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The Population Age Structure of Spotted Knapweed (Centaurea maculosa) in Montana

Published online by Cambridge University Press:  12 June 2017

Keith W. Boggs  and
Jim M. Story
Keith W. Boggs
Affiliation:
Western Agric. Res. Ctr., Corvallis, MT 59828
Jim M. Story
Affiliation:
Western Agric. Res. Ctr., Corvallis, MT 59828
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Abstract

Spotted knapweed (Centaurea maculosa Lam. # CENMA) communities were sampled to determine the relationship between age and the number of root rings, and the population age structure. Spotted knapweed taproots add one ring of secondary xylem annually. In 1984, populations were expanding with high densities of individuals in the early age classes, followed by a steady decline in the older classes. In 1985, the majority of the individuals in knapweed populations were in the older age classes. This change in the population age structure was attributed to high mortality among the young age classes due to a drought in 1985. The maximum age class at the sites ranged from 5 to 9 yr. The percentage of plants with floral stalks increased with age to a peak of 75% in the fifth year in 1984 and in the seventh year in 1985.

Keywords

Xylem root ringsroot ringsvegetative rosettesflowering agelife spanage of herbaceous dicotyledonCENMA
Type
Weed Biology and Ecology
Information
Weed Science , Volume 35 , Issue 2 , March 1987 , pp. 194 - 198
Copyright
Copyright © 1987 by the Weed Science Society of America 

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References

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