been trained as "pollard" look like. The constant cutting keeps them juvenile even though the trunks are over a half-century old.

When pollard trees are "let go", the limbs become too heavy and the tree splits apart. These trees need to be maintained with the same management system or they self-destruct.

These trees are most likely sweet chestnuts or oak.

The wood likely would be used for fuel, shepherd crooks, small wood for fences and chicken-pens.