Vinca, Garlic Mustard and an Eastern Cottontail

What: The patch of woods behind my house (dominant trees are black walnut, slippery elm, boxelder, and and Norway maple, with black cherry, honeysuckle, and common buckthorn in the understory and that is literally all) has about three different herbaceous plants growing in the understory and they form near monocrop patches. The first is Vinca spp. (or periwinkle), which I have growing in dense, impenetrable thickets closest to the walnut (walnuts have juglone in their roots which is known to inhibit growth of other plants). Farther away is a 1-2' tall forest of garlic mustard. The scilla, which I already posted about has pretty much gone through its life cycle before the garlic mustard is up.

Ecological notes: I've long just attributed this overwhelming abundance of garlic mustard and vinca to the fact that this is a heavily disturbed area and so non-native exotics like garlic mustard would thrive. The Vinca was probably ground cover from an ornamental planting. There's virtually no leaf litter (all that's there is from this year) due to an over abundance of earthworms (Lumbricus terrestris), the soils are pretty darn sandy, and there's lots of browsers and not a lot of predators.

But I've also been noticing more and more a rabbit in my backyard. The rabbit's an Eastern cottontail, Sylvilagus floridanus, which, for Vermont, is an introduced species that has largely outcompeted the native New England cottontail. We don't really ever get foxes or other rabbit predators and so I think that the rabbit population might be big enough to essentially be controlling the herbaceous layer. I see them eating violets, dandelion, the grasses, and my blueberry shrubs, but they have entirely avoided the garlic mustard and vinca.

Where: My backyard! Sandy soils, an old plowed field (abandoned in the 70s).

Other notes: I tasted a periwinkle flower and it was okay at first and then had a taste reminscent of black licorice but much worse. I haven't seen any really browse sign on them at all so stuff seems to pretty well avoid it.