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Factors Affecting Spotted Knapweed (Centaurea stoebe) Seedling Survival Rates

Published online by Cambridge University Press:  20 January 2017

Anastasia P. Maines
Affiliation:
Department of Ecology and Evolutionary Biology and Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, CO 80309
David G. Knochel
Affiliation:
Department of Ecology and Evolutionary Biology and Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, CO 80309
Timothy R. Seastedt*
Affiliation:
Department of Ecology and Evolutionary Biology and Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, CO 80309
*
Corresponding author's E-mail: [email protected]

Abstract

Predicting site vulnerability to nonnative plant establishment remains a difficult goal. Seedling survival is an important component of population dynamics and can affect the success of control strategies. Field manipulations allow potential causal mechanisms of site vulnerability to be evaluated under realistic environmental conditions. We conducted field studies to determine the effects of plant competition and differing precipitation regimes on spotted knapweed seedling survival. We also examined the effect of herbivory on rosette survival and growth. Seeds were sown into plots with vegetation intact or removed at three sites. Seeds were also sown into plots where plant competition and precipitation were manipulated in a factorial design at a single site. Field studies demonstrated that site accounted for much of the variation in emergence rate, while herbivory and plant competition affected seedling survival rates. We observed a wide range in emergence rates, with site averages ranging from 13.1 to 42.5%. Survival the following year ranged from 0.5 to 9.4% of sown seeds. Rosette survival was significantly higher when herbivores were excluded from plots. Below average precipitation reduced seedling survival; however, even with supplemental water, dry-down of exposed sites resulted in low seedling survival. Of the 8,000 seeds added to plots in one study, by autumn, only eight plants resulted, seven of which survived in watered plots with intact vegetation. Collectively, these results show that seedling survival is a critical phase in spotted knapweed population dynamics and can vary among habitats on the basis of plant competition and precipitation. Furthermore, herbivory affects all stages of the lifecycle from the seedling onward. The observed differences help explain the reported variability in seedling survival in the literature and inform efforts to control spotted knapweed using plant competition and biological controls.

Type
Research
Copyright
Copyright © Weed Science Society of America 

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Footnotes

Current address: Department of Integrative Biology, University of Colorado Denver, Denver, CO 80217

References

Literature Cited

Bates, D., Maechler, M., and Bolker, B. 2012. Lme4: Linear Mixed Effects Models Using S4 Classes. R package version 0.999999-0. Vienna, Austria The Comprehensive R Archive Network, http://CRAN.R-project.org/package=lme4.Google Scholar
Blumenthal, D., Chimner, R. A., Welker, J. M., and Morgan, J. A. 2008. Increased snow facilitates plant invasion in mixedgrass prairie. New Phytol. 179:440448.Google Scholar
Collins, A. R. and Müİller-Schärer, H. 2012. Influence of plant phenostage and ploidy level on oviposition and feeding of two specialist herbivores of spotted knapweed, Centaurea stoebe . Biol. Control 60:148153.Google Scholar
Corn, J. G., Story, J. M., and White, L. J. 2007. Effect of summer drought relief on the impact of the root weevil Cyphocleonus achates on spotted knapweed. Environ. Entomol. 36:858863.Google Scholar
Davis, M. A., Grime, J. P., and Thompson, K. 2000. Fluctuating resources in plant communities: a general theory of invisibility. J. Ecol. 88:528534.Google Scholar
DiTomaso, J. M. 2000. Invasive weeds in rangelands: species, impacts, and management. Weed Sci. 48:255265.Google Scholar
Evans, J. A., Davis, A. S., Raghu, S., Ragavendran, A., Landis, D. A., and Schemske, D. W. 2012. The importance of space, time, and stochasticity to the demography and management of Alliaria petiolata . Ecol. Appl. 22:14971511.Google Scholar
Gayton, D. and Miller, V. 2012. Impact of biological control on two knapweed species in British Columbia. J. Ecosyst. Manag. 13:114.Google Scholar
Harner, M. J., Mummey, D. L., Stanford, J. A., and Rillig, M. C. 2010. Arbuscular mycorrhizal fungi enhance spotted knapweed growth across a riparian chronosequence. Biol. Invasions 12:14811490.Google Scholar
Hejda, M., Pyšek, P., and Jarosik, V. 2009. Impact of invasive plants on the species richness, diversity and composition of invaded communities. J. Ecol. 97:393403.Google Scholar
Jacobs, J. and Sheley, R. 1998. Observation: life history of spotted knapweed. J. Range Manag. 51:665673.Google Scholar
Knochel, D. G., Flagg, C., and Seastedt, T. R. 2010a. Effects of plant competition, seed predation, and nutrient limitation on seedling survivorship of spotted knapweed (Centaurea stoebe). Biol. Invasions 12:37713784.Google Scholar
Knochel, D. G., Monson, N. D., and Seastedt, T. R. 2010b. Additive effects of aboveground and belowground herbivores on the dominance of spotted knapweed (Centaurea stoebe). Oecologia 164:701712.Google Scholar
Knochel, D. G. and Seastedt, T. R. 2009. Sustainable control of spotted knapweed, (Centaurea stoebe). Pages 211225 in Inderjit, , ed. Management of Invasive Weeds. Dordrecht, The Netherlands Springer Science + Business Media B.V. Google Scholar
Knochel, D. G. and Seastedt, T. R. 2010. Reconciling contradictory findings of herbivore impacts on spotted knapweed (Centaurea stoebe) growth and reproduction. Ecol. Appl. 20:19031912.Google Scholar
Maines, A. P., Knochel, D. G., and Seastedt, T. R. 2013. Biological control and precipitation effects on spotted knapweed (Centaurea stoebe): empirical and modeling results. Ecosphere 4:art80. http://dx.doi.org/10.1890/ES13-00094.1 Google Scholar
Maron, J. L. and Marler, M. 2008. Field-based competitive impacts between invaders and natives at varying resource supply. J. Ecol. 96:11871197.Google Scholar
Moore, W., Doyle, C., and Rahman, A. 1989. Economics of controlling Carduus nutans on grazed pasture in New Zealand. Crop Prot. 8:1624.Google Scholar
Newcombe, G., Shipunov, A., Eigenbrode, S. D., Raghavendra, A. K. H., Ding, H., Anderson, C. L., Menijivar, R., Crawford, M., and Schwarzländer, M. 2009. Endophytes influence protection and growth of an invasive plant. Commun. Integr. Biol. 2:2931.Google Scholar
[NOAA] National Oceanic and Atmospheric Administration. 2012. Boulder Monthly Climate Data: Precipitation. Washington, DC National Oceanic and Atmospheric Administration, Earth System Research Laboratory (Physical Sciences Division), http://www.esrl.noaa.gov/psd/boulder/Boulder.mm.precip.html. Accessed April 11, 2012.Google Scholar
Ortega, Y. K., Pearson, D. E., Waller, L., Sturdevant, N. J., and Maron, J. L. 2012. Population-level compensation impedes biological control of an invasive forb and indirect release of a native grass. Ecology 93:783792.Google Scholar
Peters, D. 2000. Climatic variation and simulated patterns in seedling establishment of two dominant grasses at a semi-arid-arid grassland ecotone. J. Veg. Sci. 11:493504.Google Scholar
Pinheiro, J., Bates, D., DebRoy, S., and Sarkar, D. 2012. the R Development Core Team, nlme: Linear and Nonlinear Mixed Effects Models. R package version 3.1-104. Vienna, Austria The Comprehensive R Archive Network, http://cran.r-project.org/web/packages/nlme/index.html. Accessed September 12, 2012.Google Scholar
Pokorny, M., Sheley, R., Zabinski, C., Engel, R., Svejcar, T., and Borkowski, J. 2005. Plant functional group diversity as a mechanism for invasion resistance. Restor. Ecol. 13:448459.Google Scholar
R Core Team. 2012. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL http://www.R-project.org/.Google Scholar
Ruprecht, E., Fenesi, A., and Nijs, I. 2013. Sudden changes in environmental conditions do not increase invasion risk in grassland. Acta Oecol. 47:815.Google Scholar
Schaffner, U., Ridenour, W. M., Wolf, V. C., Bassett, T., Mueller, C., Müİller-Schärer, H., Sutherland, S., Lortie, C. J., and Callaway, R. M. 2011. Plant invasions, generalist herbivores, and novel defense weapons RID A-2783-2012. Ecology 92:829835.Google Scholar
Seastedt, T. R., Knochel, D. G., Garmoe, M., and Shosky, S. A. 2007. Interactions and effects of multiple biological control insects on diffuse and spotted knapweed in the Front Range of Colorado. Biol. Control 42:345354.Google Scholar
Seastedt, T. R. and Pyšek, P. 2011. Mechanisms of plant invasions of North American and European grasslands. Annu. Rev. Ecol. Evol. Syst. 42:133153.Google Scholar
Sheley, R., Jacobs, J., and Carpinelli, M. 1998. Distribution, biology, and management of diffuse knapweed (Centaurea diffusa) and spotted knapweed (Centaurea maculosa). Weed Technol. 12:353362.Google Scholar
Story, J. M., Callan, W., Corn, J. G., and White, L. J. 2006. Decline of spotted knapweed density at two sites in western Montana with large populations of the introduced root weevil, Cyphocleonus achates (Fahraeus). Biol. Control 38:227232.Google Scholar
Story, J. M., Smith, L., Corn, J. G., and White, L. J. 2008. Influence of seed head-attacking biological control agents on spotted knapweed reproductive potential in western Montana over a 30-year period. Environ. Entomol. 37:510519.Google Scholar
Watson, A. and Renney, A. 1974. Biology of Canadian weeds. 6. Centaurea diffusa and Centaurea maculosa. Can. J. Plant Sci. 54:687701.Google Scholar
Wooley, S. C., Smith, B., King, C., Seastedt, T. R., and Knochel, D. G. 2011. The lesser of two weevils: physiological responses of spotted knapweed (Centaurea stoebe) to above- and belowground herbivory by Larinus minutus and Cyphocleonus achates . Biocontrol Sci. Technol. 21:153170.Google Scholar