When soil becomes compacted because heavy machinery moves across it or building materials are stored upon it, trees are cut off from their air and water supplies.
(soil; becomes compacted; ) (trees; are cut off; from their air and water supplies; T:When soil becomes compacted because heavy machinery moves across it or building materials are stored upon it)
soil trees
becomes compacted are cut off
from their air and water supplies T:When soil becomes compacted because heavy machinery moves across it or building materials are stored upon it