I've just noticed my neighbor laying black plastic on the ground under an
old cherry tree and I was just wondering if this is going to interfere with
the tree's water uptake. The plastic circles the tree in about a 7 foot
radius, as well as 15 feet out another 2/3 of the way around it, under the
drip zone. It's a lot of black plastic, and now it looks like bark mulch
going on top. Will water get through to the roots? Is she inadvertantly
killing the tree in order to keep weeds out of what appears to be a new
flower bed going in? Will there be masses of slugs reproducing under it?
Yikes!

What sort of "black plastic" It should be the type called landscape fabric and
it is porous That is the material that properly should be used in the situation
you describe.