Deuteronomy 20:19-20

19“When you lay siege to a city for a long time, fighting against it in order to capture it, do not destroy its trees by putting an ax to them, because you can get food from them. Do not cut them down. Are trees of the field human, to come under siege by you?

20But you may destroy the trees that you know do not produce food. You may cut them down to build siege works against the city that is waging war against you, until it falls.