Dawsey writes to Juliet from Louviers, France. He says that the trip across France was awful; there's destruction everywhere. People and tractors are trying to move the rubble. The trees are charred sticks only. The innkeeper explained that the Germans ordered the trees chopped down, stripped of branches, coated in creosote, and stuck upright in fields. This was to keep Allied gliders and soldiers from landing.
The innkeeper's story about the trees turns the trees into symbols of death and destruction, not life: creosote is highly flammable and any landing aircraft or people would've gone up in flames, destroying both the people and the trees.