Is the chemical composition of urine detrimental or beneficial for a tree?
Here is a book about dry-matter production of urine treated plants. If we consider that trees are large plants, it's fair to apply the study to trees too:

The findings of the study suggested that urine and urine products are equally as effective as mineral fertilizer especially in sandy soil and that splitting the application is a useful strategy to manage urine and urine products for optimum dry matter production.

Some plants do live in harsh environments with chalky pH and other specifics, and they may weakened by it. It's safe to say most trees are unaffected or improved by some urine, although the biggest trees are because of rain and steady underground streams (groundwater).