Skip to main content Accessibility help
×
Home

Effects of Seedling Emergence Timing on the Population Dynamics of Horseweed (Conyza canadensis var. canadensis)

  • E. Tozzi (a1) and R. C. Van Acker (a1)

Abstract

Horseweed is a surface-germinating ruderal facultative winter annual. The ruderal nature is a key adaptive characteristic that implicates emergence timing as an important recruitment factor. Experiments were established at three sites in southern Ontario, Canada, from 2009 to 2012 to determine the possible effect of emergence timing of horseweed on plant number, fecundity, and flowering timing. Emerged seedlings were tagged in 0.25-m2 plots in five 2-wk cohorts in the fall and spring of each experimental season. Each plot was followed though until the plants contained within each plot completed their life cycle. Generally, spring-emerging plants were found to flower earlier than fall-emerging plants, but with fall emergence there were higher plant densities in August each season compared with spring emergence. Overall, there was no difference in fecundity between spring- or fall-emerging cohorts, but when cohorts were parsed beyond just spring or fall emergence, we found that plants emerging in early fall and early spring were more fecund and flowered earlier than plants emerging in late fall and late spring. Disturbance (tilled versus not-tilled) significantly affected emergence levels but not emergence timing. The differences in performance among emergence cohorts are likely due to spatial or temporal density-dependent growth advantages. These results show that spring-emerging cohorts of horseweed, especially early spring–emerging cohorts, should not be discounted when considering the weediness of this species, and this may hold true for other facultative winter annual weeds as well.

Copyright

Corresponding author

Corresponding author's E-mail: etozzi@uoguelph.ca

References

Hide All
Brown, SM, Whitwell, T (1988) Influence of tillage on horseweed (Conyza canadensis). Weed Technol 2:269270
Buhler, DD, Owen, MDK (1997) Emergence and survival of Canada fleabane (Conyza canadensis). Weed Sci 45:98101
Cici, SZH, Van Acker, RC (2009) A review of the recruitment biology of winter annual weeds in Canada. Can J Plant Sci 89:575589
Dauer, JT, Mortensen, DA, Humston, R (2008) Controlled experiments to predict horseweed (Conyza canadensis) dispersal distances. Weed Sci 54:484489
Dauer, JT, Mortensen, DA, VanGessel, MJ (2007) Temporal and spatial dynamics of long-distance Conyza canadensis seed dispersal. J Appl Ecol 44:105114
Donohue, K, Dorn, L, Griffith, C, Kim, E, Aguilera, A, Polisetty, CR, Schmitt, J (2005) The evolutionary ecology of seed germination of Arabidopsis thaliana: variable natural selection on germination timing. Evolution 59:758770
Grime, JP (1977) Evidence for the existence of three primary strategies in plants and its relevance to ecological and evolutionary theory. Am Nat 111:11691194
Main, CL, Steckel, LE, Hayes, RM, Mueller, TC (2006) Biotic and abiotic factors influence horseweed emergence. Weed Sci 54:11011105
Nandula, VK, Eubank, TW, Poston, DH, Koger, CH, Reddy, KN (2006) Factors affecting germination of Canada fleabane (Conyza canadensis). Weed Sci 54:898902
Rees, M, Grubb, PJ, Kelly, D (1996) Quantifying the impact of competition and spatial heterogeneity on the structure and dynamics of a four-species guild of winter annuals. Amer. Natural. 1:32
Regehr, DL, Bazzaz, FA (1979) The population dynamics of Erigeron canadensis, a successional winter annual. J Ecol 67:923933
Van Acker, RC, Cici, SZH (2012) Timing of stinkweed and shepherd's-purse recruitment affects biological characteristics of progeny. Can J Plant Sci 92:933936
Weaver, SE (2001) The biology of Canadian weeds. 115. Conyza canadensis . Can J Plant Sci 81:867875

Keywords

Effects of Seedling Emergence Timing on the Population Dynamics of Horseweed (Conyza canadensis var. canadensis)

  • E. Tozzi (a1) and R. C. Van Acker (a1)

Metrics

Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed