Why is there a log on the back of the T-54?

ARGO: The log is there for when your stuck in Campnovka. You can use it to build a nice campfire for marshmallow roasting while you wait for the enemy to get bored staring across the open field and smell all those delicious smores cooking and then you can pound them with your artillary. JK. Most likely used to jam under the tanks treads when it was stuck in mud for traction to get out.