Plant Community Monitoring at Pea Ridge National Military Park

Vegetation Management

Vegetation management at Pea Ridge National Military Park is focused on restoring the landscape to the vegetation communities that were present at the time of the Battle of Pea Ridge in March 1862. Present day woodlands and the landscapes that reflect historical settlements help visitors better understand the events of the battle. In 1862, the area had open oak-hickory woodlands, prairie,farms, and other settlements. The park uses management actions that promote the density, form, and structure of the historical plant communities that grew at the time of the battle. Open woodlands and native species, including regeneration of oak species, are important goals for the park. One of the tools park maanagers use to restore and maintain these vegetation communities is prescribed fire. A changing climate and increases in invasive species could threaten restoration efforts. Removal of invasive species and continued prescribed burning will be vital for management success.

Plant community monitoring in the woodlands at Pea Ridge National Military Park.

NPS

Monitoring Plant Communities

Monitoring park plants is an important part of the restoration process because it tells us how plant communities may be changing over time and whether management actions are working to restore them. The National Park Service (NPS) Heartland Inventory and Monitoring Network began monitoring 7 sites on the park in 2007 following the initial prescribed burns. The NPS Ozark Highlands fire ecology program also monitors vegetation on 12 sites in the park. Information gathered from all 19 sites helps the park make vegetation management decisions.

Pea Ridge National Military Park is in the Ozark highlands of northwest Arkansas with rolling hills, narrow hollows, and broad uplands. Oak species (Quercus spp.) dominate the overstory of the oak-hickory woodlands on the park. The understory is largely oak and hickory (Carya spp.) species with a few shrub and herbaceous species. Ozark chinquapin (Castanea pumila v. ozarkensis) is a species of concern in the woodlands due to the detrimental impact of chestnut blight on its populations throughout the region.

What Do We Monitor?

The Heartland Network monitoring sites are in the oak-hickory woodlands. Plant species found on transects at each of the 7 sites are recorded. We measure ground flora cover (a measure of plant abundance), tree canopy cover, tree regeneration, and how much of the ground is covered by grass and leaf litter, exposed rock, woody debris, and bare ground. We also analyze climate data to better understand the patterns we see in plant communities.

Canopy cover at Pea Ridge National Military Park is very high, indicating that these are closed woodlands. Further management actions will be necessary to restore these areas to open woodlands.

NPS

What Have We Found?

• Temperatures have been increasing at the park, but we are not seeing significant trends in precipitation and drought. There is a great degree of variability in rainfall and drought measurements from year to year. Plants are blooming and leafing out earlier compared to the past.

• Midstory trees are denser and the forest overstory structure is a closed woodland despite the prescribed fires and the thinning of eastern redcedar (Juniperus virginiana) at the park. To restore these areas to open woodland, further treatments like prescribed burning and thinning will be necessary.

• Ground cover was similar through time with some variability that was probably in response to prescribed fires.The goal is to maintain a variety of ground cover types across the park.

• One of the park's fire management goals is to increase ground flora cover, and abundance of these plants did increase from 2007 to 2021, though it was variable. Forbs (small, non-woody, non-grass flowering plants) comprised most of the ground flora, except in 2012.

• The number of invasive species increased from 2 to 11 species, but abundance of these species remains low. Opening the woodland canopy may cause an increase in Nepalese browntop (Microstegium vimineum).

A variety of ground cover types supports a diversity of plants and animals at Pea Ridge National Military Park.

NPS

Ground Cover and Biodiversity

Plants and wildlife have varied needs for ground cover. Deep grass and leaf litter shade the ground, which in turn affects soil moisture and germination for some species of plants, including herbaceous plants and trees. More frequent fires of lower severity have been shown to help acorns germinate and oak seedlings establish compared to less frequent fires with deep litter fuels. Litter is also important for some wildlife to find insects, seeds, and places to hide. Other wildlife species use bare soil for basking, foraging for worms, and other activities. Having a variety of types of ground cover across the landscape promotes biodiversity!

For More Information

View the Full Report. Visit the Heartland Inventory & Monitoring Network website.