Restoring the Prairie of George Washington Carver's Boyhood: Plant Monitoring, 2004–2020

George Washington Carver National Monument preserves the farm in southwestern Missouri where Dr. Carver — renowned scientist, teacher and conservationist — grew up. When he was a boy in the 1800s, prairies and savannas were common there.

Before European settlement, tallgrass prairie covered about a third of Missouri. Farming and fire suppression wiped most of it out: less than 1% of the state's original tallgrass prairie remains. None of that original prairie survives at the park, but a reconstruction began in 1985.

Heartland Inventory and Monitoring Network scientists survey plants in the restored prairie, June 2020. NPS

Keeping a prairie a prairie

Tallgrass prairie was once maintained by natural fire, grazing and drought. Today the park uses prescribed fire, mowing and herbicides instead. These spur the growth of native grassland plants and stop trees from taking hold and turning the prairie into savanna or woodland. A healthy tallgrass prairie needs plenty of grasses and a wide variety of forbs (herbaceous flowering plants).

Prairie monitoring sites and burn units at the monument in Diamond, Missouri; the burn units are the areas restored to prairie. NPS

How it's monitored

The Heartland Inventory and Monitoring (I&M) Network has surveyed 7 prairie sites since 2004 — in 2004, 2005, 2008, 2012, 2016 and 2020. At each, scientists record:

• climate and fire history;
• how many plant species are present;
• plant cover — how much ground each species covers, an estimate of abundance;
• how much ground is covered by plant litter or rock;
• the number of tree seedlings and saplings.

That shows the prairie's current condition and how it's changing, so the park can judge whether its management is working.

Butterfly weed (Asclepias tuberosa) in bloom, June 2020. NPS

Findings, 2004–2020

• The plant community is fairly diverse, even with recent increases in tree seedlings and small saplings — and there are still no overstory trees.
• Diversity was similar over the years, except for fewer species in 2012, an exceptionally dry year that may also have affected some plants' abundance. Rainfall has been mostly below normal since 2000, and below normal in all but one of the six survey years.
• Since 2012 the park has targeted two sumacs (Rhus copallinum and Rhus glabra) with fire and invasive-species control — very successfully. But blackberries (Rubus spp.) seem to be taking their place at some sites, and other nonnative species appear to be slowly increasing.
• Native grasses have declined since 2004. Drought, more tree seedlings and saplings, or a change in survey methods could explain it; more data will tell.

Active management will always be needed to keep native diversity and the prairie's open structure.

Big bluestem

Big bluestem (Andropogon gerardii). NPS

Big bluestem is a warm-season bunchgrass that grows 4 to 8 feet tall. It's one of tallgrass prairie's matrix (dominant) grasses, with Indiangrass (Sorghastrum nutans), switchgrass (Panicum virgatum) and little bluestem (Schizachyrium scoparium), and gives quail and ground-nesting birds critical habitat.

On the monument's monitoring plots it averaged 15–25% cover, steady over time. Drought, temperature and competition — especially from nonnative grasses — can affect it, and one climate model shows its range shifting northeast, away from Missouri. Tracking its natural year-to-year variation now gives a baseline to compare against as the climate changes.

More: the full report · Heartland I&M Network.

Sources

Based on "Prairie Community Monitoring at George Washington Carver National Monument," National Park Service; a work of the United States government in the public domain.