Peter del Tredici has written an thought-provoking and great essay on The Flora of the Future: Celebrating the Botanical Diversity of Cities on the website the Design Observer. It is well worth a long, good read, especially if you live in an urbanized area or are interested in ecology and evolution.
He starts off with a dramatic statement:
"The concept of ecological restoration, as developed over the past 20 years, rests on the mistaken assumption that we can somehow bring back past ecosystems by removing invasive species and replanting native species. This overly simplistic view of the world ignores two basic tenets of modern ecology — that environmental stability is an illusion, and that an unpredictable future belongs to the best adapted." (source link)In short, nothing stays the same, and especially not now when we have changed the world so much when it comes to species distributions, human-built environments, and changing climates.
Read on... it is spot on and explains what is happening to plants in cities, industrial areas, and abandoned lots...