Demography of Meadow and Spotted Knapweed Populations in New York

Milbrath, Lindsey R.; Biazzo, Jeromy

doi:10.1656/045.027.0309

Cited by 3 publications

(22 citation statements)

References 21 publications

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“…These values are consistent with the maximum germination rates of other North American Centaurea species (Joley et al 2003;Nolan and Upadhyaya 1988;Pitcairn et al 2002;Young et al 2005). They are also consistent with estimates of initial seed viability in C. × moncktonii, which are higher than the actual germination rates achieved in field-placed trays (Milbrath and Biazzo 2020). The potential for high germination rates may be adaptive if the multiyear survival of dormant seeds is low (Milbrath and Biazzo 2020).…”

Section: Ecological Implicationssupporting

confidence: 76%

“…They are also consistent with estimates of initial seed viability in C. × moncktonii, which are higher than the actual germination rates achieved in field-placed trays (Milbrath and Biazzo 2020). The potential for high germination rates may be adaptive if the multiyear survival of dormant seeds is low (Milbrath and Biazzo 2020).…”

Section: Ecological Implicationssupporting

confidence: 76%

“…Emerging differences between population gene pools could also be blurred by migration or breeding with individuals elsewhere on the admixture continuum between C. nigra and C. jacea (Lachmuth et al 2019). A prior field-based study reported larger differences in C. × moncktonii germination across the same four populations tested here (Milbrath and Biazzo 2020). Our results are not incompatible with this report, as observed variation between field sites may have a strong environmental component.…”

Section: Hypothesis 3: Seed Germination Rates Will Not Vary Between Pcontrasting

confidence: 50%

“…Mature capitula were collected in August 2015 for Experiments 1-3 from four sites in central and eastern New York State and in August 2016 for Experiment 4 from one of the previous sites in central New York State ( (Milbrath and Biazzo 2020). Capitula were stored in paper bags at room temperature for 4 to 6 wk before cleaning.…”

Section: Seed Collectionmentioning

confidence: 99%

“…One important topic is germination, which is not well understood in either the hybrid or the parental species. Centaurea × moncktonii seeds usually germinate in the spring, but autumn germination can also occur (Milbrath and Biazzo 2020;Winston et al 2012). Autumn germination also occurs in other Centaurea species (Lesica and Shelly 1996;Roché et al 1997;Watson and Renney 1974), including C. jacea (Kahmen and Poschlod 2008).…”

Section: Introductionmentioning

confidence: 99%

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Seed germination ecology of meadow knapweed (Centaurea × moncktonii) populations in New York State, USA

et al. 2020

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The introduced meadow knapweed (Centaurea × moncktonii C.E. Britton), a hybrid of black (Centaurea nigra L.) and brown (Centaurea jacea L.) knapweeds, is increasingly common in pastures, meadows, and waste areas across many U.S. states, including New York. We evaluated the effects of temperature, light, seed stratification, scarification, and population on percent germination in four experiments over 2 yr. Percent germination ranged from 3% to 100% across treatment combinations. Higher temperatures (30:20, 25:15, and sometimes 20:10 C day:night regimes compared with 15:5 C) promoted germination, especially when combined with the stimulatory effect of light (14:10 h L:D compared with continuous darkness). Under the three lowest temperature treatments, light increased percent germination by 15% to 86%. Cold-wet seed stratification also increased germination rates, especially at lower germination temperatures, but was not a prerequisite for germination. Scarification did not increase percent germination. Differences between C. × moncktonii populations were generally less significant than differences between temperature, light, and stratification treatments. Taken together, these results indicate that C. × moncktonii is capable of germinating under a broad range of environments, which may have facilitated this species’ range expansion in recent decades. However, C. × moncktonii also shows evidence of germination polymorphism: some seeds will germinate under suboptimal conditions, while others may remain dormant until the abiotic environment improves. Subtle differences in dormancy mechanisms and their relative frequencies may affect phenological traits like the timing of seedling emergence and ultimately shape the sizes and ranges of C. × moncktonii populations.

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Section: Ecological Implicationssupporting

confidence: 76%

Section: Ecological Implicationssupporting

confidence: 76%

Section: Hypothesis 3: Seed Germination Rates Will Not Vary Between Pcontrasting

confidence: 50%

Section: Seed Collectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seed germination ecology of meadow knapweed (Centaurea × moncktonii) populations in New York State, USA

et al. 2020

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A 20-year evaluation of successes with biological control of spotted knapweed (Centaurea stoebe) in Colorado

Seastedt

Knochel

2021

Biological Control

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Closely related invasive species may be controlled by the same demographic life stages

Molofsky¹,

Thom²,

Keller³

et al. 2023

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Invasive species that are closely related to each other may have similar population dynamics and, therefore, be controlled by targeting similar life stages. We studied two invasive knapweed species, spotted knapweed (Centaurea stoebe subsp. micranthos) and the hybrid meadow knapweed complex (Centaurea × moncktonii) in New York, USA, to determine their individual population growth rates (λ) across several sites over three years. Both knapweed species had growth rates that were greater than 1 (spotted knapweed λ ranged from 1.005–1.440; meadow knapweed λ ranged from 1.541–2.408), but there was high variability between years and sites. One study population of meadow knapweed was composed primarily of individuals of black knapweed ancestry (C. nigra), a species that, while introduced, is not invasive. For this population, the projected dynamics were stable (λ approximately 1). Elasticity analysis showed that the flowering-to-flowering stage contributed the most to population growth rate for six of seven sites and three additional transitions were also influential for four of seven sites of spotted and meadow knapweed: the seedling-to-vegetative stage, vegetative-to-flowering stage and flowering-to-seedling stage. We simulated how increasing vital rates would affect population growth and found that both spotted and meadow knapweed followed the same pattern. The vital rate of established seedlings maturing to flowering plants had the greatest effect on population growth, followed by the survival of new and established seedlings. In all cases, the responses were non-linear, with small initial changes having a large effect. Increases in the vital rates of later stages also tended to have a positive effect on growth rate, but the effects were more modest. Although the sensitivity analysis indicated that early vital rates had the largest effect on population growth, targeting these stages is not practical for management. Rather, reducing older life stage survival or delaying maturation of vegetative individuals would be more effective. The similarity between the population dynamics and how each life stage contributes to population growth provides support that protocols developed for one species should be effective for the other species with the caveat that any biological control agent should be directly tested on the target species before being utilised.

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Demography of Meadow and Spotted Knapweed Populations in New York

Cited by 3 publications

References 21 publications

Seed germination ecology of meadow knapweed (Centaurea × moncktonii) populations in New York State, USA

Seed germination ecology of meadow knapweed (Centaurea × moncktonii) populations in New York State, USA

A 20-year evaluation of successes with biological control of spotted knapweed (Centaurea stoebe) in Colorado

Closely related invasive species may be controlled by the same demographic life stages

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Demography of Meadow and Spotted Knapweed Populations in New York

Cited by 3 publications

References 21 publications

Seed germination ecology of meadow knapweed (Centaurea × moncktonii) populations in New York State, USA

Seed germination ecology of meadow knapweed (Centaurea × moncktonii) populations in New York State, USA

A 20-year evaluation of successes with biological control of spotted knapweed (Centaurea stoebe) in Colorado

﻿Closely related invasive species may be controlled by the same demographic life stages

Contact Info

Product

Resources

About

Closely related invasive species may be controlled by the same demographic life stages