Density and Reproduction of

Yellow Toadflax (Linaria vulgaris)

in the UK and Alaska

Laura Harrison, Dr Stephen Compton & Prof. Bill Kunin

bgyljh@leeds.ac.uk

PhD student

Institute of Integrative and Comparative Biology,

University of Leeds, UK

Worldwide locations

Introduced to New England before 1672

As far North as 65 (Stainforth & Scott 1991)

Higher than 2000 m.

New Zealand

Chile

South Africa

Yellow toadflax location

• http://www.eddmaps.org/alaska/distributio

n/viewmap.cfm?sub=3800&lat=60.716198

&lng=-148.798828&zoom=4&type=m

Alaskan locations

Reproduction

Obligate outcrosser. Pollinated by Bumblebees and Halictid bees

Long flowering period.

Variable phenology.

Low germination.

Seed dormancy?

Clonal growth.Roots over several m

Tap root overwinters.

Possible from root fragments of 1 cm

Relative role in patch maintenance and expansion?

Seed limitation?

Invasion

Alaska invasiveness rank 69(Carlson 2008).

Currently disturbed areas, usually on well drained sites.

Has invaded natural areas and at high elevations (Pauchard et al 2003, Sutton et al 2007).

High genetic diversity in western N America (Ward et al 2009a)

Hybridizes with Dalmation toadflax (Ward et al 2009b)

Seed Dispersal

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 50 100 150 200

Distance (cm)

De

ns

ity

(L

. vu

lga

ris

se

ed

s / c

m 2

)

Field (3)

Field (4)

Field (5)

Field (6)

Hedge (8)

Hedge (15)

Hedge (16)

Hedge (20)

Meadow (10)

Meadow (11)

Meadow (12)

Meadow (13)

ControlHand pulling Fire

GrazingHerbicide

Glyphosate reduced density

in crops (Baig et al 1999)

with bromegrass competition(Carder 1963)

Resistance to wide range of

herbicides. Steve Seefeldt

Little research in

natural areas.

Biological Control?• No native Linaria in N America.

Rhinusa antirrhiniBrachypterolus

pulicarius

Rhinusa neta

Eteobalea serratellaMecinus janthus

Calophasia lunula

My Questions

1) (How) is ramet sexual reproduction affected by density at different spatial scales of con-specific neighbours?

2) (How) are invasive patches different from native patches? Alternative Hypotheses:

a) Denser at all spatial scales

b) Taller and more branched

c) Greater fruit and seed production per ramet

d) Absence of seed feeders

Question 1

(How) is ramet sexual reproduction affected

by density at different spatial scales of

con-specific neighbours?

Question 1

(How) is ramet sexual reproduction affected

by density at different spatial scales of

con-specific neighbours?

• Interesting: How should ecologists

measure density?

• Useful: How much and at what scale

reduce population before Allee effect?

Density varies across spatial scales

• Low impact on

native vegetation

Density varies across spatial scales

• Low impact on

native vegetation

• High impact

where dense

MF 2008

Density varies across spatial scales

MF 2008

Density varies across spatial scales

Individual with high

local scale density but

low medium scale

density

MF 2008

Density varies across spatial scales

Individual with low

local scale density but

high medium scale

density

Question 1

• Generalized linear models

– Finding minimum adequate model.

Ramet seed

or fruit

production

=

Fine scale

neighbour

density+

Medium scale

neighbour

density

Broad scale

neighbour

density+ +

Seed

Predator?

Population + Vegetation

cover

Error+

2) (How) are native patches different

from invasive patches?

Native range comparisons have been done for

Lythrum salicaria (Edwards et al 1998),

Carduus nutans (Jongejans et al 2008),

Lepidium draba (McKenny et al 2007).

Surveys of randomly

chosen populations

from 0.5 degree grid

squares in UK and

Alaska

Plant?

Environment?

Interaction?

Recent toadflax

patch records

around Haines

Climate (August 1961-1990)

UK square Haines

Cloud 68 72 %

Rain 1.7 2.2mm/day

Min temp 11.6 5.4

Max temp 21.5 16.3

Diurnal temp range 9.9 10.9

Wet days 11.6 14.2

Wind 4.6 3.2m/s

Why Haines?

Invasive plants by site in Haines

Lamb & Shephard (2007)

Picture credits Melinda Lamb, Michael Shephard and Wikipedia commons.

What am I measuring at a site?

• Location of every ramet in patch

• Nearby toadflax patches

• Shade

• Bare ground

• Other plant species

• Vegetation height

• Slope

• Soil type

What am I measuring on the plant?

• Height

• Number of flowers & fruit.

• Black & grey seed

in lowest opening fruit.

• Seed feeders

• Evidence of parasites

of seed feeders.

8 UK Populations

AW BP CM HC

IG LP MF WL

8 UK Populations

7 Haines Populations

a) Fine scale

0.1 > 0.2 m radius ring

1BP CM HC IG LP

01

00

20

03

00

40

0

0.1>0.2 m scale

De

nsity m

CK FS MB RV

01

00

20

03

00

40

0

0.1>0.2 m scale

De

nsity m

Non-overlapping notch – “Strong evidence” medians are different. +/-1.58 IQR/sqrt(n) “Roughly similar sample

sizes”

Chambers, J. M., Cleveland, W. S., Kleiner, B. and Tukey, P. A. (1983) Graphical Methods for Data

Analysis. Wadsworth & Brooks/Cole.

UK AK200

a) Fine scale

0.2 > 0.4 m ring

CK FS MB RV

05

01

00

15

02

00

0.2>0.4 m scale

De

nsity m

1BP CM HC IG LP

05

01

00

15

02

00

0.2>0.4 m scale

De

nsity m

UK AK200

a) Fine scale

0.4 > 0.8 m ring

CK FS MB RV

05

01

00

15

02

00

0.4>0.8 m scale

De

nsity m

1BP CM HC IG LP

05

01

00

15

02

00

0.4>0.8 m scale

De

nsity m

UK AK200

a) Medium scale

0.8 < 1.6 m ring

CK FS MB RV

02

04

06

08

01

00

0.8>1.6 m scale

De

nsity m

1BP CM HC IG LP

02

04

06

08

01

00

0.8>1.6 m scale

De

nsity m

UK AK100

a) Medium scale

1.6 > 3.2 m ring

CK FS MB RV

02

04

06

08

01

00

1.6>3.2 m scale

De

nsity m

1BP CM HC IG LP

02

04

06

08

01

00

1.6>3.2 m scale

De

nsity m

UK AK100

a) Medium scale

3.2 > 6.4 m ring

1BP CM HC IG LP

51

01

52

0

3.2>6.4 m scale

De

nsity m

CK FS MB RV

51

01

52

0

3.2>6.4 m scale

De

nsity m

UK AK20

b) UK ramets taller than AK.

1WL 2WL 3WL BP CM HC IG LP MF

05

01

00

15

02

00

Ra

me

t h

eig

ht cm

CK FS MB NK RV TW

05

01

00

15

02

00

Ra

me

t h

eig

ht cm

UK AK

c) Similar Fruit no

Of ramets that flowered, no of fruit in late Sept or Oct.

*Problem of survey timing and varied phenology.

CK FS MB NK

02

04

06

08

01

00

Fre

q fru

it p

er

flo

we

rin

g r

am

et

1BP09 1WL09 CM09 HC09 IG09 MF09

02

04

06

08

01

00

Fre

q fru

it p

er

flo

we

rin

g r

am

et

AKUK

d) R. antirrhini impact in the UK ?

Absent Present

02

04

06

08

01

00

12

0

Bla

ck S

ee

d

Medians not

significantly different at

α = 0.05

(non – parametric test)

Mean Absent is

significantly higher than

mean Present

(parametric)

Conclusions

• Density at fine spatial scales for someinvasive populations is within range of that for native range populations.

• However, at landscape scale the invasive range has more and larger populations.

Helpful to:

Consider the spatial scale.

Compare with the native range.

Thanks to…

Emily Cowles, Pam Randles and Tim Shields at Takshanuk Watershed council;

Gino Graziano, Steve Seefeldt and Melinda Lamb;

Haines Borough and Harbour Master;

Natural Environment Research Council.