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United States Department of Agriculture

Agricultural Research Service

Title: Increased snow facilitates plant invasion in mixed grass prairie

Authors
item BLUMENTHAL, DANA
item Chimner, Rodney - COLORADO STATE UNIVERSITY
item Welker, Jeffrey - COLORADO STATE UNIVERSITY
item Morgan, Jack

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 17, 2008
Publication Date: July 10, 2008
Citation: Blumenthal, D.M., Chimner, R.A., Welker, J.M., Morgan, J.A. 2008. Increased snow facilitates plant invasion in mixed grass prairie. New Phytologist 179:440-448.

Interpretive Summary: A number of global changes have been shown to interact with plant invasion, but relatively little is known about how altered precipitation may influence invasion. In the North American Mixedgrass Prairie, predicted changes in precipitation could help invasive species, particularly in conjunction with increases in atmospheric nitrogen deposition. We tested this possibility by seeding six invasive species into experimental plots of mixedgrass prairie treated with increased snow, summer irrigation, and/or nitrogen addition. Without added snow, seeded invasive species were rarely observed. With added snow three invasive weeds successfully invaded the plots: diffuse knapweed, baby’s breath, and Dalmatian toadflax. Given added snow, summer irrigation increased the number of baby’s breath plants, and nitrogen addition increased density and mass of Dalmatian toadflax. Increases in biomass were due in part to increases in germination and survival. In contrast to seeded invasive species, resident species did not respond to snow addition. These results suggest that increases in snowfall and variability of snowfall may make it easier for invasive species to succeed in the Mixedgrass Prairie.

Technical Abstract: Although global change is known to influence plant invasion, relatively little is known about interactions between altered precipitation and invasion. In the North American Mixedgrass prairie, invasive species are often abundant in wet and nitrogen rich areas, suggesting that predicted changes in precipitation and nitrogen deposition could exacerbate invasion. We tested this possibility by seeding six invasive species into experimental plots of mixedgrass prairie treated with a factorial combination of increased snow, summer irrigation, and N addition. Without added snow, seeded invasive species were rarely observed. Snow addition increased average above-ground biomass of C. diffusa from 0.026 to 66 g/m2, of G. paniculata from 0.1 to 7.3 g/m2 , and of L. dalmatica from 5 to 101 g/m2. Given added snow, summer irrigation increased the density of G. paniculata, and N-addition increased density and biomass of L. dalmatica. Plant density responses generally mirrored those of plant biomass, indicating that increases in biomass were due in part to increases in recruitment. In contrast to seeded invasive species, resident species did not respond to snow addition. These results suggest that increases in snowfall and variability of snowfall may exacerbate forb invasion in the Mixedgrass Prairie.

Last Modified: 9/10/2014
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