National Park Service


Date of this Version



Natural Resource Technical Report NPS/NGPN/NRTR—2013/673 / NPS 165/119659, January 2013: vii, 25 pages

Published by the United States Department of the Interior, National Park Service, Natural Resource Stewardship and Science, Fort Collins, Colorado

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Please cite this publication as:

Ashton, I. W., S. K. Wilson, D. Swanson, M. Prowatzke, and P. Graeve. 2013. Plant community composition and structure monitoring for Agate Fossil Beds National Monument: 2012 annual report. Natural Resource Technical Report NPS/NGPN/NRTR—2013/673. National Park Service, Fort Collins, Colorado.


United States government work. Public domain material.


Executive Summary

Agate Fossil Beds National Monument (AGFO) plays a vital role in protecting and managing some of the last remnants of native mixed-grass prairie in the region. The Northern Great Plains Inventory & Monitoring Network (NGPN) and Fire Ecology Program (FireEP) surveyed 12 long-term monitoring plots in Agate Fossil Beds National Monument in 2012 as part of an effort to better understand the condition of plant communities in the park. We measured plant diversity and cover, looked for the presence of exotic species that may be newly invading the park, and evaluated the amount of human and natural disturbance at all plots. This effort was the second year in a multiple-year venture to document the current status and long-term trends in plant communities in AGFO. At the end of five years, there will be an in-depth report describing the status of the plant community. In addition to upland plant monitoring, we also sampled vegetation at 12 sites along the riparian corridor at AGFO as part of a pilot study to develop a long-term monitoring approach for this area. The riparian corridor is narrow and not adequately represented in our standard sampling, but is of great ecological and management importance to the park. In 2013, we will also revisit legacy plots that were established as part of the Prairie Cluster prototype monitoring. In this report, we provide a simple summary of our results from sampling in 2012.

In the upland areas of the park, AGFO has maintained a mixed-grass prairie with low exotic cover and a high diversity of native plants. There was a severe drought in 2012, and as a result, we found that plant diversity and plant cover was in the low range of normal, but still higher than other parks in the region. Annual bromes, such as cheatgrass (Bromus tectorum), are not abundant in the park, but active management may be required to keep such low cover. For instance, off- road driving through the native prairie should be kept to a minimum. Allowing for natural disturbances such as fire may be critical to maintaining plant diversity in AGFO, but it should be balanced with the need to protect intact native communities and prevent further invasions of exotic species. Continued monitoring efforts will be critical to track changes in the condition of the vegetation communities in AGFO.

We found the riparian area to be more diverse than the upland areas of the park, but there was a high cover of exotic species, particularly pale yellow iris (Iris pseudacorus) and Kentucky bluegrass (Poa pratensis). AGFO is currently examining options for control of the iris and it will be important to consider that the patchy nature of the pale yellow iris and difficult access in the wet areas will present a challenge to control efforts. However, to retain ecological integrity it is important to pursue efforts to reduce the cover of this and other invasive plants. Since this was the first year of monitoring, it is difficult to discern trends in pale yellow iris abundance. Continued monitoring efforts in future years will be critical to track changes in the condition and the effectiveness of management activities in the riparian communities in AGFO.