W. Klooster, C. Herms, D. Herms, J. Cardina

Ohio State University

Gandhi & Herms (2010) Biological Invasions 12(2):389-405

EAB

2002: EAB discovered in SE Michigan

2004-5: Initial study on ash mortality • A. Smith (Herms Lab)

2008-11: Ecological impacts of EAB study • Collaboration between Herms (entomology) and

Cardina (horticulture) Labs

Seven Michigan State or Metroparks • All within Huron River watershed

Three to seven transects per park

Three plots per transect

• Dominant ash (Fraxinus) species • white (F. americana), green (F. pennsylvanica), black (F. nigra)

• Soil moisture classes • xeric, mesic, hydric

W E

N

S

8 m

18 m

Microplot(4-m2)

Subplot (8-m radius)

Main plot (18-m radius)

Transect

(~150 m)

Hemispherical Photographs • 2008 – 2011

• WinSCANOPY

• % Gap Fraction = sky pixels/ total pixels

original

Classified into

“canopy” and “sky”

18-m main plot

Invasive shrubs • Berberis thunbergii

• Elaeagnus umbellata

• Euonymus alatus

• Lonicera spp.

• Ligustrum vulgare

• Rosa multiflora

Native shrubs • Lindera benzoin

• Cornus spp.

• Viburnum spp.

Invasive Trees • Frangula alnus

• Rhamnus cathartica

Native Trees • Fraxinus spp.

• Carpinus caroliniana

Invasive Vines • Celastrus orbiculatus

• Lonicera japonica

Native Vine • Vitis spp.

Highland 83

0 2 4 6 8 10 12 14 16 18 20

0

45

90

135

180

225

270

315 bt1

eu3

eu2

eu1

rc3

rc4

rc2

rc1

rf2rf1

N

E

S

W CTR

Frpe Frpe

Fram

FrpeFrpe

Frpe

Frspp

Frpe

Frpe

Nat & Inv Pairs

Hemi pics

Ash trees

Objectives: • Compare native and invasive growth

• Compare plant growth to % gap fraction

Hypothesis: Growth responses will be related to canopy

gap fraction; however, growth of invasive

species will be generally greater than

growth of native species in similar light

conditions.

Invasive RGR

0 2 4 6 8 10 12 14

Native R

GR

0

2

4

6

8

10

2008 - 2009

2009 - 2010

2008 - 2011 t-value p-value* interpretation

Shrubs 2.59 0.012 nat < inv

Trees 2.91 0.004 nat > inv

Vines 1.22 0.227 No diff

* SAS PROC ttest; RGRs log-transformed to correct for non-normality

Invasive plants are not consistently

outgrowing native plants • Not greatly affected by moisture class or canopy

gap fraction (not shown)

(2010) Minimum Maximum Median

Xeric 1.34 14.35 6.97

Mesic 2.19 19.09 7.13

Hydric 2.13 21.48 7.19

canopy gap fraction

0 5 10 15 20 25

na

tive

gro

wth

(m

3)

0.0

0.5

1.0

1.5

2.0

xeric

mesic

hydric

Growth 2008 - 2011

canopy gap fraction

0 5 10 15 20 25

invasiv

e g

row

th (

m3)

0

2

4

6

8

10

xeric

mesic

hydric

Growth 2008 - 2011

By growth habit: • Shrubs did consistently outgrow tree species

By gap size (small vs. large): • No differences for native or invasive growth

By species • No consistent trends

Good News! (for once) • Ash mortality in southeast MI not causing a

dramatic increase in invasive species’ growth

Range in gap fraction may not be large

enough to affect understory growth • Species adapted to gap-phase regeneration

May be able to focus on sensitive habitats • e.g. disturbed areas, edges

• Prevent initial invasions

Annemarie Smith, Kamal Gandhi, Diane Hartzler

Paul Muelle & staff, Huron-Clinton Metroparks

Glenn Palmgren & staff, MI DNR

Delmy Sánchez, Rina Mejía, Sebastián Sáenz, Sarahi

Nuñez, Lourdes Arrueta, Christian Colindres, Alejandra

Claure, Nathan Yaussy, Eileen Duarte, Samuel Discua,

and Kevin Rice.

Funding: USDA NRI Competitive Grants, Weedy

& Invasive Species Program; OARDC Director’s

Associateship

Questions or Comments?