How dog urine can kill city trees

A sign next to a tree in D.C. asks dog owners to reconsider letting their pets urinate on it. (WTOP/Kathy Stewart)

Kathy Stewart, wtop.com

WASHINGTON – The difference between city trees and those in the suburbs may not seem big to most dog owners.

But the next time a dog is tugging on its leash, headed for a solid-looking pine to “water,” WTOP’s Garden Editor Mike McGrath says that small territorial claim could kill the tree.

Part of the problem is that trees in urban landscapes are already in the most unnatural situation imaginable, McGrath says. These trees are already struggling under stress.

“There’s very little soil available for a city tree,” he says.

That limited soil experiences a tremendous amount of compaction, while the trees are subjected to vast temperature extremes. Add in a concentrated amount of urine from a dog and the consequences could be disastrous.

“A [bigger] concentration of people in a smaller area means more dogs per tree,” he says. “That nitrogen-rich urine can add up quickly over time.”

Droughts like the one the U.S. has experienced recently can make trees even more stressed, McGrath says.

“If it hasn’t rained for two weeks and ten dogs visit that tree, that’s like spraying an herbicide at the base,” he says. “You might as well be hitting it with Round-Up.”

It comes down to educating dog owners. McGrath says they might not know they are taking part in killing a tree. But he says giving them the tools to help can go a long way, especially in city life.

“It pays dividends when people become more thoughtful,” says McGrath.

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(Copyright 2012 by WTOP. All Rights Reserved.)


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