Download Testing the Effects of Climate Change on the Competitive Ability of

 Testing the Effects of Climate Change on the Competitive Ability of Two Invasive Grassland Species: Spotted Knapweed and Yellow Toadflax Amber L. Greenall and Lauchlan H. Fraser; Thompson Rivers University; Contact Author Email: [email protected] Invasive species cause extensive ecological and economic damage. The effects of global climate change have the potential to exasperate this problem. In the grasslands of the southern interior of British Columbia, Canada, two invasive species, Spotted Knapweed (Centaurea stoebe) and, Yellow Toadflax (Linaria vulgaris) are of particular concern. The objective of this study was to determine the competitive effect of Spotted Knapweed, and Yellow Toadflax, on two native grasses and on each other under different water and temperature treatments. The two native grasses were Bluebunch Wheatgrass (Pseudoroegneria spicata) a perennial bunchgrass and Canada Bluegrass (Poa compressa) a perennial rhizomatous grass. A greenhouse pair‐wise competition trial was conducted with two temperature and two water treatments. The water and temperature conditions were an increase and a decrease from 30 year historical weather data for June, July, and August. The greenhouse experiment was conducted for 3 months. Competitive effect was determined using the following formula: CE = (P alone ‐ P neighbour)/P alone; where P alone is the mean value of the species grown alone and P neighbour is the mean value of the species grown with its neighbor. Spotted Knapweed had the largest competitive effect on the two native grasses, followed by Yellow Toadflax. Spotted Knapweed and Yellow Toadflax have the potential to adapt to an altered climate and may increase their invasiveness in the future. 2009. 62nd Society for Range Management Annual Meeting. Paper No. 100‐7.