Prairie Plant Community Monitoring at Tallgrass Prairie National Preserve

Tallgrass Prairie National Preserve

NPS

Park Prairies

Tallgrass Prairie National Preserve is in the heart of the Flint Hills in Kansas and protects 10,894 acres (4,409 hectares) of remnant tallgrass prairie. To maximize biodiversity in imperiled tallgrass prairie communities, it is important to maintain a wide variety of conditions, vegetation structures, and microhabitats to support a large number of plant and animal species. Managers use fire and grazing treatments to promote a varied and healthy tallgrass prairie on the park.

The greater prairie-chicken, an iconic tallgrass prairie species, requires different habitats at different points of its life cycle. It uses bare areas for lekking (communal breeding displays), warming, and finding insects to eat. More densely vegetated areas provide nesting spots and escape from predators. Chicks favor areas with a grass canopy for safety while eating food. Because of their varied needs, managing habitat for the greater prairie-chicken also provides habitat for an array of other organisms.

What Do We Monitor?

The Heartland Inventory and Monitoring Network has monitored sites in the western portion of the park since 1997, but our methods were not finalized until 2002. Sites are located mostly in tallgrass prairie vegetation with a few sites in rocky mixed prairie vegetation. We collect information on climate, fire history, stocking rates of grazing animals, the amount of plants and other materials covering the ground, the number and cover of prairie plant species, and the number of tree seedling and saplings. These measurements allow us to assess the current condition of the park's tallgrass prairie, track the plant community over time, evaluate the effectiveness of fire and grazing treatments, and understand how well the prairie community is meeting the habitat needs of park animals, such as the greater prairie-chicken.

Prairie plant monitoring sites at Tallgrass Prairie National Preserve.

NPS

Number of sites at each litter depth (cm). Ideally, greater prairie-chickens need up to 5 cm of grass and leaf litter to build nests and avoid predators. While average litter depth across sites was below 5 cm, individual sites had up to 16 cm. Deep litter hinders prairie-chicken movement

NPS

Plant Communities 2002–2018

Temperatures in the region around Tallgrass Prairie National Preserve have increased over the past 50 years. The amount of rain has been quite variable and there is no evidence at this time of an upward or downward trend in precipitation.

Since 2006, the frequency of prescribed fires has decreased and stocking rates of grazing animals (cattle) have been lower. Bison have been introduced as alternative grazers in Windmill Pasture. In the past, more frequent wildfires and herbivores, such as bison, grazed throughout the prairies helping maintain them. The park goal is to keep woody plant cover under 5% to prevent the prairies from turning into savannas or woodlands. We found that woody plant cover was well below this threshold but increasing on the park.

Another park goal is to maintain 30 to 60% of the area as bare ground (soil and rock) for ideal greater prairie-chicken habitat. We found that bare areas are decreasing overall. While the preserve barely met the minimum amount of bare ground on average, there was a lot of variance between plots and across years. In 2018, grass and leaf litter cover and depth were higher than the ideal for greater prairie-chicken habitat.

We did not find a change in the number of prairie plant species over time. The park continues to have characteristic tallgrass prairie plant species and there are few nonnative plants. More frequent prescribed fires and continued evaluation of grazing intensity will be important for maintaining the remnant prairies and conserving the greater prairie-chicken.

Tallgrass Prairie National Preserve

NPS

Did You Know?

Scientists don't just look at what species are present when they monitor plant communities. They often group like species together to look at how that group or guild of plants is doing over time. This can help managers understand how the different parts of an ecosystem are functioning. At Tallgrass Prairie National Preserve, we monitor plant guilds, including grasses, forbs (small, non-woody flowering plants), grass-like plants (sedges and rushes), woody plants, trees, and nonnative plants.

Grasses are usually the most abundant plants in tallgrass prairie and they provide forage for grazing animals such as cattle, deer, and bison. Forbs, while less abundant than grasses in tallgrass prairie, provide important habitat for pollinators, greater prairie-chickens, insects, and to a lesser extent large ungulates like cattle and deer. Forbs also contribute to seed production and make good cover to animals to escape predators. Grass-like plants like sedges are important for grazing animals like bison when grasses and forbs are dormant. In very low amounts, woody plants are important part of prairie habitat, but midstory and overstory trees should not grow in prairies. At the park, woody plant cover is under the maximum threshold but has been increasing over time. Only two tree seedlings were observed in the tallgrass prairie through our entire monitoring period. A group of plants that can harm ecosystems is nonnative species. While 28 species of nonnative plants have been found at the park, they remain at relatively low levels.

For More Information

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