United States Forest Service Northern General Technical

 Department of Research Station Report NRS-P-72

 Agriculture

PrOCEEdIngs Of

SYMpOsIuM On AsH 

In NOrtH AMErICa
Abstract

Proceedings of the Symposium on Ash in North America held March 9-11, 2010, in West

Lafayette, IN. Includes 5 papers and 30 abstracts covering topics related to the biology and

ecology of the ash species, ash utilization and management, and emerald ash borer.

The findings and conclusions of each article in this publication are those of the individual

author (s) and do not necessarily represent the views of the U.S. Department of

Agriculture or the Forest Service. All articles were received in digital format and were edited

for uniform type and style. Each author is responsible for the accuracy and content of his

or her paper.

The use of trade, firm, or corporation names in this publication is for the information and 

convenience of the reader. Such use does not constitute an official endorsement or approval 

by the U.S. Department of Agriculture or the Forest Service of any product or service to the 

exclusion of others that may be suitable.

Manuscript received for publication February 2010

Published by: For additional copies:

U.S. FOREST SERVICE U.S. Forest Service

11 CAMPUS BLVD., SUITE 200 Publications Distribution

NEWTOWN SQUARE, PA 19073 359 Main Road

Delaware, OH 43015

FAX: (740) 368-0152

Email: nrspubs@fs.fed.us

August 2010

Visit our homepage at: http://www.nrs.fs.fed.us

Cover Photos: Ash basket, Les Benedict, St. Regis Mohawk Tribe; street trees, Mary Carol 

Hunter, University of Michigan; lumber, Daniel Cassens, Purdue University; seeds, Robert 

Karrfalt, U.S. Forest Service. Photos of basket, street trees, lumber and seeds all used with 

permission.

 
SYMpOsIuM On AsH In NOrtH AMErICa

Proceedings of a Conference held at Purdue University,

West Lafayette, IN

March 9-11, 2010

Edited by:

Charles H. Michler, U.S. Forest Service

Matthew D. Ginzel, Purdue University

Sponsored by:

U.S. Forest Service, State and Private Forestry

Hardwood Tree Improvement and Regeneration Center at Purdue University

Hosted by:

Purdue University, Departments of Entomology

and Forestry and Natural Resources

Published by:

U.S. Forest Service, Northern Research Station

Newtown Square, PA

Steering Committee:

Lenny Farlee, Purdue University Department of Forestry & Natural Resources

Jodie Ellis, Purdue University Department of Entomology

Organizing Committee:

 Dave Burgdorf

 Paul Chaloux

 Kurt Gottschalk

 Bob Karrfalt

John Leif

Noel Schneeberger

Ray Stoner

Tom Ward

Bruce Wight

The Steering Committee wishes to thank Susan Wright and other members of the U.S. Forest Service Northern 

Research Station communications group for technical editing and publishing of these proceedings. The Steering 

Committee also thanks Janis Gosewehr, Department of Forestry & Natural Resources at Purdue University, for 

her contribution.

Judy Loo

Liz Jackson

Charles Michler

Randy Morin

Ron Overton
Review Procedures

Manuscripts for invited oral presentations were assigned to an editor and peer-reviewed by at least two professionals 

unless otherwise indicated. Reviews were returned to authors to revise their manuscripts. Revised manuscripts were 

then submitted to the Northern Research Station, U.S. Forest Service, for final editing and publishing.

The Steering Committee is grateful to the following professionals for providing peer reviews of manuscripts for the 

proceedings:

 Preston Aldrich

 Matt Bumgardner

 Ed Cesa

 Lenny Farlee

 Matthew Ginzel

 Ralph Johnson

 Robert Karrfalt

 Rob Morrissey

 Ron Overton

 Cliff Sadof

 Keith Woeste

 Lisa Worthen
 CONTENTS

ABSTRACTS

The Significance of Black Ash And Splint Basketry to the Akwesasne Kanienkehaka (Mohawk)................................ 1

Les Benedict

Present State, Use, and Perspectives of the Genus Fraxinus in Mexico ........................................................................2

Consuelo Bonfil

Black Ash Silviculture Projects in New York and Maine............................................................................................. 3

Michael R. Bridgen

Wood Characteristics of and Uses for Ash Lumber .....................................................................................................4

Dan Cassens

Ash, the Emerald Ash Borer, and Private Forest Land Management............................................................................5

Tom Crowe

Forest Host Mapping: Implications for Pest Survey and Modeling .............................................................................6

James R. Ellenwood

Comparing Metabolomic Profiles of Asian and North American Ash Species (Genus Fraxinus) to Investigate the 

Basis for Resistance to Emerald Ash Borer..............................................................................................................7

Darla French and Rick Meilan

Understanding and Integrating Native Knowledge to Determine and Identify High Quality Ash Resources..............8

Suzanne Greenlaw, Marla R. Emery, Robin W. Kimmerer, and Michael Bridgen

Impact of Extensive Street Tree Loss on Urban Dwellers’ Sense of Place .....................................................................9

Mary Carol Hunter

The U.S. Forest Service National Seed Laboratory and Fraxinus Ex Situ Genetic Conservation ...............................10

Robert P. Karrfalt

Emerald Ash Borer Aftermath Forests: The Dynamics of Ash Mortality and the Responses of 

Other Plant Species ..............................................................................................................................................11

Kathleen S. Knight, Daniel A. Herms, John Cardina, Robert Long, Joanne Rebbeck, Kamal J.K. Gandhi,

Annemarie Smith, Wendy S. Klooster, Catherine P. Herms, and Alejandro A. Royo

Cost of Potential Emerald Ash Borer Damage in U.S. Communities, 2009-2019.....................................................12

Kent F. Kovacs , Robert G. Haight, Andrew M. Liebhold, Deborah G. McCullough, Rodrigo J. Mercader, and Nathan W. Siegert

National Insect and Disease Risk Map (NIDRM)—Cutting Edge Software for Rapid Insect and Disease Risk 

Model Development.............................................................................................................................................13

Frank J. Krist, Jr.

Silvics and Silviculture of Ash in Mixed Hardwood Forests of the Southern Bottomlands and Loessial Hills...........14

Steve Meadows

Trends in Domestic and International Markets for Ash Logs and Lumber................................................................15

Dan Meyer
The Distribution of Ash in North America................................................................................................................. 16

Randall S. Morin

Large-scale Reintroduction of Ash..............................................................................................................................17

Ronald Overton

Genetic Transformation of Fraxinus spp. for Resistance to the Emerald Ash Borer ....................................................18

Paula M. Pijut, Rochelle R. Beasley, and Kaitlin J. Palla

Climate Change Poses Additional Threat to the Future of Ash Resources in the

Eastern United States............................................................................................................................................. 20

Anantha Prasad, Louis Iverson, Stephen Matthews, and Matthew Peters

Ashes to Ashes: Large Fraxinus Germplasm Collections and their Fates .....................................................................21

Kim C. Steiner and Paul Lupo

Observations on Ashes Used in North America and Suggested Ash Replacements......................................................22

T. Davis Sydnor

Exploring the Molecular and Biochemical Basis of Ash Resistance to Emerald Ash Borer..........................................23

Justin G.A. Whitehill, Daniel A. Herms, and Pierluigi Bonello

Building a Comprehensive Collection of Ash Germplasm ..........................................................................................25

Mark P. Widrlechner

PAPERS

Strike One! Aluminum. Strike Two! Maple. Will EAB be Strike Three?...................................................................... 26

Brian Boltz and Jan Wiedenbeck

Patterns Among the Ashes: Exploring the Relationship between Landscape Pattern

and the Emerald Ash Borer.................................................................................................................................... 32

Susan J. Crocker, Dacia M. Meneguzzo, and Greg C. Liknes

Overcoming Obstacles to Interspecies Hybridization of Ash ......................................................................................41

Jennifer L. Koch, David W. Carey, Mary E. Mason, and M. Nurul Islam-Faridi

Population-level Variation of Fraxinus americana L. is Influenced by Climate Differences

across the Native Range ......................................................................................................................................... 45

Renée Marchin

Ex Situ Conservation of Ash Seed in Canada ..............................................................................................................54

Dale Simpson

POSTER ABSTRACTS

Adventitious Shoot Regeneration of Fraxinus nigra Marsh........................................................................................ 58

Rochelle R. Beasley and Paula M. Pijut

Estimating Outside-bark Stem Volume to Any Top Diameter for Ash in Wisconsin .................................................. 59

Paul F. Doruska and Timothy D. Hart

Survey for Tolerance to Emerald Ash Borer within North American Ash Species....................................................... 60

Jennifer L. Koch, Mary E. Mason, David W. Carey, Kathleen Knight, Therese Poland, and Daniel A. Herms
Climatic Controls on Emerald Ash Borer Dispersal.................................................................................................. 61

Greg C. Liknes, Susan J. Crocker, and Dacia M. Meneguzzo

A Technique for Mapping Urban Ash Trees Using Object-based Image Analysis.......................................................62

Dacia M. Meneguzzo, Susan J. Crocker, and Greg C. Liknes

Adventitious Shoot Regeneration and Rooting of Fraxinus americana.....................................................................63

Kaitlin J. Palla and Paula M. Pijut

Response of Young Ash Trees to Cultural Treatments not all Positive.......................................................................64

Felix Ponder, Jr.

2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 1

THE sIgnIfICanCE Of blaCK asH and splInt basKEtrY 

tO tHE AKwEsasnE KanIEnKEHaKa (MOHawK)

Les Benedict

 St. Regis Mohawk Tribe Environment Division.

To contact, call (518) 358-5937

or email at les.benedict@srmt-nsn.gov.

Black ash basketry is one of the many ways in which the 

Akwesasne Kanienkehaka identify with and express their 

rich heritage. The Kanienkehaka have faced multiple 

cultural and social challenges since their first contact 

with European society. These challenges have sometimes 

had negative social, psychological, lifestyle, and health 

consequences for the Kanienkehaka.

Black ash basketry directly connects the Kanienkehaka 

to their past and is linked to language and ceremonies. 

For many, it expresses their cultural identity. Black ash 

basketry is considered a form of medicine, providing 

healing through the Kanienkehaka’s expression of the 

natural world and of their cultural heritage.

Without black ash, the Kanienkehaka will lose a resource 

that defines their culture, provides a link to their heritage, 

and serves as an important medicine. 
2 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

PrEsEnt statE, usE, and pErspECtIVEs Of

tHE gEnus FRAXINUS In MEXICO

Consuelo Bonfil

Departamento de Ecología y Recursos Naturales, Facultad de 

Ciencias,Universidad Nacional Autónoma de México,

Ciudad Universitaria, México D. F. 04510.

To contact, call (5255) 5622-4912 or email at cbonfil@gmail.com.

The genus Fraxinus is found in the main mountain areas 

of Mexico and, like many other Holarctic genera, reaches 

its southern limit in Central America. The Comisión 

Nacional para el Estudio de la Biodiversidad reports 21 

species of Fraxinus, but a detailed assessment of their 

status still needs to be done. If synonymous names are 

removed, there are probably 13 species and one variety 

of Fraxinus in Mexico: F. anomalla, F. berlandieriana, F. 

cuspidata, F. dipetala, F. dubia, F. gooddingii, F. gregii, F. 

papillosa, F. pringlei, F. purpusii (var. purpusii and var. 

vellerea), F. rufescens, F. udhei, and F. velutina. The

presence of two of them (F. anomalla and F. dipetala) in 

Mexico still needs to be confirmed, and the status of F. 

pringlei is doubtful and needs revision.

Many of the species found in northern Mexico are 

shared with the southwestern United States (F. anomalla, 

F. berlanderiana, F. dipetala, F. gooddingii, F. gregii, F. 

papillosa, and F. velutina). Three other species from 

central/south Mexico are also in Guatemala or even 

Honduras (F. dubia, F. purpusii, and F. uhdei). Only F. 

rufescens (and perhaps F. pringlei) is endemic to Mexico, 

where it grows in the central states.

Most species of Fraxinus are found in protected humid 

slopes in temperate (Quercus-Pinus) forests and as part 

of riparian vegetation, but species such as F. uhdei

are also elements of moist forests. Still others (such 

as F. rufescens) are found in the transition between 

temperate and tropical deciduous forests and even in 

xeric shrublands. F. uhdei is the only species that has a 

widespread distribution in Mexico, and therefore it is 

the only one that has been relatively well studied. It is a 

common urban tree, very abundant in Mexico City and 

Guadalajara, where it shows a weedy behavior. Because 

of its fast growth and high survival rate, it is a commonly 

cultivated species for reforestation programs. Ecological 

and forestry studies of other species present in Mexico 

still need to be done.

The main pest of Fraxinus in Mexico is Hylesinus aztecus

Wood (Coleoptera, Curculionidae), a bark beetle, which 

has caused large declines in urban ashes. The emerald 

ash borer (Agrilus planipennis) has not been reported 

in Mexico, but its rapid spread through the United 

States makes it very probable that it will be able to reach 

Mexico in the near future.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 3

BlaCK asH sIlVICulturE prOJECts

In NEw YOrK and MaInE

Michael R. Bridgen

Professor, SUNY College of Environmental Science and Forestry, 

Ranger School, 257 Ranger School Rd.,Wanakena, NY 13695.

To contact, call (315) 848-2566 or email at bridgen@esf.edu.

Silvicultural activities on stands of black ash (Fraxinus 

nigra Marsh.) are limited by the quality of the site, which 

is usually poorly drained, and by the low commercial 

value of slow-growing, small-diameter trees. Silviculture 

recommendations for black ash focus on its role as the 

primary raw material in the manufacturing of handcrafted baskets.

This paper reports the success of artificially establishing 

two black ash stands in northern New York using planted 

seedlings. Gas exchange and stomatal conductance of 

planted seedlings were studied to determine the impact 

of site quality on seedling physiology. Results of thinning 

projects in northern New York and Maine are also 

reported.

Planted seedlings should be protected with tube shelters, 

both to minimize deer browsing and to escape weed 

competition with increased early height growth. These 

shelters, however, decrease seedling photosynthesis 

rates to about one-third that of seedlings growing in 

full sunlight. Stomatal conductance rates are similarly 

decreased.

A black ash stand in the Brasher Falls State Forest in 

New York was thinned to three residual densities, using 

a randomized block design. Four years after treatment, 

stand density showed no effect on either crop tree 

diameter growth or understory seedling development.

A black ash stand near Presque Isle, ME, was cruised and 

marked for thinning using stocking charts developed 

by Erdmann and others (1987). The simulator models, 

NE Twigs, SILVAH, and FIBER, were used to predict 

future growth rates. NE Twigs and SILVAH yielded 

similar results, but FIBER, which is more applicable 

to spruce/fir forests and uneven-aged stands, predicted 

much higher annual increment rates. Simulation of the 

plots thinned to 50-, 75-, and 100-percent crown cover, 

as opposed to the control plot (no cutting), showed 

consistently increasing volume production rates and 

diameter growth for black ash over the 20-year simulated 

period.
4 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

WOOd CHaraCtErIstICs Of and

usEs fOr asH luMbEr

Dan Cassens

Purdue University, Department of Forestry and Natural Resources,

175 Marsteller St., West Lafayette, IN 47907-2033.

To contact, call (765) 434-3644 or email at dcassens@purdue.edu.

Ash is one of about 16 commercial hardwood lumber 

groups and accounts for about 5 percent of total 

hardwood lumber production in the eastern hardwood 

region. Ash wood has several interesting characteristics 

and applications. This presentation will briefly review 

the lumber characteristics of the different species. Then 

the quality/color characteristics, physical properties, 

mechanical properties, grading and pricing, log and 

lumber weights, and important applications will be 

outlined. Numerous photographs illustrating details will 

be presented.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 5

AsH, tHE EMErald asH bOrEr, and prIVatE

fOrEst land ManagEMEnt

Tom Crowe

Crowe Forest Management, Leo, IN 46765.

To contact, email at toms.trees@hotmail.com.

Forest management through emerald ash borer (EAB) 

will be a dynamic process that will change based on the 

best information available at the time. Management 

decisions will depend on the anticipated time of EAB 

arrival; the diameter and number of ash present in the 

forest stand; the diameter and number of other desirable 

and undesirable species present in the stand (especially 

exotic invasives); the current and anticipated future ash 

markets; and, most importantly, the long-term economic 

and biological impact that the loss of ash will have on the 

residual stand in terms of future stocking level and natural 

regeneration.

As a consulting forester for more than 25 years in 

northeastern Indiana, I was first introduced to EAB in 

a woods near Quincy, MI, in 2003. It was obvious how 

devastating this insect would be. In addition, because 

EAB is difficult to identify (initially), management will 

need to be proactive. In early 2004, EAB was found in my 

primary work area. Based on very strong ash markets at 

that time and the potential for heavy mortality before the 

next scheduled harvests (typically 10-year intervals; most 

woods are <20 acres in size), my recommendation was to 

harvest all merchantable ash when conducting a harvest 

for a landowner. Financially, this approach worked well 

for about 2 years. However, ash regeneration thrives on 

disturbance; because of more aggressive harvesting, ash 

was more dominant in the understory than ever.

In late 2005, EAB was found in Huntington County 

and, soon after, the price plummeted, at least locally. In 

addition, new locations of EAB were being identified and 

subsequent quarantines made it difficult to market a large 

amount of ash, particularly during the summer (generally 

a desirable time to harvest ash due to low moisture 

content). In quarantined areas, the decision at that time 

was to include as much ash as possible and still attract a 

competitive price. In areas that were not quarantined, I 

continued to sell all merchantable ash.

I have serious concerns that ash (now undesirable) and 

other undesirable species will further dominate stand 

regeneration. Observations over the years have shown 

that many older timber harvests failed to regenerate 

acceptable species (even following timber stand 

improvement and completing openings). Observations 

also indicate that recent harvest openings include a high 

percentage of undesirable seedlings, such as ash, elm 

(vulnerable to Dutch elm disease), ironwood, blue beech, 

buckeye, and box elder, due to the abundant seed bank 

present immediately prior to the timber harvest. The 

presence of any invasive species only compounds that 

problem. Attempts to attain better natural regeneration 

have led to my current management philosophy: to 

increase management of the seed bank within the forest 

stand. My philosophy applies to management of any 

stand, with or without EAB. The goal is to minimize 

the amount of undesirable regeneration to improve 

the regeneration of desirable species and the longterm economic viability of the woodlands. Understory 

treatments (timber stand improvement) are done to 

eliminate or reduce the number of less desirable seed 

prior to a timber harvest. For example, treatment of any 

exotic invasives is mandatory. Harvests are delayed until 

EAB results in moderate to heavy mortality, usually 2 to 

5 years, with the accompanying loss of seed bank.

EAB is now observed almost daily in my work area. 

The price of ash is now relatively stable, although 

considerably lower than 4 or 5 years ago. It is also 

anticipated that the current price is not likely to improve 

significantly. The current price appears to be relatively 

unaffected, except for the best trees, even when the trees 

have been dead for less than a year or two. The current 

timber markets in my area are primarily handles and 

pallets with some grade and sucker-rod.

As a general rule, each woods is treated on a case-bycase basis. In woods that have a considerable amount of 

high quality ash or a very small component of ash, I still 

recommend proceeding with the timber harvest as soon 

as possible, prior to mortality. Regarding tree planting, 

ash has not been a component since 2005.
6 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

FOrEst HOst MappIng: IMplICatIOns

fOr pEst surVEY and MOdElIng

James R. Ellenwood

Remote Sensing Program Manager, Forest Health Technology

Enterprise Team, U.S. Forest Service, 2150 Centre Ave.,

Bldg. A, Suite 331, Fort Collins, CO 80526.

To contact, call (970) 223-4950) or email at jellenwood@fs.fed.us.

The Forest Health Technology Enterprise Team has 

developed forest-health risk maps for the past decade. 

Each subsequent rendition has improved upon previous 

renditions by acquiring and developing better data. 

Part of the improvement has focused upon host data 

of individual tree species. Knowledge of a host species’ 

extent and density is critical to the success of an 

integrated pest management endeavor. The purpose of 

this presentation is to highlight developments pertaining 

to the different ash species modeled for the forest risk 

mapping project. The developed products can be used by 

land managers, policymakers, and resource specialists for 

strategic planning, monitoring, and resource allocation 

for a given forest-health concern. A scale assessment 

of alternative data for host mapping will also be 

demonstrated.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 7

COMparIng MEtabOlOMIC prOfIlEs Of AsIan

and NOrtH AMErICan asH spECIEs (gEnus

FRAXINUS) tO InVEstIgatE tHE basIs fOr

rEsIstanCE tO EMErald asH bOrEr

Darla French and Rick Meilan

Department of Forestry and Natural Resources, Purdue University.

DF is corresponding author; to contact, email at dfrench@purdue.edu.

At present, North American ash (Fraxinus spp.) 

are under attack by the emerald ash borer (Agrilus 

planipennis Fairmaire; EAB), an invasive species native 

to eastern Asia. Interestingly, Asian ash species are 

comparatively resistant to this phloem-feeding insect. 

Most researchers currently working on EAB are focused 

on improving detection, monitoring, biological control, 

and eradication methods in an attempt to protect 

our population of North American ashes against the 

advancing infestation front. To date, however, little 

work has been done to determine why our North 

American ash species seem to be so markedly different 

from the Asian ash species in EAB susceptibility. If we 

can determine that the difference is due to metabolites 

produced by one species but not by another, we might 

be able to exploit those differences to engineer ash trees 

with elevated resistance to EAB. One objective of this 

research is to compare the metabolomic profiles of North 

American and Asian ash species. Seedlings of susceptible 

North American ash species (white, green, black) are 

being grown in a greenhouse alongside resistant Asian 

ash species (Chinese, Manchurian), plus two European 

ash species that have unknown resistance. Seedlings will 

be challenged with methyl jasmonate root drenches to 

simulate insect feeding; some will be left untreated to 

serve as controls. Phloem, root, and leaf samples will 

be harvested from each seedling at various times and 

subjected to high performance liquid chromatographymass spectrometry and gas chromatography-mass 

spectrometry analyses. Additionally, high-throughput 

sequencing is being used to compare the transcriptomic 

profiles of infested and uninfested green ash trees 

in an attempt to determine genes that are up- or 

down-regulated in response to EAB feeding. Once 

candidate genes have been identified, a set of molecular 

experiments will be conducted to investigate the 

function of various genes in the jasmonate pathway in 

tissue harvested from these same trees.
8 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

UndErstandIng and IntEgratIng NatIVE KnOwlEdgE 

tO dEtErMInE and IdEntIfY HIgH

QualItY asH rEsOurCEs

Suzanne Greenlaw, Marla R. Emery,

Robin W. Kimmerer, and Michael Bridgen

State University of New York College of Environmental Science and Forestry

 (SG, RWK, MB), U.S. Forest Service, Northern Research Station (MRE).

SG is corresponding author;

to contact, email at Suzanne_Greenlaw@hotmail.com.

Black ash (Fraxinus nigra) is spiritually, economically, 

and culturally connected to Native American tribes 

throughout its range. Considered a cultural keystone 

species, black ash can be pounded and split along 

its growth rings to produce exceptionally strong 

and pliable strips to weave into baskets. Black ash 

harvesters and basketmakers (subsequently referred 

to as “experts”) report increasing difficulty obtaining 

basket-grade wood. Emerald ash borer will contribute 

to this problem. We report here on a study that seeks 

to address this concern by documenting the traditional 

ecological knowledge (TEK) of harvesting basketgrade black ash. We will attempt to combine TEK 

with U.S. Forest Service Forest Inventory and Analysis 

(FIA) data to model tree and site characteristics 

associated with basket-grade wood and estimate the 

current supply and spatial distribution of basket-grade 

trees. Ongoing consultation with tribes and Native 

American experts is a central component of the study 

design.

During the summer of 2009, we conducted interviews 

with experts in the Wabanaki tribes of Maine and New 

Brunswick, Canada. Interviewees were asked about the 

wood characteristics needed for basketmaking and the 

environmental cues used to identify sites and individual 

trees, as well as any observations of changes in quality, 

supply, and spatial distribution of basket-grade trees. 

Preliminary results suggest that site characteristics, 

genotype, and life history interact to determine whether 

an individual tree will be basket-grade quality. We hope 

to consult with experts in the Mohawk Nation during the 

spring of 2010. Interview findings will then be validated 

through fieldwork, in preparation for identifying and 

analyzing relevant variables in the FIA data set. Results 

will contribute to the identification of strategies for 

management and/or restoration.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 9

IMpaCt Of EXtEnsIVE strEEt trEE

lOss On urban dwEllErs’ sEnsE Of plaCE

Mary Carol Hunter

University of Michigan, School of Natural Resources and Environment.

 To contact, call (734) 615-1413 or email at mchunter@umich.edu.

I took advantage of a natural experiment that occurred 

in southeast Michigan when an exotic insect pest 

caused the death and removal of more than 10,000 

urban street trees within several years. Where dead 

street trees were clustered, the ecological and aesthetic 

integrity of neighborhoods changed dramatically, and 

the restorative benefits provided by these trees were lost. 

This paper will consider the impact of street tree loss on 

a community’s sense of place and resultant interest in 

environmental stewardship. 

In 2007, 1,300 households were selected to receive 

a four-page survey about their reaction to the loss of 

street trees and their attitudes toward urban nature. 

Households were selected based on physical, social, and 

economic criteria and the property’s location on a street 

with either great (>70 percent) or limited (<30 percent) 

street tree loss. Forty-three percent of the sample 

population responded.

The results are described in relation to these categorical 

topics: sense of place (a psychological measure 

of security, attachment, contentment), degree of 

engagement in urban nature as experienced from home 

and neighborhood, degree of engagement or interest 

in helping the ecological recovery process, likelihood 

of physical participation in habitat creation (spending 

time, getting dirty), intellectual participation (using 

educational materials that may alter perception and 

action), economic participation (spending money on tree 

installation and habitat improvement), and community 

participation (planting new trees or enhancing habitat in 

the neighborhood and nearby park). Eighty-one percent 

of the survey participants said that street trees contribute 

to a sense of pride in the neighborhood; 68 percent said 

they believe that street trees enhance the sense of wellbeing. Of those who lost street trees in front of their 

home, 13 percent use their front porch less, 17 percent 

close the blinds or drapes more often, 11 percent spend 

more time gardening, and 56 percent report getting less 

enjoyment from driving down their home street.

The results of this scientific inquiry are being used 

to inform design options and suggest management 

strategies for urban nature in residential areas ranging 

along a continuum of environmental stewardship. 

This guidance is being shared on the Web site http://

natureforcities.snre.umich.edu/, developed as an 

outreach component of this research.
10 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

THE U.S. FOrEst SErVICE NatIOnal SEEd LabOratOrY

and FRAXINUS EX sItu gEnEtIC COnsErVatIOn

Robert P. Karrfalt

Director, U.S. Forest Service, National Seed Laboratory, Wright Forestry Center,

1007 N 725 W, West Lafayette, IN 47906.

To contact, email at rkarrfalt@fs.fed.us.

The U.S. Forest Service’s National Seed Laboratory 

(NSL) has as part of its mission the conservation of 

genetic resources for the Forest Service and Forest 

Service cooperators through long-term seed storage. 

The Forest Service recognizes ash as one of four priority 

species for genetic conservation. The NSL is in charge 

of the Forest Service ash preservation plan. NSL 

cooperates with the Natural Resources Conservation 

Service (NRCS) Rose Lake Plant Materials Center and 

the Agricultural Research Service North Central Plant 

Introduction Station. The main activities of the NSL are 

described as follows:

Planning – Collections were principally made in areas 

where emerald ash borer (EAB) was active or areas near 

active EAB infestations. Some collections have also been 

made to provide a wider geographic spread of the genetic 

material for research. As a general rule of thumb, seeds 

are collected from 50 individual mother trees evenly 

spread over an Omernik level III ecoregion. Every ash 

species existing in an ecoregion is collected. In 2010 

Geographic Information Systems (GIS) mapping will 

start.

Cooperative Collections – The NSL staff was able to make 

some collections directly, but many more seeds were 

gathered by cooperators. Many persons are in the right 

place to collect seeds, and the program tries to encourage 

collection by providing training and supplies. It was 

found that without training, volunteers had difficulty in 

making any collections at all. Cooperators are contacted 

through a variety of avenues. Seeds collected through 

the NRCS Rose Lake Plant Materials Center are tested, 

stored, and distributed by the NSL.

Documenting collections –To the fullest extent possible, 

the following information is taken as a minimum 

on every seed tree: Name of seed collector, date 

of collection, GIS coordinates (or other locator 

information), a 6- to 9-inch twig sample with a healthy 

terminal bud, a leaf, and a photo of both the bark and 

the whole tree or stand in which it was growing.

Handling seed collections – All seed lots are given a 

cold treatment for at least 2 weeks to force the exit of 

seed weevils. This procedure makes removal of weevildamaged seeds easier in the seed-cleaning equipment. 

Then the seed lots are dried thoroughly with air at 

30-percent relative humidity, and empty seeds and trash 

are removed. X-ray and excised embryo tests are done 

to ensure that only seed lots of acceptable viability are 

placed in freezer storage. A security backup sample of 

each lot is placed at the National Center for Genetic 

Resource Preservation in Fort Collins, CO. All seed lots 

are listed in the Genetic Resource Information Network 

and made available for research and breeding projects 

when researchers contact the NSL directly.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 11

EMErald asH bOrEr aftErMatH fOrEsts: THE dYnaMICs Of asH 

MOrtalItY and tHE rEspOnsEs Of OtHEr plant spECIEs

Kathleen S. Knight, Daniel A. Herms, John Cardina, Robert Long, Joanne Rebbeck, 

Kamal J.K. Gandhi, Annemarie Smith, Wendy S. Klooster,

Catherine P. Herms, and Alejandro A. Royo

U.S. Forest Service (KSK, RL, JR, AAR), Northern Research Station;

Department of Entomology (DAH, KJKG, AS, AAR), The Ohio State University,

Ohio Agricultural Research and Development Center;

Department of Horticulture and Crop Science (JC, WSK, CPH),

The Ohio State University, Ohio Agricultural Research and Development Center

Current address: Warnell School of Forestry and Natural Resources (KJKG),

University of Georgia; Ohio Department of Natural Resources, Division of Forestry (AS).

KSK is corresponding author; to contact, call (740) 368-0063

or email at ksknight@fs.fed.us.

The effects of emerald ash borer (EAB) (Agrilus 

planipennis) on forest ecosystems are being studied 

through a collaborative research program involving 

the U.S. Forest Service’s Northern Research Station 

and The Ohio State University. We are monitoring the 

decline and mortality of >4,500 ash trees and saplings, 

EAB population density, changes in understory light 

availability, responses of both native and invasive plant 

species, changes in species composition and forest 

structure, and effects on other organisms and ecosystem 

processes in more than 250 monitoring plots (and subsets 

thereof) in forests in Ohio, Michigan, and Pennsylvania 

along a gradient of EAB-infestation duration. The plots 

are located in forest stands representing different ages and 

habitat types to include all five ash tree species native to 

the region (Fraxinus americana, F. pennsylvanica, F. nigra, 

F. profunda, and F. quadrangulata). Yearly monitoring 

began in 2004 and is continuing.

Our results suggest a dismal future for ash in these 

ecosystems. Pre-EAB patterns of ash canopy health are 

functions of landscape position and nutrient availability. 

With the arrival of EAB, however, ash mortality in all 

areas reaches nearly 100 percent--regardless of initial 

ash density, size, habitat, or diversity. A forest stand 

can progress from nearly all healthy trees to nearly all 

dead ash trees within 6 years. EAB populations increase 

rapidly, peak, and then decline as the infestation 

progresses through the landscape. They then persist 

at low densities and kill small ash saplings as they 

reach susceptible size (3-cm diameter at breast height). 

Invasive plant species are present in these ecosystems 

and have the potential to increase as canopy gaps open, 

and distributions of both invasive plants and ash species 

depend on land use history and habitat. Indirect impacts 

of EAB on other organisms are likely. 
12 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

COst Of pOtEntIal EMErald asH bOrEr daMagE

In U.S. COMMunItIEs, 2009-2019

Kent F. Kovacs, Robert G. Haight, Andrew M. Liebhold,

Deborah G. McCullough, Rodrigo J. Mercader, and Nathan W. Siegert

Department of Resource Economics (KFK), University of Nevada, Reno, Reno, NV 89557;

U.S. Forest Service, Northern Research Station (RGH), 1992 Folwell Ave., St. Paul, MN 

55108; U.S. Forest Service, Northern Research Station (AML),

180 Canfield St., Morgantown, WV 26505

Departments of Entomology and Forestry (DGM), Michigan State University,

East Lansing, MI 48824; Department of Entomology (RJM, NWS),

Michigan State University, East Lansing, MI 48824.

RGH is corresponding author;

to contact, call (651) 649-5178 or email at rhaight@fs.fed.us

Emerald ash borer (EAB; Agrilus planipennis Fairmaire), 

a phloem-feeding beetle native to Asia, was discovered 

near Detroit, MI, and Windsor, ON, in 2002. As of 

March 2009, isolated populations of EAB have been 

detected in nine additional states and Quebec. EAB 

is a highly invasive forest pest that has the potential 

to spread and kill native ash trees (Fraxinus spp.) 

throughout the United States. There is little scientific 

literature on the number of ash trees in developed areas, 

the cost of treating trees to prevent infestation, and 

the cost of removing trees in response to infestation. 

We estimate the discounted cost of ash treatment 

and removal on developed land defined by the 2001 

National Land Cover Database within communities 

defined by the U.S. Census in a 25-state study area 

centered on Detroit. We used 100 simulations of 

EAB spread and infestation over the next decade 

(2009-2019).

Results indicate more than 37 million ash trees occur 

on developed land in communities. The simulations 

predict an expanding EAB infestation that will likely 

encompass most of the 25 states and warrant treatment 

or removal of more than 17 million ash trees. The mean 

discounted cost of treating and removing those trees is 

$9.9 billion. States with the highest proportions of ash 

trees treated or removed (>90 percent) are those known 

to have established outlier populations present in 2009 

that are predicted to expand and quickly spread across 

their entirety (West Virginia, Maryland, Delaware, 

Wisconsin, and Vermont).

Expanding the land base to include developed land 

outside, as well as inside, communities nearly doubles 

the estimates of the number of ash trees treated or 

removed and the associated cost. The estimates of 

discounted cost suggest that a substantial investment 

might be efficiently spent to slow the expansion of 

isolated EAB infestations and postpone the ultimate 

costs of ash treatment and removal.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 13

NatIOnal InsECt and DIsEasE RIsK Map (NIDRM)

—CuttIng EdgE sOftwarE fOr rapId InsECt and

dIsEasE rIsK MOdEl dEVElOpMEnt

Frank J. Krist, Jr.

U.S. Forest Service, Forest Health Technology Enterprise Team,

2150 Centre Ave., Bldg. A, Suite 331, Fort Collins, CO 80525-1891.

To contact, call (970) 295-5845 or email at fkrist@fs.fed.us.

The Forest Health Technology Enterprise Team 

(FHTET)of the U.S. Forest Service is leading an 

effort to produce the next version of the National 

Insect and Disease Risk Map (NIDRM) for targeted 

release in 2011. The goal of this effort is to update 

spatial depictions of risk of tree mortality based on: 

(1) newly derived 240-m geospatial information 

depicting the distribution of tree hosts, pests, 

and associated factors influencing risk, and (2) 

modifications of risk models, including emerald ash 

borer, used in the 2006 NIDRM (www.fs.fed.us/

foresthealth/technology/nidrm.shtml) with improved 

national consistency and precision.

Streamlining the construction of a higher resolution 

NIDRM that contains hundreds of spatial models by 

pest and host requires the development of a Windows 

desktop application that can facilitate rapid model 

assemblage. FHTET is in the final stages of building 

a desktop Risk Modeling Application (RMAP) using 

Microsoft Visual C# and ArcGIS Engine (ESRI Inc., 

Redlands, CA) technology. This application allows users 

to weight, rank, and overlay a wide range of geographic 

information system layers to model the potential 

susceptibility and vulnerability of forested landscapes 

to attack by individual insects and diseases. Although 

RMAP is run as a stand-alone application outside of 

ArcGIS, it does require an Arc/Info and Spatial Analyst 

(version 9.3) license. A database, such as SQL Server 

2005, is also required for file and data management 

utilities within RMAP.
14 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

SIlVICs and sIlVICulturE Of asH In MIXEd HardwOOd

fOrEsts Of tHE sOutHErn bOttOMlands

and lOEssIal HIlls

Steve Meadows

U.S. Forest Service, Southern Research Station.

To contact, call (662) 686-3168 or email at smeadows@fs.fed.us.

This presentation describes the silvics of green ash 

(Fraxinus pennsylvanica), pumpkin ash (F. profunda), 

Carolina ash (F. caroliniana), and white ash (F. 

americana). Green ash is the primary ash species in 

southern bottomlands. Pumpkin ash and Carolina 

ash are relatively minor species with limited ranges 

that occur on very wet bottomland sites. White ash 

is the primary ash species in the loessial hills and on 

other upland sites across the South. The natural range, 

distribution across site types, and associated forest cover 

types within the southern United States are outlined 

for each species. Silvical characteristics addressed in 

the presentation include (1) site requirements, (2) 

reproductive characteristics, (3) shade tolerance, (4) 

flood tolerance, (5) drought tolerance, (6) fire tolerance, 

(7) competitive ability, (8) growth rate, and (9) 

damaging agents. Timber values and wildlife uses of each 

of the four species are discussed as well. Silvicultural 

guidelines are presented for green ash and white ash 

in natural, mixed-species, southern hardwood forests. 

Topics addressed include (1) recommended regeneration 

methods in both even-aged and uneven-aged stands, 

and (2) recommended thinning prescriptions under the 

guiding principle of stand quality management.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 15

TrEnds In dOMEstIC and IntErnatIOnal

MarKEts fOr asH lOgs and luMbEr

Dan Meyer

To contact, call (800) 638-7206 or email at dan@hardwoodreview.com.

While ash is a “minor” commercial hardwood species 

relative to oak, poplar, and maple, it still accounts for 

roughly 3 percent of all hardwood lumber produced, 

with an estimated kiln-dried value exceeding $150 

million annually. More than 35 percent of all ash grade 

lumber produced is exported. We will examine decadal 

trends in domestic and international markets for ash 

logs and lumber and forecast market conditions for the 

coming year.
16 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

THE dIstrIbutIOn Of asH In NOrtH AMErICa

Randall S. Morin

U.S. Forest Service, Northern Research Station, Forest Inventory and Analysis,

11 Campus Blvd., Suite 200, Newtown Square, PA 19073.

To contact, call (610) 557-4054 or email at rsmorin@fs.fed.us.

Ash trees have been important to the people of North 

America for thousands of years. Of the nine ash species, 

white ash (Fraxinus americana L.) and green ash (F. 

pennsylvanica Marsh.) are the most widely distributed. 

These ashes are common yet not dominant in most 

forests of the eastern United States and into Canada. 

They also make up a large proportion of trees in the 

riparian lands and shelterbelts of the Midwest and in 

urban areas across the country. Due to the importance 

of ash for water protection, durable products, shade, 

and shelter, the ecological and economic value of ash is 

huge. A variety of stressors impact the health of ash trees. 

The most important stressors are the emerald ash borer 

(EAB) (Agrilus planipennis Fairmaire) and ash yellows 

(Mycoplasmalike organisms), both of which threaten 

the future of the species. We use Forest Inventory and 

Analysis (FIA) plot data from across the eastern United 

States to analyze patterns in the distribution and health 

of ash trees, saplings, and seedlings across forest types, 

stand sizes, crown classes, and ownerships. We also assess 

the current and future trends in the distribution of ash 

through the use of EAB range and spread maps. Even 

though EAB has been active in the forests of several 

states for >5 years, ash volumes continue to increase 

across most of the eastern United States as forests 

continue to mature.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 17

LargE-sCalE rEIntrOduCtIOn Of asH

Ronald Overton

Area Regeneration Specialist, U.S. Forest Service,

Northeastern Area State and Private Forestry, West Lafayette, IN.

To contact, call (765) 496-6417 or email at roverton@fs.fed.us.

No strategies currently exist for reintroducing ash; 

progression of emerald ash borer (EAB) through 

the eastern United States is likely to be a decadeslong process, and extirpation of ash from this area 

is likely to take even longer. Reintroduction of ash 

into areas where it has been extirpated by EAB will 

require addressing technical issues as well as social 

and political issues. Technical issues include what 

type of material will be introduced, for example, 

EAB-resistant (if any) or non-resistant native species, 

resistant interspecific hybrids, or resistant genetically 

modified material; and how and by whom the 

material will be produced for reintroduction. Social 

and political issues include how the development, 

production, and establishment of this material will 

be funded; and, perhaps, how this material will 

be accepted and used by public agencies, private 

landowners, and the general public.

Resistant ash developed by either standard breeding 

methods or genetic modification is likely to be used 

first by the ornamental horticulture industry, where 

small numbers of clonal varieties (relative to natural 

populations) are commonly deployed. Successful 

restoration of ash into natural ecosystems will require 

material with the capability of successfully competing 

and regenerating in perpetuity. These characteristics 

will require genetically diverse populations that 

are also genetically well-adapted to local climatic 

conditions. Availability of diverse sources of native 

ash germplasm will be essential for producing a 

genetically diverse and well-adapted population 

of material for reintroduction in both urban areas 

and natural ecosystems, so current germplasm 

conservation efforts need to be continued and expanded 

as EAB infestations spread.

Once suitable material has been developed, it will need 

to be increased before commercial production can 

begin. Both the reforestation and conservation nursery 

industry and the ornamental nursery industry have 

sufficient capacity to produce commercial amounts of 

material for deployment.

While there are several possible alternatives for 

reintroduction of ash, actual development and 

deployment of material will depend on the resources 

available. The most successful U.S. tree restoration 

programs to date involve American chestnut and the 

white pines in the western United States. Both of these 

programs feature tree species of significant economic, 

cultural, and ecological value, i.e, “charismatic 

megaflora.” Funding and support for these programs 

have been sufficient to maintain a moderate level of 

activity over several decades, resulting in slow but steady 

progress on resistance to diseases that were introduced 

more than 100 years ago.

Billions of ash trees in the eastern United States are 

likely to be killed by EAB. The value of street trees, 

the cost of removing them, and the timber value of 

ash likely to be killed in the eastern United States will 

amount to billions of dollars. However, it remains 

to be seen whether ash will have the “charisma” 

needed to generate public support for funding largescale restoration programs. If it does, the germplasm 

conservation efforts now underway for ash will provide 

a more diverse and well-adapted source of material than 

has any other U.S. species restoration program to date.
18 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

GEnEtIC transfOrMatIOn Of FRAXINUS spp. fOr

rEsIstanCE tO tHE EMErald asH bOrEr

Paula M. Pijut, Rochelle R. Beasley, and Kaitlin J. Palla

U.S. Forest Service (PMP), Northern Research Station,

Hardwood Tree Improvement and Regeneration Center (HTIRC),

715 West State St., West Lafayette, IN 47907; Purdue University (RRB, KJP),

Department of Forestry and Natural Resources, HTIRC,

715 West State St., West Lafayette, IN 47907.

PMP is corresponding author; to contact, call (765) 496-2162

or email at ppijut@purdue.edu. or ppijut@fs.fed.us.

The emerald ash borer (EAB; Agrilus planipennis

Fairmaire) (Coleoptera; Buprestidae) is a wood-boring 

beetle that poses substantial risk to the ash resource 

in North America. Ash species native to the United 

States and known to be susceptible to EAB are Fraxinus 

pennsylvanica (green ash), F. americana (white ash), and 

F. nigra (black ash) trees, which are major components 

of the landscape; and blue ash (F. quadrangulata) and 

pumpkin ash (F. profunda), which are less common 

species. Ash timber is valued for applications requiring 

strong, hard wood. Green ash is used both for solid 

wood applications, such as crating, boxes, and tool 

handles, and for fiber in the manufacture of fine papers. 

White ash is the primary commercial hardwood used 

in the production of baseball bats; it also is made into 

furniture, flooring, doors, and cabinets. Black ash is 

typically used for interior furniture and cabinets, and 

Native Americans require this species for the art of 

basketry. Beyond manufacturing, ash trees play an 

important ecological role by providing aesthetic value, 

and shelter and food for wildlife. EAB threatens these 

resources and may permanently alter forest ecosystems 

throughout North America. The development of 

transgenic Fraxinus spp. exhibiting resistance to EAB 

attack will have great economic and ecological benefits 

for landowners, the nursery and forest products 

industries, and the U.S. foreign trade of ash lumber and 

logs.

This research will result in the development of an 

Agrobacterium-mediated transformation system for 

Fraxinus spp. with recovery of transgenic plants resistant 

to EAB. In addition, this research will initiate studies of 

effective deployment strategies for transgenic ash trees. 

Data generated will be used for risk assessment, which is 

necessary for commercial release. Another major focus of 

future studies will be to examine the use of sterility genes 

to further modify transgenic ash to alter flowering and 

prevent gene escape.

An adventitious shoot regeneration and rooting protocol 

was first developed for green ash and is being optimized 

for black and white ash. The best regeneration medium 

for freshly isolated green ash hypocotyls was Murashige 

and Skoog (MS) medium supplemented with 13.3 μM 

6-benzylaminopurine (BA) plus 4.5 μM thidiazuron 

(TDZ). The effect of in vitro-germinated seedling age 

on adventitious shoot regeneration from hypocotyl 

explants was also studied. Results showed that hypocotyl 

explants from freshly isolated embryos exhibited a higher 

organogenic potential than 4- to 15-day-old explants. 

Adventitious shoots from hypocotyls were established 

as proliferating shoot cultures following transfer to MS 

basal medium with Gamborg B5 vitamins supplemented 

with 10 μM BA plus 10 μM TDZ. A high rooting 

percentage was achieved when adventitious shoots were 

rooted on woody plant medium containing 4.9 μM 

indole-3-butyric acid (IBA) plus 5.7 μM indole-3-acetic 

acid (IAA) with a combination of a 10-day dark culture 

period followed by a 16-h photoperiod. Rooted plants 

were successfully acclimatized to the greenhouse, and 

100 percent survived after overwintering in cold storage. 

This regeneration system provided a foundation for 

developing a genetic modification protocol for green 

ash. We are also investigating an adventitious shoot 

regeneration system using leaf or internodal explants.

A genetic transformation protocol was first developed 

for green ash hypocotyl explants and is currently being 

optimized for black and white ash. Green ash hypocotyls 
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 19

were transformed using Agrobacterium tumefaciens

strain EHA105 harboring binary vector pq35GR 

containing the neomycin phosphotransferase (nptII) 

and β-glucuronidase (GUS) fusion gene. After a 

1-day pre-culture on regeneration medium, hypocotyl 

explants were transformed in the presence of 100 μM 

acetosyringone using 90-sec sonication plus 10-min 

vacuum-infiltration. Kanamycin at 20 mg l-1 was used 

for selecting transformed cells. Adventitious shoots 

regenerated on MS medium supplemented with 13.3 

μM BA, 4.5 μM TDZ, 50 mg l-1 adenine sulfate, and 

10 percent coconut water. GUS- and polymerase chain 

reaction (PCR)-positive shoots from the cut ends of 

hypocotyls were produced via an intermediate callus 

stage. Presence of the GUS and nptII genes in GUSpositive shoots was confirmed by PCR, and copy 

number of the nptII gene in PCR-positive shoots was 

determined by Southern blotting. Three transgenic 

plantlets were acclimatized to the greenhouse and then 

successfully survived overwintering in cold storage. 

Studies are underway using a construct containing the 

Cry8Da protein of Bacillus thuringiensis for genetic 

transformation of ash for resistance to EAB.
20 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

ClIMatE CHangE pOsEs addItIOnal tHrEat

tO tHE futurE Of asH rEsOurCEs

In tHE EastErn UnItEd StatEs

Anantha Prasad, Louis Iverson,

Stephen Matthews, and Matthew Peters

U.S. Forest Service, Northern Research Station (AP, LI, SM, MP),

Delaware, OH; The Ohio State University (SM), Columbus, OH

AP and LI are corresponding authors;

to contact, call (740) 368-0097

or email at aprasad@fs.fed.us or Iiverson@fs.fed.us.

It is becoming increasingly clear that climate change has 

the potential to alter the distribution of plant species all 

over the world. In the United States, ash (Fraxinus spp.) 

is encountering the double threat of short-term emerald 

ash borer (EAB) infestation, which could decimate ash 

throughout the country, and longer term perturbations 

due to climate change. We have modeled the change 

in potential suitable habitats of numerous tree species 

in the eastern United States by relating the abundances 

of tree species according to U.S. Forest Service Forest 

Inventory and Analysis data to 38 climate, soil, and 

landscape predictors using decision-tree based ensemble 

statistical techniques (DISTRIB). We alter the climate 

variables in the ensemble and predict abundances 

according to two carbon emission scenarios (high and 

low) and three Global Circulation Models (GCMs). 

In addition to the DISTRIB model, we assess how 

landscape fragmentation is affecting the colonization 

potential of the tree species, using a spatially explicit 

cellular model (SHIFT). The outputs of DISTRIB and 

SHIFT provide a fairly reasonable assessment of the 

potential habitat changes that can be expected due to 

future climate changes predicted by GCMs. However, 

these models do not include biological and disturbance 

factors that may influence species’ response to climate 

change. To address some of these uncertainties, we take 

into account 9 biological and 12 disturbance-related 

factors by synthesizing the literature and scoring the 

factors by order of importance.

Here we assess the impact of climate change on ash 

species according to our habitat change models and 

combine these results with a “risk of spread model” that 

we have developed by modifying the SHIFT model 

(to determine the risk of human-mediated long-range 

dispersal of EAB). We will then paint a picture of the 

future of ash species in the eastern United States.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 21

AsHEs tO asHEs: LargE FRAXINUS gErMplasM

COllECtIOns and tHEIr fatEs

Kim C. Steiner and Paul Lupo

The Pennsylvania State University (KCS, PL).

KCS is corresponding author;

to contact, call (814) 865-2566 or email at steiner@psu.edu.

As the emerald ash borer (EAB) threatens the survival 

of our ash species, measures should be taken to preserve 

their genetic variability in the event that we discover 

a way to restore populations destroyed by the beetle. 

As it happens, large germplasm collections exist for 

our most important and widely distributed eastern 

species of the genus, white ash (Fraxinus americana

L.) and green ash (F. pennsylvanica Marsh.). The white 

ash collection, organized by Calvin Bey with the U.S. 

Forest Service, was begun in 1973 and comprised the 

progenies of 228 trees representing 39 presumptively 

native populations from throughout the species’ natural 

distribution. Seed collections were made from an 

additional 16 populations, but it is unclear at this time 

whether these were ever out-planted. The green ash 

collection, organized by Kim Steiner at Penn State, was 

begun in 1975 and comprised the progenies of 216 trees 

representing 60 range-wide populations. Long-neglected 

as scientifically “obsolete,” these provenance collections 

have taken on renewed significance as germplasm 

repositories in the face of a serious biological threat to 

the genus.

The white ash collections were planted at 25 locations 

scattered from Louisiana and Alabama to New 

Brunswick and Nebraska. Most plantations had 

progenies from 16 to 27 provenances, and one contained 

as many as 35. It appears that the complete collection 

was not represented at any one location. Each plantation 

contained five replicate blocks with five-tree family plots. 

The green ash collections were planted at 12 locations 

in the northeastern and north-central United States, 

from Maine to Maryland and west to Nebraska. 

Most plantations contained progenies from 16 to 

45 provenances, but all 60 were represented at one 

location in Pennsylvania. Most plantations contained 3 

to 10 replicate blocks with four-tree provenance plots 

containing nested, one-tree family plots. However, one 

plantation contained only two replicates of provenance 

plots, and two plantations were designed with two- or 

four-tree family plots completely randomized within 

blocks.

Of the 25 white ash plantations, 7 are believed to 

still exist in a recoverable condition with >30 percent 

survival. All have been (or will be) remeasured and 

remapped. Two of the others still exist but are in very 

poor condition. The remaining 16 tests were failures or 

no longer exist because of land use conversion. The best 

single collection of germplasm is in Jefferson County, 

KS, with 44 families representing 27 provenances and 

>70 percent survival. A plantation at Michigan State 

University’s Kellogg Forest still contains 32 replicated 

provenances, although survival is down to 33 percent. 

EAB has been trapped at the edge of this plantation.

Of the 12 green ash plantations, 7 are believed to have 

>30 percent survival and be recoverable as mapped 

germplasm collections. The remaining plantations have 

all been destroyed and the sites converted to other 

uses. The best single collection of germplasm is in 

Centre County, PA, with 216 families representing 60 

provenances and 85 percent survival. Two plantations 

maintained by Michigan State University contain most 

provenances and are in good condition. EAB has been 

trapped near one.

In the presentation we will outline priorities for 

germplasm protection in the two species based on these 

collections of range-wide genetic material. 
22 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

ObsErVatIOns On asHEs usEd In NOrtH AMErICa

and suggEstEd asH rEplaCEMEnts

T. Davis Sydnor

School of Environment and Natural Resources,

2021 Coffey Rd., Columbus, OH 43210;

to contact, call (614) 292-3865

or email at sydnor.1@osu.edu.

Ten replicates of 20 taxa of Fraxinus spp. were planted 

in northeastern Toledo, OH, in 2005. Thirteen North 

American, three European, and three Asian taxa were 

evaluated, as was one purported hybrid. Most of the trees 

are in a wide median; a smaller number were planted 

in a lawn panel along the roadway. Three soil types are 

represented in these urban soils. Plants were mulched 

during establishment but were not treated with pesticides. 

Emerald ash borer (EAB) began to emerge from some taxa 

in 2007. Plant genetics, nursery propagation method, and 

soil type seem to impact the time required before EAB 

development is visually confirmed by characteristic exit 

holes and frass-packed serpentine galleries. 

Recommended replacements were identified based on 

the following assumptions: The large growing ashes 

were appropriately sized for the site, replacements 

should be large in size, and the original trees were 

well adapted to the site and did not require a species 

substitution. Thirty-four species of trees were identified 

as potential replacements. Silvicultural characteristics 

such as tolerance of shade and flooding were noted 

for each species. This information appears in the 2005 

Extension Bulletin 924, Ash Replacements for Urban 

and Woodland Plantings. Specific examples will be 

presented at the conference.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 23

EXplOrIng tHE MOlECular and bIOCHEMICal basIs

 Of asH rEsIstanCE tO EMErald asH bOrEr

Justin G.A. Whitehill, Daniel A. Herms, and Pierluigi Bonello

Department of Plant Pathology (JGAW, PB), The Ohio State University, 2021 Coffey Road, 

Columbus, OH 43210; Department of Entomology (DAH), The Ohio State University,

Ohio Agricultural Research and Development Center, 1680 Madison Ave.,

Wooster, OH 44691. JGAW is corresponding author;

to contact, email at whitehill.5@buckeyemail.osu.edu.

Larvae of the emerald ash borer (EAB) (Agrilus 

planipennis) feed on phloem of ash (Fraxinus spp.) 

trees. It is hypothesized that the resistance of Asian 

species of ash (e.g., Manchurian ash, F. mandshurica) to 

EAB is due to endogenous defenses present in phloem 

tissues in the form of defensive proteins and/or toxic 

secondary metabolites. We have taken a proteomic and 

metabolomic approach to understand the interactions 

between EAB larvae and ash phloem that are 

fundamental to elucidating mechanisms of resistance 

to EAB.

To identify proteins that may be responsible for 

resistance of Manchurian ash to EAB, we used 

Differential in Gel Electrophoresis (DIGE) to compare 

its constitutive phloem proteome with that of the 

closely related but highly susceptible North American 

black ash (F. nigra). Differentially expressed proteins 

were sequenced using nano-liquid chromatographymass spectrometry (MS)/MS, and putative functions 

were assigned. Hierarchical clustering of 355 

phloem proteins with concentrations that differed 

substantially (>twofold, P < 0.05) between black and 

Manchurian ash revealed protein expression patterns 

that were nearly diametrically opposed, despite the 

very close phylogenetic relationship between the two 

species. Proteins in Manchurian ash that may be 

associated with resistance include enzymes involved 

in the synthesis of lignans and flavonoids, oxidative 

enzymes, a PR-10 protein, and an aspartic protease. 

Future functional studies are needed to identify what 

roles these proteins may play, if any, in resistance of 

Manchurian ash to EAB.

Chemical characterization of phloem tissue of North 

American (green, white, black, blue), European (F. 

excelsior), and Manchurian ash revealed qualitative 

similarities in the constitutive phenolic profiles of 

black, European, and Manchurian ash, while individual 

compounds differed quantitatively. Phloem chemistry 

of green and white ash was similar qualitatively and 

quantitatively, as reported by Eyles et al. (2007). 

The phenolic profile of blue ash comprised mainly 

hydroxycoumarins and showed no similarity to the 

other species. The similarities and differences in 

phenolic profiles among species corresponded with their 

phylogenetic relationships (Wallander 2008).

The ability of methyl jasmonate (MeJA) (an endogenous 

plant stress hormone that regulates defense responses) 

to induce ash phloem chemistry was also investigated by 

applying 1 M MeJA to the outer bark of Manchurian 

and white ash. Treatment with MeJA increased 

concentrations of total phenolics in both ash species, 

suggesting that induced and constitutive phenolic 

chemistry may play a role in EAB resistance. These 

studies provide a foundation for ongoing investigations 

on the role phenolics may play in ash resistance to EAB. 

Discovery of resistance-related proteins and secondary 

metabolites that confer resistance to EAB would 

accelerate breeding and /or selection of resistant trees for 

restoration of ash to natural and urban forests.
24 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

LItEraturE CItEd

Eyles, A.; Jones, W; Riedl, K; Herms, D.A.; Cipollini, 

D.; Schwartz, S.; Chan, K.; Bonello, P. 2007. 

Comparative phloem chemistry of Manchurian 

(Fraxinus mandshurica) and two North American 

ash species (F. americana and F. pennsylvanica).

Journal of Chemical Ecology. 33: 1430-1448.

Wallander, E. 2008. Systematic of Fraxinus (Oleaceae) 

and evolution of dioecy. Plant Systematics and 

Evolution. 273: 25-49.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 25

BuIldIng a COMprEHEnsIVE COllECtIOn

Of asH gErMplasM

Mark P. Widrlechner

Horticulturist, USDA-Agricultural Research Service (ARS)

North Central Regional Plant

Introduction Station, Iowa State University,

G212 Agronomy Hall, Ames, IA 50010;

to contact, call (515) 294-3511

or email at mark.widrlechner@ars.usda.gov.

The U.S. National Plant Germplasm System (NPGS) 

has conserved seed collections of ash (Fraxinus) 

germplasm at the USDA-ARS North Central Regional 

Plant Introduction Station (NCRPIS) in Ames, IA, 

since the 1970s. The initial focus was on samples 

acquired from Yugoslavia but gradually expanded to 

include representation from other areas, including 

North America. At the time emerald ash borer (EAB) 

(Agrilus planipennis) was introduced into southeastern 

Michigan, the NCRPIS maintained a relatively small ash 

germplasm collection that did not encompass the range 

of taxonomic and genetic variation in North American 

species vulnerable to EAB, nor in Asian species that coevolved with EAB. In the current NCRPIS Project Plan, 

this gap in the collection was recognized and plans made 

to address it.

As plans were refined, it became clear that proper 

sampling of North American and Asian ash would require 

a multi-institutional, collaborative effort. Fortunately, 

efforts were already underway within the USDANRCS (at the Plant Materials Center in Rose Lake, 

MI), the U.S. Forest Service National Seed Laboratory, 

and other public and tribal organizations to mobilize 

collection in North America. Collaborations were 

quickly established involving the Morton Arboretum and 

Beijing Botanical Garden, supported by the USDA-ARS 

Plant Exchange Office, to collect ash seeds in China. 

The NPGS recognized the value in bringing together 

the seed collections made by these organizations for 

long-term preservation at the National Center for 

Genetic Resources Preservation (NCGRP) in Fort 

Collins, CO, and for the selective integration of those 

collections into the ash working collection, actively 

curated at the NCRPIS.

In January 2009, a meeting and teleconference was 

held in Annapolis, MD, bringing together as many 

parties as possible involved with ash seed collection 

to develop standard collection and documentation 

protocols and a comprehensive plan for North 

America. The collection strategy centers on a stratified 

sampling of native populations of all North American 

Fraxinus species, based primarily on taxonomy and 

ecogeographic zones. This approach recognizes the 

urgency of collecting in regions being colonized 

by EAB. Since 2007, considerable progress has 

been made sampling native ash populations. The 

NCRPIS now conserves 237 accessions (78 percent 

of which are North American). Seed storage can also 

be complemented by cryogenic storage of dormant 

vegetative buds, with protocols recently developed in 

collaboration with NCGRP. Together, these efforts 

will create a publicly accessible, comprehensive ash 

germplasm collection that can serve as a foundation 

for research on EAB, Fraxinus genetics, and the 

eventual restoration of ash in our forests and 

communities. 
26 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

StrIKE OnE! AluMInuM. StrIKE twO! MaplE.

WIll EAB bE strIKE tHrEE?

Brian Boltz and Jan Wiedenbeck

Larimer & Norton (BB), Timber Division of Hillerich & Bradsby,1

1 Hemlock St., Warren, PA 16365; and

U.S. Forest Service, Northern Research Station (JW),

241 Mercer Springs Rd., Princeton, WV 24740. JW is corresponding author;

to contact, call (304) 431-2708 or email at jwiedenbeck@fs.fed.us.

AluMInuM bats ... strIKE OnE!

The aluminum bat arrived on the scene in the 1970s 

(although originally patented in 1924; Sheldon 2008) 

and quickly gained a significant share of the baseball 

bat market. Within a few years, the majority of youth 

bats, which make up about 33 percent of the overall 

bat market, were made out of aluminum. Likewise, 

the majority of adult bats—bats used by high school 

and college players—also are made of aluminum (or a 

metal alloy) today. Considering all levels of baseball and 

softball, non-wood bats (aluminum, metal alloys, and 

composites) now compose 90 to 95 percent of annual 

bat sales (personal communication with M. May of the 

Sporting Goods Manufacturers Association, Nov. 17, 

2009).

The high-end and most widely recognized market 

for wooden bats is professional baseball–the major 

and minor leagues. Baseball bats manufactured for 

professional baseball constitute an estimated 18 percent 

of the wood bat market. Retail bat sales, however, 

represent a much larger proportion of the wooden 

bat market (65 percent). These sales are to youth and 

little league players who have aspirations of advancing 

to professional baseball and need to learn how to hit 

Abstract.—Baseball bats made out of white ash (Fraxinus americana L.) have been the standard for 

professional baseball since the beginning of the game in 1849. Until the mid- to late-1970s, ash was 

the principal material used for all baseball (and softball) bats – major league, minor league, adult, and 

youth. The market share of baseball bats made from wood eroded precipitously in the late 1970s and 

early 1980s as a result of the introduction of aluminum bats. Wooden bats now constitute less than 10 

percent of bat production and sales.

Despite reduced demand for ash in bat production, the emerald ash borer’s (EAB) presence became 

a threat to manufacturers of ash baseball blanks (termed “billets”) in July 2009 with the first 

substantiation of the presence of EAB in southwestern New York. Billet manufacturers are having to 

shift their ash procurement regions, and contingency plans for using alternate species in wood bat 

manufacture are being formulated.

with a wooden bat. In addition, a few adult baseball 

leagues that mandate the use of wood bats can be found 

scattered around the country. These leagues reportedly 

have been gaining popularity (Wikipedia contributors 

2009). Today, total annual demand for wood bats is 

about 1.3 million.

MaplE bats ... strIKE twO!

The species of wood used for bats were quite diverse in 

the early years of the game of baseball, but for decades 

white ash has been the dominant material. Oak (Quercus

spp.) was used by a handful of players during the early 

days of baseball when ball players made their own bats or 

had them made by a local woodworker. Babe Ruth and a 

few other major league players during the first half of the 

20th century used hickory (Carya spp.), a denser, heavier 

wood than ash. Both hickory and oak were too heavy 

to swing fast and thus fell into disfavor. For major and 

minor leaguers, adults, and youth, ash was the material 

of choice for all baseball and softball bats until the midto late-1970s. Ash, with a specific gravity of 0.55 (green 

moisture content basis; Forest Products Laboratory 

1999), is a strong, resilient, straight-grained wood with 

excellent surface hardness.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 27

As recently as 1998, maple (specifically sugar or “rock” 

maple; Acer saccharum Marsh) bats were essentially 

non-existent. The maple bat’s first appearance in a major 

league game was in 1997. By 1998 a handful of players 

were using the maple bat. The new bat went from being 

a curiosity to being a known entity in just 2 years as 

major league players, always seeking opportunities that 

might gain them a few more points on their batting 

average, tested maple bats made to their specifications. 

The use of maple bats by a couple of big-name players, 

Conseco and Bonds, helped cultivate interest in maple 

bats throughout professional baseball.

In Major League Baseball (MLB), an estimated 25 

percent of the bats were maple bats in 2004. The high 

rate of adoption of maple for baseball bats by major 

league players continued for several years but appears 

to have leveled off since 2008. In 2009-2010, it is 

estimated that 50 percent of the bats used in MLB are 

made of sugar maple. This percentage is down slightly 

(perhaps 5 percent) from the peak usage rate seen in 

2008.

The decline in use of maple baseball bats by major league 

players is associated with heightened concern about the 

risks associated with the number and nature of broken 

maple bats. During a 3-month period in 2008, all bats 

that cracked or broke during MLB games were collected 

for analysis. It was found that bats made of maple broke 

into multiple pieces (as opposed to just cracking or 

delaminating) much more frequently than ash. Analysis 

of these breaks showed that the grain was not straight in 

many of the failed maple bats, causing a high percentage 

of the breaks (Major League Baseball Association 2008). 

Nine new rules governing baseball bat manufacture were 

adopted by MLB before the 2009 season to reduce this 

risk. Early reports indicate that the incidence of broken 

bats during the 2009 season was reduced by 30 percent 

compared to 2008 (Glier 2009).

Two Strikes but Still Swinging ... Ash 

Baseball Bats

Ash remains the dominant species used for bats in the 

wider bat market (75 to 80 percent of wood bats) as 

baseball players in the minor leagues have not adopted 

maple bats to the same extent as major league players 

have. The difference in the market share held by maple 

versus ash between the major and minor/adult leagues 

is attributable, in part, to the higher price of maple 

bats. Maple bat prices are 25 to 40 percent higher than 

ash bats of a comparable style and quality. Not only are 

stumpage prices for the higher grades of sugar maple 

twice those of white ash in Pennsylvania and New 

York (New York State Department of Environmental 

Conservation 2009, The Pennsylvania State University 

2009), but the volume of baseball bat blanks, known as 

“billets,” recovered per log is 20 percent higher for ash 

than for maple.

Essentially all of the white ash harvested for the baseball 

bat market is harvested from a fairly narrow northsouth zone that runs along the state line between New 

York and Pennsylvania. Common belief is that the 

ash resource to the south of this zone is not as hard as 

desired, and to the north the ash is too heavy to satisfy 

the weight distribution specifications sought by major 

league players. High-quality ash of the sort that can be 

used to make bats for players in MLB is straight-grained, 

with the horizontal grain deviation along the bottom 

20 inches of the bat (the handle portion, which is most 

susceptible to breakage) not offset more than 1 inch. 

This high-quality ash wood also has consistent-width 

growth rings with 8 to 9 growth rings per inch being 

preferred. Only 6 to 7 percent of the billets produced 

from select ash logs procured from this zone of New 

York and Pennsylvania are of sufficiently high quality to 

produce baseball bats for MLB.

Larimer & Norton: Manufacturing 

Billets for America’s Top Producer of 

Wood Bats

The history of Larimer & Norton (L&N), the timber 

and sawmill division of Hillerich & Bradsby (H&B), 

manufacturer of the Louisville Slugger, mirrors the 

history of the ash baseball bat.

In 1954, H&B acquired L&N, a sawmill company in 

northern Pennsylvania, to secure its access to ash billets 

for the manufacture of its wood baseball bats. The 

acquisition also gave H&B an added measure of quality 

control over its raw material. The vast majority of bat 
28 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

manufacturers buy billets from multiple sources on the 

open market. H&B is one of the only bat manufacturers 

that make their own billets. In fact, all of the billets used 

by H&B to manufacture Louisville Slugger wood bats are 

produced by L&N.

In the mid-1970s, L&N was manufacturing 7 million 

ash billets per year at 11 sawmill operations, all but one 

of which were in the New York–Pennsylvania ash quality 

zone. Then aluminum entered the picture and L&N’s 

production of ash billets dropped to about 1 million per 

year.

H&B did not turn its back on the aluminum bat market. 

In 1974 it entered the market, and in 1978 it began to 

manufacture aluminum bats at a plant in Ontario, CA. 

However, H&B has held fast to its commitment to be the 

premier wood bat manufacturer, and its wood bat product 

line is still considered the company’s flagship business. 

While only 5 to 10 percent of all bats manufactured 

industry-wide are made of wood, 40 to 50 percent of the 

bats made by H&B are wooden.

As recently as 2004, L&N had 100+ employees, 6 

sawmills, and a dimension operation that produced rough 

turnings, rectangular blanks, and moldings for sale to 

companies in other sectors of the wood products industry. 

Then maple, market globalization, and the recession 

began to complicate the marketplace and operating 

environment. The maple phenomenon has led L&N to 

shift some of its billet production away from white ash 

to sugar maple (ash to maple ratio is now 80:20). Today, 

L&N operates three sawmills in northern Pennsylvania 

with 35 employees and produces approximately 725,000 

ash and maple billets per year.

A Field Trip to Larimer & Norton’s 

Forest and Sawmill Operations

Ash billets are produced at Larimer & Norton’s sawmills 

in Akeley, PA (north of Warren) and Troy, PA (north 

of Williamsport) while hard maple billets are produced 

at its sawmill in Galeton, PA (west of Wellsboro). The 

Akeley and Galeton mills also have dry kilns and billet 

finishing operations. Billets for adult and professional bats 

(both ash and maple) are dried and finished at the Akeley 

facility. The drying and finishing of billets for youth bats, 

which still make up approximately one-third of L&N’s 

production, is carried out at the Galeton mill location.

L&N owns and manages 6,300 acres of forest land in 

the same region. The L&N forests currently provide a 

very small percentage of the log volume processed in 

the L&N mills—approximately 3 percent of L&N’s 

annual log input. The L&N forests were heavily 

harvested in the 1960s and 1970s, so it will be another 

10 to 20 years before the ash on these forests will be 

in the 15- to 17-inch diameter at breast height range, 

which will yield logs of sufficient size for manufacture 

into bats. Such logs should have small-end diameters of 

at least 11 inches and preferably 15 inches and larger.

L&N buys about 75 percent of its logs as “gate logs”—

logs delivered directly to its three sawmills by loggers 

and neighboring mills that know what type and quality 

of ash or hard maple logs the L&N sawmills seek to 

buy. Stumpage sales are the source of approximately 

22 percent of L&N’s ash and maple logs with the 

remaining 3 percent obtained from company-owned 

forests. When L&N buys stumpage or harvests its own 

forests, it must resell the logs of other species. L&N has 

three foresters – two focused on procurement and one 

focused on forest land management.

Inside the Mill

If you have visited a sawmill producing lumber, your 

image of a sawmill is not an accurate portrayal of a 

sawmill producing billets for baseball bats. Logs arrive 

at the mill in 10- and 14-foot lengths. This is where the 

similarities with standard sawmill processing systems 

end. The logs are bucked (cut) to 40-inch lengths in 

the log yard. These short logs are not debarked before 

entering the mill, nor are they sawn. Rather, the 

breakdown process involves boring or turning on a 

lathe.

Producing billets using a lathe is the longstanding 

method used throughout the industry. L&N produces 

only 30 percent of its billets in this way. All maple 

billets and 60 percent of the ash billets are produced 

on a boring machine that is unique within the industry 

(Fig. 1). Overall, 70 percent of L&N’s billets are 

produced on its four boring machines.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 29

The billets, at this point in the process referred to as 

“rough billets,” are 3 inches in diameter (for adult and 

professional bats) and 40 inches in length. Depending 

on the diameter of the log, eight or more billets can be 

recovered from each of the 40-inch-long logs. Thus, on 

average, 24 billets are produced from 10-foot-long logs 

and 32 are produced from the 14-foot logs. Recoveries 

—the volume of usable rough billets produced, divided 

by the volume of the short log—are higher for ash than 

for maple. Ash recoveries typically range from 80 to 

90 percent while maple recoveries range from 65 to 

75 percent. Maple recoveries are lower because maple 

exhibits more internal defects than ash. This insufficient 

quality leads to a higher percentage of the rough maple 

billets being culled.

The rough billets are stacked for shipment and drying. 

Whereas in drying lumber, stickers are placed between 

layers to allow for air passage through the lumber stacks, 

stickers are not needed when drying billets. Maple and 

ash billets are dried together, but in both cases the billets 

are dried to a target moisture content range of 10 to 12 

percent using a mild temperature schedule. Total drying 

time for each batch of billets, which consists of 11,000 

pieces, is 28 to 30 days. The drying of ash billets is fairly 

straightforward as few drying- related defects arise. 

Maple billets can end check during drying, especially 

in the winter, so lower temperatures and longer drying 

times are necessary.

After drying, the billets are sent to a finish processing 

line where they are redoweled to a smaller size (down 

Figure 1.—Billet boring machine on which 70 percent of 

L&N’s billets for baseball bats are produced.

to 2.75 inches diameter for adult bats) and trimmed 

to 37 inches in length. At this point they are graded 

and weighed, then sorted into billet bundles based on 

these attributes (Fig. 2). The straightness of the grain 

is the most important quality factor. The slope of the 

grain cannot exceed 3 inches along the length of the 

billet. Grain straightness differences are evident when 

comparing the “Major League Quality” billet on the left 

and the “Low-end Retail” billet on the right in Figure 2.

All finished billets are shipped to the Louisville Slugger 

factory in Louisville, KY. The Galeton billet warehouse 

ships an average of 2 truckloads per month of billets for 

youth (and softball) bats. There are 10,000 billets per 

truckload. The Akeley warehouse ships an average of 6 

truckloads of billets per month with 7,000 billets per 

Figure 2.—Billet quality classes and grade-weight sorted 

bundles of finished billets awaiting shipment.

truckload, sized and sorted for use in manufacturing 

adult and professional bats.

EMErald AsH BOrEr THrOws

AnOtHEr CurVE at AsH Bats—

WIll THIs BE StrIKE THrEE?

The emerald ash borer’s (EAB) presence became a real 

and present hazard for ash billet manufacturers in 

July 2009. The first substantiation of the presence of 

EAB in the “ash quality zone” occurred in Cattaraugus 

County, NY. Owing to this discovery, Cattaraugus and 

Chautauqua Counties in the far southwestern region of 

New York now have EAB quarantines in place. Ash logs 
30 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

can no longer be procured from these two counties by 

primary processors outside the quarantine zone.

For L&N, the adjustment process has begun. The two 

L&N mills that process ash are represented by the 

westernmost and southernmost star icons on the map 

in Figure 3. For these ash mills, the procurement zone 

is only 50 miles—this is the maximum economically 

feasible distance the sawmill can reach out for logs. 

For the Akeley ash mill, about 35 percent of its 

procurement zone is now quarantined. Consequently, 

the Akeley mill’s procurement zone probably will have 

to expand out further, or the mill will have to offer 

a higher price for stumpage and logs available from 

within the 50-mile radius.

If when additional neighboring counties are affected 

and come under quarantine, more significant strategic 

Figure 3.—Emerald ash borer infestation and quarantine map with L&N’s mill locations (designated with stars) 

and procurement region (cross-hatched) superimposed in the northern Pennsylvania, southern New York region.

adjustments will be required. A range of possibilities 

exists for L&N. Since L&N has three active mills and 

still owns one of its recently closed- down facilities, 

shifting maple production to the Akeley mill and ash 

production to one of the other facilities could be feasible 

for some length of time.

If EAB becomes widespread in the region and the 

counties in which the L&N mills are located come 

under the quarantine, ash logs will likely be abundant 

(for a few years) as forest landowners seek to harvest 

ash trees before they begin to die. The EAB compliance 

agreement into which producers will need to enter if 

they are to continue producing ash products will allow 

L&N to ship its billets (which have been debarked and 

dried) through other states to the Louisville Slugger 

plant in Kentucky.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 31

Glier, Ray. 2009. MLB getting a grip on broken bats; 

fewer incidents in 2009. [online]. Available: http://

www.usa.today.com/sports/baseball/2009-08-03-

broken-bats_N.htm (Accessed November 22, 2009).

Major League Baseball Association. 2008. Safety 

tests for maple bats mandated. [online].

Available: http://mlb.mlb.com/news/press_releases/

press_release.jsp?ymd=20081209&content_

id=3708345&vkey=pr_mlb&fext=.jsp&c_id=mlb 

(Accessed November 22, 2009).

New York State Department of Environmental 

Conservation. 2009. Stumpage price report. Winter 

2009/#74. Albany: NY. New York State Department 

of Environmental Conservation. 2 p.

Sheldon, George. 2008. Marketing the aluminum bat. 

NINE: A Journal of Baseball History and Culture. 

17(1):170-175.

The Pennsylvania State University. 2009. Timber 

market report. Second Quarter 2009. University 

Park, PA: The Pennsylvania State University. 2 p.

Wikipedia contributors. 2009. Baseball bat. [online]. 

Available: http://en.wikipedia.org/w/index.

php?title=Baseball_bat&oldid=330675945.

(Accessed December 9, 2009).

The “harvest now” behavior that some landowners will 

pursue is a concern for L&N as it looks to the future. 

This behavior will cause more ash to come on the 

market sooner but make ash less available a few years 

out. If, in the end, the EAB does not infest and kill 

a high proportion of the ash, the principal outcome 

of this preemptive harvest strategy will be to have 

severely distorted size and age-class distributions of the 

unaffected ash resource.

Ultimately, switching to other species is a strategy that 

could be required. Such species would include maple, 

of course, but other species also exist that have similar 

specific gravities and hardness values. Beech (Fagus 

grandifolia Ehrh.), yellow birch (Betula alleghaniensis

Britton), and red oak (Quercus rubra L.) are among 

the top prospects. If this scenario comes to pass, it 

might indeed be strike three for ash baseball bats, but 

it will not be the end of the game for wood baseball 

bat manufacturers. There are more species, and more 

innings, left to be played.

LItEraturE CItEd

Forest Products Laboratory. 1999. Wood handbook—

Wood as an engineering material. Gen. Tech. Rep. 

FPL-GTR-113. Madison, WI: U.S. Department 

of Agriculture, Forest Service, Forest Products 

Laboratory. 463 p.
32 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

PattErns aMOng tHE asHEs: EXplOrIng tHE rElatIOnsHIp

bEtwEEn landsCapE pattErn and tHE EMErald asH bOrEr

Susan J. Crocker, Dacia M. Meneguzzo, and Greg C. Liknes

Research Forester (SJC, DMM) and Research Physical Scientist (GCL), U.S. Forest Service, 

Northern Research Station, 1992 Folwell Ave, St. Paul, MN 55108.

SJC is corresponding author;

to contact, call (651) 649-5136 or email at scrocker@fs.fed.us.

Abstract.—Landscape metrics, including host abundance and population density, were calculated 

using forest inventory and land cover data to assess the relationship between landscape pattern and 

the presence or absence of the emerald ash borer (EAB) (Agrilus planipennis Fairmaire). The Random 

Forests classification algorithm in the R statistical environment was used to create a model relating 

the relative importance of landscape predictor variables to the presence/absence of EAB detected from 

2003 to 2009. The dataset was then subdivided, based on quarantine year, to create two subsequent 

models: (1) data from 2003 to 2007 and (2) data from 2008 to 2009. Model accuracy was 85.3, 

91.6, and 89.6 percent, respectively. While population density was ranked as the top predictor 

variable in all three models, analysis of the models separated by quarantine year showed variation 

among the other top predictors. Measurements of urban development and forest edge influenced 

the model more among counties quarantined between 2003 and 2007, and host abundance was an 

important predictor among counties quarantined in 2008 and 2009.

INTRODUCTION

America’s forests are home to more than 8.8 billion ash 

trees (Fraxinus spp.) greater than 1 inch diameter at 

breast height (U.S. Department of Agriculture [USDA] 

Forest Service ). The distribution of ash is spatially 

skewed. Ninety-three percent of all ash trees are found 

in the eastern half of the conterminous United States; 72 

percent of these individuals are within the northeastern1

region. The abundance, functionality, and utility of ash 

make it an ecologically and economically valuable tree 

species. As a prominent component of riparian forests, 

ash plays an important role in reducing runoff and 

enhancing soil stability (Goforth et al. 2002). Ash is a 

valuable commercial species used in the manufacturing 

of numerous wood products, including furniture, pulp 

and paper, crating, and baseball bats (USDA Animal and 

Plant Health Inspection Agency [APHIS] 2005). Ash 

was widely sold as nursery stock and planted in urban 

settings because of its rapid growth and high tolerance of 

environmental stress.

In recent years, the sustainability of the Nation’s ash 

resource has been threatened by the introduction of 

a wood-boring beetle identified as the emerald ash 

borer (EAB) (Agrilus planipennis Fairmaire). Native 

to southeast Asia, EAB was first identified in North 

America near Detroit, MI, in 2002 (Cappaert et al. 

2005). Throughout North America, EAB is a pest 

of ash. All native ash trees are susceptible to EAB 

infestation regardless of species, size, or vigor (Poland 

and McCullough 2006). Tree mortality can be rapid: 

trees can die within 3 or 4 years of infestation (Kovacs et 

al. 2009). EAB mortality estimates range in the tens of 

millions of trees (Poland and McCullough 2006, Kovacs 

et al. 2009). Thus far, EAB has been identified in 13 

states and 2 Canadian provinces.

The spread of EAB in the United States has occurred 

through artificial and natural means. Long-range 

dispersal was the result of human transportation of 

infested firewood and nursery stock, while natural 

dispersal followed short-range flight of beetles to new 

hosts (Cappaert et al. 2005). Factors governing natural 

dispersal include host availability, insect flight capacity, 

physical barriers, and meteorological conditions 

(Cappaert et al. 2005). 

1Includes Maine, New Hampshire, Vermont, Massachusetts, 

Connectcut, Rhode Island, New York, Pennsylvania, New Jersey, 

Delaware, Maryland, West Virginia, Ohio, Indiana, Michigan, 

Illinois, Wisconsin, Missouri, Iowa, Minnesota, North Dakota, 

South Dakota, Nebraska, and Kansas. 
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 33

Of particular interest in this study was the influence of 

physical obstacles in the dispersal of EAB. The level of 

forest fragmentation in EAB-infested areas makes it a 

challenge to understand how EAB populations respond 

to the arrangement and availability of suitable habitat 

(Schultz and Crone 2001). Therefore, the purpose of this 

study was to identify how well landscape characteristics 

(i.e., landscape pattern metrics) predict the presence 

or absence of EAB. To accomplish this goal, we used 

forest inventory data, land cover imagery, and a spatial 

analysis algorithm to quantify patterns on the landscape. 

A classification algorithm was then used to identify the 

relative importance of these potential predictor variables. 

Our motivation was to assess the role of landscape pattern 

in the dispersal of EAB and provide insight on habitat 

suitability and risk.

METHODS

Study Area

To investigate the potential effects of landscape pattern 

on EAB, we examined county-level data from Illinois, 

Indiana, Ohio, and Kentucky. Counties ranged from 

highly fragmented to heavily forested and represented long, 

short, or no EAB infestation intervals. EAB was detected 

in Ohio, Indiana, Illinois, and Kentucky in 2003, 2004, 

2006, and 2009, respectively. Michigan was not included 

in the study because EAB is considered “generally” infested 

throughout all counties in the Lower Peninsula.

Distribution of EAB

Presence/absence of EAB and quarantine establishment 

was determined for all counties in the study area using 

state-level data (Illinois Department of Agriculture 2009, 

Indiana Department of Natural Resources 2009, Kentucky 

Department of Agriculture 2009, Ohio Department of 

Agriculture 2009). If EAB was present within a county, 

the year of detection was also recorded. Since the rules 

for quarantine establishment varied, the entire county 

was considered quarantined if any portion of the county 

(township or a multi-county group) was quarantined 

by the state. EAB has not been found in all quarantined 

counties. Counties were classified according to the 

presence/absence of EAB infestations. Quarantine year was 

used only as a means of splitting our dataset and was not 

considered in the classification process.

Landscape Metrics

Landscape metrics are measurements that quantify and 

describe aspects of landscape pattern (Griffith et al. 

2000). In this study, 19 metrics were calculated from 

various data sources, including raster land-cover data 

and ground-level plot data (Table 1). Selected metrics 

describe (1) the amount and spatial arrangement of 

forest and host availability, and (2) aspects of non-forest 

landscape pattern, such as population and road density.

Data from the Forest Inventory and Analysis (FIA) 

Program of the U.S. Forest Service were used to 

calculate county-level estimates of ash trees per acre 

and ash basal area. Measures of urban development and 

supplementary measures of forest pattern were gathered 

from the National Land Cover Database of 2001 

(NLCD) (Homer et al. 2004) and datasets by Riemann 

et al. (2009), where one pixel is equivalent to 30 meters, 

or approximately 98 feet. Additional data required to 

calculate airport presence/absence, population density, 

area of park land, and road density were gathered from 

the National Atlas of the USA and the Environmental 

Systems Research Institute (ESRI), Inc., respectively 

(ESRI 2008, National Atlas of the US 2009). To assess 

potential changes in host availability by county as EAB 

dispersal increased over time and space, measures of 

ash abundance and the percentage of forest land were 

compared by quarantine year.

Morphological Spatial Pattern 

Analysis

GUIDOS software (European Commission, Joint 

Research Centre, Institute for Environmental 

Sustainability, Ispra VA, Italy) was used to assign forest 

pixels from the NLCD 2001 to one of seven classes 

(core, islet, bridge, edge, loop, branch, and perforation). 

Pixel assignment was completed using morphological 

spatial pattern analysis (MSPA) algorithms that 

were based on the connectivity and geometry of the 

pixels (European Commission 2009, Soille and Vogt 

2009). To describe the spatial pattern or degree of 

fragmentation of forest land, a map of the new pixel 

classification was produced. Pixel counts of each class 

were divided by the total number of pixels in each 

county to obtain percentages of each class by county.
34 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

Modeling the Presence/Absence of EAB

A dataset of explanatory variables was constructed from 

calculated landscape metrics (Table 1). The Random 

Forests (RF) algorithm in the R statistical software 

environment (Version 2.8.1 [http://www.r-project.

org/]) was used to create a model relating EAB presence/

absence to the input variables (Breiman 2001). Cutler 

et al. (2007) found that RF outperformed commonly 

used modeling techniques, such as logistic regression, 

in classifications of lichens, cavity-nesting birds, and the 

presence of invasive plants. RF provided diagnostics that 

identified the relative importance of each variable. Refer 

to Appendix A in Cutler et al. (2007) for a description 

of the Gini index and its use as an indicator of variable 

importance. By withholding observations (known as 

the out-of-bag sample, or OOB) as it builds a suite of 

classification trees, RF also provided an assessment of the 

classification accuracy.

Three iterations of the model were constructed using 

different county combinations in an effort to examine 

potential differences between these populations. The 

first iteration included data for all counties in the 

study area (ALLDATA). After the initial model was 

run, subsequent model iterations were completed to 

assess potential changes in county-level attributes. This 

decision resulted from analysis of mean values of percent 

forest and ash abundance by county and quarantine year. 

To accomplish this goal, a second iteration of the model 

was built using only a portion of the dataset: data for all 

non-quarantined counties and those counties that were 

quarantined from 2003 to 2007 (PRE-2008). The final 

iteration included data for all non-quarantined counties 

and data from counties quarantined in 2008 or 2009 

(POST-2007). Year of quarantine was used to divide 

the datasets between the PRE-2008 and POST-2007 

models; however, it was not used to determine presence 

or absence of EAB. Presence/absence records were 

used within the model to determine whether EAB had 

become established in a county; these records are based 

on confirmed infestations recorded by each state. The 

PRE-2008 model was used to forecast the presence/

absence of EAB in counties quarantined in 2008 and 

2009.

Table 1.—Calculated landscape metrics

Metric Metric description Data source

 Ash density 1 Ash trees per acre of county land Forest Inventory and Analysis

Ash density 2 Ash basal area as a percentage of total basal 

area Forest Inventory and Analysis

Percent forest Percent of county area that is forested NLCD 2001

Percent branch Percent of forest that is connected at one end to 

edge, perforation, bridge, or loop NLCD 2001/ GUIDOS

Percent bridge Percent of forest that is connected at both ends 

to different core patches NLCD 2001/ GUIDOS

Percent core Percent of forest that is the interior area of a 

forest patch, excluding forest perimeter NLCD 2001/GUIDOS
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 35

Percent edge Percent of forest that is the outside perimeter of a 

forest patch NLCD 2001/GUIDOS

Percent islet Percent of forest that is connected and too small 

to contain core NLCD 2001/ GUIDOS

Percent loop Percent of forest that is connected at both ends 

to the same core patch NLCD 2001/ GUIDOS

Percent perforation Percent of forest that is in the inside perimeter of 

a forest patch NLCD 2001/ GUIDOS

Percent agriculture Percent of county area that is classified as 

agriculture

NLCD 2001 (Riemann et al. 

2009)

Percent developed Percent of county that is classified as urban 

development

NLCD 2001(Riemann et al. 

2009)

Percent forest less than

1 pixel 

Percent of forest within 1 pixel of a developed 

edge (urban development, agriculture, and 

barren land)

NLCD 2001 (Riemann et al. 

2009)

Percent forest 1 to 3

pixels

Percent of forest 1 to 3 pixels from a developed 

edge (urban development, agriculture, and 

barren land)

NLCD 2001 (Riemann et al. 

2009)

Percent forest greater 

than 3 pixels 

Percent of forest that is greater than 3 pixels 

from a developed edge (urban development, 

agriculture, and barren land)

NLCD 2001 (Riemann et al. 

2009)

Percent parks Percent of county area designated as park ESRI data and maps 2008

Road density Miles of major roads per square mile ESRI data and maps 2008

 Airports Presence or absence of an airport in the county

National Atlas of the USA

 Population density Number of people per square mile National Atlas of the USA

Table 1.—continued
36 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

Figure 1.—Comparison of average percent forest and ash density (trees per acre) for 

quarantined counties by year.

A B

RESULTS

The complete dataset consisted of 402 counties. During 

the study period (2003-2009), 120 counties were 

placed under state quarantine. EAB had been positively 

confirmed in 97 of these counties. Comparison of 

county-level averages for percent forest and ash density 

(trees per acre) by quarantine year shows that counties 

quarantined in 2008 and 2009 had more forest land 

and a higher number of ash trees per acre than counties 

quarantined prior to 2008 (Fig. 1).

Results from the ALLDATA model show that overall 

accuracy was high. Based on the OOB, the RF classifier 

was able to correctly assign presence/absence to 342 

counties (out of a total of 402 counties) for 85.3-percent 

agreement. As measured by the mean decrease in the 

Gini index, population density provided the most 

explanatory power of patterns of EAB presence/absence, 

followed by percent core, percent forest within 1 to 3 

pixels, percent developed, and road density (Table 2).

When the 2008-2009 quarantine counties were 

excluded from model development (PRE-2008 model), 

classifier accuracy increased to 91.6 percent. The model 

performed very well in non-quarantined counties and 

in highly developed areas. Misclassified counties tended 

to occur along the boundary between quarantined and 

Figure 2.—Classification output from PRE-2008 model (A) and forecast of 2008-2009

counties using the PRE-2008 model (B).
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 37

non-quarantined counties (Fig. 2A). Similar to the 

ALLDATA model, population density was the topranked predictor variable; percent developed, percent 

forest within 1 to 3 pixels, percent core, and percent 

edge were also highly ranked (Table 2).

The POST-2007 model had a classification accuracy of 

89.6 percent (303 out of 338 counties). As with earlier 

models, population density was identified as the most 

important explanatory variable with respect to EAB 

presence. Unlike the previous models, however, measures 

of host abundance had high predictive value; ash basal 

area and ash trees per acre ranked third and fourth, 

respectively (Table 2). Percent forest within 1 to 3 pixels 

and percent developed were also among the top five 

predictors, ranking second and fifth, respectively.

When the PRE-2008 model was used to forecast 

presence/absence in the 2008-2009 quarantine counties, 

the accuracy was 49.1 percent (27 out of 55 counties). 

Misclassified counties had no apparent spatial pattern, 

and classification errors were relatively balanced between 

false positives and false negatives (Fig. 2B).

DISCUSSION

Overall, models based on landscape metrics performed 

well in explaining the presence/absence of EAB. 

Population density, along with percent developed and 

percent forest within 1 to 3 pixels of a developed edge, 

were the most important variables in all modeling 

scenarios, indicating humans play a dominant role in 

EAB dispersal. Similarly, investigations by Muirhead 

et al. (2006) found a positive relationship between 

human population epicenters and the probability of 

EAB infestation. The PRE-2008 model, which had the 

highest classification accuracy, also identified percentage 

of core forest and forest edge as important variables. 

These findings indicate that forest edges may influence 

EAB dispersal. Interestingly, investigation of EAB in its 

native range shows that EAB is known to attack solitary 

trees and trees along edges (Chinese Academy of 

Science 1986). Additional research is required, but early 

analysis of model results indicates that EAB infestations 

prior to 2008 may be influenced by areas with a high 

proportion of forest edge.

Conversely, POST-2007 model results show that core 

and edge metrics, which had high importance in the 

PRE-2008 model, were replaced by metrics of host 

abundance as important indicators of EAB presence. 

The discrepancy between the models highlights a 

potential change in the relevance of explanatory 

variables over space and time. Infestations immediately 

following the initial introduction of EAB may have 

relied heavily on human activity. Later EAB infestations 

(those detected after 2007) may have depended heavily 

on ash abundance. The influence of host abundance 

is highlighted by an analysis of forestation and ash 

density, which indicates that the levels of these two 

attributes remained low and relatively stable for 

counties quarantined between 2003 and 2007, and then 

dramatically increased among counties quarantined 

after 2008 (Fig. 1). Presence of EAB in more heavily 

forested counties may be related to (1) increased 

awareness of EAB and a resulting change in human 

activities or (2) a change in EAB population dynamics 

in response to more continuously available habitat. 

Overall, results seem to suggest a change in variable 

importance over time and/or space and the emerging 

importance of the level of habitat availability.

This assessment of the relationship between landscape 

pattern and the presence of EAB has shown that models 

based on landscape metrics can help provide a measure 

of the importance of condition-level attributes with 

regard to EAB presence. However, a change in the 

explanatory variables across space and time makes it 

difficult to predict future patterns of infestation. We 

hope further investigation will yield more consistent 

results and better predictive models.
38 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

Table 2.—Ranking of the importance of explanatory variables (landscape metrics) 

by model and associated mean decrease in Gini index values.

Order of variable importance (high to low) by model

ALLDATA model PRE-2008 model POST-2007 model

Variable ∆ Gini Variable ∆ Gini Variable ∆ Gini

Population density 21.14 Population density 11.58 Population density 9.41

Percent core 12.11 Percent developed 9.56 Percent forest 1 to 3 

pixels 5.89

Percent forest 1 to 3 

pixels 12.06 Percent forest 1 to 3 pixels 8.11 Ash density 2 5.50

Percent developed 11.33 Percent core 7.74 Ash density 1 4.82

Road density 10.29 Percent edge 7.51 Percent developed 4.34

Percent edge 9.41 Percent forest 

greater than 3 pixels 6.14 Road density 4.27

Ash density 2 9.36 Road density 6.07 Percent forest less 

than 1 pixel 4.23

Percent forest 

greater than 3 pixels 8.65 Ash density 1 5.76 Percent core 4.17

Ash density 1 8.39 Percent forest less 

than 1 pixel 4.70 Percent edge 3.83

Percent forest less 

than 1 pixel 7.53 Percent forest 4.47 Percent forest greater than 3 pixels 3.72

Percent parks 7.52 Ash density 2 4.38 Percent agriculture 3.19

Percent agriculture 6.24 Percent parks 4.34 Percent parks 3.08

Percent forest 6.14 Percent branch 3.66 Percent forest 3.06

Percent branch 4.91 Percent agriculture 3.65 Percent branch 2.51

Percent islet 3.92 Percent islet 2.55 Percent islet 1.77

Percent bridge 2.27 Percent bridge 1.64 Percent perforation 1.12

Percent perforation 1.51 Percent loop 1.32 Percent bridge 1.08

Percent loop 1.48 Percent perforation 1.16 Percent loop 1.05

Airports 0.89 Airports 0.45 Airports 0.48
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 39

Literature Cited

Breiman, L. 2001. Random forests. Machine Learning. 

45: 5-32.

Cappaert, D.; McCullough, D.G.; Poland, T.M.; Siegert, 

N.W. 2005. Emerald ash borer in North America: 

a research and regulatory challenge. American 

Entomologist. 51(3): 152-165.

Chinese Academy of Science, Institute of Zoology, 1986. 

Agrilus marcopoli Obenberger. Agriculture Insects 

of China, part I. Beijing, China: China Agriculture 

Press. 445 p.

Cutler, D. R.; Edwards, Jr., T.C.; Beard, K.H.; Cutler, 

A.; Hess, K.T.; Gibson, J.; Lawler, J.J. 2007. Random 

forests for classification in ecology. Ecology. 88(11): 

2783-2792.

ESRI. 2008. ESRI® Data and Maps 2008. Redlands, 

CA: Environmental Systems Research Institute, Inc.

European Commission, Joint Research Centre. 2009. 

GUIDOS. [online]. Available: http://forest.jrc.

ec.europa.eu/download/software/guides.

Goforth, R.; Stagliano, D.; Lee, Y.; Cohen, J.; Penskar, 

M. 2002. Biodiversity analysis of selected riparian 

ecosystems within a fragmented landscape.

Lansing, MI: Michigan Natural

Features Inventory. 148 p.

Griffith, J.A.; Martinko, E.A.; Price, K.P. 2000. 

Landscape structure analysis of Kansas at three 

scales. Landscape and Urban Planning. 52: 45-61.

Homer, C.; Huang, C.; Yang, L.; Wylie, B.; Coan, M. 

2004. Development of a 2001 National Land Cover 

Database for the United States. Photogrammetric 

Engineering and Remote Sensing. 70(7): 829-840.

Illinois Department of Agriculture. 2008. Fifth 

amendment to the emerald ash borer interior

quarantine. [online]. Available: http://www.agr.state.

il.us/eab/data/200902186640.pdf.

Indiana Department of Natural Resources. 2009. 

Emerald ash borer website. [online]. Available: 

http:/www.in.gov/dnr/entomolo/3443.htm.

Kentucky Department of Agriculture. 2009. State 

quarantines 20 counties to contain emerald ash 

borer. [online]. Available: http://www.kyagr.com/pr/

newscenter/eabquarantine.htm.

Kovacs, K. F.; Haight, R.G.; McCullough, D.G.; 

Mercader, R.J.; Siegert, N.W.; Liebhold, A.M. 2009. 

Cost of potential emerald ash borer damage in U.S. 

communities, 2009-2019. Ecological Economics. 

doi:10.1016/j.ecolecon.2009.09.004.

Muirhead, J.R.; Leung, B.; van Overdijk, C.; Kelly, 

D.W.; Nandakumar, K.; Marchant, K.R.; MacIsaac, 

H.J. 2006. Modelling local and long-distance 

dispersal of invasive emerald ash borer Agrilus 

planipennis (Coleoptera) in North America.

Diversity and Distributions. 12: 71-79.

National Atlas of the US. 2009. National Atlas – 

Raw data download. [online]. Available: http://

nationalatlas.gov/atlasftp.html.

Ohio Department of Agriculture. 2009. Ohio’s EAB 

quarantine and regulations. [online]. Available: 

http://www.agri.ohio.gov/divs/plant/eab/eab-index.

aspx#tog.

Poland, T.M.; McCullough, D.G. 2006. Emerald ash 

borer: invasion of the urban forest and the threat 

to North America’s ash resource. Journal of Forestry. 

104(3): 118-124.

Riemann, R.; Lister, T.; Lister, A.; Meneguzzo, D.; Parks, 

S. 2009. Development of Issue-relevant Stat level 

analyses of fragmentation and urbanization. In: 

McWilliams, W.; Moisen, G.; Czaplewski, R., comps. 

Proceedings, Forest Inventory and Analysis (FIA) 

Symposium 2008; 2008 October 21-23; Park City, 

UT. Proc. RMRS-P-56CD. Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Rocky 

Mountain Research Station. 1 CD.

Schultz, C.B.; Crone, E.E. 2001. Edge-mediated 

dispersal behavior in a prairie butterfly. Ecology. 

82(7): 1879-1892. 

Soille, P.; Vogt, P. 2009. Morphological segmentation 

of binary patterns. Pattern Recognition Letters. 30: 

456-459.
40 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

U.S. Department of Agriculture, Animal and Plant 

Health Inspection Agency. 2005. Emerald ash borer; 

Quarantine areas. Federal Register. 70: 249-253.

U.S. Department of Agriculture, Forest Service, Forest 

Inventory and Analysis Program, Forest Inventory 

and Analysis Data Online (FIDO). [online]. 

Available: http://fiatools.fs.fed.us/fido/index.html.

U.S. Department of Agriculture, Forest Service, 

Forest Inventory and Analysis Program. [online]. 

Available: http://www.fia.fs.fed.us/tools-data/

default.asp.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 41

OVErCOMIng ObstaClEs tO IntErspECIEs

HYbrIdIZatIOn Of asH

Jennifer L. Koch, David W. Carey,

Mary E. Mason, and M. Nurul Islam-Faridi

Research Biologist (JLK), Biological Technician (DWC), U.S. Forest Service, 

Northern Research Station, 359 Main Rd., Delaware, OH 43015;

Research Associate (MEM), Department of Entomology, The Ohio State 

University/Ohio Agricultural Research and Development Center,

1680 Madison Ave., Wooster, OH 44691; Research Geneticist (MNI),

U.S. Forest Service, Southern Research Station, and Research Geneticist, 

Cytogenetics Laboratory, Texas A & M University,

College Station, TX 77843. JLK is corresponding author;

to contact, call (740) 368-0188 or email at jkoch@fs.fed.us

Tree species that share a long co-evolutionary history 

with insects and pathogens are likely to have developed 

mechanisms of resistance that allow them to coexist. 

When insects and pathogens are introduced to different 

parts of the world, high levels of susceptibility can be 

observed, presumably in part due to the lack of coevolutionary history between the insect (or pathogen) 

and host. In such cases, use of non-native tree species 

as a source of resistance for introgression into native 

susceptible tree species can be quite helpful. Examples 

of interspecific hybrids include hybrid hemlocks 

with resistance to hemlock wooly adelgid and hybrid 

chestnut trees resistant to chestnut blight (Hebard 

2006, Montgomery et al. 2009). If first-generation 

hybrids show good resistance to the insect or pathogen, 

then a back-cross breeding program may be initiated 

to produce seedlings for restoration that preserve the 

introgressed resistance in a progeny set with most of the 

characteristics of the native parent species. This approach 

is being used by The American Chestnut Foundation 

and would be the model approach used to produce 

emerald ash borer (EAB)-resistant North American ash 

species.

The success of this strategy depends on the existence 

of genetically controlled resistance to EAB in Asian 

ash species and the ability to inter-breed these resistant 

species with susceptible North American ash species. 

Evidence of EAB resistance in Asian ash species has 

been reported (Liu et al. 2007), but controlled testing 

is limited to a single horticultural selection of F. 

mandshurica (Rebek et al. 2008). Little is known about 

interspecies hybridization in ash, with the exception of 

two cultivars (‘Northern Gem’ and ‘Northern Treasure’) 

that have been described as hybrids between Manchurian 

ash and black ash (F. nigra) (Davidson 1999). Northern 

Treasure has been reported as EAB-susceptible (Rebek 

et al. 2008). We have begun to establish a collection of 

Asian ash species (and other exotic species) at the U.S. 

Forest Service, Northern Research Station, in Delaware, 

OH, to identify species with EAB resistance for use 

as parents in a breeding program. We have performed 

controlled cross-pollinations with more than 30 species 

combinations of ash with little success. We have 

identified several challenges to controlled pollinations to 

produce hybrids, and our program is addressing them.

Obstacles to interspecific crosses in Fraxinus include 

between-species differences in reproductive biology 

and genetics, such as differing ploidy levels, differing 

pollination systems and phenology, and potential 

genetic incompatibility (Wright 1957, Wallander 

2001). Although the majority of ash species are 

2n=46, important exceptions influence hybrid 

breeding programs. The exceptions include white 

ash (F. americana) 2n=46, 92, or 138; pumpkin ash 

(F. profunda) 2n=138; velvet ash (F. velutina) 2n=46 

or 92; and Chinese ash (F. chinensis) 2n=92 or 138. 

While ploidy level differences do not always result in 

complete incompatiblity, the resulting F1 progeny are 

often sterile. Accordingly, we need to carefully match 

known ploidy levels when choosing parents for initial 

crosses. The ploidy levels of blue ash (F. quadrangulata) 

and Manchurian ash (F. mandshurica) are unknown, 

so cytogenetic work is being conducted to establish 

the ploidy number of these species. Preliminary 
42 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

results indicate both species are 2n=46. Genetically 

determined incompatibility is another natural barrier 

to hybridization. Genetic incompatibility may be 

structural, such as when there are different chromosome 

numbers or gross differences in genome organization 

(major deletions or transpositions that prevent proper 

chromosome pairing at mitosis and meiosis), or it may 

be biochemical, such as the expression of S-glycoproteins 

(Broothaerts and Nerum 2003, Wheeler et al. 2009).

Differences in pollination system (insect, windpollinated) represent significant barriers to natural cross 

hybridization but may be relatively easily overcome by 

controlled cross-pollination techniques. Storing pollen 

and manually pollinating flowers allows the crossing 

of species without regard to their natural pollination 

system. It is not known how genes controlling the 

pollination system might segregate in an F1 or F2 hybrid 

population, so our initial efforts have focused largely on 

species pairs with similar reproductive biology. Many 

ash species are dioecious or androdioecious, meaning 

that both male and female trees must be collected and 

established, increasing the minimum number of trees 

required for breeding. Differences in phenology are 

closely related to differences in reproductive biology 

and create real barriers to natural hybridization. By 

maintaining known female trees as potted ramets 

for long periods, we are able to control the timing of 

flowering. The female trees are kept in a cold storage 

area until fresh pollen of the desired species has been 

collected or until local trees have shed the bulk of their 

pollen. It has been suggested that the large size of the 

genus Fraxinus will make crosses between sub-genera 

impossible (E.Wallander, pers. comm.). However, there 

are few to no cross-compatibility data to determine 

exactly what the maximum allowable phylogenetic 

distance is between parents that results in successful 

hybridizations.

Perhaps the greatest restriction to hybridization 

identified to date is the limited number of Asian ash 

accessions available in the United States. The United 

States has only a limited amount of ash from China, 

Korea, Japan, and eastern Russia, and much of it is not 

yet reproductively mature. Some species are represented 

by only one or two accessions in all the U.S. gardens 

and arboreta, a limitation that in some cases became 

apparent only after our thorough review of accession 

records. Continued thorough review of accession 

records and DNA analysis will be necessary to ensure 

unique material is being accessioned. Seed collections 

from China were distributed widely throughout the 

United States. For example, the North American 

China Plant Exploration Consortium (NACPEC) is 

made up of many member gardens and arboreta that 

all share collected seed. A single Manchurian ash seed 

collection in 1997 (NACPEC97048) is documented 

as 25 specimens under 9 accession numbers in 7 

different gardens. A more recent seed collection effort by 

NACPEC, headed by the Morton Arboretum (Chicago, 

IL), included a wide range of ash species in China; it 

should be a valuable resource once the seeds germinate 

and the trees become sexually mature.

Yet another challenge is presented once successful 

pollinations produce potentially hybrid seedlings. 

To rule out pollen contamination (including selfpollination), DNA-based methods to confirm the hybrid 

parentage of seeds produced from controlled crosses 

are being optimized. Despite the expectation that selfcompatibility and pollen contamination would be rare, 

each cross may result in only a few seeds, so hybrid 

confirmation is essential. Our initial efforts to confirm 

several putative hybrids using SSR or AFLP markers 

uncovered some inconsistencies in the parent trees. 

Several trees seemed to cluster inappropriately based 

upon their marker genotype.

We expanded the number of reference samples included 

for each species of interest and began to carefully 

document the phenotypes of the exotic ash in our 

research collection. The ITS region of a subset of 

individuals was sequenced and these data confirmed 

that our AFLP-based groupings were consistent with the 

published phylogenies (Wallander 2008). Based upon 

both AFLP and ITS sequence results, however, several 

samples in question were incorrectly identified at the 

species level.

We were able to trace several incorrectly identified 

accessions back to the Chinese Academy of Sciences 

Botanical Garden in Beijing. In one case, the seed 
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 43

was directly distributed from the Chinese Academy 

to arboreta in the United States in the 1980s, and in 

another case seed was distributed to a botanical garden 

in another country in 1963, which then supplied 

materials to the United States. All accessions derived 

from this seed source that we have analyzed to date 

have been determined to be incorrectly identified as 

F. chinensis. In fact, they appear to be F. pennsylvanica. 

Furthermore, several seed lots imported from China by 

reputable U.S. seed companies have also been shown 

to be incorrectly identified as either F. chinensis or F. 

bungeana. To date, we have found eight specimens and 

seedlots that were incorrectly identified as either the 

Asian species F. chinensis or F. bungeana, all of which 

are consistent with F. pennsylvanica, based on AFLP 

genotyping. It appears that seed has been routinely 

collected from F. pennsylvanica growing in China and 

distributed as F. chinensis and F. bungeana. The seeds 

from these species are very similar, which has likely 

contributed to the mistaken identities.

This work accents the importance of confirming the 

identity of closely related species when initiating a 

hybrid breeding program or other scientific experiments. 

For example, comparisons of proteomics, metabolomics, 

and transcriptomics between EAB-resistant Asian ash 

species and EAB-susceptible North American ash species 

are of less value if the species of interest have not been 

identified correctly. Furthermore, these findings also 

demonstrate that the number of Asian ash accessions 

currently in the United States may be even more limited 

than records show.

It is our long-term goal to overcome the obstacles 

described here to establish an interspecific breeding 

program using exotic ash species as sources of EAB 

resistance that can be introgressed into native North 

American species. F1 hybrids with EAB resistance may 

have immediate value to the nursery industry as street 

trees. F1 progeny, as well as subsequent generations, will 

also be valuable genetic resources for determining the 

heritability and molecular mechanisms of resistance. 

Backcross generations created through careful selection 

of parents for both North American characteristics and 

EAB resistance may someday provide the resources 

needed to re-establish EAB-resistant North American 

ash species in our forests. Gene conservation activities 

involving North American ash species are a critical 

component of such a breeding program so that genetic 

diversity across the native range is preserved for use in 

advanced generations of breeding.

LItEraturE CItEd

Broothaerts, W.; Van Nerum, I. 2003. Apple selfincompatibility genotypes: an overview. Acta 

horticulturae. 622: 379-387.

Davidson, C.G. 1999. ‘Northern Treasure’ and 

‘Northern Gem’ hybrid ash. HortScience. 34: 

151-152.

Hebard, F. V. 2006. The backcross breeding program 

of the American chestnut foundation. Journal of 

the American Chestnut Foundation. 19: 55-77.

Liu, H.; Bauer, L.S.; Miller, D.L.; Zhao, T.; Gao, R.; 

Song, L.; Luan, Q.; Jin R.; Gao, C. 2007. Seasonal 

abundance of Agrilus planipennis (Coleoptera: 

Buprestidae) and its natural enemies Oobius agrili

(Hymenoptera: Encyrtidae) and Tetrastichus 

planipennisi (Hymenoptera: Eulophidae) in 

China. Biological Control. 42: 61-71.

Montgomery, M. M.; Bentz, S.E.; Olsen, R. T. 2009. 

Evaluation of hemlock (Tsuga) species and hybrids 

for resistance to Adelges tsugae (Hemiptera: 

Adelgidae) using artificial Infestation. Journal of 

Economic Entomology. 102: 1247-1254.

Rebek, E.J.; Herms, D.A.; Smitley, D.R. 2008. 

Interspecific variation in resistance to emerald 

ash borer (Coleptera: Buprestidae) among North 

American and Asian ash (Fraxinus spp.) PlantInsect Interactions. 37: 242-246.

Wallander, E. 2001. Evolution of wind-pollination 

in Fraxinus (Oleaceae) – an ecophylogenetic 

approach. Gothenburg, Sweden: University of 

Gothenburg. 129 p. Ph.D. dissertation.
44 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

Wallander, E. 2008. Systematics of Fraxinus

(Oleaceae) and evolution of dioecy. Plant 

Systematics and Evolution. 273: 25-49.

Wheeler, N.; Nielsen, D.; Smith, C.; Tomkins, J.; 

Abbott, B.; Atkins, M.; Blackmon, B.; Staton, M.; 

Ficklin, S.; Hebard, F.; Sisco, P.; Carlson, J.,

Barakat, A.; Powell, W., Baier, K., Anagnostakis, 

S.; Kubisiak, T.; Burdin, C.; Sederoff, R. 2009. 

Annotated EST-based SSR and SNP genetic maps 

for Chinese chestnut. [online]. Available: http://

www.fagaceae.org/sites/default/files/nov09conf/

program.pdf. (Accessed December 15).

Wright, J. W. 1957. New chromosome counts in Acer

and Fraxinus. Morris Arboretum Bulletin.

 8: 33-34.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 45

POpulatIOn-lEVEl VarIatIOn Of FRAXINUS

AMERICANA L. Is InfluEnCEd bY ClIMatE

dIffErEnCEs aCrOss tHE natIVE rangE

Renée Marchin

Department of Plant Biology, North Carolina State University, Raleigh, NC 27695-7612.

To contact, email at renee_marchin@ncsu.edu.

Abstract.—This paper reviews population variation in Fraxinus americana (white ash) to 

determine whether intraspecific variation in various physiological traits affects growth and survival 

in F. americana and to correlate any intraspecific variation in F. americana with temperature or 

precipitation differences throughout the species range. Beginning in the 1980s, results from common 

garden studies indicated that differences in growth and survival in F. americana are the result of 

ecotypic variation in the species. Recently, further insights into the mechanisms controlling these 

ecotypic differences in growth were made in a common garden at the edge of the species range. This 

project in northeastern Kansas found significant differences in morphology, phenology, and stomatal 

regulation among 44 F. americana populations. Even after 30 years of growth in the common 

garden, these population differences were well-correlated with climatic differences (temperature and 

precipitation) at the location of population origin. Temperature requirements for leaf emergence 

of F. americana populations in the common garden were positively correlated with the latitude of 

population origin. Differences in water use efficiency among other F. americana populations were 

observed and may be caused by morphological traits, such as variation in leaf mass per area and foliar 

nitrogen concentration. Thus, the original observations of differences in growth among F. americana

ecotypes are likely caused by adaptive differentiation among populations.

INTRODUCTION

Interest in the ecology of Fraxinus (ash) species has 

increased due to the recent discovery of an exotic insect 

pest, the emerald ash borer (Agrilus planiplennis), in 

North America. The wood-boring beetle has caused the 

death of millions of ash trees (MacFarlane and Meyer 

2005) and has seriously threatened the survival of 

native North American Fraxinus species. When tools to 

conserve and manage ash species are being developed, 

it is important to consider how ecologically important 

traits vary among natural populations. High levels 

of intraspecific variation in morphology, physiology, 

growth, and phenology are commonly observed in tree 

species with large ranges that cover different climatic, 

edaphic, and biotic regions (Donselman and Flint 1982, 

Geber and Dawson 1993, Abrams 1994, Aspelmeier and 

Leushner 2004).

Tree physiology often changes along climatic 

gradients and may be driven by adaptation to 

temperature differences and/or differences in water 

availability throughout the species range. In the 

case of the temperate deciduous tree F. americana

L. (white ash), the natural species range includes 

the eastern half of the United States and extends 

into parts of southern Canada (Fig. 1). Even 

without accounting for the devastation caused by A. 

planiplennis, models predicting future suitable habitat 

for the species indicate that its range will decrease 

in the future as a result of a northward shift in 

optimum growing conditions (Prasad et al. 2007). An 

understanding of the natural variation in traits that 

affect growth, susceptibility to A. planiplennis, and 

survival of Fraxinus species is necessary for directing 

management strategies and conservation efforts.
46 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

Figure 1.—Natural range of F. americana in North America 

(shaded region, USDA Forest Service, www.na.fs.fed.us). 

Sources ( and o) of the 44 F. americana populations 

grown in the common garden (*) at Nelson Environmental 

Study Area in northeastern Kansas are also indicated. Ten 

populations originating from along an east-west precipitation 

gradient are identified by open circles. From Marchin et al. 

2008.

F. americana is a ring-porous angiosperm native to the 

temperate deciduous forests of the eastern United States. 

This hardwood is an early successional species that is 

often one of the first trees to colonize abandoned fields 

and thus is important for forest regeneration across its 

range (Schlesinger 1990). The wood of F. americana

is valued for its strength and is used for furniture and 

baseball bats (Nesom 2000).

Prior to this century, not much was known about the 

extent of intraspecific variation in the physiology and 

growth of F. americana. Recent work in a F. americana

common garden in northeastern Kansas, however, 

revealed intraspecific variation for several important 

ecological traits (Marchin 2006, Marchin et al. 2008). 

Located in a marginal habitat at the western edge of the 

species range where the required degree of adaptation 

may exceed the limits of phenotypic plasticity in some 

genotypes, this study site likely allowed a full expression 

of range-wide genetic variation in response to abiotic 

stresses (Paschke et al. 2003, Stanton et al. 2000).

The main focus of this review is to (1) determine 

whether there are differences in morphology, 

phenology, gas exchange, and stomatal regulation 

•

among F. americana populations, (2) determine whether 

intraspecific variation in these traits affects growth and 

survival in the species, and (3) correlate intraspecific 

variation in F. americana with a corresponding climate 

variable to define the causal mechanism driving genetic 

divergence in the species.

METHODS: THE COMMON GARDEN 

APPROACH

For many years, it has been known that F. americana is 

genetically variable throughout its range, partly owing 

to the presence of polyploidy (Wright 1944). These 

differences in ploidy level vary across the species range, 

with diploids (46 chromosomes) occurring throughout 

the species range. Tetraploids (92 chromosomes), 

however, are restricted to regions south of latitude 35°N, 

and hexaploids (138 chromosomes) are found between 

latitudes 35° and 40°N (Black and Beckmann 1983, 

Schlesinger 1990). Triploid and pentaploid embryos 

have also been observed, although the prevalence of these 

individuals in natural populations is unknown (Black and 

Beckmann 1983).

To better understand how this genetic variation affected 

growth and to identify the best seed sources for various 

geographical locations, the U.S. Forest Service, North 

Central Forest Experiment Station initiated a rangewide provenance test of F. americana in 1976 (Clausen 

1980, Clausen et al. 1981). Open-pollinated seeds 

were collected from native parent trees at 59 locations 

throughout the species’ range and planted in a nursery 

in Illinois. It was observed that under the common 

environment of the nursery, tetraploids grew taller than 

other ploidy levels (Clausen et al. 1981). These 1-yearold seedlings were later transplanted to 22 plantations 

throughout the eastern United States and Canada.

This review primarily focuses on one of the F. americana

common gardens, located in Kansas at the western 

edge of the species range (University of Kansas, Nelson 

Environmental Study Area, 39.0°N, 95.2°W, 299 m asl). 

At this common garden site, mean annual precipitation 

is 879 mm, with large interannual variation (± 200 

mm SD). Mean annual temperature is 11.9°C, and 

mean temperature during the growing season (April–

September) is 20.4°C (see Jefferson County, Table 1). 
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 47

Trees in the common garden were 30 years old at the 

time of the study. The common garden is set up in a 

block design, with each of the 44 populations (Fig. 

1) represented by 25 trees (5 blocks with 5 replicate 

trees from each population). In 2004, 40 of the 

44 populations were still represented by at least 10 

individuals, although one population (East Baton Rouge, 

LA) had no surviving trees in the common garden.

To determine possible mechanisms driving genetic 

variation in F. americana, two subsets of populations 

were selected a priori. One subset of 10 populations 

formed a north-south latitudinal gradient that ranged 

from 30.8° to 46.6°N and originated within a narrow 

longitudinal range (approximately 89°W). Similarly, the 

second subset of 10 populations formed an east–west 

precipitation gradient ranging from 79.5° to 95.7°W 

and originating within a narrow latitudinal range 

(approximately 39°N). These subsets of populations 

Table 1.—Climatic data from the common garden (located in Jefferson County, KS

and the locations represented in the common garden. From Marchin et al. (2008

Populations in the latitudinal gradient are indicated by a single cross (†);

populations in the east-west precipitation gradient are indicated by a double cross (‡).

can indicate the climatic control over known trait 

variation by maximizing differences caused by one 

climate parameter (e.g., precipitation) and minimizing 

differences caused by other factors (e.g., temperature, 

photoperiod). All physiological measurements were 

performed on three to five individuals per population, 

and when possible, all measured trees were located in 

one block to minimize microsite differences among trees.

RESULTS

Population-level Responses in Growth 

and Survival

After only 3 years of seedling growth in the originally 

established 22 F. americana common gardens, height 

varied significantly among populations and plantations, 

revealing a strong genotype × environment interaction 

(Clausen 1980). The patterns of variation in height 

indicated the presence of northern and southern 
48 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

ecotypes divided at approximately 39°N (Roberds et al. 

1990). Populations of the southern ecotype had greater 

growth than the northern ecotype throughout most of 

the F. americana range, excluding the extreme northern 

latitudes (Clausen et al. 1981, Roberds et al. 1990). 

Therefore, foresters recommended collecting seed up to 

300 km south of a F. americana plantation location.

As the F. americana trees aged, the height differences 

among populations became more accentuated at most 

plantation sites. The mean percentage of total variation 

attributed to provenance, taken across 10 common 

gardens, increased from 28.6 percent at age 3 to 38.5 

percent at age 13 (Clausen 1984, Rink and Kung 1991). 

In contrast, the mean variance component attributed 

to populations-within-provenances decreased from 

11.9 percent at age 3 to 7.5 percent at age 13 in the 

same study sites (Clausen 1984, Rink and Kung 1991), 

indicating that mean between-provenance variation is 

more than three times greater than within-provenance 

variation. Interestingly, the common garden in Kansas 

was an exception to this trend. Here, the betweenprovenance variance component for height of 13-yearold trees was 10 percent, while the within-provenance 

variance component was 31 percent (Rink and Kung 

1991.

In the central zone between the northern and southern 

ecotype, at approximately 39°N, growth and survival 

are highest among populations that originated from 

locations closest to the common garden (Schuler 1994, 

Marchin et al. 2008). This result was confirmed by 

two common gardens located at opposite edges of the 

species range. At the common garden in north-central 

West Virginia, Schuler (1994) examined trees 15 years 

after establishment and found height and survival were 

highest in populations originating from the immediate 

vicinity of the common garden. Among 30-year-old 

trees in the Kansas common garden, similar results were 

found: Stem circumference and survival were highest in 

populations originating closest to the common garden 

(Fig. 2) (Marchin et al. 2008). In both studies, survival 

and growth in the common garden were lower in 

provenances originating either to the north or south of 

the common garden (Fig. 2).

Taken together, these studies indicate that adaptive 

differentiation has occurred in F. americana in response 

to range-wide climatic variation. Evidence suggests that 

the genetically controlled differences in growth and 

survival among F. americana populations are related 

to differences in temperature and/or precipitation 

patterns throughout the species’ range. There are high 

degrees of variation in climatic variables throughout 

the F. americana range (Table 1), with mean annual 

temperature ranging from 4.3 to 19.4 °C and mean 

annual precipitation ranging from 749 to 1602 mm.

Figure 2.—(a) Stem circumference (n = 1-25) and (b) 

survival (n = 25) regressed against latitude of origin for 44 

Fraxinus americana populations grown in a common garden 

located in Jefferson County, KS. Populations representing 

an east-west precipitation gradient along latitude 39oN are 

identified by open symbols. From Marchin et al. 2008.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 49

Temperature-influenced Intraspecific 

Variation

As indicated by the differences in survival among 

ecotypes of F. americana, there is variation in cold 

tolerance among F. americana populations. Alexander et 

al. (1984) found that stem tissue of the northernmost 

populations had lower killing temperatures (–42.6 

°C, –41.4 °C) than did the southernmost populations 

(–33.7 °C, –30.8 °C) in two different years. This 

result suggests that southern tree populations 

require lower temperatures or more time to reach 

maximum potential cold hardening than do northern 

tree populations. Additionally, it has been shown 

that southern populations have lower temperature 

requirements for bud break in the spring in Kansas 

(Marchin 2006), indicating that these populations may 

be more susceptible to damaging late-spring frosts. The 

lower growth and survival of southern F. americana

populations in the Kansas common garden is likely at 

least partially controlled by temperature-related traits.

Because killing temperatures of northern F. americana

populations are low (Alexander et al. 1984), the 

mechanism controlling differential growth and survival 

among northern populations is likely different from that 

of southern populations. The lower stem circumference 

of northern populations may still be controlled by 

temperature-related traits, however, because there are 

phenological differences among populations. The range 

for mean date of leaf emergence among populations 

in the Kansas common garden was 26 days, which 

is comparable to reported time intervals for other 

deciduous temperate tree species (Scotti-Saintagne et 

al. 2004, Borchert et al. 2005). A significant linear 

relationship was found between temperature sum for 

spring leaf emergence and latitude of origination among 

F. americana populations, where northern populations 

had higher temperature requirements for bud break 

than southern populations (Marchin 2006). In forest 

ecosystems, early greening of canopies is critical for net 

ecosystem primary production. A difference of a few 

days in canopy development accounted for more than 20 

percent of the interannual change in net photosynthetic 

production in a northeastern North American forest 

(Myneni et al. 1997).

Another possible cause of the differential growth and 

survival observed among F. americana populations is 

differences in photosynthetic capacity or rates of lightsaturated photosynthesis (Asat). Leaf gas exchange 

parameters, such as net photosynthesis (A) and stomatal 

conductance (gs

), have been found to vary significantly 

among populations of the closely related species F. 

pennsylvanica (green ash; Abrams et al. 1990). This 

variation among genotypes in Asat is maintained by 

simultaneous changes in biochemical and stomatal 

characteristics during photosynthesis (Geber and 

Dawson 1997).

Because the amount and intensity of solar radiation in 

different habitats is a source of population variation 

in Asat (Fitter and Hay 2002), it is possible that F. 

americana populations along a north-south latitudinal 

gradient would have differences in Asat. One study 

comparing 10 F. americana populations that originated 

along such a latitudinal gradient found no significant 

variation in Asat or gs

 (p=0.35, p=0.25, respectively) 

among F. americana populations (Table 2; Marchin 

2006). The sample size analyzed in this study was 

low (n=3-5 individuals), however, and perhaps better 

sampling would reveal significant differences among 

populations. Indeed, there does appear to be a trend 

between mean Asat and latitude, where northern F. 

americana populations have the lowest mean Asat

(Table 2). Populations with lower inherent rates of 

photosynthesis would also have lower potential growth 

rates (Larcher 2003).

Precipitation-influenced Intraspecific 

Variation

Changes in water availability across a species range have 

been found to drive intraspecific differences in drought 

tolerance in a number of tree species (Schmidtling and 

Froelich 1993, Roupsard et al. 1998, Adams and Kolb 

2004). Water is one of the most important resources 

for tree growth; up to 90 percent of the variation in the 

annual width of tree rings can be explained by variations 

in rainfall (Kozlowski et al. 1991). It is not surprising 

then to observe population variation in F. americana that 

is related to precipitation differences across the species’ 

range.
50 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

Table 2.—Leaf gas exchange (n = 3-5) in Fraxinus americana populations originating 

from locations along a latitudinal gradient and grown in a common garden in 

Jefferson County, KS

Genetic differentiation for water-related traits in F. 

americana can be analyzed in a common garden by 

choosing a subset of populations where precipitation 

is known to differ among the locations of origin, but 

temperature variation is minimized. In the east–west 

precipitation gradient analyzed here, mean annual 

precipitation at the source of these populations ranges 

from 765 mm year–1 in the west (Otoe, NE) to 

1261 mm year–1 in the east (Tucker, WV; Table 1). 

Among these 10 populations, survival in the common 

garden was only about 50 percent for the easternmost 

population (Randolph, WV) but rose to 96 percent for 

the westernmost population, which originated closest to 

the common garden (Otoe, NE; Fig. 2). Similarly, stem 

circumference in the easternmost populations (Tucker, 

WV; Randolph, WV; Wayne, OH) was only about half 

that in the westernmost populations (Otoe, NE; Adams, 

IL).

The stable carbon isotope ratio of leaves (foliar δ13C) 

provides a time-integrated measure of the ratio of leaf 

inter-cellular CO2 concentration to atmospheric CO2

concentration (ci

/ca). The ci/ca ratio depends on stomatal 

conductance and photosynthetic demand for CO2 and 

thus indicates water-use efficiency (Farquhar et al. 1989, 

Ehleringer 1991). In the Kansas common garden, foliar 

δ13C values were significantly negatively correlated with 

annual precipitation at the location of origin (Fig. 3; 

Marchin et al. 2008). Eastern populations from wetter 

regions exhibited lower δ13C values and were therefore 

less conservative in their water use when compared 

with western populations that originated from drier 

climates. A more conservative strategy for water use may 

have contributed to higher survival, particularly when 

considering that the common garden experienced periods 

of extreme drought in the past 30 years.

The responses of these F. americana populations suggest 

wide-range adaption of F. americana to the local moisture 

regime. Differentiation in leaf mass per area (LMA) and 

foliar nitrogen (N) concentration (on an area basis, Na) 

was also evident among F. americana populations from 

across the east–west precipitation gradient (Marchin et al. 

2008). Increases in LMA and Na indicate increases in the 

quantity of photosynthetic apparatus per unit leaf area 

(Fitter and Hay 2002) and, thus, increases in water-use 

efficiency (Li et al. 2000, 2004). The superior growth and 

survival of provenances originating from the western edge 

of the species range where the climate is driest is thus 

likely attributable, at least in part, to their high LMA and 

Na.

Figure 3.—Foliar carbon isotope ratios of Fraxinus

americana populations (n = 3-6) from an east-west 

precipitation gradient when grown in a common garden. The 

population originating from Jefferson County, KS, near the 

common garden is indicated by the filled star. (Marchin et 

al. 2008)

 

Location Latitude Asat{± SD) gs (± SD) Slope of Asat-N 

Relationship 

Ontonagon, MI 46.6 7.94 ± 4.26 0.127 ± 0.136 9.6

Forest, WI 45.7 6.46 ± 1.67 0.062 ± 0.018 2.6

Forest, WI 45.7 8.20 ± 2.09 0.080 ± 0.027 -4.6

Effingham, IL 39.1 9.35 ± 3.30 0.111 ± 0.078 12.5

Effingham, IL 39.0 9.98 ± 2.11 0.118 ± 0.037 3.1

Gallatin, IL 37.6 11. 27 ± 2.68 0.150 ± 0.076 3.2

Oktibbeha, MS 33.4 11. 25 ± 1.83 0.159 ± 0.068 1.3

Oktibbeha, MS 33.4 9.18 ± 3.71 0.118 ± 0.082 -2.7

Oktibbeha, MS 33.4 10.04 ± 2.52 0.104 ± 0.033 2.3

George, MS 30.8 9.85 ± 4.26 0.164 ± 0.101 10.2
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 51

CONCLUSIONS

Genetically based differences in morphology, phenology, 

and stomatal regulation among populations of F. 

americana are correlated with temperature and/or 

precipitation differences at the site of population origin. 

The physiological responses of F. americana trees, which 

are still apparent after 30 years in a different climate, 

affect the ability of individual populations to grow and 

survive in novel climates. Populations with the highest 

growth and survival at the edge of the species range 

originated from climates of similar annual temperature 

and precipitation to that of a Kansas common garden. A 

thorough understanding of population variation can be 

used to determine the potential for adaptive evolution 

in F. americana, as well as the genotypes that may be 

most successful in a given region under predicted future 

climatic and biotic conditions.

The spread of A. planipennis to new sites has seriously 

threatened the continued existence of Fraxinus species 

in North America. The current situation for Fraxinus

has been compared to the past devastation of Castanea 

dentata (American chestnut) trees by the fungal chestnut 

blight. Knowledge of the physiological variation among 

populations can direct seed-collection efforts aimed 

at conserving diversity in F. americana. While we face 

a difficult challenge in preserving Fraxinus species in 

North American temperate forests, the cultural and 

ecological importance of these species provides a strong 

incentive for solving the problem.

Literature Cited

Abrams, M.D.; Kubiske, M.E.; Steiner, K.C. 1990. 

Drought adaptations and responses in 5 genotypes 

of Fraxinus pennsylvanica Marsh - Photosynthesis, 

water relations, and leaf morphology. Tree 

Physiology. 6: 305-315.

Abrams, M.D. 1994. Genotypic and phenotypic 

variation as stress adaptations in temperate tree 

species - a review of several case-studies. Tree 

Physiology. 14: 833-842.

Adams, H.D.; Kolb, T.E. 2004. Drought responses of 

conifers in ecotone forests of northern Arizona: 

tree ring growth and leaf sigma C-13. Oecologia. 

140: 217-225.

Alexander, N.L.; Flint, H.L.; Hammer, P.A. 1984. 

Variation in cold-hardiness of Fraxinus americana

stem tissue according to geographic origin.

Ecology. 65: 1087-1092.

Aspelmeier, S.; Leuschner, C. 2004. Genotypic 

variation in drought response of silver birch 

(Betula pendula): leaf water status and carbon 

gain. Tree Physiology. 24: 517-528.

Black, C.L.; Beckmann, R.L. 1983. The variability of 

nuclear DNA and its implications for polyploidy 

in white ash (Fraxinus americana L, Oleaceae).

American Journal of Botany. 70: 1420-1423.

Borchert, R.; Robertson, K.; Schwartz, M.D.; WilliamsLinera, G. 2005. Phenology of temperate trees 

in tropical climates. International Journal of 

Biometeorology. 50: 57-65.

Clausen, K.E. 1980. Survival and early growth of 

diploid white ash planted in the central hardwood 

region. In: Garrett, H; Cox, G., eds. Proceedings, 

Third Central Hardwood Forest Conference, 

Columbia, MO: 374-383.

Clausen, K.E. 1984. Nonlinear regressions and 

contour plots: Techniques for selection and 

transfer of white ash provenances. Forest Science. 

30: 441-453.

Clausen, K.E.; Kung, F.H.; Bey, C.F.; Daniels, R.A. 

1981. Variation in white ash. Silvae Genetica. 30: 

93-97.

Donselman, H.M.; Flint, H.L. 1982. Genecology of 

eastern redbud (Cercis canadensis). Ecology. 63: 

962-971.

Ehleringer, J.R. 1991. 13C/12C fractionation and its 

utility in terrestrial plant studies. In: Coleman, D.; 

Fry, P., eds. Carbon isotope techniques. New York, 

NY: Chapman and Hall: 187-200.

Farquhar, G.D.; Ehleringer,J.R.; Hubick, K.T. 1989. 

Carbon isotope discrimination and photosynthesis. 

Annual Review of Plant Physiology and Plant 

Molecular Biology. 40: 503-537.

Fitter, A.; Hay, R. 2002. Environmental physiology of 

plants. San Diego, CA: Academic Press.
52 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

Geber, M.A.; Dawson, T.E. 1993. Evolutionary 

responses of plants to global change. In Kareiva, P.; 

Kindolver, J.; Huey, R., eds. Biotic interactions and 

global change. Sunderland, MA: Sinauer Associates, 

Inc.: 179-197.

Geber, M.A.; Dawson, T.E. 1997. Genetic variation 

in stomatal and biochemical limitations to 

photosynthesis in the annual plant, Polygonum 

arenastrum. Oecologia. 109: 535-546.

Kozlowski, T.T.; Pallardy, S.G. 1997. Physiology of 

woody plants. 2nd ed. San Diego, CA. Academic 

Press.

Larcher, W. 2003. Physiological plant ecology. 4th ed. 

Berlin, Germany: Springer. 540 p.

Li, C.Y.; Berninger, F.; Koskela, J.; Sonninen, E. 2000. 

Drought responses of Eucalyptus microtheca

provenances depend on seasonality of rainfall in 

their place of origin. Australian Journal of Plant 

Physiology. 27: 231-238.

Li, C.Y.; Liu, S.R.; Berninger, F. 2004. Picea seedlings 

show apparent acclimation to drought with 

increasing altitude in the eastern Himalaya. TreesStructure and Function. 18: 277-283.

MacFarlane, D.W.; Meyer, S.P. 2005. Characteristics 

and distribution of potential ash tree hosts for 

emerald ash borer. Forest Ecology and Management. 

213: 15-24.

Marchin, R. 2006. Population variation in Fraxinus 

americana L. (white ash) in a common garden 

at the edge of the species range. Lawrence, KS: 

University of Kansas. M.A. Thesis.

Marchin, R.M.; Sage, E.L.; Ward, J.K. 2008. 

Population-level variation of Fraxinus americana

(white ash) is influenced by precipitation 

differences across the native range. Tree Physiology. 

28: 151-159.

Myneni, R.B.; Keeling, C.D.; Tucker, C.J.; Asrar, G.; 

Nemani, R.R. 1997. Increased plant growth in the 

northern high latitudes from 1981 to 1991. Nature. 

386: 698-702.

Nesom, G. 2000. White ash: Fraxinus americana

L. In: Plants Database. Washington, DC: U.S. 

Department of Agriculture, Natural Resources 

Conservation Service.

Paschke, M.; Bernasconi, G.; Schmid, B. 2003. 

Population size and identity influence the reaction 

norm of the rare, endemic plant Cochlearia 

bavarica across a gradient of environmental stress. 

Evolution. 57: 496-508.

Prasad, A.; Iverson, L.; Matthews, S.; Peters, M. 2009. 

A climate change atlas for 134 forest tree species of 

the eastern United States [Database]. http://www.

nrs.fs.fed.us/atlas/tree.

Rink, G.; Kung, F.H.1991. Height and diameter 

variation in twelve white ash provenance/progeny 

tests in eastern United States. In: McCormick, 

L; Gottschalk, K., eds. Proceedings, 8th Central 

Hardwood Forest Conference. Gen. Tech. Rep. NE 

148. Radnor, PA: U.S. Department of Agriculture, 

Forest Service, Northeastern Forest Experiment 

Station: 179-187.

Roberds, J.H.; Hyun, J.O.; Namkoong, G.; Rink, G. 

1990. Height response functions for white ash 

provenances grown at different latitudes. Silvae 

Genetica. 39: 121-129.

Roupsard, O.; Joly, H.I.; Dreyer, E. 1998. Variability 

of initial growth, water-use efficiency and carbon 

isotope discrimination in seedlings of Faidherbia 

albida (Del.) A. Chev., a multipurpose tree of 

semi-arid Africa. Provenance and drought effects.

Annales Des Sciences Forestieres. 55: 329-348.

Schlesinger, R.C. 1990. Fraxinus americana L. White 

Ash. In: Burns, R.M.; Honkala, B.H., tech. coords. 

Silvics of North America. Vol. 2, Hardwoods. Agric. 

Handbk. 654. Washington, DC: U.S.Department of 

Agriculture: 333-338.

Schmidtling, R.C.; Froelich, R.C. 1993. Thirty-seven 

year performance of loblolly pine seed sources in 

eastern Maryland. Forest Science. 39: 706-721.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 53

Schuler, T.M. 1994. Survival and growth of white 

ash families and provenances 15 years after 

establishment in West Virginia. Res. Pap. NE-684. 

Radnor, PA: U.S. Department of Agriculture, Forest 

Service, Northeastern Forest Experiment Station. 7 p.

Scotti-Saintagne, C.; Bodenes, C.; Barreneche, T.; 

Bertocchi,E.; Plomion, C.; Kremer, A. 2004. 

Detection of quantitative trait loci controlling 

bud burst and height growth in Quercus robur L.

Theoretical and Applied Genetics. 109: 1648-1659.

Stanton, M.L.; Roy, B.A.; Thiede, D.A. 2000. Evolution 

in stressful environments. I. Phenotypic variability, 

phenotypic selection, and response to selection in 

five distinct environmental stresses. Evolution. 54: 

93-111.

Wright, J. 1944. Genotypic variation in white ash.

Journal of Forestry. 42: 489-495.
54 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

EX sItu COnsErVatIOn Of asH sEEd In Canada

Dale Simpson

Natural Resources Canada, Canadian Forest Service—Atlantic Forestry Centre,

PO Box 4000, Fredericton, NB E3B 5P7.

To contact, call (506) 452-3530 or email at Dale.Simpson@nrcan.gc.ca.

Abstract.—The National Tree Seed Centre began an ash seed collection program in 2004 in 

response to the threat imposed on the ash resource in Canada by emerald ash borer (Agrilus 

planipennis Fairmaire). Ash seed stores very well when dried to an 8-percent moisture content and 

frozen at -20 °C. Collections are made from a minimum of 15 trees per population. Seed is kept 

separate by tree. Viability tests are conducted to evaluate seed quality before storage. More than

520 collections have been made from five species. At least another 1,200 collections must be made 

to complete sampling throughout the species’ ranges in Canada.

INTRODUCTION

Ash species are an integral component of many of 

the forest ecosystems in Canada. The range of black 

ash (Fraxinus nigra Marsh.) extends from the Atlantic 

Provinces, Quebec, and Ontario to the southeastern 

corner of Manitoba. Green ash (F. pennsylvanica Marsh.) 

is found in parts of Nova Scotia and New Brunswick, 

and through the southern portions of Quebec and 

Ontario. Its range extends farther west than black 

ash, reaching across the lower half of Manitoba and 

Saskatchewan. White ash (F. americana L.) is found 

throughout the Maritime Provinces and southern 

Quebec and Ontario. Blue ash (F. quadrangulata Michx.) 

and pumpkin ash (F. profunda [Bush] Bush) are not 

common and are found only in a few locations in the 

Carolinean Forest of southwestern Ontario (Farrar 

1995). Ash wood is strong and durable. White ash is 

used primarily for tool handles, snow shoes, and baseball 

bats whereas black ash is prized by First Nations people 

for weaving baskets. Seeds serve as a food source for 

wildlife.

With the discovery of emerald ash borer (EAB; Agrilus 

planipennis Fairmaire) in Windsor, ON, in 2002, the 

future of the ash resource is uncertain. Since that time, 

the insect has steadily spread into southwestern Ontario 

but has also leapfrogged to such distant locations as 

Ottawa and southeast of Montreal (Fig. 1). Mortality 

of ash trees has had a devastating impact on urban and 

forest landscapes. With no natural enemies and no 

inherent resistance within the trees, this exotic insect 

has the potential to wipe out ash in Canada, resulting 

in the loss of native species and varieties—with 

repercussions on the ecosystems where ash occurs. 

The official position in Canada is that EAB cannot be 

eradicated (Marchant 2007). Therefore, an effort must 

be made to collect and preserve the genes, thereby 

conserving the natural genetic variation that will be 

critical for the development of resistant planting stock. 

One means of conservation is collecting and storing 

seed.

National Tree Seed Centre

The National Tree Seed Centre was established by 

the Canadian Forest Service in 1967. Its purpose was 

to collect, store, and provide seed of known origin 

and quality for research. Since then, its role has been 

expanded to include the long-term storage of seed 

for genetic conservation. Seed stored for genetic 

conservation will be made available only for specific 

research projects, such as identifying genes that confer 

resistance, or for hybrid breeding programs, genomics 

studies, or restoration plantings.

The Seed Centre has excellent storage facilities that 

consist of three large walk-in freezers maintained at -20 

°C. All seed is stored in hermetically sealed glass jars. 

This method of storage ensures that the moisture content 

of the seed is maintained during storage, the seed is 

protected from agents trying to enter the jars, and the 

local environment is protected from anything trying to 

escape from the jars.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 55

Figure 1.—Locations 

in Canada where 

emerald ash borer has 

been detected. Source: 

http://www.inspection. 

gc.ca/english/plaveg/

pestrava/agrpla/

mc/200907canada.gif

Table 1.—Germination of ash seed from several species stored at -20 °C at the National

Tree Seed Centre

Species Number of seedlots Years in storage Germination (%)

F. americana 17 27 76

F. nigra 4 15 78

F. pennsylvanica 3 10 66

Ash Seed Collection, Processing, 

Testing, and Storage

Ash seed collections began in 2004 at a time when EAB 

was emerging as a threat to the ash resource. There was 

an opportunity for the Seed Centre to become active 

in conserving the ash genetic resource. Data from ash 

seedlots already in storage indicated that the seed stored 

well at -20 °C (Table 1).

Seed collections aim to sample the genetic variation 

present in a population. A population can comprise a 

number of stands or a distribution of trees within an 

environmentally homogeneous area. A minimum of 15 

trees are sampled, with the seed kept separate by tree. 

This protocol serves many purposes (e.g., to evaluate 

seed quality, assess changes in viability during storage, 

and evaluate genetic variation among trees within 

populations). To reduce the chance of collecting seed 

from related trees, trees are spaced 50–100 m apart. 

Various techniques are employed for seed collection. The 

most frequently used method is pole pruning, whereby 

seed-bearing branches are removed. In some instances, 

trees are climbed. Generally, 4-5 L of seed and debris are 

collected.

Good seed collections have been made in the Maritime 

Provinces, with fewer collections made in other 

provinces (Fig. 2). The challenge has been to engage 

seed collectors and agencies in these provinces. There has 

been more enthusiasm during the last couple of years, so 

it is hoped that the level of interest will continue to grow 

and that collectors will be in place to take advantage of 
56 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

Table 2. Number of ash seed collections in storage at the National Tree

 Seed Centre

Species Number of collections

F. americana 222

F. nigra 149

F. pennsylvanica 154

F. profunda 1

F. quadrangulata 1

Figure 2.—Locations of ash seed collections stored at the National Tree Seed Centre.

good seed crops. Seed from more than 520 collections 

is in storage at the Seed Centre (Table 2). About 42 

percent of the collections are white ash, 29 percent are 

green ash, and 28 percent are green ash.

Seed undergo some processing before storage. First, 

coarse debris (such as leaves, leaf rachises, and stems 

to which the seeds were attached) is removed. Green 

and white ash seed are de-winged, whereby about 50 

percent of the wing is removed. The seed are then put 

into an aspirator, which blows away the debris as well as 

most empty and insect-damaged seed. These processing 

treatments also reduce the volume of seed to store. 

However, black ash seed cannot be de-winged in this 

manner and are stored fully intact. After cleaning and 

processing, the final volume can be 1-2 L of seed.

Seed quality of each collection is determined by 

conducting a viability test, which indicates whether an 

embryo is alive and capable of germinating. Results from 

viability tests can be obtained within 14 days, whereas 

germination tests may require 4-12 months to complete, 

depending on the species, due to treatments required 

to alleviate seed dormancy. To conduct viability tests, 
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 57

Seed are stored under two categories: research and 

conservation. When seed is limiting for a seedlot, 

the entire quantity is allocated to conservation. Seed 

stored for research is freely available, upon request, 

for research. When a seedlot becomes exhausted, a 

fresh collection is not made. On the other hand, seed 

stored for conservation will remain there indefinitely. 

Seed from these collections will be provided only for 

research that aims to advance the knowledge required 

for the preservation of the species, such as genomics, 

breeding, and re-establishment/preservation plantations. 

Approximately 2,000 seed are stored for conservation; 

on average, 3,000 seed are stored for research.

the seed is removed from the pericarp and placed in 

water at 3 °C for 96-120 hours. The purpose of this 

treatment is to soften the seed coat and allow the seed 

to absorb water, making it easier to process. After the 

seed is soaked, a scalpel is used to make a longitudinal 

incision the length of the seed coat, through which 

the embryo is removed. The embryo is placed on 

germination medium (VersaPakJ) in a germination box. 

Three replications of 25 seed each are prepared. The 

germination box is placed in a germination cabinet set 

at 25 °C with a daily light duration of 8 hours. After 

14 days, the embryos are assessed. An embryo is viable 

if it remains the same color as it was when excised, 

one or both cotyledons turn green, and/or the radicle 

starts to develop. Of the three principal ash species, 

green ash seed are least dormant and the embryos 

often exhibit considerable development during the 14 

days, with cotyledons turning green and growing as 

well as elongation of the radicle. In contrast, black ash 

embryos are very dormant and exhibit little growth, 

usually remaining milky white in color with minimal 

elongation.

An identification card is placed in each sealed jar and 

the species and seedlot numbers are marked on the 

lid. Before storage, the moisture content of the seed 

is determined. The maximum moisture content is 8 

percent, and moisture contents are typically 6.5-8.0 

percent. Seed at these moisture contents tolerate 

freezing and store well. All seed are stored at -20 °C.

THE FUTURE

Seed collecting must continue, particularly in areas 

where EAB is well established and is killing trees. It is 

important to sample and store these genes before they 

are lost forever. Seed must be collected from populations 

growing on a variety of sites throughout a species’ 

range in order to sample the range of natural genetic 

variation. As a minimum, the following number of 

collections must be made: F. americana - 230, F. nigra

- 460, F. pennsylvanica - 430, F. profunda - 30, and F. 

quadrangulata - 50.

At some point, a genetic analysis should be conducted 

for each species to evaluate the pattern of genetic 

variation and possibly identify areas with more or less 

variation. Additional seed collections can be made in 

areas exhibiting more genetic variation.

Areas should be revisited after EAB has moved through 

in case there are trees that are still alive. Such trees may 

have somehow escaped the ravages of EAB or may be 

genetically resistant. Such trees (if they exist) should be 

clonally propagated and their resistance evaluated.

A bank is only as good as its poorest vault. It is prudent 

to store seed samples at a second location as a back-up 

in case of a catastrophe at the principal storage facility. 

The National Tree Seed Centre and the United States 

National Center for Genetic Resources Preservation 

have entered into an agreement to store samples of each 

other’s seed.

ACKnOwlEdgMEnts

Appreciation is extended to A. Mosseler for reviewing a 

draft of this paper and to I. DeMerchant for preparing 

Figure 2.

LItEraturE CItEd

Farrar, J.L. 1995. Trees in Canada. Markham, ON: 

Fitzhenry and Whiteside Ltd. 502 p.

Marchant, K.R. 2007. Managing the emerald ash borer 

in Canada. In: Gottschalk, Kurt W., ed. Proceedings, 

17th U.S. Department of Agriculture interagency 

research forum on gypsy moth and other invasive 

species 2006. Gen. Tech. Rep. NRS-P-10. Newtown 

Square, PA: U.S. Department of Agriculture, Forest 

Service, Northern Research Station: 67-69.
58 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

AdVEntItIOus sHOOt rEgEnEratIOn Of

FRAXINUS NIGRA MarsH.

Rochelle R. Beasley and Paula M. Pijut

Purdue University (RRB), Department of Forestry and Natural 

Resources, Hardwood Tree Improvement and Regeneration Center 

(HTIRC), 715 West State St., West Lafayette, IN 47907

and U.S. Forest Service (PMP),Northern Research Station,

HTIRC, 715 West State St.,West Lafayette, IN 47907.

PMP is corresponding author; to contact,

email at ppijut@purdue.edu. or ppijut@fs.fed.us.

Fraxinus nigra Marsh. (black ash) is a native ash species 

occurring in Newfoundland west to Manitoba and 

south to Iowa, Illinois, West Virginia, and Virginia. 

Although it is not a commercially important species, 

it has significant ethnobotanical importance to Native 

American tribes of the eastern United States. The 

seeds are important forage for wildlife, the wood is 

preferred for making splints for basketry, and the wood 

is also used for flooring and furniture. F. nigra have 

immature embryos at seed set combined with complex 

stratification requirements, making the species difficult 

to regenerate naturally from seed. Because of this 

difficulty, an in-vitro adventitious shoot regeneration 

system would be beneficial for mass propagation 

and improvement of this species. The development 

of such a system will also provide the basis for an 

Agrobacterium-mediated transformation system for 

emerald ash borer resistance. To date, no in-vitro 

regeneration protocol for black ash has been developed. 

An adventitious shoot regeneration system for F. nigra

is currently being optimized using hypocotyls extracted 

from aseptic seeds. Hypocotyls were cultured on a 

Murashige and Skoog (MS) medium containing 13.3 

μM 6-benzylaminopurine (BA) plus 4.5 μM thidiazuron 

(TDZ) for callus and shoot induction. Shoots were 

successfully regenerated using a combination of MS 

medium with Gamborg B5 vitamins (MSB5), 10 μM 

BA, and 10 μm TDZ for 4 weeks, and then they were 

transferred to MSB5 medium with 6.7 μM BA, 1 μM 

indole-3-butyric acid (IBA), and 0.29 μM gibberellic 

acid (GA3) for shoot elongation. Once elongated, the 

shoots were successfully micropropagated using MSB5 

medium with 13.3 μM BA, 1 μM IBA, 0.29 μM GA3, 

and 0.2 g L-1 casein hydrolysate. Rooting of elongated 

microshoots was successful using woody plant medium 

containing 4.5 μM IBA plus 5.7 μM indole-3-acetic acid 

with a 10-day dark incubation, and rooted shoots are 

undergoing acclimatization.
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 59

EstIMatIng OutsIdE-barK stEM VOluME tO 

anY tOp dIaMEtEr fOr asH In WIsCOnsIn

Paul F. Doruska and Timothy D. Hart

Professor of Forestry (PFD), College of Natural Resources (TDH),

University of Wisconsin-Stevens Point,

800 Reserve St., Stevens Point, WI 54481.

PFD is corresponding author;

to contact, call (715) 346-3988

or email at pdoruska@uwsp.edu.

The future of Wisconsin’s estimated 742 million 

ash trees (5 million of which are in urban settings 

composing 20 percent of Wisconsin’s urban forests) is 

being considered based on the presence of the emerald 

ash borer. Part of this discussion includes the stem 

volumes of these ash trees. An outside-bark volume 

ratio equation was developed for individual trees, 

allowing one to estimate outside-bark stem volume 

(cubic feet) to any top diameter limit for green and 

white ash trees in Wisconsin. Outside-bark stem 

diameters were estimated at predetermined heights 

aboveground on 84 standing trees in central Wisconsin, 

using two Laser Technology Inc. Criterion RD 1000 

optical dendrometers with lines of sight perpendicular 

to one another. A subset of trees was felled to validate 

the diameter estimates obtained with the optical 

dendrometers, and a paired t-test confirmed that no 

differences exist (p-value = 0.36) between the standing 

tree diameter estimates and the corresponding felled 

tree measurements. An outside-bark, total stem volume 

equation was then developed. The equation explained 

about 98 percent of the variation present and possessed 

a mean absolute error of 1.4 cubic feet per tree. A ratio 

equation was subsequently developed to estimate the 

proportion of outside-bark stem volume present in a 

given tree up to a given top diameter. The ratio equation 

explained about 86 percent of the variation present 

in the data and possessed a mean absolute error of 

0.015 (or 1.5 percent). Applying the ratio equation to 

volumes derived from the total stem volume equation 

on validation data resulted in a mean absolute error of 

4.5 cubic feet per tree. Use of the outside-bark total 

stem volume and ratio equations should allow resource 

managers to make more informed management and 

utilization decisions about ash trees in Wisconsin.
60 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

SurVEY fOr tOlEranCE tO EMErald asH 

bOrEr wItHIn NOrtH AMErICan asH spECIEs

Jennifer L. Koch, Mary E. Mason, David W. Carey,

Kathleen Knight, Therese Poland, and Daniel A. Herms

U.S. Forest Service, Northern Research Station (JLK, DWC, KK), 

359 Main Rd., Delaware, OH 43015; Department of Entomology 

(MEM, DAH), The Ohio State University,

Ohio Agricultural Research and Development Center,

1680 Madison Ave., Wooster, OH 44691;

U.S. Forest Service, Northern Research Station (TP),

1407 S. Harrison Rd., East Lansing, MI 48823.

JLK is corresponding author;

to contact, email at jkoch@fs.fed.us.

Since the discovery of the emerald ash borer (EAB) 

near Detroit, MI, in 2002, more than 40 million ash 

trees have been killed and another 7.5 billion are at 

risk in the United States. When the EAB outbreak was 

initially discovered, our native ash species appeared to 

have no resistance to the pest. Variation in the response 

of native ash species to EAB may have gone unnoticed 

in the Detroit area and surrounding suburbs, where 

ash was a popular street tree. Because the vast majority 

of street trees are vegetatively propagated horticulture 

selections, it is likely only a limited number of genotypes 

were represented. The establishment of “ash-free” zones 

may have delayed observations of ash trees with any 

tolerance to EAB in some areas. As the beetle spread 

away from urban areas into more genetically diverse 

native stands and woodlots, plots were established to 

monitor the impact of EAB. The health of more than 

3,000 ash trees in infested forests in Michigan and 

Ohio has been monitored yearly using a canopy health 

index. In these areas EAB has been present for several 

years, and almost all of the ash trees are dead. However, 

our yearly inventory has identified a small number of 

trees that have persisted. Approximately 1.0 percent 

of the ash trees have remained alive and 0.1 percent 

have retained a healthy crown appearance. To date, we 

have identified and grafted 18 select “lingering ash”: 15 

Fraxinus pennsylvanica, 2 F. americana, and 1 F. nigra. 

These trees were selected from the main canopy layer and 

did not include seedlings or saplings. Initial feeding and 

landing studies have been performed on a subset of these 

trees, and preliminary results indicate that some of the 

lingering ash selections are less preferred by the beetle. 

We are ramping up propagation of each selection for the 

establishment of field test plots and further analysis using 

insect bioassays to distinguish trees that are “escapes” 

from those that may be tolerant or even resistant to 

EAB. Those selections that display tolerance/resistance 

to EAB will be further analyzed using molecular 

and biochemical methods to identify the underlying 

mechanisms. Although some of these trees still may 

succumb to EAB infestation, the mechanisms that allow 

them to “linger” longer than their counterparts may be 

further enhanced through breeding. Conceivably, under 

lower insect pressure, the trees that can survive longer 

may be capable of co-existing with EAB. 
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 61

ClIMatIC COntrOls On

EMErald asH bOrEr dIspErsal

Greg C. Liknes, Susan J. Crocker, and Dacia M. Meneguzzo

U.S. Forest Service, Northern Research Station,

St. Paul, MN 55108. SJC is corresponding author;

to contact, call (651)649-5136

or email at scrocker@fs.fed.us.

We examine whether emerald ash borer (EAB) is limited 

not only by the presence of ash, but also by climatic 

factors. Using the WorldClim and CRU TS 2.1 global 

climate datasets, we delineate the native climatic range 

of EAB in Asia and the climatically equivalent areas 

in North America. Using a data-mining approach, we 

identify which of a suite of bioclimatic variables are 

important factors in the native range of EAB. A map of 

locations in North America that satisfy both climatic and 

host criteria is presented.
62 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

A tECHnIQuE fOr MappIng urban asH trEEs

usIng ObJECt-basEd IMagE analYsIs

Dacia M. Meneguzzo, Susan J. Crocker, and Greg C. Liknes

U.S. Forest Service, Northern Research Station,

St. Paul, MN 55108.

SJC is corresponding author;

to contact, call (651) 649-5136

or email at scrocker@fs.fed.us.

Ash trees are an important resource in the State of 

Minnesota and a common fixture lining the streets 

of the Twin Cities metropolitan area. In 2009, the 

emerald ash borer (EAB), an invasive pest of ash, was 

discovered in the city of St. Paul. To properly respond 

to the new-found threat, decisionmakers would benefit 

from detailed, spatially explicit information on the 

urban ash resource. Although the Forest Inventory and 

Analysis (FIA) Program is responsible for inventorying 

the Nation’s forests, it does not currently include treecovered lands in urban areas unless they meet FIA’s 

definition of “forest.” Because this definition includes 

minimum area, width, and density requirements, shade 

and boulevard trees are excluded from the inventory. 

Therefore, we investigate the use of remote- sensing 

procedures to supplement FIA inventory data. We 

present a technique for identifying ash tree canopies 

using eCognition Developer 8 image segmentation 

software and four-band high-resolution imagery. A finescale map of ash trees is produced for a study area in the 

Twin Cities. 
2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72 63

AdVEntItIOus sHOOt rEgEnEratIOn

and rOOtIng Of FRAXINUS AMERICANA

Kaitlin J. Palla and Paula M. Pijut

Purdue University (KJP), Department of Forestry and Natural Resources,

Hardwood Tree Improvement and Regeneration Center (HTIRC),

 715 West State St., West Lafayette, IN 47907;

 and U.S. Forest Service (PMP),

Northern Research Station, HTIRC, 

715 West State St.,West Lafayette, IN 47907.

KJP is corresponding author;

to contact, e-mail at kpalla@purdue.edu.

White ash (Fraxinus americana) trees provide both 

ecological and economic benefits. Loss of this North 

American endemic would disturb the environment. The 

urban ash tree industry in the United States would also 

suffer, as would manufacturers of baseball bats, furniture, 

and cabinets. The emerald ash borer (EAB) is an invasive 

species that is fatal to a tree once the borer infests it. 

There are no known means of complete eradication 

or evidence of any innate resistance in F. americana. 

The threat from this pest becomes more urgent with 

each growing season, making the development of an 

in-vitro plant regeneration and transformation system 

a valuable goal. As a first step toward this objective, 

a protocol for adventitious shoot regeneration and 

rooting was developed from freshly isolated hypocotyls 

obtained from mature embryos of white ash. The best 

regeneration medium for hypocotyls was Murashige 

and Skoog (MS) medium supplemented with 13.3 μM 

6-benzylaminopurine (BA) plus 4.5 μM thidiazuron 

(TDZ). Sixty-four percent of hypocotyl segments 

produced adventitious shoots, with a mean of 3.5 

adventitious shoots induced per explant. Adventitious 

shoots from hypocotyls were established as proliferating 

shoot cultures following transfer to MS medium with 

Gamborg B5 vitamins (MSB5) supplemented with 10 

μM BA plus 10 μM TDZ. For in-vitro rooting trials, 

woody plant medium with indole-3-acetic acid (IAA) 

[2.9, 5.7, or 8.6 μM] plus 4.9 μM indole-3-butyric acid 

(IBA) were tested under 10-day dark treatment followed 

by culture in the light. Early results show successful 

(77.1 percent) rooting of in-vitro shoots on medium 

containing 4.9 μM IBA plus 5.7 μM IAA. Rooted plants 

were successfully acclimatized to the culture room. 

This regeneration system from hypocotyls provides 

a foundation for Agrobacterium-mediated genetic 

transformation of white ash for resistance to the EAB.
64 2010 Proceedings Symposium on Ash in North America GTR-NRS-P-72

REspOnsE Of YOung asH trEEs tO

Cultural trEatMEnts nOt all pOsItIVE

Felix Ponder, Jr.

Research Soil Scientist, U.S. Forest Service, Northern Research Station, 208 Foster Hall, 

Lincoln University, Jefferson City, MO 65102;

to contact, call (573) 681-5575 or e-mail at fponder@fs.fed.us.

Calcium cyanamide (CaN2), an alkaline nitrogenous 

fertilizer containing about 22 percent N and 20 

percent lime, was evaluated as a fertilizer for young 

white ash (Fraxinus americana L.). Neither height nor 

diameter of 4-year-old ash trees treated with three 

annual applications of CaN2 at rates of 448, 672, 896, 

and 1,120 kg/ha was significantly different from the 

unfertilized control trees. Following two applications 

of CaN2 at the rates applied to younger trees, 7-yearold white ash were taller and larger in diameter than 

the unfertilized control trees, but differences were not 

significant.

The effects of tree shelters on the performance and 

leaf nutrient concentrations of planted green ash (F. 

pennsylvanica) were investigated at age 3. Mean survival 

of trees with shelters was 92 percent compared to 62 

percent without shelters. Sheltered trees had significantly 

more stem and root biomass than trees without shelters. 

Foliar phosphorus, calcium, and magnesium levels were 

significantly higher and potassium was significantly 

lower in green ash leaves from trees with shelters than in 

green ash leaves without shelters.

Annual height measurements taken for green ash 

in another planting, grown with and without tree 

shelters, indicated considerable dieback after year 

5, and measurements were terminated after year 8. 

Mean survival was not different between tree shelter 

treatments, but it declined from 88 percent after 1 

year to 55 percent by year 8. Green ash trees with 

shelters were taller than those without shelters after the 

first growing season. But by year 5, height differences 

between treatments disappeared. The exact cause of the 

dieback and eventual mortality is not known, and there 

was no difference in the amount of dieback between tree 

shelter treatments. The author speculated that insects 

were responsible for the decline.
Michler, Charles H.; Ginzel, Matthew D., eds. 2010. Proceedings of

symposium on ash in North America. Gen. Tech. Rep. NRS-P-72. 

Newtown Square, PA: U.S. Department of Agriculture, Forest Service, 

Northern Research Station. 64 p.

Includes 5 papers and 30 abstracts covering topics related to the biology and

ecology of the ash species, ash utilization and management, emerald ash borer., 

and other threats to ash, and genetics and conservation of ash species

KEY WORDS: green ash, black ash, white ash, blue ash, emerald ash borer, 

Fraxinus.

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