Since it burns holes in lawns, it would seem there would be some potential for damage to tree or shrub roots below. Otherwise what you sometimes see is brown zones on shrubs etc. that have become marking posts receiving repeated doses over time.

In the rainy season it's not much of a problem although a 70 pounder is on the larger side. My 35 lb male has created definite yellow and brown patches where he likes to mark. Also the 60 lb female pees right at the base of the back steps and that grass is all dead since the first freeze, I assume from a combination of extreme cold, high traffic, and urine.

When I had a larger male dog and a smaller yard, I put sheets of plexiglass in front of the plants he liked to pee on repeatedly. You could still smell it, and the grass died, but it saved the shrubbery.

I would imagine that a Japanese maple would be pretty susceptible to damage, being so shallow rooted. It's not the ammonia so much, that breaks down fast, as just way too much nitrogen in one spot. I have not known anything to counteract the excess of nitrogen other than lots of water. My grass at the base of my back steps was fine over the summer so long as I hosed it down frequently, in addition to regular lawn watering.

I have a 'Red Edge' Hebe with a brown patch due to repeated sprays by cats.