Moved into house three years ago. Large vine maple in front yard, near concrete path but at least 2/3 of roots are not paved over. Leaves change color and fall off at lesat a month prior to any other vine maples in neighborhood (including others in our yard). One theory was lack of water, but we maintained good watering last year, and I am already noticing a large percentage of branches with no leaves, mid-July, this year--after an extremely wet May and June in the Puget Sound region. Leaves don't have obvious disease appearance, just changing and falling early. Lifespan issue? Disease? Other suggestions? I suspect plant is at least twenty years old.