Effects of nitrogen addition on the invasive grass Phragmites australis and a native competitor Spartina pectinata

Published source details Rickey M.A. & Anderson R.C. (2004) Effects of nitrogen addition on the invasive grass Phragmites australis and a native competitor Spartina pectinata. Journal of Applied Ecology, 41.
Share Tweet Email

Summary

The common reed Phragmites australis has increased dramatically in distribution and abundance within the USA in the last 100 years. Nitrogen availability has been found to be the most significant environmental constraint on plant growth in sand prairies. When nitrogen is no longer a limiting resource, species previously limited may increase in abundance. This study determined the effect of nitrogen addition on the growth of this invasive species compared with an indigenous competitor species, prairie cordgrass Spartina pectinata.

Study populations: Plants from three Illinois populations of common reed P.australis from Banner Marsh (Peoria County), Lincoln (Logan County) and Herrin (Williamson County) were used in the experiment. Analysis indicated that all of these populations were of the European/Asian haplotype M, and that individuals within each population were highly related.

Experimental design: Twenty Phragmites plants from each of the three populations were collected (between 8 to 15 April 2001) and planted in a garden at Funks Grove (McLean County, Illinois) in 32 L (7-gallon) pots on 21 April 2001 and grown until August 2002. Following a year of growth in the garden, high-nitrogen (45 g N/m²) and low-nitrogen (5 g N/m²) treatments were applied to plants grown from paired rhizome cuttings from each plant. Nitrogen addition was in the form of urea pellets.

Native Spartina pectinata seedlings were purchased from a nursery in Wisconsin. One seedling was planted in each pot as a competitor species with each P.australis. In August 2002, plants were harvested and above- and below-ground biomasses were determined for both species.

Average (± SE) P.australis above- and below-ground biomasses were significantly higher in the high-nitrogen treatment (68.4 ± 2.6 g above- and 39.0 ± 4.5 g below-ground) than the low-nitrogen treatment (37.3 ± 2.0 g and 25.5 ± 4.5 g).

There were no differences in S.pectinata above- and below-ground biomasses between high- (46.8 ± 3.2 g and 71.4 ± 9.6 g) and low- (45.4 ± 3.5 g and 50.3 ± 6.5 g) nitrogen treatments.

The ratio of P.australis to S.pectinata biomass was used to compare their relative response between nitrogen treatments. The average ratio of P.australis to S.pectinata for the high-nitrogen treatment (2.72 ± 0.499) was significantly higher than the low-nitrogen treatment (1.83 ± 0.42), indicating that nitrogen at the higher level was cempetatively beneficial to P.australis at the expense of S.pectinata.

Conclusions: This study supports the hypothesis that common reed P.australis benefits from increased nitrogen, and may be more likely to displace the native prairie cordgrass S.pectinata in nitrogen-rich environments. Control of P.australis may be aided by reducing nutrient input in areas invaded by P.australis.

Note: If using or referring to this published study, please read and quote the original paper. The original paper can be viewed at: http://blackwellpublishing.com/submit.asp?ref=0021-8901