National Park Service

 

Date of this Version

3-2016

Citation

Natural Resource Report NPS/NGPN/NRR 2016/1145 / NPS 317/131809, March 2016: ix, 38 pages

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

Also available at: http://science.nature.nps.gov/im/units/ngpn/

http://www.nature.nps.gov/publications/nrpm/

Please cite this publication as:

Ashton, I. W. and C. J. Davis. 2016. Plant community composition and structure monitoring for Scotts Bluff National Monument: 2011-2015 summary report. Natural Resource Report NPS/NGPN/NRR—2016/1145. National Park Service, Fort Collins, Colorado.

Comments

United States government work. Public domain material.

Abstract

Executive Summary

The Northern Great Plains Inventory & Monitoring Program and Fire Effects Program have been monitoring vegetation in Scotts Bluff National Monument for over 18 years. While methods have changed slightly, this report summarizes data from over 80 locations from 1998-2015. Below, we list the questions we asked using these data and provide a summarized answer. For more details see the full report. A summary of the current condition (2011-2015) and trends (based on 1988-2015) in plant communities at Scotts Bluff is found in Table ES-1.

1. What is the current status of plant community composition and structure of SCBL grasslands (species richness, cover, and diversity) and how has this changed from 1998 to 2015?

SCBL plays a vital role in protecting and managing some of the last remnants of native mixed-grass prairie in the area. Native plant diversity is at a moderate level compared to other grasslands in the region (Table 10), but diversity is spatially variable. We found no significant trends in native diversity or evenness from 1998 to 2015, but both are threatened by the increasing cover of annual bromes (Figure 9). There has been an increase in annual brome abundance since the 1990s and continued control efforts will be necessary to maintain native prairie within SCBL.

2. How do trends in grassland condition correlate with climate and fire history?

The large variability in SCBL’s climate makes it difficult to discern strong patterns linking temperature, precipitation, and plant community structure (e.g. exotic cover, diversity). Native diversity increased in plots with longer times since burning. There is an adaptive management program planned for 2017 which should provide better guidance to the park on the role of prescribed fire in managing annual bromes.

3. What, if any, rare plants were found in SCBL long-term monitoring plots?

We identified 35 rare plant species in SCBL between 1998 and 2015; eight of these are considered critically imperiled within Nebraska. These plants are found in such low abundance and in such few plots, it is unlikely that plant community monitoring will be able to detect any trends in rare plant abundance. We recommend more targeted surveys of rare plant species of concern be completed when funds are available.

4. Was the SCBL golf course restoration effective at creating a grassland community dominated by native species? The golf course restoration project had mixed results. While some native grasses were established in one of the monitoring plots, establishment was poor in the other. To improve the rates of success and the establishment of native species, future projects should include funds to cover invasive plant control for many years (~10) after planting.

5. What is the composition and structure of riparian forests at SCBL? The riparian forest in SCBL is a fairly diverse assemblage of cottonwood, willow species, green ash, and box elder. Exotic grasses and forbs are common in the understory of the riparian forest, viii and continuing control efforts will be necessary to prevent their spread. The large abundance of green ash and box elder seedlings suggests that a transition to ash-dominated forests is underway.

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