If fires are allowed to run through the forest and the leaves are burned, the most valuable fertilizing elements are changed by the heat into gases and escape into the air, and the valuable humus is destroyed.
(fires; are allowed; ) (the valuable humus; is destroyed; ) (fires; to run; through the forest) (the leaves; are burned; ) (the most valuable fertilizing elements; are changed; by the heat; into gases) (the most valuable fertilizing elements; escape; into the air)
fires the valuable humus fires the leaves the most valuable fertilizing elements the most valuable fertilizing elements
are allowed is destroyed to run are burned are changed escape
through the forest
by the heat into gases
into the air