ROCKS AROUND OAK TREE TRUNK
WE ARE CONSIDERING PURCHASE OF A HOUSE WHERE THE LANDSCAPE WAS RECENTLY CHANGED, ADDING A LOT OF LANDSCAPE ROCKS AROUND THE TRUNK OF A MATURE OAK TREE. THE HOUSE IS AT ABOUT 1300 FEET ELEVATION IN AND FACES SOUTHWEST. DURING THE SUMMER, DAYTIME TEMPERATURES REGULARLY REACH THE UPPER 90'S OR LOW 100'S THE TREE APPEARS TO BE EXHIBITING SIGNS OF STRESS, WITH DEAD OR DYING BRANCHES IN THE CANOPY. I BELIEVE THAT THE ROCKS ARE ESSENTIALLY "COOKING" THE CROWN OF THE ROOT SYSTEM, WHICH IS CAUSING THIS DAMAGE.
Certified GKH Gardening Expert
Most likely the tree is declining because of root disturbance. There shouldn't be anything under a tree but mulch out to the dripline. In one photo, there are a number of shrubs under the tree that someone must have removed to make way for the rocks, causing even more site disturbance. If you purchase the home, I would suggest moving the rocks away from the trunk. Vegetation, even grass, under a tree takes nutrients away from the tree. One of the worst things a person can do is suffocate the tree roots with raised beds under a tree, which is a popular design. Hopefully with correct watering and fertilization, the tree will recover.