My, what a lovely spring we're having up here.
Amanda, I never had any problem with the hardy clumping bamboos that I grew up here, they died back to the ground as a perennial, but checking with the closer source is a good idea. I really don't think they will be any different than dealing with other tough clumping grasses.
Diane, I can't imagine marble leaching anything, it's a very hard stone remaining intact for centuries. What a great find! My only thought would be how slippery it might be when wet...(if it's polished).
Jim, and all, my old community garden is on 'the Avenue' in Minneapolis (Franklin Avenue, for the locals). We grew food, but also had an extensive series of walking paths, open areas and quiet sitting spaces tucked away. I never experienced much intentional damage, but we often found folks sleeping there in the early hours. In the late afternoons and at night, the local inebriates used the tables to hang out, often left their trash behind, but I always felt their respect for what was growing around them. Perhaps because we let them use the restrooms, perhaps because we set clear limits with certain behaviors, perhaps because it is one of the few spaces left that has a bit of humanity. Community gardens in the innercity represent so much more than we can ever know...
Jan, necrotic spots may be causes by a fungus, a bacteria or possibly by some abiotic factor. Hard to tell from your description what these spots look like, are they necrotic or are they perhaps a rust-type fungus? which leaves? underside or on top or both?, what type of rose? Perhaps you could get a hand lens and look carefully. Please take my email and contact me directly, if you like.
Best, Lisa in Mpls.