My neighbor wants to build a large stone wall with plantings within feet of our heritage oak tree. Can anyone tell me if this will cause damage to the tree to have additional weight or water across its root system?
That should be expected. You do not want to undertake cuts or fills within the root zones of mature trees you are hoping to keep in good health.
Any change around the dripline is a hazard to native oaks! Try to talk your neighbor out of any major change of grade or moisture around your tree. If your neighbor refuses to relent, make sure that the other side of the tree stays dry in the summers. When I moved to my present property fifteen years ago, one of the four huge, ancient valley oaks within was in obvious decline, gone 'twiggy' (my own description) where the branches begin to die back and subsequent sprouts come out in bushy clumps closer to the trunk. I was advised to remove the three to four feet deep of soil someone had previously packed around the trunk to make it easier to access the barn. I removed all of it from the trunk, restoring the flare at the base, and lined broken concrete around the hole to create a sturdy and lasting well ringing the trunk some six feet away. Within a couple of years the tree began making a recovery and is doing quite well today! Research Armillaria, oak root fungus, and other problems that plague native oaks when people start messing with them around the drip line. Perhaps you can get your neighbor to take a more careful approach to landscaping.
Although you saw an improvement in this instance tree wells are not recommended as they do not include the root system - the bulk of the underground part of the tree is still buried by the fill that the well is holding back.
I understand that. It was an imperfect solution to a dire situation. Removing it all would mean no access to the barn. I had to weigh between access and tree. I didn't design it, just inherited the problem when we bought the property. While the well is not out to the end of the drip line, it does open out the trunk and flare and a good portion around one part of the tree, the other side is normal grade. It gets absolutely no summer water. I am quite pleased at the recovery of this tree. The dieback ceased, new healthy growth began (not the twiggies) and it looks nearly as robust as the other three. Now if I could just find a good control for velvety oak ants! Other than the summer branch drop, these ants are the one downside of having these superb trees closeby. They get scary out here sometimes, mass migrations, invading the house, setting up home in the walls on occasion. I sleep outside during the summer and awoke one night to my bedding and me covered with thousands of them, stinky little @#%!
