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Individual Highlight

Ecosystem services affected by atmospheric nitrogen seposition

Photo of A coastal sage scrub community from Box Springs Mountain located to the east of the University of California campus in Riverside, California, in which exotic annual grasses are invading the existing plant community resulting in decreased native plant diversity. When the grass becomes dry later in summer, it creates elevated fire danger, resulting in more frequent fire that impedes regeneration of the native species. The end result is vegetation type change and resulting loss of native plant diversity and associated impacts on other organisms that depend on the native plant species. A coastal sage scrub community from Box Springs Mountain located to the east of the University of California campus in Riverside, California, in which exotic annual grasses are invading the existing plant community resulting in decreased native plant diversity. When the grass becomes dry later in summer, it creates elevated fire danger, resulting in more frequent fire that impedes regeneration of the native species. The end result is vegetation type change and resulting loss of native plant diversity and associated impacts on other organisms that depend on the native plant species. Snapshot : Forest Service scientists describe the ecosystem services affected by chronic N deposition in the southern California coastal sage scrub vegetation type.

Principal Investigators(s) :
Fenn, Mark E. 
Research Location : This project and research paper was the result of a national workshop attended by all coauthors that took place at the Santa Monica Mountains National Recreation Area, near Thousand Oaks, California in February 2015.
Research Station : Pacific Southwest Research Station (PSW)
Year : 2017
Highlight ID : 1393

Summary

Coastal sage scrub vegetation in southern California has been converting rapidly to exotic annual grassland over the past 30 to 40 years. This vanishing vegetation type includes plant and insect species of concern under the Endangered Species Act and provides habitat for endangered wildlife, such as the California gnatcatcher, and game animals, such as the California quail and mule deer. Ecological responses to atmospheric nitrogen deposition include increases in exotic invasive annual grasses, loss of native shrub and forb cover, reduced diversity of native annual forbs and arbuscular mycorrhizal fungi, and elevated nitrogen mineralization. The conversion of coastal sage scrub to grassland is likely caused by a combination of elevated nitrogen depositionthat promotes increased grass biomass and frequent fire, which in turn prevents re-establishment of native shrubs and forbs. As native forbs and shrubs disappear, so does the habitat for sensitive species native to this area. The increase in fire frequency affects a number of ecosystem services because the fire itself directly impacts residential property owners, while the landscape changes induced by fire affect the vegetation and wildlife communities that are valued by many beneficiaries, including tourism-dependent businesses, recreational birders, and people who value undisturbed habitats of the Mediterranean California Ecoregion.

Forest Service Partners

External Partners

 
  • National Park Service Resources for the Future U.S. Geological Survey University of Maryland U.S. Environmental Protection Agency