The pine trees with their fresh foliage growing in a life-threatening lava environment represent the eternal life-cycle of growth, reproduction, individual death and new germination.
The wall running from the front right corner of the picture into the far left and disappearing on the horizon across the sea somehow into the sky, represents the development of all things in our world coming from an unknown beginning and developing into an unknown future.
It can stand for the evolution of humankind or the evolution of the universe alike. As far as we know, it is a one-way road to eternity.