Q. I noticed a lot of green tubes in the small valley on Glazier Way that crosses between Huron Pkwy. and Green Rd. What’s going on?

A. That’s the Glazier Hills Nature Area. More than 100 different native plant species have been identified in this 1.7-acre city park, including the fragile fern (Cystopteris fragilis), which is found in only a few sites within Ann Arbor.

Miller Creek flows through the valley, and more than 300 trees were recently planted there as part of the Miller Creek stabilization project. It’s coordinated by the Washtenaw County Water Resources Commission, whose deputy director, Harry Sheehan, has found that small trees are more cost-effective than large trees, which often struggle with the transport and transplant process. But small trees are vulnerable to being eaten by deer and other browsing animals.

Those green “grow tubes” protect the baby trees, letting in light and air but holding in humidity. They will remain for three to five years, until the trees’ trunks thicken and their leaves get above browsing height.

Got a question? Email question@aaobserver.com.