Tom Vanderpoel offers suggestions
Stewards often visit each others’ sites to share ideas. It is a special treat when the highly experienced Tom Vanderpoel schedules a visit to Somme Prairie Grove. As Land Manager for Citizens for Conservation, he has done decades of detailed work on a few high-quality restoration areas. A person just doesn’t get the knowledge Tom has without long and intense focus.
We visited the “Pothole Pond” where a stand of solid cattails had increasingly crowded out nearly every other plant over about an acre. (Which cattails? Both species – for scientific names of all species, see note at end.) After pulling and scything the edges for years, with modest results, we herbicided the patch and planted diverse wetland seed about a decade ago.
The pond is now diverse and beautiful, with five endangered or threatened species and, more important, a great deal of conservative diversity. BUT a couple of patches of bluejoint grass have started to spread as monocultures. We excluded bluejoint from the early seed mixes because of this very worry. Will it now wipe out this diverse (but immature) community?
|Tom Vanderpoel, right, has supervised some of the region's most diverse wetland restorations. Here he trades thoughts |
with Rob Sulsky, who has been developing propagation techniques that help his efforts.
Tom has two conflicting thoughts. On the one hand, he thinks that the monocultural aspect is likely temporary and brief. The other species will re-invade the bluejoint sod as that matures.
On the other hand, he says, “If you see this continue, you might try damaging the bluejoint with Poast (an herbicide that kills only grass) and inter-seeding with tough sedges and diverse forbs right after.” Might. He doesn’t know. Every site is different, at this stage of our knowledge. Watch carefully. Try different approaches.
The sedge meadow north of the Swale Pond has almost the opposite problem. For decades it’s been a “few-culture” of mostly bluejoint grass and sedge (pellita). Years ago he said of this area, “I like it. Now start putting the forbs in.” I didn’t. There’s only so much time, and I understood needs better on the upland prairie/savanna/woodland areas. But this beautiful wetland deserves better.
|The Swale Pond itself is richly diverse, but the formerly grazed area around it is almost a monoculture |
(or "two-culture") of blue joint grass and sedge.
“What species, specifically?” I now ask. He recommends: boneset, water dock (“that one the butterflies appreciate so much”), spotted Joe-Pye-weed, swamp candles, shining aster (puniceus), tufted loosestrife.
Tom says, “I think a few of those species will break down the monoculture and promote diversity. Then soon it will be orchids and everything else.” Here and there, already, were patches of winged loosestrife. Tom recommended seeding especially around those areas.
We looked at a “new” (most work done in the last ten years) wetland in the northwest corner. It had been dense ash, sandbar willow, reed canary grass, etc. Now, with modest seeding, it is mostly rice cutgrass, manna grass, and other such common but classy species – with the occasional eared gerardia and even prairie white-fringed orchid. Patches of iris and cordgrass are here and there – along with continuing infestations of reed canary, purple loosestrife, cattail, and common reed.
Tom said, “Pretty cool start. Be relentless on the reed canary; it’s the worst invasive we have. Put the big sedges into the cutgrass; pour forbs into the sparse areas; bur reed could be important here.” He looked darkly at a couple of areas where the herbiciding of reed canary or loosestrife had left a few square feet of bare ground. “These are dangerous for re-infestation by junk, he said.” Manna grass happened to be ripe in the area; Tom started grabbing handfuls of it and broadcasting them on the bare patches.
Left: a bag of seeds of the sedge Carex vesicaria (a species that may deserve to be on Tom Vanderpoel's sometimes-changing list of "The Ten Warriors" - species that help seal off wetlands from invasion by malignant species)
He glanced at the ditch of cattail and river bulrush along the railroad track to the west. “You might want to nuke that whole stand,” he said. Lot’s more to discuss here, but I wanted to save time for one last place.
One white oak area needed thought. Though Somme Prairie Grove was savanna originally, one hundred years of farming had eliminated the bur oaks from the north half. When these 90 acres were bought for forest preserve, white oaks were planted in the former pastures and crop fields. Whites are okay savanna stand-ins for bur in the short run, but it seems like fires of savanna intensity are gradually burning them out. Young burs (planted by us and squirrels) are ruthlessly browsed to dwarfs by the deer. We’re protecting them with cages, so they can replace the whites over time, if the whites continue to succumb to fire.
After thirty years of restoration, some of the open white oak areas support rich, diverse, conservative savanna herb flora: grove sandwort, violet bush clover, two-flowered Cynthia, small sundrops, wild hyacinth, savanna blazing star, pale Indian-plantain, Canada milk vetch, slender wheatgrass, wide-leaved and Leiberg’s panic grasses, and scores more.
Downwind of the open-est part of the grassland, the big white oaks are dying from fire. Underneath, a few-culture of big bluestem etc. is replacing the much better stuff. How concerned should I be?
|Intense fire is critical to the natural dynamic of the savanna. For one thing, it controls invaders. But at Somme it's been |
killing (artificial, planted) white oaks that may be temporarily important to the structure of the habitat.
Tom recommended back-burning through the best groves. “You wouldn’t want to lose diversity of this quality,” he said. Yet, lack of sufficient fire is often a big challenge. Putting more restrictions might add too much complexity to burns, conducted by contractors who don’t know the site intimately, and who are at the mercy of weather, traffic on nearby highways, competition for time and resources from other deserving sites. I wonder if there are better solutions. Perhaps more burn resources, some day? Perhaps creative fire breaks. Perhaps speeding up the recovery of the bur oaks by spending more time shelping them?
This question seems not resolvable at this point. Comments from readers are (always) welcome.
Index of scientific names for common names cited.
Scientific names of plants cited, from Plants of the Chicago Region by Swink and Wilhelm (1994)
ash – Fraxinus pennsylvainca
big bluestem – Andropogon gerardii
bluejoint grass – Calamagrostis canadensis
boneset – Eupatorium perfoliatum
bur oak – Quercus macrocarpa
bur reed – Sparganium sp.
Canada milk vetch – Astragalus canadensis
cattail – Typha latifolia and angustifolia
common reed – Phragmites australis
cordgrass – Spartina pectinata
eared gerardia – Tomanthera auriculata
grove sandwort – Arenaria lateriflora
iris – Iris virginicus
Leiberg’s panic grass – Panicum Leibergii
manna grass – Glyceria striata
pale Indian-plantain – Cacalia atriplicifolia
purple loosestrife – Lythrum salicaria
reed canary grass – Phalaris arundinacea
rice cutgrass – Leerzia orzoides
river bulrush – Scirpus fluviatilis
sandbar willow – Salix interior
savanna blazing star – Liatris scariosa
sedges, tough or big (“The Ten Warriors” that compete especially well with reed canary): Carex stricta, haydenii, buxbaumii, pellita, lacustris, trichocarpa, atheroedes, utriculata, sartwellii, emoryi, and aquatilus
shining aster - Aster puniceus
slender wheatgrass – Agropyron (or Elymus) trachycaulum
spotted Joe-Pye-weed – Eupatorium maculatum
small sundrops – Oenothera perennis
swamp candles – Lysimachia terrestris
tufted loosestrife – Lysimachia thrysiflora
two-flowered Cynthia – Krigia biflora
violet bush clover – Lespediza violacea
water dock – Rumex orbiculatus
white-fringed orchid – Habenaria (or Platanthera) leucophaea
white oak – Quercus alba
wide-leaved panic grass – Panicum latifolium
wild hyacinth – Camassia scilloides
winged loosestrife – Lythrum alatum