Black Hill invasives

mixed blessingSunday brought us back to Black Hill Regional Park, this time with Carole Bergmann in the first of two field trips to look at invasive non-indigenous plant species. We explored an area quite close to the patch where Baltimore Checkerspots are being reared. The newly-paved hard-surface Black Hill Trail, which snakes through the park property, is a mixed blessing. This hike-bike trail, much wider than the footpath it replaced, exposes more forest floor to daylight, allowing opportunists like Japanese Stiltgrass (Microstegium vimineum) to take over.

still tastyAnother common invasive to be found in the park, one that I am less familiar with, is Wineberry (Rubus phoenicolasius), a tasty raspberry cousin with impossibly red drupes. It hopscotches across habitat by sending out hairy red canes that droop over and root when they touch ground.

long pastOne of the bad guys we met in Karen Molines’ spring class, Garlic Mustard (Alliaria petiolata) is all done by this time of year, leaving nothing but dry stalks.

mile a secondBut Mile-a-Minute, a/k/a Asiatic Tearthumb (Polygonum perfoliatum), is just coming into fruit. This annual will continue producing fruit and seeds until frost.

Even though Polygonum and Microstegium can form dense mats that choke out all diversity in the ground cover, Carole (in her capacity as botanist for the county park system) gives less management attention to sprawling and trailing species like these and more to climbing vines and shrubs like Oriental Bittersweet (Celastrus orbiculatus). These are species that can weaken and kill mature oaks and hickories and hence open up yet more gaps in the canopy. While the bittersweet is the bane of upcounty forests, in the south the big problem is Porcelainberry (Ampelopsis brevipedunculata).

Near the boat landing area, Carole showed us a meadow that had been largely restored. Most of the Autumn Olive (Elaeagnus umbellata) has been removed, and Spotted Knapweed (Centaurea stoebe), a thistle lookalike that is usually thought of as a pest of the west, is under control.

lunchBonus invertebrate for the trip was this Wheel Bug (Arilus cristatus) munching on a Japanese Beetle.