Which is worse?
This? Buckthorn-choked savanna?
A lawn grown under the oak trees, mowed, fertilized, and watered on a regular basis.
Well, this one certainly looks better, carefully kept, all neat and tidy.
I hope you already know the answer. Actually, they are both terrible. Both sites guarantee the demise of our oak trees, because neither situation allows acorns to sprout and grow into new trees.
In the top picture, shade from the buckthorn prevents the acorns that fall from the oak trees from sprouting; In the lower picture herbicides and the lawn mower prevent germination of acorns and wild flowers.
Buckthorn and other invasive shrubs leaf out early and abscise their leaves late, thereby allowing very little light to reach the ground. All this shade has kept oak trees from sprouting and reproducing, guaranteeing their eventual demise. The dense cover also keeps wildflowers and sedges from germinating and growing on the woodland floor. Without a herbaceous carpet, the soil will soon erode away. In addition, trees rely on the dense fibrous roots of sedges to keep them adequately hydrated.
Brenda, fellow Wild Ones member, was faced with 6 acres of a buckthorn, garlic mustard infested Oak Savanna many years ago.
In her words:
“My property is a rolling 6 acre Oak savanna. It primarily contains mature White Oak and Red Oak with some Shagbark Hickory, Black Walnut, various hawthorn and cherry. I have worked actively for the last 20 years to clear a disturbed woodland thick with cherry trees and honeysuckle, with the only flower present seeming to be garlic mustard, to open the forest floor to sunlight. “ Brenda cut down and then herbicided the stumps of Buckthorn and Honeysuckle,.
“It is now rich in a diverse blend of native plants – most of which volunteered when given sunshine. The woods are host to many butterflies, dragonflies, bees, and various insects. The birds visiting include rose breasted grosbeak, indigo bunting, orioles, hummingbird, scarlet tanager and woodpeckers.”
A Northern Kane County Wild Ones walk through Brenda’s savanna, last May with Shooting Star, Wild Geranium, various Trillium, Blue-eyed Grass, Sweet Cicely, and others in bloom.
Valerie, Wild Ones member and Kane County Forest Preserve Educator had the opposite problem. When she purchased her wooded, 2-acre lot in 1998, it was a monoculture of even-aged White Oak in a sea of manicured turf grass, similar to the 2nd photo above.
Valerie’s goal was to turn the area into what it had been before–a biologically diverse oak-hickory woodland. Her first step was to mow the turf grass as low as possible, then over-seed it with seeds from savanna grasses, sedges, and forbs. Acorns, buried by squirrels began to sprout and grow into trees, as will all nut trees–Shagbark Hickory (Carya ovata), Black Walnut (Juglans nigra), Butternut (Juglans cinerea), and American Hazelnut (Corylus americana). With weeding, some herbiciding, more seeding, and controlled burns over the years, she has been successful.
Valerie’s savanna last August with Purple Coneflower and Joe Pye Weed in bloom.
We think of Purple Coneflower (Echinacea purpurea) as a prairie plant, but in nature it is more often found in Bur Oak savannas. Joe Pye Weed is a denizen of woodlands, as well, and prospers especially well in woods that have been burned.
White Oak with Purple Giant Hyssop (Agastache scrophulariaefolia). Purple Giant Hyssop isn’t, however, purple–at it’s best, it is very pale lavender. It has great architectural presence: the square stems grow up to 8‘ tall, clothed with bold opposite leaves and topped with dense spikes of tubular flowers from mid-July to mid-September. The numerous stamens that protrude from each blossom give the spike a fringed appearance. Butterflies love it.
In nature, it is found in open woods, especially at the edge of clearings.
Another deeper section of the woods, with more Joe Pye Weed.
Project Quercus of McHenry County Land Conservancy says that “our beloved oak trees are under stress, and if nothing changes, they may be largely gone from the local landscape within 20 years.” 20 years!
What to do? Let’s follow the example of the two property owners above.
Late fall and winter are the perfect time to cut out the brush that is choking our savannas and woodlands. Cut the shrubs to the ground and paint the stump with Brush-Be-Gone or Garlon. If you don’t want to use chemicals, you can cover the stump with black plastic and, given time, it will die. Or you can girdle the tree trunk by removing a section of the bark encircling the tree. Best time to do this is early spring before the tree leafs out.
If you have scattered oak trees situated in turf, interseeding is the best way to turn it into a savanna. Either mow or burn the existing turf grass, then sow seed either in spring or fall. Plant grasses and sedges such as Penn Sedge (Carex pensylvanica), Grass Sedge (C. jamesii), Common Wood Sedge (C. blanda), Hairy Wood Sedge (C. hirtifolia), Woodland Brome (Bromus pubescens), Bottlebrush Grass (Hystrix patula); add forbs such as Wild Geranium (Geranium maculatum), Virginia Waterleaf (Hydrophyllum virginianum), False Solomon’s Seal (Smilacina racemosa), Short’s Aster (Aster shortii), and Zig-zag Goldenrod (Solidago flexicaulis).
Set the mower high and mow the turf grass when necessary to keep it from over-shading the new emerging plants.
This is just an outline–I suggest you read The Tallgrass Restoration Handbook for Prairies, Savanna, and Woodlands by Stephen Packard and Cornelia F. Mutel.
Let this be the year.