Could this just be an attempt to proof the fuel tank against small arms, shrapnel and small drone dropped munitions? Or just to reduce the trucks IR signature? Wood is a very effective barrier, insulator even when used in small planks.
It actually increases the intelligence of Russian vehicles.
We all know the average russian soldier is as thick as two short planks. Therefore strapping a number of short planks to a vehicle actually increases the intelligence of that vehicle, therefore mitigating to some extent against the relative lack of intelligence of the Russian Soldiers.
Apparently.