Digging out a mysteriously dead Japanese maple, homeowner uncovers a deep, 6-inch-wide tunnel

Beneath the stump of a dead Japanese maple, one homeowner found what appeared to be a substantial underground tunnel while working in the yard and turned to the internet for advice on avoiding a new tree's demise.

What happened?

"This morning I was digging out the stump of our recently and mysteriously deceased Japanese maple and a wall collapsed to reveal a sizable tunnel! It's about 6 inches wide and goes down DEEP, like 3' or so. Presumably it continues underground," the gardener wrote in a Reddit post sharing a video of the tree trunk and mystery tunnel. 

"Gopher? Groundhog? And could this be the cause of my maple's demise?"

What the heck is tunneling under my garden??!
byu/renry_hollins ingardening

(Click here if the embedded video does not appear.)

Japanese maples can be especially sensitive to changes in soil conditions, moisture, and root disturbance.

Why does it matter?

Suburban yards often provide soft, irrigated soil, ornamental plantings, and shelter, all of which can make them appealing to burrowing animals. Homeowners may not realize how much is happening below the surface until a plant dies, a walkway shifts, or the ground suddenly gives way.

Underground tunnels can affect root stability, drainage, and overall soil structure. If a burrowing animal was active near the maple's roots, it may have added stress to the tree, even if it was not the sole cause of its death.

Finding a deep tunnel beneath a dead tree adds another layer of cleanup, cost, and concern. And finding ways to manage underground pests humanely and without toxic chemicals can also be challenging. 

What are people saying?

Commenters had plenty to say, including theories on what made the tunnel and advice moving forward. 

"That looks a bit like the start of a sinkhole," said one. "How much water comes out of that drain pipe next to the hole?"

"Any time there is a mountain of dirt moved and dug next to a tree, it's a groundhog," another added. 

"Put in metal mesh netting. It is the only way," a third advised regarding how to protect a new tree. "At least 1/2 inch, but really recommend 1/4 inch mesh. Make sure you put in a whole twice as deep as the root ball and 2x to 3x as wide as the branch circumference to allow growth. The metal will limit growth of root system and tree but will protect against burrowing animals."

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