How Illinois Kicked the Exotic Habit
From: Exotic Pests of Eastern Forests, Conference Proceedings - April 8-10, 1997, Nashville, TN, Edited by: Kerry O. Britton, USDA Forest Service & TN Exotic Pest Plant Council
For the purpose of this paper, an exotic species is defined as "a
plant or animal not native to North America." The history of folly
surrounding the premeditated and accidental introduction of exotic animals
has been well-documented (De Vos et al. 1956, Elton 1958, Hall 1963, Laycock
1966, Ehrenfeld 1970, Bratton 1974/1975, Howe and Bratton 1976, Moyle 1976,
Courtenay 1978, Coblentz 1978, Iverson 1978, Weller 1981, Bratton 1982,
Vale 1982, and Savidge 1987).
In 1963, Dr. E. Raymond Hall wrote, "Introducing exotic species
of vertebrates is unscientific, economically wasteful, politically shortsighted,
and biologically wrong." Naturalizing exotic species are living time
bombs, but no one knows for sure how much time we have. For example, the
ring-necked pheasant (Phasianus colchicus), touted as the Midwestern
example of a good exotic introduction, has recently developed a nefarious
relationship with the greater prairie chicken (Tympanuchus cupido) in Illinois.
Parasitism of prairie chicken nests by hen pheasants and harassment of displaying
male chickens by cock pheasants are contributing to the decline of prairie
chickens in Illinois (Vance and Westemeier 1979). The interspecific competition
between the exotic pheasant (which is expanding its range in Illinois) and
the native prairie chicken (which is an endangered species in Illinois)
may be the final factor causing the extirpation of the prairie chicken from
Illinois; it has already been extirpated from neighboring Indiana.
In 1953, Klimstra and Hankla wrote, "In connection with the development
of a pheasant adapted to southern conditions, the compatibility of pheasants
and quail (Colinus virginianus) needs to be evaluated. It would be
unwise to establish a game bird that would compete with another desirable
species." It has been recently discovered that ring-necked pheasants
also parasitize quail nests (Westemeier et al. 1989). Management at Illinois'
prairie chicken preserves now include pheasant control 12 months of the
Michigan is apparently not moved by the potential threats that exotic
animals pose (Huggler 1991). They recently released the Sichuan or "brush"
pheasant (Phasianus colchicus strauchi) into the wild, and Indiana
officials are considering the same move. The preferred habitat of the Sichuan
pheasant and the ruffed grouse (Bonasa umbellus) overlap. Consequently,
if the "brush" pheasant becomes fully naturalized, it may become
a serious competitor to the native ruffed grouse.
The raccoon dog (Nytereutes procynoides), a member of the dog
family, apparently is native to Asia. Between 1927 and 1957, they were introduced
to Europe both intentionally and accidentally as escapees from fur farms.
As a result of their high reproduction rate, omnivorous feeding habits,
and general lack of enemies, they have spread rapidly throughout northern
and western Europe. Later, like the nutria (Myocuster coypus), they
were brought to the United States as fur-bearing stock. Raccoon dogs prefer
forested, riparian habitats, marshes, and dense cover surrounding lakes.
They are opportunistic, eating a wide variety of plants and animals, including
eggs, fish, and carrion. They are the only canid that hibernates, but they
are not "deep sleepers." On warm days, they forage and in the
southern parts of their range, they do not hibernate at all (Ward and Wurster-Hill
1990). If raccoon dogs were to escape captivity and become fully naturalized,
they have all the characteristics to become a serious predator of many native
species of wildlife.
On July 23, 1983, it became illegal to possess, propagate, or release
a raccoon dog in Illinois. But three separate fur farms had purchased raccoon
dogs before the law was passed. On July 11, 1984, the Illinois Department
of Conservation paid $41,000 to buy the raccoon dogs from those fur farmers.
The rusty crayfish (Orconectus rusticus), originally sold as fish
bait, is an aggressive exotic species that replaces native crayfish (Page
1985). Four species of crayfish are currently listed on Illinois' endangered
species list. The establishment of rusty crayfish in Illinois would be a
serious threat to these native species. Consequently, as of June 29, 1990,
the importation, possession, and sale of live rusty crayfish was banned
The Issue of Exotic Plant Materials
Dr. Hall was right about the dangers of introducing exotic vertebrates,
and his analysis applies to the introduction of exotic plant material as
well (Reed 1977). Unfortunately, less is appreciated about the tremendous
damage that is occurring to our continent's ecosystems due to the escape
and naturalization of exotic plants (Bratton 1982); Harty 1986; Mooney and
Drake 1986). In Illinois, as elsewhere, the perceived merits versus the
perceived impacts associated with introducing exotic plant species are argued
as a matter of philosophy among wildlife biologists, soil conservationists,
foresters, landscapers, and ecologists. However, evidence is mounting to
indicate that the introduction of exotic plant species has resulted in major
ecological damage and caused serious management problems.
Multiflora rose (Rosa multiflora) is the classic Midwestern example
of an exotic species run amuck, aggressively overgrowing pastures and abandoned
farm ground. It was originally promoted in the 1940s for use as a living
fence, erosion control, and wildlife food and cover, with the added assurance
during its initial promotion that it would not spread or become a nuisance.
These claims seem naive in retrospect. Nevertheless, variations of the same
scenario have been used to promote autumn olive (Elaeagnus umbellata),
bush honeysuckle (Lonicera tatarica), amur honeysuckle (L. maackii),
and many other exotic species. Klimstra (1956) was one of the first to point
out the problems associated with the widespread planting of multiflora rose;
moreover, he questioned the REAL versus the PERCEIVED value of multiflora
rose for wildlife habitat planting.
In Illinois, 811 species, or 29 percent, of the state's flora are naturalized
from foreign countries (Henry and Scott 1980). Not all these species can
be classified as problem species today, but Tartarian honeysuckle, amur
honeysuckle, tree-of-heaven (Ailanthus altissima), thistle (Carduus
nutans), Canada thistle (Cirsium arvense), crown vetch (Coronilla
varia), giant teasel (Dipsacus laciniatus), European beach grass
(Elymus arenarius), tall fescue (Festuca pratensis), sericea
lespedeza (Lespedeza cuneata), multiflora rose, Japanese honeysuckle
(Lonicera japonica), purple loosestrife (Lythrum salicaria),
white poplar (Populus alba), smooth and shining buckthorn (Rhamnus
cathartica and R. frangula), and Johnson grass (Sorghum halepense),
are just a few examples of exotic plant introductions causing farmers, foresters,
land-managers, and grounds-keepers considerable problems in various regions
of the state (West 1984; Schwegman 1988).
Moreover, autumn olive, osage orange (Maclura pomifera), and winged-euonymus
(Euonymus alatus), three of the long-term "neutrals" in
the game of exotic roulette, have now adapted sufficiently to Illinois'
conditions that they, too, are becoming naturalized weeds, spreading from
plantings into the landscape (Nyboer and Ebinger 1978, Ebinger and Lehnen
1981, Ebinger et al. 1984, Nestleroad et al. 1987). Ebinger (1983) summarizes
the problems that naturalized exotic shrubs (multiflora rose, Japanese honeysuckle,
autumn olive, winged-euonymus, and blunt-leaved privet (Ligustrum obtusifolium)
are causing managers of natural areas in Illinois. Additionally, climbing
euonymous (Euonymous fortunei) and oriental bittersweet (Celastrus
orbiculatus), two popular ornamental vines, are becoming invaders in
southern Illinois forests (Schwegman 1991, personal communication).
Why Did We Plant Exotics in the First Place?
The common refrain associated with the promotion of exotic plant materials
is that "they are hardy, disease free, have few, if any, insect pests,
reproduce or propagate easily, and provide food or cover for wildlife."
These characteristics are precisely what makes exotic species such serious
competitors when released into a new ecosystem or habitat.
Two recent examples of this scenario are the release of "Elsmo"
lace-bark elm (Ulmus parviflora Jacq.), and "Redstone"
Cornelian cherry dogwood (Cornus mas L.) by the Soil Conservation
Service (Plants for Conservation 3(1) January 1991, and Plants for Conservation
3(2) July 1991). Siberian elm (Ulmus pumila) was promoted to replace
American elm (Ulmus americana) as a streety tree after the American
elm was devastated by an introduced pathogen that caused Dutch Elm disease.
Siberian elm failed in its original purpose, but was successful at naturalizing
into many parts of the country. Now lace bark elm is being promoted to replace
Siberian elm. From an ecological standpoint, we seem to be trapped on a
devil's merry-go-round. Cornus mas has been in the landscaping trade for
years, known as Cornelian cherry (Rehder 1960); it seems unfortunate that
we would now be promoting it for conservation purposes. There are at least
11 species of shrubby dogwoods native to the eastern United States. These
native species offer equivalent soil conservation benefits and an abundance
of fruits for wildlife with no ecological risks.
Sawtooth oak (Quercus acutissima), a species from Asia, provides
another example of promoting an exotic species as an alternative wildlife
food plant (Hopkins and Huntley 1979). Thirty-six years ago, Klimstra (1956),
pointed out the potential problems associated with planting multiflora rose.
Similarly, Coblentz (1981), has pointed out the lack of foresight and, more
importantly, the lack of hindsight in promoting the exotic sawtooth oak
over the 37 species of oaks native to the southeastern United States for
mast production for wildlife.
In spite of the mounting evidence of the ecological dangers associated
with exotics and the skyrocketing costs of controlling them, exotic species
continue to be tested and promoted for the same worn-out reasons:
- wildlife habitat plantings (autumn olive and bush honeysuckle)
- landscaping purposes (blackthorn and purple loosestrife)
- wood and fiber production (Princess tree [Paulownia tomentosa] and
- soil conservation practices (crown vetch and multiflora rose)
- forage improvement (Johnson grass and tall fescue)
What Is At Risk Because of Exotic Plants?
Entire plant communities, such as fens, bogs, and marshes, can be significantly
altered by invasive plant species, such as purple loosestrife (Thompson
et al. 1987). Endangered species, such as Kankakee mallow (Iliamna remota)
may be crowded out of its last habitat by multiflora rose and the bush honeysuckles
(Glass 1986, personal communication). Common plants, such as bluebells (Mertensia
virginica) are being crowded out of forests by garlic mustard (Iverson
et al. 1991). The native high-bush cranberry (Viburnum trilobum)
is known to hybridize with the ornamental, Viburnum opulus. This
may result in the loss of the native genotype, or it could result in creating
an aggressive hybrid species similar to the case of Spartina anglica
Oak reproduction is a major concern of foresters, ecologists, wildlife
biologists, and natural area managers, and naturalized exotic shrubs and
vines are now being identified as serious competitors to oak regeneration.
A recent example is oriental bittersweet, which is becoming a serious pest
on many hardwood regeneration sites in the Appalachians (McNab and Meeker
What Are The Costs Associated With Exotic Introductions?
Although the economic cost of controlling exotic introductions can be
calculated, the ecological damage cannot be measured in dollars. For example,
Brandenburg Bog in northeastern Illinois, was purchased to preserve, protect,
and perpetuate a rare calcareous fen community. Purple loosestrife is invading
the fen, and it may be beyond eradication (Heidorn 1986, personal communication).
The direct cost of this exotic species to the State of Illinois in this
example is at least $379,000, the cost of purchase in 1973. However, "Brandenburg
Bog is the premier calcareous fen in the state and as such is irreplaceable"
How Illinois Kicked The Exotic Habit A Case History
The Illinois Department of Conservation nurseries began producing autumn
olive in 1964. By 1982, our nurseries were distributing more than 1,000,000
autumn olive seedlings a year, which represented about 20 percent of the
state nursery's production of all species combined (Sternberg 1982). We
also produced large numbers of bush honeysuckles.
In 1983, our Seedling Needs Committee met to review the needs of the
department relative to seedling production. This is a standing committee
comprised of representatives from the divisions of Wildlife Resources, Forestry,
Public Lands, Planning, and Natural Heritage. The issue of exotics and the
role of the state nurseries in their production, was addressed by the committee.
The committee agreed that further production of exotic plant materials in
our nurseries was not necessary if suitable native species could be grown
as substitutes for the exotics. The concept of substituting native species
for exotic species is compelling when one considers that:
- native species comprise 99 percent of the wildlife species we manage
habitat for, and they evolved with native plant species. Furthermore, there
is no hard evidence to support the contention that exotic plant materials
are superior to native species for wildlife (Martin et al. 1951)
- there is no reason to believe that native species of trees and shrubs
cannot be grown in nurseries using techniques similar to those we use to
grow exotics (Schopmeyer 1974)
- when developing landscaping plans for state parks, conservation areas,
and other Department of Conservation facilities, it seems more appropriate
to use native plant materials in keeping with the natural setting (Hightshoe
- future management problems caused by introducing new exotic plant materials
could be reduced if we promoted and planted native species for conservation
Today, our nurseries produce 67 species of native trees and shrubs for
use in developing wildlife habitat, reclamation projects, and community
restorations (Table 1). The seeds necessary to propagate these native species
are collected from state parks and conservation areas by our wildlife biologists,
foresters, natural heritage biologists, site superintendents, maintenance
workers, and volunteers.
Table 1. Native trees and shrubs grown at Illinois Department of Conservation
|Carya ovalis, C. cordiformis,
C. glabra, C. tomentosa
|various Hickory species
||Red osier dogwood
||Iowa crab apple
||Wild black cherry
||Swamp white oak
|Quercus prinoides var. acuminata
||Yellow chestnut oak
In 1977, the Illinois nursery system moved forward once more by producing
big bluestem (Andropogon gerardii) and Indian grass (Sorghastrum
nutans) seed for prairie reconstructions. By 1980, our Mason Tree Nursery
had expanded its operation to include 37 different species of prairie forbs.
In 1983, 35,000 prairie forbs were obtained from 596 m2 of bed space (Wallace
et al. 1986).
The grass and forb program has been very successful. Production for 1991
included 54 forb species and 7 grass species (Table 2); 293,457 prairie
forb rootstocks were grown in 1,900 m2 of bed space. In addition, attempts
to grow woodland herbaceous species have been initiated with 13 species
currently involved (Table 3). Approximately $4 million in capital improvements
at the Mason Nursery has increased seed bed space from 16 ha to 40 ha and
built a 279 m2 greenhouse for herbaceous production. The facility is also
equipped with a grass seed cleaning and processing facility and a center
pivot irrigation system, which will allow expansion of the grass seed collection
area to 16 hectares (Pequignot 1992, personal communication).
Besides attempts to eliminate exotic species from our nursery operations,
educational articles discussing the problems with exotic plants and animals
have been published in our department's official publication, Outdoor Highlights
(Harty 1985; Schwegman 1985, 1988). Moreover, a colorful flier was prepared
that explained the problems associated with planting purple loosestrife
and recommended measures for its control. Species-specific alert fliers
were produced for garlic mustard (Alliaria petiolata), rudd (Scardineus
erythrophthalmus), rusty crayfish, and zebra mussels (Dreissena polymorpha).
A slide tape program describing the problems associated with exotic plant
species in Illinois was also produced for use in educating the general public.
Table 2. Native prairie forb and grass species grown at the Mason Tree
Nursery, Topeka, Illinois
|Aster novae-angliae||New England aster|
|Astragalus tennesseensis||Ground plum|
|Baptisia lactea||White wild indigo|
|Baptisia leucophaea||Cream wild indigo|
|Boltonia decurrens||Decurrent false aster|
|Calcalia plantaginea||Prairie Indian plantain|
|Camassia scilloides||Wild hyacinth|
|Ceanothus americanus||New Jersey tea|
|Coreopsis lanceolata||Tickseed coreopsis|
|Coreopsis palmata||Prairie coreopsis|
|Coreopsis tripteris||Tall tickseed|
|Dalea candida||White prairie clover|
|Dalea foliosa||Leafy prairie clover|
|Dalea purpurea||Purple prairie clover|
|Desmanthus illinoensis||Illinois mimosa|
|Desmodium canadense||Showy tick trefoil|
|Desmodium illinoense||Illinois tick trefoil|
|Dodecatheon meadia||Shooting star|
|Echinacea pallida||Pale coneflower|
|Eryngium yuccifolium||Rattlesnake master|
|Helianthus occidentalis||Western sunflower|
|Heliopsis helianthoides||False sunflower|
|Heuchera richardsonii||Prairie alumroot|
|Hieracium longipilum||Hairy hawkweed|
|Iliamna remota||Kankakee mallow|
|Iris shrevei||Wild blue iris|
|Lespedeza capitata||Round-headed bush clover|
|Lespedeza leptostachya||Prairie bush clover|
|Liatris aspera||Rough blazing star|
|Liatris pycnostachya||Prairie blazing star|
|Liatris spicata||Marsh blazing star|
|Monarda fistulosa||Wild bergamont|
|Napaea dioica||Glade mallow|
|Parthenium integrifolium||American feverfew|
|Physostegia virginiana||False dragonhead|
|Polytaenia nuttalli||Prairie parsley|
|Potentilla arguta||Prairie cinquefoil|
|Prenanthes aspera||Rough white lettuce|
|Ratibida pinnata||Drooping coneflower|
|Rosa carolina||Pasture rose|
|Rudbeckia subtomentosa||Fragrant coneflower|
|Silene regia||Royal catchfly|
|Solidago rigida||Rigid goldenrod|
|Zizia aurea||Golden alexanders|
Thirty-four (34) vegetation management circulars were prepared by various
authors for the Illinois Nature Preserves Commission. These circulars provide
information about specific exotic plant species and management recommendations
for their control or eradication. Many of these circulars have been published
in the Natural Areas Journal.
In addition to these efforts, two other publications, Landscaping for
Wildlife, and Illinois Prairie: Past and Future A Restoration Guide,
promote the use of native species and point out the problems associated
with exotic plant species.
Another significant step forward was the development of a windbreak manual
for Illinois (Bolin et al. 1987). This is a cooperative effort by the University
of Illinois, Department of Forestry, Cooperative Extension Service, the
USDA Soil Conservation Service, and the Illinois Department of Conservation.
The issue of exotics was addressed early in the planning of this manual,
and the committee, which is comprised of inter-agency foresters, wildlife
biologists, and natural-heritage biologists, recommended 30 native trees
and shrubs and three nonnative species as suitable for use for windbreaks
and snow trips in Illinois (Table 4). The three nonnative species to Illinois,
Norway spruce (Picea abies), blue spruce (Picea pungens),
and Douglas-fir (Pseudotsuga mensiesii), have been planted throughout
Illinois for many years and have not been found to reproduce spontaneously
from seed. This has proven to be a prudent compromise.
Table 3. Native woodland herbaceous species grown at the Mason Tree Nursery,
|Actaea pachypoda||Doll's eyes|
|Asarum canadense||Wild ginger|
|Claytonia virginica||Spring beauty|
|Dicentra cucullaria||Dutchman's breeches|
|Isopyrum biternatum||False rue anemone|
|Polygonatum commutatum||Solomon's seal|
|Smilacina racemosa||False Solomon's seal|
The Illinois Department of Transportation has also been quite cooperative
regarding management of exotics along right-of-ways and cloverleafs adjacent
to Department of Conservation properties. For the past three years, the
Department of Conservation and the Soil Conservation Service (SCS) have
been working cooperatively to collect seeds from native shrubs for the SCS
to evaluate at their Elsberry Plant Improvement Center in Missouri.
Table 4. Native tree and shrub species recommended for windbreaks and
snow trips in Illinois (Bolin et al. 1987)
|Aronia melanocarpa||Black Chokeberry|
|Cornus alternifolia||Alternative-leaved dogwood|
|Cornus drummondii||Rough-leaved dogwood|
|Cornus obliqua||Pale dogwood|
|Cornus racemosa||Gray dogwood|
|Cornus stolonifera||Red osier dogwood|
|Crataegus crus-galli||Cock-spur thorn|
|Crataegus mollis||Red haw|
|Crataegus phaenopyrum||Washington hawthorn|
|Juniperus communis||Common juniper|
|Juniperus virginiana||Red cedar|
|Malus ioensis||Iowa crab apple|
|Picea abies||Norway Spruce|
|Picea pungens||Blue spruce|
|Pinus strobus||White pine|
|Prunus americana||Wild plum|
|Prunus virginiana||Common chokecherry|
|Taxus canadensis||Canada yew|
|Thuja occidentalis||Arbor vitae|
|Viburnum acerifolium||Maple-leaved arrowwood|
|Viburnum prunifolium||Black haw|
|Viburnum rafinesquianum||Downy arrowwood|
|Viburnum recognitum (V. Dentatum)||Smooth arrowwood|
|Viburnum rufidulum||Southern black haw|
|Viburnum trilobum||High-bush cranberry|
Seventeen species are currently being evaluated for their wildlife food
and cover value (Table 5).
Table 5. Native shrubs being evaluated as food and cover plants by the
Soil Conservation Service's Plant Improvement Center, Elsberry, MO
|Aronia melanocarpa||Alternate-leaved dogwood|
|Cornus drummondii||Rough-leaved dogwood|
|Cornus obliqua||Pale dogwood|
|Cornus racemosa||Black chokeberry|
|Cornus alternifolia||Gray dogwood|
|Juniperus virginiana||Red cedar|
|Prunus americana||Wild plum|
|Prunus virginiana||Common chokecherry|
|Ribes americana||Wild black currant|
|Thuja accidentalis||Arbor vitae|
|Viburnum prunifolium||Black haw|
|Viburnum recognitum (V. dentatum)||Smooth arrowwood|
|Viburnum trilobum||High-bush cranberry|
On January 1, 1988, Illinois passed the Illinois Exotic Weed Act. Exotic
weeds are defined as "... plants not native to North America which,
when planted, either spread vegetatively or naturalize and degrade natural
communities, reduce the value of fish and wildlife habitat, or threaten
an Illinois endangered or threatened species."
There are currently three listed species-Japanese honeysuckle, multiflora
rose, and purple loosestrife. It is unlawful to sell, buy, offer for sale,
or distribute seeds, plants, or plant parts without a permit issued by the
Illinois Department of Conservation. A violation of the act is a Class B
misdemeanor, and listed plants are confiscated and destroyed.
On May 25, 1989, the Director of the Illinois Department of Conservation
signed a department policy on the planting and removal of exotic plant species.
The policy lists 12 species which cannot be used on DOC property and lists
five species which can be used only for short rotation, research, or erosion
control (Table 6).
Table 6. List of exotic plant species and their permissible uses on Illinois
Department of Conservation properties as authorized by Policy Manual Code
No. 2450 dated May 25, 1989
|Scientific Name||Common Name||Permissible Uses|
|Celastrus orbiculatus||Round-leaved Bittersweet||None|
|Coronilla varia||Crown vetch||None|
|Elaeagnus umbellata||Autumn olive||None|
|Euonymus alatus||Winged euonymus||None|
|Euonymus fortunei||Climbing euonymus||None|
|Festuca elatior||Tall fescue||Critical erosion area|
|Lespedeza cuneata||Serecia lespedeza||Cover crop and nigrogen fixation|
|Lonicera japonica||Japanese honeysuckle||None|
|Lonicera maackii||Amur honeysuckle||None|
|Lonicera tartarica||Tartarian honeysickle||None|
|Lythrum salicaria||Purple loosestrife||None|
|Melilotus alba||White sweet clover||Short rotation cropland|
|Melilorus officinalis||Yellow sweet clover||Short rotation cropland|
|Rhamnus frangula||Glossy buckthorn||None|
|Robinia||Black locust||Strip mine reclamation, nurse crop in black walnut plantation, mixed with 34 other species in forest application with unfavorable site conditions|
|Rosa multiflora||Multiflora rose||None|
Once exotics become naturalized, they often change community species
composition, alter structure, and reduce natural diversity of native plant
and animal communities. Moreover, if an exotic becomes naturalized and spreads
throughout a system, getting it out of that system is like trying to unscramble
It is the responsibility of all natural resource professionals to provide
proper and prudent management advice to private and public landowners and
managers. To continue to ignore the documented consequences associated with
introducing exotic species in the name of soil conservation, wildlife management,
or reforestation, would fall short of this obligation.
A giant step forward is necessary to head off the invasion of exotic
plant materials into the natural landscape. We must redirect our reforestation
and wildlife habitat restoration efforts away from exotics and toward the
utilization of native plant species that are compatible with native ecosystems.
Illinois is extremely fortunate to have natural resource agencies and
resource professionals who have taken decisive action in addressing the
issue of exotic species.
Laycock (1966) described the pursuit of exotic species as a "perpetual
relay race with one generation passing the stick to the next." I am
happy to report that the Illinois Department of Conservation has not dropped
the baton. It is the author's hope that this paper will stimulate activity
in other states to address the issue of exotic species within their jurisdiction.
I wish to acknowledge the following people and their agencies because
they are the ones who worked together so successfully to address the issue
of exotic plant species in Illinois. Richard Oliver, Steve Brady, Ray Herman,
and Gene Barickman, Soil Conservation Service; Mike Bolin, University of
Illinois Extension Service; Gary Rolfe, Department of Forestry, University
of Illinois; Al Mickelson, Stewart Pequignot, and Dick Little, Division
of Forestry, Illinois Department of Conservation; John Schwegman and Carl
Becker, Division of Natural Heritage, Illinois Department of Conservation,
and Guy Sternberg, Division of Special Services, Illinois Department of
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