National Park Service


Date of this Version



Natural Resource Report NPS/NRPC/ARD/NRR—2011/322 / NPS 920/106686, February 2011: 22 pages

Published by the United States Department of the Interior, National Park Service, Natural Resource Program Center, Denver, Colorado

Also available at:

Please cite this publication as:

Sullivan, T. J., T. C. McDonnell, G. T. McPherson, S. D. Mackey, and D. Moore. 2011. Evaluation of the sensitivity of inventory and monitoring national parks to nutrient enrichment effects from atmospheric nitrogen deposition: Northern Great Plains Network (NGPN). Natural Resource Report NPS/NRPC/ARD/NRR—2011/322. National Park Service, Denver, Colorado.


United States government work. Public domain material.


Northern Great Plains Network (NGPN)

National maps of atmospheric N emissions and deposition are provided in Maps A and B as context for subsequent network data presentations. Map A shows county level emissions of total N for the year 2002. Map B shows total N deposition, again for the year 2002.

There are three parks in the Northern Great Plains Network that are larger than 100 square miles: Badlands (BADL), Missouri (MNRR), and Theodore Roosevelt (THRO). In addition, there are 10 other smaller parks.

Total annual N emissions, by county, are shown in Map C for lands in and surrounding the Northern Great Plains Network. County-level emissions within the network ranged from less than 1 ton per square mile to between 5 and 20 tons per square mile. In general, annual county N emissions were less than 5 tons per square mile throughout most of the network. Point source emissions of oxidized (nitrogen oxides, NOx) and reduced (ammonia, NH3) N are shown in Map D. There are several point sources of oxidized N, and one point source of reduced N, within the network that are larger than about 2,000 tons per year. Urban centers within the network and within a 300 mile buffer around the network are shown in Map E. There are relatively few urban centers of any magnitude within this network, although Denver is close to the southwestern network boundary.

Total N deposition in and around the network is shown in Map F. Included in this analysis are both wet and dry forms of N deposition and both the oxidized and reduced N species. Total N deposition within the network ranged from as low as 2 to 5 kg N/ha/yr to the northwest to greater than 10 kg N/ha/yr in the southeast. Most of the I&M parks in this network are located within the lower N deposition zone.

Land cover in and around the network is shown in Map G. The predominant cover types within this network are generally grassland/herbaceous, row crop, and pasture/hay.

Map H shows the distribution within the principal I&M park that occurs in this network (BADL) of the five vegetation types thought to be most responsive to nutrient N enrichment effects (arctic, alpine, grassland and meadow, wetland, and arid and semi-arid). The predominant sensitive vegetation type is grassland and meadow.

Park lands requiring special protection against potential adverse impacts associated with nutrient N enrichment from atmospheric N deposition are shown in Map I. Also shown on Map I are all federal lands designated as wilderness, both lands managed by NPS and also lands managed by other federal agencies. The land designations used to identify this heightened protection included Class I designation under the CAAA and wilderness designation. There is very limited Class I or wilderness area within this network.

Network rankings are given in Figures A through C as the average ranking of the Pollutant Exposure, Ecosystem Sensitivity, and Park Protection metrics, respectively. Figure D shows the overall network Summary Risk ranking. In each figure, the rank for this particular network is highlighted to show its relative position compared with the ranks of the other 31 networks.

The Northern Great Plains Network ranks at the bottom of the third quintile, among networks, in N Pollutant Exposure (Figure A). Nitrogen emissions and N deposition within the network are both moderate. However, the network Ecosystem Sensitivity ranking is higher, within the highest quintile among networks (Figure B). This is mainly because there are some vegetation types in this network that are among those expected to be especially sensitive to nutrient enrichment effects from N deposition. This network ranks in the second lowest quintile in Park Protection, having limited amounts of protected lands (Figure C).

In combination, the network rankings for Pollutant Exposure, Ecosystem Sensitivity, and Park Protection yield an overall Network Risk ranking that is in the middle quintile, slightly below the median among all networks (Figure D). The overall level of concern for nutrient N enrichment effects on I&M parks within this network is considered Moderate.

Similarly, park rankings are given in Figures E through H for the same metrics. In the case of the park rankings, we only show in the figures the parks that are larger than 100 square miles. Relative ranks for all parks, including the smaller parks, are given in Table A and Appendix B. As for the network ranking figures, the park ranking figures highlight those parks that occur in this network to show their relative position compared with parks in the other 31 networks. Note that the rankings shown in Figures E through H reflect the rank of a given park compared with all other parks, irrespective of size.

Park-specific Pollutant Exposure rankings for the three parks in this network that are larger than 100 square miles are shown in Table A and Figure E. MNRR is relatively high, in the second highest quintile, in Pollutant Exposure; BADL and THRO are in the lowest and second lowest quintiles, respectively, among parks. Pollutant Exposure for each of the smaller parks is ranked in the second lowest or middle quintile. Among the larger parks, BADL and THRO are ranked in the second highest quintile, and MNRR in the middle quintile with respect to Ecosystem Sensitivity (Figure F). The smaller parks exhibit a range of Ecosystem Sensitivity rankings, from the lowest quintile (Jewel Cave, JECA; and Mount Rushmore, MORU) to the highest quintile (Agate Fossil Beds, AGFO; Scotts Bluff, SCBL, and Wind Cave, WICA). BADL, THRO, and WICA are in the highest quintile in Park Protection, whereas most other parks, including MNRR, are ranked in the middle quintile for Park Protection (Figure G, Table A).

For the larger parks, the overall Summary Park Risk ranking places THRO and BADL in the highest and second highest quintile, respectively, with MNRR ranked in the middle quintile (Figure H). Among the smaller parks, the Summary Risk ranking is Very High for WICA and Niobrara (NIOB) and Very Low to Moderate for the other small parks.