May, Laura , Baldwin, Lyn .
The impact of Spotted Knapweed (C. maculosa) on the grassland community of Lac du Bois Provincial Park.
The mid-elevation grassland community of Lac du Bois Provincial Park in interior BC is becoming increasingly invaded by exotic plant species, including Centaurea maculosa (Spotted Knapweed). Introduced into the USA in the 1920’s C. maculosa has infested over 5 million acres of grassland in North America. The roots of C. maculosa exude the phytotoxin (Â±)-catechin, causing root death in neighboring plants. This phytotoxic chemical is believed to be partly responsible for knapweed’s invasive success. Plant community data and greenhouse experiments on the impact of treating native seeds with the phytotoxin (Â±)-catechin, were used to examine 3 primary questions: 1) Is high abundance of C. maculosa correlated with grassland community compositional change? 2) What native species persist in areas of high knapweed abundance and which are absent? 3) Is persistence or absence correlated with resistance / susceptibility to treatment with (Â±)-catechin? Thirty-eight Modified Whittaker Plots were used to sample the grassland community in areas of low and high knapweed abundance. Seeds from eight native species were treated with three concentrations (0, 2.0 mg/mL and 0.5 mg/mL) of (Â±)-catechin. Radical root growth and percent germination were measured over a 6-week period. The results indicate that C. maculosa abundance is negatively correlated with native plant species abundance and significantly alters plant community composition. Radical root growth and percent germination were significantly negatively affected by treatment with (Â±)-catechin in at least one species (Antennaria umbrinella) that was absent in areas with high knapweed abundance . Other morphological differences such as root reddening and tissue death were noted at high (Â±)-catechin concentrations in several other examined species. Past studies have failed to conclusively link greenhouse results with ‘in field’ plant community patterns, however, this study links field observations of plant community patterns with observed tolerance to a phytotoxin.
Log in to add this item to your schedule
1 - Thompson Rivers University, Biological Sciences, 3465 Overlander dr, Kamloops, BC, V2B 6X4, Canada
2 - Thompson Rivers University, Biological Science, 900 McGill Road, P.O. Box 3010, Kamloops, BC, V2C 5N3, Canada
Modified Whittaker Plot.
Presentation Type: Oral Paper:Papers for Sections
Location: Council Chambers/SUB
Date: Monday, July 28th, 2008
Time: 10:00 AM