The Trees of Tree Town
For most of the city's history, most trees have been ornamental: people planted them because they liked the way they looked. "People really love identical, symmetrical alleys of trees, like classical European gardens," says Tony Reznicek, assistant director and curator at the University Herbarium, who maintains michiganflora.net, a website listing every plant known to grow in the state.
"Personally, I think that's terrible," adds Reznicek, who learned to love trees from his European-born mother. "We should celebrate some more uniquely American horticulture ideals. And not planting all the same kind of trees is an absolute minimum because you open yourself up to all sorts of problems if you do that; not just something that will come through and kill everything, but diseases and pests that can build up when they have lots to eat."
After the devastating effects disease and invasion had on single species, Reznicek says, "We seem to have hopefully learned our lesson a little bit. I do notice a lot greater diversity of trees planted now, though." Not that all diversity is good, he adds: "I see lots of people that, whenever a tree comes up in their yard, they're reluctant to cut it down. That means their yards are full of weedy, invasive trees. [Non-native] buckthorn are fast spreaders because they're bird dispersed, and at first glance they don't look too bad or too dangerous. But they're really quite nasty things."