By Bernie Buchholz
A thriving copse of low juneberry is an attractive feature on several remnant knobs at Nachusa Grasslands. These dense clusters of identical plants offer a strong visual contrast to the lovely chaos of diverse prairie surrounding them.
In our sandy soils Amelanchior humilis, aka low juneberry or shadblow, grows about 18 inches tall in dense copses about 30 feet across. Prescribed fire tends to burn only part way into the cluster and fire only top-kills the perimeter plants.
Could we create a copse on the highly degraded, but recovering, Fame Flower Knob that we’ve been restoring since 2006? We had previously planted scattered low juneberry plugs and none survived, probably due to repeated prescribed fire.
Below photo #1: Shadblow on Doug’s Knob remnant; copyright Charles Larry.
The Flora of the Chicago Region by Wilhelm and Rericha says the species occurs in mesic to dry-mesic woodlands and savanna. At Nachusa, copses of low juneberry are found in upland sandy soils underlain with sandstone, arguably in both historic open prairie and historic savanna habitats. It is promising that our remnant seed source is thriving on the same soil types as our target plantings on both remnant and adjacent planted prairie areas.
Larry Creekmur of Creston, IL grew three trays of 38 plugs each and generously assisted with the plug planting on October 26, 2014. We targeted one site on the remnant with the same northeast exposure as the seed source and two sites immediately adjacent to the remnant in a 2012 planting. We tried three elevation levels on the knob. The moisture levels appear similar.
Photo #2: Larry Creekmur with planted plugs protected with plastic cylinders.
At each of the three planting sites we planted 38 plugs on 6-inch centers to mimic the dense growth of existing copses. To deter predation while the plants were establishing, we placed a translucent plastic tube around each plug, each supported by a metal stake. After the first winter, the survival rate was about 85%, although we did not do an actual census.
Photo #3: Finished installation.
Our management practice has been to burn the remnant and surrounding plantings almost annually during active restoration. We believed, however, that prescribed fire posed a considerable risk to the shrubs’ survival while the plugs were getting establish. We tried to protect the plugs from prescribed fire in different ways: by reducing adjacent plant matter within 5 feet; heavily wetting just before fire; and with fire retarding foam, also just before prescribed fire.
We were very frustrated when fire repeatedly burned through our defensive efforts. We finally had success in fall 2020 by erecting used corrugated steel panels, but we only had the resources to protect the remnant site which was about 6’ x 5’.
Photo #4: Corrugated protection.
After eight years only the remnant planting site shows the making of a copse. There are now about 150 stems of various sizes compared to the 38 stems planted. The perimeter of the cluster, however, is not noticeably larger than the original planting.
Photo #5 Remnant location after 8 years.
Observations about the process:
- Planting plugs in close together seems like a sound strategy.
- Fire will likely penetrate, but not kill the copse for years to come.
- We might have planted all 114 plugs in one location creating a larger starting copse.
- Only metal panels protected the new plugs from fire.
- The other two planting sites were not protected from fire and are much less vigorous and less dense.
- Effective protection from fire might have accelerated the plugs’ development.
- We might have done simple soil cores to possibly find a planting site with “depth to sandstone” like the source site.
It looks like it will take at least another decade or two before the planted copse is wide enough and dense enough to act as a barrier to prescribed fire, thereby protecting its core.
We think this effort will ultimately succeed. Check back in a decade, but don’t wait to try it yourself.