The landscape in the last chapter adds to the tension because it symbolizes all the struggles and fears the two are facing.
A man is dead because Kino has killed him and they are on the run. At first the wind hides their footprints, but when it stops their footprints are revealed.
The landscape is foreign to them and they, themselves, feel the distress of not knowing where they are. There are "evils" in the night. There are trees that "bleed" and are "blinding". they must hide behind a tree of thorns. All these details add to the idea that the two are unsafe, and, with their fear apparent, the reader's tension is sure to be high, too.