Carbon dating shows that trees growing out of bigger trunks, like the spruce shown in this painting, can actually be several hundred years old. Trees which seem dead because they no longer have greenery to photosynthesize with are supported by neighboring trees through their root systems to continue living. A tree which has lost all its mechanisms for new growth, like leaves or needles, can stay alive through its connection to other trees. 

 Part of the painting series There Is More Than You Can See.