Seltsame Kreise in der Provinz Lüttich (Waimes): Bewässerung durch US-amerikanische Landwirte? Bereich namens „Staatsforst Rohrbusch“.

Planted different species of trees in between others?

Aliens

Well im not an expert in this exact case but somewhere i assume this could be similar to the technique where you plant a different species around a patch to prevent cross polination.

For example there is a certain mango farming technique where they plant a buffer of disease resistant gmo mango plants around a field with non gmo mango plants as a buffer to prevent diseases from reaching the non gmo’s inside.

But again its probably not a gmo test here and im not sure if its exactly done to prevent unwanted polination, i could completely be wrong here

Edit: did some googeling and found out there are forrest restoration experiments going on the hautes fagnes nature reserve, could be part of that to check growth conditions