SPECIES: Fraxinus pennsylvanica

Table of Contents


INTRODUCTORY


 

AUTHORSHIP AND CITATION:
Gucker, Corey L. 2005. Fraxinus pennsylvanica. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].

FEIS ABBREVIATION:
FRAPEN

SYNONYMS:
Fraxinus pennsylvanica var. pennsylvanica Marshall
Fraxinus pennsylvanica var. subintergerrima Vahl. [47,227,269]

NRCS PLANT CODE [289]:
FRPE

COMMON NAMES:
green ash
red ash

TAXONOMY:
The scientific name of green ash is Fraxinus pennsylvanica Marsh. (Oleaceae) [79,108,110,124,165,227,297]. This review will not distinguish between green ash varieties as they are not recognized consistently, and many systematists do not consider them valid taxa [108,124,188,289].

Taylor [280] describes a rare white ash (F. americana) green ash hybrid in an area near Ann Arbor, Michigan, where both species occur.

LIFE FORM:
Tree

FEDERAL LEGAL STATUS:
None

OTHER STATUS:
None

DISTRIBUTION AND OCCURRENCE

SPECIES: Fraxinus pennsylvanica
GENERAL DISTRIBUTION:
Green ash is widely distributed in the United States and Canada. Its native range extends from Nova Scotia west to southeastern Alberta and south through central Montana to southeastern Texas, Florida, and the east coast [167,269]. Green ash is nonnative in Utah and Colorado, where it has escaped as an ornamental and colonized [302,304]. Some suggest that green ash trees along the Clark Fork River in western Montana are also escaped ornamentals [177]. The The US Geological Survey provides a distributional map of green ash.

ECOSYSTEMS [99]:
FRES10 White-red-jack pine
FRES13 Loblolly-shortleaf pine
FRES14 Oak-pine
FRES15 Oak-hickory
FRES16 Oak-gum-cypress
FRES17 Elm-ash-cottonwood
FRES18 Maple-beech-birch
FRES19 Aspen-birch

STATES/PROVINCES: (key to state/province abbreviations)
UNITED STATES

AL AR CO CT DE FL GA
IL IN IA KS KY LA ME
MD MA MI MN MS MO MT
NE NH NJ NY NC ND OH
OK PA RI SC SD TN TX
UT VT VA WV WI WY DC

CANADA
AB MB NB NS ON PE PQ
SK

BLM PHYSIOGRAPHIC REGIONS [32]:
7 Lower Basin and Range
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands

KUCHLER [175] PLANT ASSOCIATIONS:
K017 Black Hills pine forest
K081 Oak savanna
K084 Cross Timbers
K089 Black Belt
K095 Great Lakes pine forest
K098 Northern floodplain forest
K099 Maple-basswood forest
K100 Oak-hickory forest
K101 Elm-ash forest
K103 Mixed mesophytic forest
K104 Appalachian oak forest
K106 Northern hardwoods
K109 Transition between K104 and K106
K111 Oak-hickory-pine
K112 Southern mixed forest
K113 Southern floodplain forest

SAF COVER TYPES [90]:
14 Northern pin oak
15 Red pine
16 Aspen
20 White pine-northern red oak-red maple
21 Eastern white pine
26 Sugar maple-basswood
27 Sugar maple
39 Black ash-American elm-red maple
40 Post oak-blackjack oak
42 Bur oak
44 Chestnut oak
52 White oak-black oak-northern red oak
55 Northern red oak
57 Yellow-poplar
59 Yellow-poplar-white oak-northern red oak
60 Beech-sugar maple
61 River birch-sycamore
62 Silver maple-American elm
63 Cottonwood
64 Sassafras-persimmon
65 Pin oak-sweetgum
75 Shortleaf pine
81 Loblolly pine
82 Loblolly pine-hardwood
87 Sweetgum-yellow-poplar
88 Willow oak-water oak-diamondleaf (laurel) oak
89 Live oak
91 Swamp chestnut oak-cherrybark oak
92 Sweetgum-willow oak
93 Sugarberry-American elm-green ash
94 Sycamore-sweetgum-American elm
95 Black willow
96 Overcup oak-water hickory
97 Atlantic white-cedar
101 Baldcypress
102 Baldcypress-tupelo
103 Water tupelo-swamp tupelo
108 Red maple
110 Black oak
203 Balsam poplar
217 Aspen
220 Rocky Mountain juniper
222 Black cottonwood-willow
235 Cottonwood-willow
236 Bur oak

SRM (RANGELAND) COVER TYPES [252]:
411 Aspen woodland
412 Juniper-pinyon woodland
421 Chokecherry-serviceberry-rose
422 Riparian
732 Cross timbers-Texas (little bluestem-post oak)
733 Juniper-oak
805 Riparian
809 Mixed hardwood and pine

HABITAT TYPES AND PLANT COMMUNITIES:
Green ash is recognized as a dominant species in the following vegetation classifications:

AR: [259]
GA: [306]
KS: [181]
NE: [7]
MA: [166]
MD: [49]
MN: Voyageurs National Park [176]
MO: [80]
MT: [128,129,133,134,183]
ND: [106,107,131,213]
NY: [234]
OK: [142]
SC: [306]
TX: Trinity River floodplain [217]
WY: [65]
Custer National Forest of ND, SD, and MT [130]
Great Plains: [35,132]

MB: [53]
PQ: [293]

Green ash is a component of many vegetation and cover types across its range. The sugarberry-American elm (Celtis laevigata-Ulmus americana)-green ash cover type is found in southern forests from eastern Texas east to the Gulf Coast region and north to the major river floodplains of southern Illinois. This cover type occupies clay or silt loam soils and is considered successionally "long-term." Pure stands of green ash are occasional on moist flats or in shallow sloughs [159]. On low flats and sloughs of the Mississippi River floodplain, this type is typical after heavy cutting or fire. Other important associated species include dwarf hackberry (C. tenuifolia), water hickory (Carya aquatica), and willow oak (Quercus phellos) [221].

Western U.S.: Green ash is restricted to riparian areas in the westernmost portion of its range.

Montana: In central and eastern Montana, the green ash/chokecherry (Prunus virginiana) habitat type is common. This type is typical on older terraces of the Missouri River and commonly lines sections of the Yellowstone, Powder, Tongue, Milk, and Little Missouri rivers [133]. Lesica [183] recognizes a green ash-American elm/chokecherry vegetation association in which boxelder (Acer negundo) and Rocky Mountain juniper (Juniperus scopulorum) can occur. Quaking aspen (Populus tremuloides) may occur in the early successional stages. Associated shrubs include American plum (Prunus americana) and Saskatoon serviceberry (Amelanchier alnifolia) [133,183].

Wyoming: Green ash occurs in riparian areas of Wyoming in the boxelder-green ash-American elm/common snowberry (Symphoricarpos albus) community type. Other species common in this vegetation type are bur oak (Q. macrocarpa), hophornbeam (Ostrya virginiana), and cutleaf coneflower (Rudbeckia laciniata) [65].

Colorado: Green ash, American elm, and boxelder are typically present as minor species and contribute less than 1% coverage on the Arkansas and South Platte river drainages of eastern Colorado. The dominant species are plains cottonwood (Populus deltoides ssp. monilifera) and peachleaf willow (Salix amygdaloides). Saltcedar (Tamarix chinensis) often forms a dense subcanopy or shrub layer on the Arkansas River floodplain [187].

North-central U.S. and south-central Canada: In many forest cover types of the northern Great Plains and the Great Lakes regions, green ash is important. Green ash is typical in the bur oak cover type in the Black Hills of South Dakota and Wyoming where interior ponderosa pine (Pinus ponderosa var. scopulorum), American elm, and plains cottonwood are common as well [87]. In the northern Great Plains, green ash commonly invades the cottonwood (Populus spp.) forest cover type as succession advances beyond the pioneer stages [173]. In the sugar maple-basswood (Tilia americana) cover type of western Wisconsin and central Minnesota, green ash, hackberry, bitternut hickory (Carya cordiformis), and several oak (Quercus spp.) species occur together [111]. Green ash is also a major associate of the silver maple (Acer saccharinum)-American elm cover type that occurs in central U.S. forests and Canada's Great Lakes-St. Lawrence forest region. This type is considered "subclimax" along river bottoms and floodplains [222]. Along the Red, Assiniboine, Souris, and other rivers of Manitoba and eastern Saskatchewan, green ash is an important component of maple-elm-ash floodplain communities [33].

Manitoba: The eastern deciduous forest of Manitoba has a canopy dominated by green ash, American elm, and boxelder and a shrub-dominated understory of beaked hazelnut (Corylus cornuta), chokecherry, and American cranberrybush (Viburnum opulus var. americanum). This forest is predominant on nutrient-rich basic substrates [53]. Green ash is also typical of flooded and nonflooded woodlands surrounding Lake Manitoba. The forest nearest to the lake is often flooded in the spring and supports a mixture of green ash, shining willow (Salix lucida), peachleaf willow, and sandbar willow (S. interior). Forests beyond these rarely flood and are dominated by balsam poplar (Populus balsamifera), quaking aspen, green ash, boxelder, black willow (S. nigra), and American hazelnut (C. americana) [189].

North Dakota: Green ash is a dominant species in several upland hardwood habitat types of southwestern North Dakota. The green ash-American elm/chokecherry habitat type occupies mesic sites with gentle slopes and loam to silt loam soils [107]. The green ash/chokecherry vegetation type occupies intermittent drainages and narrow draws with slopes of up to 40% and soils containing more than 35% clay. The green ash/common snowberry vegetation is restricted to floodplains and tributaries of the Little Missouri River. The clay content of these soils is often 30% to 59%. The eastern cottonwood (P. deltoides)-green ash community type occurs on Missouri River floodplains. It is considered a mid-seral type that develops into the green ash/common snowberry type [106].

In west-central North Dakota, green ash-box elder forests are typical in river valleys of the Knife River Indian Villages National Historic Site [61].

Green ash is common in upland draws, valley bottoms, and moderately steep north- and east-facing slopes of the Badlands. Green ash-dominated vegetation abuts mixed-grass prairies in the uplands and cottonwood and silver sagebrush (Artemisia cana) in the valleys. American elm trees commonly occur with green ash in the northern Badlands. Boxelder and Rocky Mountain juniper are occasional associates in the bottomlands. Quaking aspen is present in disturbed stands that have experienced fire or die-off in the past. Bur oak associates with green ash north of the Killdeer Mountains [213].

Minnesota: Managers in Voyageurs National Park recognize a rare ash-elm/trillium (Trillium spp.) vegetation type. Canopy dominants in this type are black ash (Fraxinus nigra), green ash, and American elm. Ash-elm/trillium habitats are moist with deep, nutrient-rich soils [176].

Wisconsin: Green ash, swamp white oak (Q. bicolor), and common buckthorn (Rhamnus cathartica) are important in floodplain forests of southeastern Wisconsin's eastern ridges and lowland provinces. These species dominate soils with neutral pH that are typically moist throughout the growing season and experience spring flooding at intervals of every 2 to 3 years [85].

Along the lower 230 miles (370 km) of the Wisconsin River floodplain that includes 100-year-flood regions, river birch (Betula nigra), silver maple, black ash, green ash, eastern cottonwood, swamp white oak, black willow, and American elm are consistently found together [285].

Nebraska: Green ash is a subdominant species of dry bur oak-bitternut hickory forests along the Missouri River and northern red oak (Q. rubra var. rubra)-American basswood climax forests in eastern Nebraska. The green ash-American elm forest type is also found on most of Nebraska's river floodplains. However, it is most well developed on larger river floodplains [7].

In the bottomlands of Lost Creek in the Schultz Prairie of south-central Nebraska, green ash occupies savannah-like riparian vegetation. Associated canopy species may include bur oak, white mulberry (Morus alba), and/or silver maple. Roughleaf dogwood (Cornus drummondii) and American bittersweet (Celastrus scandens) are characteristic of the understory. A decreased fire frequency in this prairie region is thought to have facilitated an expansion of woody vegetation [240].

North-central Nebraska's Niobrara River valley supports hardwood communities where green ash is dominant. Other typical hardwood species include bur oak, basswood, boxelder, hophornbeam, black walnut (Juglans nigra), and American elm [163].

Illinois: In Vermilion County's Horseshoe Bottom Nature Preserve, silver maple, green ash, and black ash dominate all diameter classes in swamp communities [180]. Along the Oakwood Bottoms Greentree Reservoir of the Shawnee National Forest, green ash occurs in pin oak-cherrybark oak (Q. palustris-Q. pagoda) communities. This vegetation type is restricted to old fields [281].

Indiana: Green ash populates poorly drained sites in the old-growth Ginn Woods of east-central Indiana. Other species of the Ginn Woods include silver maple, red maple (A. rubrum), shellbark hickory (Carya laciniosa), American sycamore (Platanus occidentalis), and eastern cottonwood [18].

South-central U.S.: Abandoned agricultural fields and floodplains are typical green ash habitat in the south-central plains and coasts. Hook [145] describes green ash in association with the baldcypress (Taxodium distichum) cover type of the coastal plains. In the lower Midwest states, green ash is considered important in the sassafras-common persimmon (Sassafras albidum-Diospyros virginiana) cover type. Green ash commonly invades this pioneer type on old-field sites with deep soils [17].

Kansas: In the eastern portion of Kansas, the green ash-American elm-hackberry vegetation type occurs in temporarily flooded forests. Green ash is also a common component of the pecan (C. illinoensis)-hackberry forests found in the Cherokee lowlands, Glaciated Regions, and the Osage Cuestos area. The eastern cottonwood-black willow floodplain forests and bur oak-Shumard oak (Q. shumardii)-bitternut hickory/Indian woodoats (Chasmanthium latifolium) communities also provide green ash habitat [181].

Missouri: Green ash is a component of Boone County's old-growth Schnabel Woods, where some trees are as old as 205 years. Since the last study of this area, 40 years ago, green ash importance has declined, however. The dominant canopy species of the Schnabel Woods is sugar maple (A. saccharum), and other canopy species include northern red oak (Q. rubra), white oak (Q. alba), chinkapin oak (Q. muehlenbergii), basswood, and slippery elm (Ulmus rubra) [235].

In floodplain forests of northern Missouri's Dissected Till Plains, green ash dominates several forest types. In the black willow-green ash forest type, green ash has an importance value of 77. Green ash importance is just over 20 in the silver maple-American elm-green ash and oak-green ash-river birch forest types. Researchers indicate that green ash is well represented in the sapling stage and will likely remain in the area long term if there are no major disturbances [80].

Oklahoma: The green ash-American elm and American elm-slippery elm-sugarberry-hackberry-green ash vegetation associations are widespread throughout Oklahoma. In the Red River drainage, the green ash-cedar elm-(Ulmus crassifolia)-sugarberry vegetation type is typical, and the loblolly pine (Pinus taeda)-green ash-American elm/longleaf woodoats (C. sessiliflorum) community is common on floodplains and Coastal Plain swamps [142].

Arkansas: Along the Cache River floodplain of northeastern Arkansas, the Texas red oak (Q. texana)-green ash vegetation type populates low-lying areas. Sites occupied by this community may be flooded 90 to 100 days of the year [259].

Texas: Simpson [257] describes green ash in piney woods, Gulf prairies, marshes, post oak (Q. stellata) savannahs, blackland prairies, Cross Timbers, Rio Grande floodplains, and the Rolling Plains of eastern Texas.

In the Big Thicket National Preserve of southeastern Texas, green ash is common in flatland hardwood forests between the Trinity and Neches rivers where standing water is typical after heavy rains. Other species associated with this habitat are swamp chestnut oak (Q. michauxii), willow oak (Q. phellos), laurel oak (Q. laurifolia), and loblolly pine [194]. In low flood plains of the Roy E. Larsen Sandylands Sanctuary, green ash associates with water tupelo (Nyssa aquatica), sweetgum (Liquidambar styraciflua), baldcypress, and red maple [195].

Louisiana: Green ash is widely distributed in the Cat Island Swamp of Feliciana Parish. In the swamp, sugarberry and baldcypress are the most conspicuous canopy species but water tupelo, overcup oak (Q. lyrata), and pecan are also found [77].

Southeastern U.S.: Along the Gulf and Atlantic coasts and in the interior southeastern states, green ash associates with many vegetation types. The overcup oak-water hickory forest type is green ash habitat on floodplains and back water basins of the Gulf and Atlantic coast states and in Tennessee and southern Illinois. Sugarberry, American elm, water locust (Gleditsia aquatica), red maple, and/or Texas red oak are also typical of these forests [158]. In the coastal plains states, green ash is occasional in the baldcypress forest cover type [145]. On islands and levees of southern Louisiana and southwestern Mississippi, green ash associates with sugarberry and American elm in the live oak cover type [88].

Kentucky: In old-growth woodlands of Pennyroyal Plain, green ash is important in the subcanopy and understory. The common upper canopy vegetation of this area is dominated by a mix of shagbark hickory (Carya ovata), red maple, slippery elm, sweetgum, pin oak, swamp chestnut oak, and southern red oak (Q. falcata) [60].

Virginia: The hardwood forests of Virginia's lower Coastal Plain characteristically include green ash, American elm, red maple, cherrybark oak, swamp chestnut oak, willow oak, and/or laurel oak [58].

Tennessee: Green ash is an occasional species in wet and moist bottomland hardwood forests of the Natchez Trace State Forest, State Resort Park, and Wildlife Management Area of western Tennessee. Wet bottomland hardwood forests occupy poorly drained sites with moderate to high soil fertility. Other wet bottomland forest species include red maple, sweetgum, willow oak, and black willow. Moist bottomland hardwood forest canopies are diverse and may include yellow-poplar (Liriodendron tulipifera), sweetgum, white oak, loblolly pine, and/or red maple. Soils in moist bottomland forests are well drained, and soil fertility remains moderate to high [258].

North Carolina: Along the expansive floodplain of Tyrrell County's Scuppernong River, an assortment of bald cypress, loblolly pine, swamp tupelo (N. biflora), sweetgum, red maple, and green ash typically dominate the overstory. Occasionally water tupelo and Atlantic white-cedar (Chamaecyparis thyoides) are found [208].

South Carolina: The laurel oak-green ash and swamp chestnut oak-green ash floodplain forest types are common in Congaree Swamp National Park of central South Carolina [306].

Mississippi: Sharkey County is home to the Green Ash Research Natural Area. The vegetation of this area is dominated by Texas red oak, green ash, and American elm. There are old-growth green ash trees between 200 and 250 years old in the area [78].

Alabama: Green ash is typical of bottomland communities that line small streams in the lower Alabama Piedmont. Sweetgum and red maple are often found with green ash in these narrow floodplains with moderately well-drained soils [114].

Georgia: The swamp chestnut oak-green ash vegetation type is common on high-elevation floodplains in Georgia's Piedmont province. The red maple-green ash type is common in Georgia and occupies lower elevation floodplains. The sweetgum-laurel oak-green ash vegetation type is rare and occupies moderately wet to dry alluvial floodplains near Savannah [306].

Florida: Green ash is associated with several forest communities on the Apalachicola River floodplain of northwestern Florida. Other species occurring with green ash include sugarberry, water oak (Q. nigra), red maple, and planertree (Planera aquatica). Researchers estimate that within this 175 mi (454 km) floodplain 14,200 tons (12,900 tonnes) of ash leaf litter (predominantly Carolina ash (Fraxinus caroliniana) and green ash) falls annually [89].

Northeastern U.S. and southeastern Canada: Swamps and floodplains are typical green ash habitats in the northeastern United States and southeastern Canada. Green ash is common in mature sassafras-common persimmon forest types that occur in the mid-Atlantic states. Green ash replaces this pioneer type on upland and lowland old fields with deep soils [17].

Quebec: Green ash is a dominant canopy species in silver maple-green ash forests in the Lac des Deux-Montagnes area. This forest type occurs at elevations between 65.6 and 73.5 feet (20-22.5 m) on imperfectly or poorly drained soils. Red-osier dogwood (Cornus sericea ssp. sericea) and riverbank grape (Vitis riparia) dominate the shrub layer of silver maple-green ash forests. Green ash is also typically present in northern red oak and eastern white pine (Pinus strobus) forests that occupy well-drained soils at elevations of 79 to 98 feet (24-30 m) [293].

Massachusetts: The overstories of many small river floodplain forests in eastern Massachusetts are green ash dominated. The silver maple-green ash-pin oak vegetation type is typical of small tributaries of the Connecticut and Nashua rivers where flooding occurs. This type also occurs on island edges in the Merrimack River. Green ash is present but less common in the red maple-silver maple-swamp white oak and silver maple-green dragon (Arisaema dracontium) vegetation types [166].

New York: Green ash and black ash are codominants in the silver maple-ash forest type that is common along ravines and floodplains at the southern edge of Cayuga Lake in Tompkins County. In this vegetation type, silver maple contributes up to 70% of the total canopy coverage, and green and black ash together make up 5% to 15% cover [154].

Ohio: On poorly drained sites that are part of northwestern Ohio's Black Swamp, green ash occurs with silver maple, black ash, American elm, bur oak, and shellbark hickory [39].

Maryland: Green ash is a dominant species in the American sycamore-green ash-box elder-silver maple vegetation type characteristic of bottomlands in the Piedmont and Appalachian provinces. Along the Pocomoke River, green ash occurs in the abundant baldcypress vegetation association often together with red maple and sweetgum. Green ash also occurs in river birch-American sycamore vegetation in bottomlands and along shorelines of the Potomac River [49].

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

SPECIES: Fraxinus pennsylvanica

 

 

Kitty Kohout, Wisconsin State Herbarium

GENERAL BOTANICAL CHARACTERISTICS:
This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available [44,47,62,84,108,109,110,124,155,177,206,227,249,257,269,272,294,297,304,312,317].

Green ash is a deciduous tree with high branches and a slender growth form. It grows to 100 feet (40 m) in the southern part of its range but is typically half that height in the northern portion of its range [84,110,124,167,269]. Some research indicates height differences across the east to west range of this species as well. Trees found in New York are typically greater than 100 feet (30 m) tall, while those in South Dakota rarely exceed 49 feet (15 m) [1]. South Carolina's state champion green ash tree grows in the bottomland hardwood floodplain forest of Congaree National Park and was last measured in 2002. This tree was 143 feet (43.6 m) tall, and had a crown spread of 96 feet (29 m) and a circumference of 181 inches (460 cm) [263]. The 2004-2005 National Tree Register reports that the national champion green ash tree grows in Cass County, Michigan, and is 95 feet (29 m) tall, 259 inches (658 cm) in circumference, and has a 95-foot (29 m) canopy spread. This tree was last measured in 1995 [11].

The trunk of green ash trees is large and straight [269]. When subjected to prolonged periods of flooding, trunks may become enlarged at the base [110]. Under dry conditions, the outer bark is between 5 and 7 mm thick at breast height, while the inner bark measures a thickness of 1.5 to 2.5 mm [211].

Green ash leaves are opposite, odd-pinnately compound, and measure between 4.3 and 12 inches (11-30 cm) long by 3 to 7.1 inches (8-18 cm) wide [110,124]. Commonly there are 5 to 9 leaflets that are typically 2 to 4 inches (6-10 cm) long and 2 to 5 cm wide. Though thin, leaflets are "firm and leathery" [269]. Flowers appear before the leaves and are borne on old wood [110,304]. Female flowers are short, dense panicles with 200 to 300 flowers per panicle [269]. Trees as small as 20 to 30 feet (6-8 m) tall with dbh of 3 to 4 inches (8-10 cm) have produced flowers [167]. However, abundant flowers are not produced until trees are approximately 8 to 10 inches (20-30 cm) in diameter (review by [93]). The fruit is a single-seeded, winged samara measuring 10 to 15 mm long [108,269]. Seeds are small [308].

The rooting habit of young and adult green ash trees has been investigated by several researchers. Lateral roots are long with few branches. Fine lateral roots average 0.25 to 0.55 mm in diameter [48]. The rooting depth of green ash on fine-textured soils is described as shallow, between 5 and 10 feet (2-3 m). Although the root system is considered extensive, green ash trees may topple with high winds (reviews by [226,301]). In East Brunswick, New Jersey, 2- and 3-year-old green ash saplings were planted and excavated 3 years later. Maximum root spread for the saplings was 1.68 times their driplines, and crown and trunk diameter were significantly (p=0.01) correlated with root spread [103]. In eastern Nebraska, researchers examined the root depth and spread of several green ash trees representing a range of ages. A 3-year-old green ash tree in Lancaster County had roots that extended approximately 5 feet (2 m) deep and spread 8 feet (2 m) in diameter. A 24-year-old tree from Pawnee County had a root spread of a little over 30 feet (9 m) and a depth of more than 8 feet (2 m). In Merrick County, a 45-year-old green ash tree had roots that spread 44 feet (13 m) and extended 10 feet (3 m) deep [266]. For information on green ash mycorrhizal associations and their effect on green ash growth and/or resource acquisition, see [12,14,15,45].

Male and female trees: Green ash is dioecious. Morphological differences between male and female green ash trees were studied in Winnipeg, Manitoba. From a sample of 45 green ash trees between 15 and 45 years old, researchers found that the crown of male trees was generally rounder, broader, and fuller than female tree crowns [233]. However, from 6 male and 6 female green ash trees in the same area between 254 and 373 inches (644-948 cm) tall, researchers found that female trees had significantly greater shoot length (p=0.04), greater lateral shoot length (p=0.0005), and a greater number of lateral shoots (p=0.007) than male trees [74].

Adaptations to flooding: Green ash trees tolerate flooding through a variety of physiological and morphological adaptations. Researchers have observed shoot lenticels, adventitious roots, increased lateral root production coupled with decreased downward root growth, and succulent roots with large air spaces [199]. Oxidation of the rhizosphere, accelerated anaerobic respiration in secondary roots, and the growth of new secondary roots are important flood adaptations as well [146,278].

Phenotypic variation: Green ash trees exhibit a high level of phenotypic variation, and many researchers have highlighted differences in the growth rate, survival, drought tolerance, appearance, and cold tolerance of green ash seedlings grown from seed collected in northern vs. southern and eastern vs. western locations. Seed collected from similar latitudes in New York, Ohio, Illinois, Nebraska, and South Dakota represented a gradient of decreasing annual precipitation. Drought resistance of the seedlings increased from east to west locations when grown in a common location. South Dakota seedlings had small, thick leaves, while New York seedlings' leaves were thin and large [1]. A similar study compared 6-month to 1-year-old seedlings grown in a common area from seed collected from 39 different locations in the Great Plains. Researchers observed an increase in drought tolerance, decrease in size of parent trees, and an increase in the percentage of trees with dark green foliage as location of the seed varied from south to north and east to west locations [202].

Growth rates decreased and winter hardiness increased in green ash trees grown from seed collected in more northerly latitudes. Green ash seed was collected from the Coastal Plain region of North and South Carolina and from the Mississippi River valley from southern Illinois to southern Louisiana and Mississippi. Five and ten years following planting in a common location, green ash trees from northern seed grew slower than those from southern seed [303]. Twenty seedlings collected from 9 eastern United States and Canada locations grown in a common nursery were easily sorted into 2 distinct groups. Northern seedlings collected from Maine, Michigan, Wisconsin, Ontario, and Minnesota grew slowly, dropped leaves early in the fall, and resisted winter kill. Southern seedlings collected from South Carolina, North Carolina, and Virginia had rapid growth rates, retained their leaves until late fall, and suffered more damage with cold winter temperatures. The length of stem damage from winter cold was 0.1 inch (0.3cm) and 5.7 inches (14 cm) in the northern and southern seedlings, respectively [314].

RAUNKIAER [228] LIFE FORM:
Phanerophyte

REGENERATION PROCESSES:
Green ash reproduces both through seed production and vegetative sprouting [250]. Two studies in Montana investigated sexual and asexual regeneration of green ash. In east-central Montana, studies in 17 green ash stands from 6 sites revealed that both vegetative regeneration and seed production were important to regeneration. The stands were uneven aged, suggesting an irregular recruitment pattern. On average 33% of green ash trees had live basal sprouts, and the likelihood of finding sprouts was greater for large-size trees than small trees. The average density of seedlings was 10 plants/100 m in all stands, but 9 of 17 stands had 0 to 1 plants/100 m. Stands with a greater number of seedlings typically had a more uneven age distribution than those without seedlings. Likely vegetative regeneration, which is typically coupled with periodic disturbances such as drought, fire, or logging, created the more even-aged communities [184].

In a postfire study, Lesica [185] found heavy reliance on vegetative regeneration and decreased production of seedlings by green ash trees recovering from fire. Green ash woodland sites in eastern Montana that burned in August or September between 1988 and 1998 were studied in 2001. There were more sprouts, fewer seedlings, and more dead trees on burned sites compared to unburned sites. Likely fire killed green ash seed on or near the soil surface, restricting seedling recruitment to seed producing trees, many of which were killed in the fires. The average number of sprouts, seedlings, and dead trees on unburned and 3- to 13-year-old burned sites is presented below. Data were collected from 0.025-ha circular plots [185].

Population attribute (mean) Burned Unburned
Sprouts 4.3 1.3
Diameter of sprouts (mm) 1.56 0.84
Seedlings 1.8 8.1
Dead trees 1.43 0.14

Pollination: Flowers are wind pollinated [22,167]. Male flowers mature earlier than female flowers, and female flowers are receptive from the time of bud opening to the time the stigma withers. Female receptiveness lasts 7 to 10 days for individual trees and 2 to 3 weeks for populations [277,315]. Some have observed green ash trees just 7 years old and 12 feet (3.7 m) tall flowering, but typically flowering occurs after trees reach 3 to 4 inches (8-10 cm) in diameter and/or a height of 20 feet (6 m) [316].

The majority of pollen produced travels 25 to 50 feet (7.6-15 m) from the source tree. Wright [313] counted the number of pollen grains from open-grown green ash trees at increasing distances from the source tree. The number of pollen grains from white and green ash trees was 2,502, 1,110, 110, and 2 from stations 25, 50, 150, and 400 feet (7.6, 15, 45.7, and 122 m) from the source tree, respectively. However, because of collection technique limitations, the author suggests that these numbers may incorporate an error factor of 2 or 3 [313].

Breeding system: Green ash trees are dioecious [110,124,269]. With male and female flowers on separate, wind-pollinated trees, outcrossing is mandatory and the potential for genetic exchange is great.

Seed production: Ash trees exhibit a masting behavior [38]. Sutherland and others [273] suggest that ash trees produce good seed crops every 5 or more years, while others suggest that good seed crops are produced every year by green ash [308]. Wright [316] reported a high percentage of male and female flowers each year and a high percentage of annual seed production by female trees.

In the Philadelphia area, green ash trees monitored from 1947 to 1951 revealed that a large number of flowers did not necessarily dictate a large number of seeds, but greater than 33% of observed green ash trees produced large seed crops for 2 or 3 sequential years [315]. Along the north shore forest margin of Quebec's St. Lawrence estuary, green ash seed production was high even when many trees showed signs of damage from ice and debris flows [179]. In forest fragments of southeastern Michigan, researchers monitored seed rain from May through February for 2 years. The basal area of green ash averaged 3 m/ha in the forests. Over the 2-year period, 73% of the 2.7 ft (0.25 m) seed traps received green ash seed rain, and an average of 60 green ash seeds were produced/m/year. The number of seeds trapped was greater in areas with a greater density of mature green ash trees [198].

Seed dispersal: Green ash seeds are primarily dispersed by wind but movement by water is also likely [10,167]. Animals cache ash seed [72], which may subsequently germinate and establish.

Dispersal distance: The dispersal distance of green ash seeds is dependent on season and time since seed shed. Seeds shed in the winter potentially move great distances from the source on frozen surfaces; seeds dropped in the fall typically rest near the parent tree [280]. Sutherland and others [273] report that ash seeds may travel 300 feet (100 m) or more from the parent tree.

The natural invasion of a reforestation project in the Tensas River National Wildlife Refuge was evaluated 6 years following Texas red oak and water oak plantings. The frequency of green ash volunteers was 61.9%, and green ash tree size averaged 13 inches (3.3 cm) dbh. The distance of planted fields ranged from 423 to 2,100 feet (129-640 m) from forested edges. Most green ash plants occurred on plots within 850 feet (259 m) of the forested edge. The density of green ash in nearby forested areas was not reported [197].

Green ash colonization of the Ouchita Wildlife Management Area of northeastern Louisiana resembled an "advancing front." Agriculture was abandoned in the area in 1984. In May of 2000, green ash, although not planted on the reclaimed site, was the most dominant woody species in terms of basal area and density. The density of green ash saplings was 800/ha within 30 feet (10 m) of the bordering forest edge and 70/ha at 300 feet (80 m) from the edge [28].

Seed banking: The length of time green ash seed remains viable in the soil likely depends on site conditions including temperature, flooding, and/or soil type. Sutherland and others [273] suggest that ash seeds are viable for up to 3 to 4 years in the seed bank. However, no green ash seed germination from seed bank samples in baldcypress-green ash swamps along the Cache River of Illinois. Sampling was conducted in April of 1992 and 1993 in 9 intact swamp forests and 51 former swamp sites that have been farmed for the last 1 to 50 years. Under greenhouse conditions, no green ash seedlings emerged from the swamp soil samples [204]. As sampling and laboratory techniques can affect seed bank study results [26,171], green ash may have been present in the seed bank despite its failure to emerge in the greenhouse.

Germination: Green ash seed requires cold stratification to germinate. Seeds dispersed in the fall and winter germinate the following spring [22]. Taylor [280] indicates that approximately 50% of the green ash seeds shed in the spring initiate germination with those that overwintered on the ground; the other 50% initiate germination the following spring. The embryos of newly fallen green ash seed are dormant. Temperatures near 40 F (5 C) are optimal for endosperm digestion, and germination is encouraged at daily temperatures alternating between 70 and 90 F (20-30 C) [268].

Green ash seeds can also germinate in flooded conditions. Seed collected in the fall was stratified for 30 days and put in 2 inches (5 cm) of tap water. Thirty percent of immersed seeds germinated [82].

Other research indicates that moisture affects seed viability and germinability. In a plantation, 500 seeds from 3 green ash trees were collected weekly from 31 August to 2 November 1970. Seeds slated for germination testing were stratified for 90 days at 40 F (5 C). The moisture content of other seeds was evaluated following collection. Researchers found that seed viability increased with maturity in consecutive weekly harvests. They also found that seeds with greater than 71% moisture content may not be fully mature, but seeds with 9% to 19% moisture were likely fully mature. The study also revealed that the moisture content of green ash seeds was influenced by late fall precipitation [70].

Seedling establishment/growth: Green ash seedlings establish best in partially shaded sites with moist soil or litter [209]. Researchers found more 1- to 5-year-old seedlings grew under a partial canopy than in open- or closed-canopy hardwood river bottom forests of southern Illinois. A greater number of 1- and 2-year-old seedlings established on sites with low (0.5 inch (1.3 cm)) litter depths than those with deeper litter (0.5-2 inches (1.3-5 cm)) [151].

From controlled studies, researchers established that ideal soil temperatures for green ash seedling growth are above 61 F (16 C). Green ash seedling growth increased with increasing soil temperatures from 50 to 70 F (8-20 C). Exceedingly low root zone soil temperatures adversely affected root growth and resource partitioning [13].

Green ash seedlings studied in 34 stands along North Dakota's Missouri River floodplain occurred in all sampled stands but average density and frequency were greatest on sites with "intermediate to high" nutrient levels [161].

Flood tolerance of seedlings: In southern Illinois, green ash seedling survival and development were monitored in flooded and nonflooded conditions. Seedlings developed "well past the cotyledon stage" were exposed to water levels approximately 1 inch above the soil surface. No green ash seedlings died after 60 days of flooding; green ash seedlings in saturated soils averaged 7.8 inches (19.9 cm) tall, while those in well-watered, well-aerated conditions averaged 1.4 inches (3.5 cm) tall [150]. However, no seedlings survived when green ash seedlings were subjected to flooding levels 1 foot (0.3 m) above the soil surface [149].

Seedling survival and growth: Seedling establishment, survival, and growth have been extensively studied. In central Ohio, researchers followed the establishment and survival of black ash, green ash, and white ash seedlings in open meadows and deciduous forests. Ashes made up 69.9% of 2,553 seedlings monitored. Significantly more (p≤0.05) ash seedlings emerged on lowland than upland sites and in forests than open meadows. Average ash seedling production was 24121(s x) new seedlings/100 m/year from 1984 to 1993. In 1988 and 1990, seedling production peaked at approximately 800 to 1,000 new seedlings/100 m. Production in 1988 and 1990 was significantly greater (p≤0.05) than for any other year. Peak production was not correlated with any observed annual or seasonal climate events. The average life span of ash seedlings was 5 to 7 months. The seedling population produced in June of 1990 was 916. By October of the same year, 66.7% were dead; by May of 1991, 96.6% were dead. Survivorship was likely affected by white-tailed deer browsing; deer occurred in densities of 0.6 to 0.7 animal/ha in the area [38].

Growth: Green ash trees produce more than 1 growth flush per season [135], and growth rates may increase with flooding frequency. Johnson [162] studied 34 stands along 80 river miles (100 km) of North Dakota's Missouri River. From tree core analyses, Johnson estimated mean total radial tree growth at 26.8 mm for 17 green ash trees grown for 15 years during high flooding frequencies. Trees grown for a 15-year period in the absence of flooding averaged 20.4 mm total radial tree growth. From 14 trees, Johnson estimated that the annual radial growth rate of green ash was 2.1 mm/year.

Asexual regeneration: Green ash is capable of producing root crown and epicormic sprouts, and both are typical following disturbances. Many report "prolific" and "vigorous" root crown sprouting following fire, logging, or other events that damage the trunk [167,183,247,248]. Epicormic sprouting is common following lesser damage to branches. Observations of green ash trees in Winnipeg, Manitoba, indicate that epicormic shoot production may not only be stimulated through damage. Researchers suspect that environmental and/or genetic cues may also signal epicormic shoot production [232].

The importance of vegetative sprouting following logging is illustrated in the following 2 studies. On the Tombigbee River floodplain in Choctaw County, Alabama, green ash trees were cut on 2 sites, 1 in early June and the other in early October. A total of 83 green ash trees were cut and monitored following logging. More than 50% of the stumps were sprouting 32 months after the fall harvest, while less that 50% had sprouted by the 3rd postharvest year in the summer harvest areas [115]. Secondary succession of mixed-hardwood forests in southeastern Virginia's Chowan River basin was studied following logging. Forests were clearcut from 2 and 20 years before the study period and allowed to regenerate naturally. Early coppice forests were dominated by red maple and ash, primarily green ash [265].

Flooding may also stimulate vegetative regeneration in green ash. The north shore forest margin of Quebec's St. Lawrence estuary has experienced an increase in the frequency of extreme flooding events in the 1950s and 1970s. Green ash trees damaged from these events regenerated from the root crown and at the point of breakage on damaged stems [179]. On an island in the Chippewa River near Eau Claire, Wisconsin, 96% of the counted green ash stems were sprouts. This finding may indicate a reliance on asexual regeneration on sites where the likelihood and/or frequency of disturbance is high [22].

SITE CHARACTERISTICS:
Green ash is most often described in association with riparian areas, floodplains, and swamps, but is also found in areas that periodically experience drought conditions. In the Great Plains states, green ash is described on floodplains, streambanks, lake margins, and ravines but is also typical on homesteads and in shelterbelt and windbreak plantings [124,269,294]. Moist to wet habitats are typical green ash habitats described for the southeastern United States as well [84,110]. In Florida green ash is common on floodplains and calcareous river swamps [62]. In Michigan sites occupied by green ash are at least seasonally wet [297]. Green ash occurs on both wet and dry sites in Arkansas [155].

Soils: Green ash tolerates a variety of soil types. Fertile, clay, silt, and/or loam soils that range from poorly to well drained are the most common generic descriptions of green ash soils [10,167,167,269].

Several researchers have described the soils in green ash vegetation types; soils are described below:

Vegetation type Area of focus Soil description
sugarberry-American elm-green ash major river floodplains from eastern Texas to Atlantic Coast & southern Illinois clay or silt loams [159]
green ash/chokecherry southwestern North Dakota >35% clay, pH 7.9-8.1
green ash/western snowberry southwestern North Dakota 30-59% clay, pH 8.0-8.3 [106]
green ash/chokecherry central and eastern Montana clay loam to sandy loam, water table <1 m in drought [133]
green ash-American elm western North Dakota pH 6.6-7, chemical ions in order of decreasing concentrations: Ca>Mg>Fe>K>P>Na>Mn>Zn>Sr>Cu [300]
green ash/chokecherry northwestern South Dakota moderately fertile, P levels low, N moderately low, 4-20% organic matter, neutral pH [296]
The green ash-American elm forest type when compared to other forest types in the area
had the highest organic matter, total N, and replaceable Ca and Mg levels [300].

On the Missouri River floodplain of North Dakota, green ash dominates soils with high clay content. Green ash seedlings and saplings display wide ecological tolerances with respect to soil nutrients, organic matter, and water capacity [162]. In eastern Texas, soils supporting green ash are heavy limestone clays, acidic sands, or sandy loams receiving ample water [257].

Plantations, shelterbelts, and reclaimed farmlands: Many have studied the relationships between soils and green ash growth in plantations, shelterbelts, and reclaimed agricultural areas. Soil analysis of a 6-year-old green ash plantation on the Neches River terrace in Tyler County, Texas, revealed a positive correlation between green ash height and pH of the A1 horizon. The pH of the A1 horizon ranged from 4.14 to 6.35 and accounted for 94.6% of the variation in green ash tree height, which ranged from 4.5 to 18.1 feet (1.4-5.52 m). Green ash height and fine soil materials at a depth of 2.5 feet (0.76 m) were negatively correlated. Correlations were reported as significant (significance levels not reported) [307].

In shelterbelts of Swift County, Minnesota, green ash survival and growth were monitored for 5 years on 3 different soils. Green ash survival was "excellent" regardless of soil type. However, trees planted on excessively drained, droughty, sandy loam soils grew slowly, while trees on silty, clay loam, calcareous soils with poor drainage grew best. Cloudy and rainy weather during the establishment period likely enhanced survival rates [55].

On abandoned farmlands of southwestern Quebec, green ash seedling survival and growth were compared on sites with stony littoral, sandy beach, dry-mesic moraine, mesic moraine, morainic ridge, and wet marine soils. Green ash survival was greater than 70% on all sites; however, height growth was best on nutrient-rich, fine-textured, well-drained dry-mesic moraine soils. Green ash displayed wide ecological tolerances of the soils studied, which ranged from rapidly to imperfectly drained with sand contents of 31% to 86% and clay contents of 7% to 26% [63].

Flooded soils: Green ash is flood tolerant, but studies indicate that green ash is more common on temporarily flooded sites. The elm-ash-cottonwood forest type is common along rivers and streams in the north-central states, and the forest dominants reportedly tolerate flooding for up to 50% of the growing season [209]. In lowland forests of southern Ontario, green ash constancy was 90% on temporarily flooded sites, 70% on sites located 49 feet (15 m) inland from ponds, and 30% on mounds in ponds that were raised above water level [92]. In the Piedmont of Georgia, researchers indicate that green ash "rapidly succumbs" to continued inundation during the growing season [94]. In lower hardwood swamp forests and backwaters or flats, green ash is typical on sites where flooding is not continuous [250].

Controlled experiments found reduced growth  in green ash seedlings grown in flooded conditions. Flood levels were 2 inches (5 cm) above the soil surface and lasted for 32 days. The relative growth rate of green ash leaves was 46% of well-watered controls. Root and stem growth of flooded seedlings were 6% and 73% of controls, respectively. The net photosynthetic rate of flooded green ash seedlings was 50% of controls by flood-day 8 and 30% by flood-day 32 [123].

Elevation: Below are the few areas that report elevational tolerances for green ash:

Area Elevation
Colorado >6,000 feet [120]
western North Dakota
(green ash-American elm type)
1,890-3,200 feet [300]
central and southern Texas >3,000 feet [257]
Utah "lower" elevations [304]
West Virginia "low" elevations [272]
southern Appalachians > 3,000 feet [84]

Climate: The wide range occupied by green ash implies a wide tolerance of climatic conditions. In a review of green ash, Kennedy [167] reports that green ash grows in humid to subhumid environments with average annual precipitation levels between 15 and 59.8 inches (380-1,520 mm), low average January temperatures of -0.4 to 55 F (-18 to 13 C), mean July temperatures from 64 to 81 F (18-27C), and an average number of 120 to 280 frost-free days.

In a 2-year study in the Little Missouri Badlands of North Dakota, where green ash grows, minimum and maximum temperatures reached -35 F (- 31C) and 105 F (41 C), respectively, and annual precipitation averaged 15.75 inches (400 mm) [318]. The climate described for green ash habitats in southeastern Texas is much milder. Reported minimum and maximum temperatures were 51.1 F (10.6 C) and 81.7 F (27.6 C), respectively, and annual precipitation averaged 52 inches (1,320 mm) in the Big Thicket National Preserve. However, the frequency of tropical storms and hurricanes in this region can be high [194]. A temperate climate regime is reported for the northern shore of Quebec's St. Lawrence estuary, which supports an almost pure green ash stand. From 1960 to 1988, the mean annual precipitation was 38.9 inches (987 mm), 9.1 inches (231 mm) of which was snow. The average January temperature was 10.9 F (-11.7 C), and the mean July temperature was 67.1 F (19.5 C) [179].

Drought tolerance: Although overwhelmingly described as a riparian, floodplain species, green ash has survived drought conditions in several areas. In southeastern South Dakota, green ash survival was 63% over a 5-year period (1934-1939) that included 2 years described as "the most severe droughts ever to visit" the area. The author cautioned that green ash should not be planted on upland sites with fine-textured soils, suggesting an increased likelihood of green ash tree mortality during drought conditions on these sites [191]. Green ash trees in windbreaks of western Minnesota suffered severe drought conditions in 1934. By the end of that summer, just 8% of green ash trees were dead or dying. However, in western Kansas, green ash mortality was 33% at the end of a 4-year-long drought. Trees investigated were all mature, established green ashes [8].

Cold tolerance: Green ash survival is consistently high in shelterbelt plantings of the northern Great Plains, where winters can be severe. However, green ash may suffer slightly increased winterkill with age, injury from late-spring frosts, and occasional broken stems from drifting snow [100]. Green ash seedlings grown from seed collected in Wisconsin were exposed to low temperatures and stomatal closure was measured. Green ash seedlings exposed to 3 days of 37 F (3 C) temperatures had increased stomatal closure with each successive day. Treatments of 43 to 48 F (6-9 C) did not produce the same response, suggesting that 37 F (3 C) is below green ash's cold tolerance [172]. Dormant 1-year-old twigs collected from an area near Greenville, Mississippi, and a site in St. Paul, Minnesota, were used to evaluate the freezing resistance of green ash. Researchers defined freezing resistance as the lowest temperature at which no injury occurred. Green ash bud and cortex xylem tissue from Mississippi resisted freezing at temperatures of -20 F (-30 C) and -40 F (-40 C), respectively. Bud and cortex xylem tissue from Minnesota resisted temperatures of -40 F (-40 C) and -90 F (-70 C), respectively [243].

SUCCESSIONAL STATUS:
Green ash is described as a pioneering, early successional, mid-successional, subclimax, climax, and old-growth species in the literature. In American beech (Fagus grandifolia)-sugar maple forests of southern Indiana, green ash is an early, open-field colonizing species that is later replaced by American beech and sugar maple [309]. The hackberry-elm-ash (Celtis-Ulmus-Fraxinus spp.) vegetation type occupying low flats and sloughs of the Mississippi River floodplain is considered temporary and typically follows heavy cutting and/or fire events [221]. Green ash appears early in the successional development of alluvial soils, sometimes as a pioneer or as a replacement to cottonwood, quaking aspen, and/or black willow communities [167]. The quaking aspen-green ash community type on floodplains of the Missouri River is a mid-seral type that is later replaced by the green ash/western snowberry type [106].

The cases in which green ash is labeled a late-successional or climax species are equally abundant. In the successional development of Nebraska's river floodplains, green ash is identified as a late-seral species [7]. The sugarberry-American elm-green ash cover type is identified as persistent by several authors [159,250]. Studies of 34 stands along 80 river miles (100 km) of North Dakota's Missouri River floodplain revealed an increased importance of green ash with increased substrate depth and increased stand age [162]. Along rivers and streams of the north-central states, the elm-ash-cottonwood forest type is considered subclimax [209]. After studying a sere along the Yellowstone River from Glendive to Sidney, Montana, researchers categorized green ash as a climax species [40]. Green ash also occurs in the old-growth Schnabel Woods of Boone County, central Missouri. However, the importance of green ash has declined over the last 40 years in the area [235]. Kindscher and Holah [169] report that green ash importance increases with increasing stand age in plains cottonwood-hardwood gallery forests of the Great Plains, and a dense layer of green ash saplings is common in old-growth stands.

Shade tolerance: Green ash is often described as moderately shade tolerant. Shade tolerance, however, decreases with increasing age of green ash trees [159,250].

Several have studied green ash seedling growth under shaded conditions. Growth and morphological differences were apparent in 2-year-old green ash seedlings grown under different levels of shading. After 5 weeks, seedlings in 4%, 8%, and 100% of full sun ceased to grow, but growth continued in 20% and 40% of full sun. Leaf thickness increased linearly with decreased shading. Trees in heavy shading had poorly developed crowns, reduced height growth, and fewer and smaller branches. The growth rate of trees grown in moderate shade and full sun conditions exceeded that of trees grown in heavy shade [25].

Findings were similar for nursery-grown green ash seedlings subjected to full sun and shade treatments in Lincoln, Nebraska. Comparisons of seedlings grown in full sun and shade (18% full sun) revealed that leaf blade area was larger and leaves were thinner on shade-grown trees. Relative growth rate (pretreatment growth rate/posttreatment growth rate) was 1.27 in shade and 2.85 in full sun [196].

General disturbance: Green ash easily colonizes disturbed sites when a seed source is available. In a study of green ash ecology, Taylor [280] reported that green ash frequency increased as the amount of disturbed area increased. In the Opinicon Lake area of southeastern Ontario, succession was monitored in 2 hay fields abandoned in 1970. Half of one field was ploughed in 1975. On 3 sides, fields were bordered by forests dominated by American elm, white ash, green ash, and sugar maple. In all plots, the occurrence of green ash was 54% for all years (1976-1994). Researchers indicated that green ash seed was likely wind dispersed; birds or small mammals may have also aided dispersal by caching seed [72].

Canopy release: Many studies indicate increased green ash growth in forest openings. Sites in several mixed-hardwood forests of southeastern Virginia's Chowan River basin were clearcut 2 to 19 years prior to study and allowed to regenerate naturally. Regeneration in the mixed-hardwood forests was dominated by ash, primarily green ash, and red maple. Most early regeneration was due to sprouting [265]. Green ash was also identified as the species that most quickly colonized forest openings in an extensive study of 34 stands along 80 river miles (100 km) of North Dakota's Missouri River floodplain [162].

In the Little Missouri National Grasslands of southwestern North Dakota's Custer National Forest, canopy removal experiments were monitored for 7 years in degraded green ash-dominated woody draws. Sites that had 40% of the overstory canopy removed were compared to those with no removal. Green ash tree heights were significantly (p=0.04) greater on sites with partial canopy removal for the 3rd, 4th, 5th, and 6th posttreatment years [291]. Harvesting 40% of the trees in the area also stimulated green ash sprouting and seedling growth. Seedling height was greater on harvested than unharvested sites, and within the harvested sites increases were greater on sites closed to grazing [41].

Green ash increased in importance following harvests in oak-dominated, mixed bottomland hardwood forests along the Tombigbee River floodplain in Choctaw County, Alabama. Before harvesting in the summer and fall of 1992, green ash made up 5% of the preharvest stems. Following harvest, green ash contributed 22% to the total number of stems in the area [116].

Secondary and old-growth forest comparisons: Green ash is found in both secondary and old-growth forests. Researchers compared 2nd-growth (<150 years old) and old-growth (>150 years old) forests in the Wayne National Forest of southeastern Ohio. Green ash was present as a canopy species in only 2nd-growth forests, as a sapling in most forests over 70 years old, and as a seedling in all forest age classes sampled [112]. On Horseshoe Lake Island in Alexander County, Illinois, green ash was most important in old-growth forests. Old-growth stands had been relatively undisturbed, while 2nd-growth stands were undisturbed for just the last 75 years [239]. Researchers predicted that green ash would "gradually diminish" from the approximately 100-year-old bottomland forests in Virginia's Meherrin River in Greensville County [251].

Floodplain succession: The patterns of green ash succession on alluvial floodplains are similar for many different rivers and regions. Green ash typically invades pioneer communities early in succession and remains in mature floodplain communities. Along a sinuous section of the Bogue Chitto River in Washington Parish, Louisiana, green ash occurred on the youngest surfaces referred to as the herb-forest transition zone and the oldest surfaces on the upper floodplain margin or the cut bank of the upstream river bend [238]. Studies of a sere along the Yellowstone River from Glendive to Sidney, Montana, suggest green ash is a climax species. Newly formed river sandbars were populated by quaking aspen and willow (Salix spp.) communities. Willows died out approximately 20 years following establishment. After about 100 years, quaking aspen declined and shrubs, primarily Wood's rose (Rosa woodsii) and western snowberry, increased in importance. Green ash colonized young quaking aspen communities, persisted through the shrub-dominated stage, and was common as a seedling in subsequent communities. The researcher expected green ash seedlings would replace decadent green ash adults, and thus green ash is likely a climax species [40].

Along the Missouri River of southeastern South Dakota, the 1st established woody vegetation is a black willow-sandbar willow community that is soon invaded by quaking aspen. The black willow-quaking aspen community persists for nearly 15 years before willow trees begin to die. More mesic conditions prevail after the loss of willows. Quaking aspen growth deteriorates about 50 years following establishment. With the loss of quaking aspen, green ash, American elm, and boxelder dominate the floodplain [311]. Another reach of the Missouri River floodplain in North Dakota, extending from the Garrison Dam to the Oahe Reservoir, has also been well studied. On recent alluvial deposits, quaking aspen and peachleaf willow are pioneers. Green ash and boxelder are 1st to reach tree size in the eastern cottonwood-peachleaf willow forests and persist in intermediate- and old-aged stands as well. The oldest trees in the study area were 300 to 350 years old, and green ash seedlings occurred in stands of all ages [161].

Using aerial photographs, ring counts, and/or stem cross sections, researchers reconstructed and evaluated forest floodplain succession on the Republican River of Clay County, Kansas. First to invade floodplain alluvium were sandbar willow, peachleaf willow, and quaking aspen; these species established on 1- or 2-year-old substrates. Within 10 years, red mulberry (Morus rubra), American elm, green ash, and boxelder appeared. Hackberry established when the floodplain surface was 10 to 30 years old. Sandbar willow survived only about 10 years, peachleaf willow survived for approximately 30 years, and quaking aspen died within 100 years of establishment. In 100- to over 150-year-old stands, American elm and hackberry dominated, but green ash was present as well. Below is the average basal area of green ash in different-aged stands [31]:

Stand age (years) 0-10 (n=8) 10-30 (n=17) 30-60 (n=7) >60* (n=7)
Trees <6 cm dbh <0.005 0.03 0.03 0.06
Trees >6 cm dbh 0 0.03 1.84 1.41
*Within the >60-year-old-stands, 2 were over 100 years old, 1 was 120 years old, and 1 was 150 years old.

Flooding: In a review, Hook [144] classified green ash as moderately flood tolerant. This tolerance rating suggests that green ash can develop from a seedling to a mature tree in soils that are waterlogged approximately 50% of the time. Winter, spring, and/or early summer flooding are most typical in green ash habitats. For more information on the survival and growth of green ash seedlings grown in flooded conditions, see the Seedling establishment/growth discussion above.

Eighteen years of vegetation change were monitored in Hickory Creek streambank forests of northeastern Illinois. Green ash dominated the frequently flooded lowland sites from the streambank margin to 3 feet (1 m) above bank level. The researcher described green ash as "very flood tolerant." Over the course of the 18-year-study, the relative density of green ash decreased but relative dominance increased [30].

Within the Montezuma National Wildlife Refuge of central New York, researchers compared 2 seasonally flooded sites to a nonflooded control site. The eastern pool was flooded in the spring from mid-March to mid- or late July. The western pool was flooded from mid-September to mid-November. Vegetation was surveyed in 1965 (before flooding of the western pool and 1 year following flooding of the eastern pool), in 1979 (2 years after the end of flooded conditions), and in 1995 (18 years after discontinued flooding in the area). Researchers found that in 1995 the density of saplings in the eastern and western pools was 30 to 90/ha, respectively, but was 270/ha in the control area. Sapling cores suggested that the majority of sapling recruitment occurred from 1967 to 1973, indicating lower recruitment levels in times of flooding. Green ash density and basal area are provided below for the flooded and nonflooded periods [76].

Site East-
flooded 1964-1977
West-
flooded 1966-1977
Control
year density
(trees/ha s x)
basal area (m/ha) density basal area density basal area
1965 160 7 ---- 140 0 ---- ---- ----
1979 170 47 8.2 2.4 190 38 5.8 1.8 330 92 6 2.2
1995 170 30 9.3 3.0 ---- 8.7 3.0 530 138 4.7 1.4

Extreme weather events: Typically a majority of green ash trees survive the high winds and/or ice that accompany extreme weather events. In eastern Ontario, the mortality of 62 green ash trees (>3.9 inches (9.9 cm) dbh) was 24.2% for 1996 to 1998 (after ice storms). Mortality was 4.4% from 1999 to 2000, and no green ash trees died in 2001. Damaged trees died relatively quickly [147]. In a "50- to 100-year" ice storm event that deposited ice 0.8 inch (2 cm) thick on branches of bottomland forests species in western New York's Till Plain, the average green ash crown damage was just 10% [246].

Following Hurricane Hugo, researchers evaluated the damage to mixed bottomland hardwood species in Congaree Swamp National Park of South Carolina. Winds exceeded speeds of 96.3 miles/hour (155 km/h) in forests that had been relatively undisturbed for the previous 100 years. In slough areas, 4 of 29 sampled green ash trees were uprooted; in bottomland sites, just 2 of 41 green ash trees were uprooted [225]. The number of recruits, defined as number of individuals to reach 2 cm dbh, increased significantly (p<0.05) following Hurricane Kate in old-growth southern mixed hardwood forests north of Tallahassee, Florida. There were 2 prehurricane (1978 to 1984) green ash recruits and 11 posthurricane (1985 to 1992) recruits. Increased recruitment was likely facilitated by the overstory mortality that followed the high wind speeds of 99 miles/hour (160 km/h) over areas with soils saturated by the storm [27].

SEASONAL DEVELOPMENT:
Green ash produces flowers before leaves [304]. The process from the start of inflorescence bud growth to fruit set takes 3 years for green ash trees, and on average 1/3rd of the flower buds initiated produce flowers [231]. In a review, Farmer and Pitcher [93] report that male trees flower almost every year, while female trees flower every 2 to 5 years.

From a 5-year study of 5 green ash trees in the Quetico-Superior Wilderness Center of northeastern Minnesota, Ahlgren [6] reported an "abrupt" increase in stem expansion with an "extreme" rise in temperature. Green ash bud swell coincided with flowering but occurred only after temperatures had reached 70 F (20 C) or more. The 1st trees leafed out on 10 April, and the last trees to leaf out did so on 3 June. The earliest trees to shed their leaves did so on 19 September, and the latest trees dropped leaves on 3 October [6]. In Ithaca, New York, researchers found that green ash seedlings initiated root growth in mid- to late May when temperatures were between 54 and 59 F (12-15 C); root growth ceased in the fall when temperatures were 40 to 50 F (6-8 C) [135]. In Manitoba, Remphrey [230] reports that shoot growth begins sometime from mid-April to early May. Green ash leaf fall is typically earlier than other associated species including maples (Acer spp.), elms, plums (Prunus spp.), alders (Alnus spp.), and oaks [308].

Below are the reported fruiting and flowering dates for green ash:

State or region Flowering dates Fruiting dates
Florida spring [62,317] ----
Illinois April-May [206] ----
north-central Texas February-March [79] ----
West Virginia April-May [272] ----
Blue Ridge province April-May [312] ----
Carolinas April August-October [227]
Great Plains April-May [124] ----
New England ---- 2July -25 September [249]
north-central Plains mid-April August-September [269]
Quetico-Superior Wilderness Center of northeastern Minnesota 1st flowered on 23 April; last initiation of flowering on 25 May* Seeds fell 3 October** [6]
*Based on a 5-year-long study of 5 trees; tree age and site occupied varied.
**Based on a single year of study.

FIRE ECOLOGY

SPECIES: Fraxinus pennsylvanica
FIRE ECOLOGY OR ADAPTATIONS:
Fire adaptations: Green ash trees sprout from the root crown following top-kill [183,247,248]. However, green ash may survive low-severity fires. Fire-scarred green ash trees have been studied in the Mississippi River delta by Hepting [140] and Toole [283]. Green ash may also produce epicormic sprouts when fires scorch but do not kill the main trunk.

The high seed production potential [38,308], wind-dispersed seed [22,167], and wide ecological tolerance of seedlings [63,162] make green ash a likely candidate for off-site colonization of burned sites. It is noted, however, that green ash seed on or near the soil surface does not survive fire [185].

Fire regimes: A wide range of fire regimes is described for green ash habitats. The savannah-like prairie-forest ecotones are more likely to experience frequent fire than are wet bottomland deciduous habitats. However, a variety of anthropogenic, climatic, and environmental conditions have affected and continue to affect the fire ecology of green ash habitats.

Prairie-forest ecotones: Many have suggested that fire may be important in woody draws and riparian areas of the Great Plains; however, the preEuropean settlement fire frequency of these habitats is largely unknown. Although riparian draws of the northern Great Plains are typically moister, greener, and more humid than surrounding grasslands, the narrow size of these draws, coupled with the high frequency of grassland fires before active fire suppression in the area, suggests that fires did burn these areas especially during drought conditions [255]. Other researchers have suggested that green ash/chokecherry habitats are fire adapted because most associated species display some fire tolerance and/or postfire sprouting ability [133]. Based on research that suggested low-severity fires promoted regeneration by thinning stands and promoting sprouting, Lesica [183] reasoned that some level of fire was important to the maintenance of upland green ash stands in eastern Montana. In a study designed to test his hypothesis, Lesica [185] found more sprouts, fewer seedlings, and more dead trees on burned sites than on similar nearby unburned sites. All sites burned in wildland fires. The low number of seedlings on burned sites suggested that fire killed green ash seed on or near the soil surface, making seedling recruitment dependent on seed-producing trees, a lot of which were killed by fire. However, green ash sprout production was greater on burned sites suggesting that asexual reproduction may compensate for a temporary lack of sexual recruitment. For more information on this and other green ash fire studies, see the Fire Effects section.

In bur oak-dominated gallery forests of eastern Kansas, land surveys and aerial photograph data indicate that these forests occupied less area in the mid-1800s than they did in the 1900s. Increased woody vegetation in tallgrass prairies was attributed to decreased fire frequency and/or fire severity in postsettlement time [2]. Heinselman [138] suggests that quaking aspen parklands of northwestern Minnesota and west-central Canada that occur where southern boreal forests meet prairies experienced low-severity fires every 2 to 15 years in presettlement time. Fire severity likely varied with forest age and time since fire in the savannah-like vegetation where quaking aspen, balsam poplar, bur oak, green ash, and boxelder are typical. In the bottomlands of Lost Creek in the Schultz Prairie of south-central Nebraska, green ash occupies savannah-like riparian vegetation. Woody vegetation in this area is thought to have increased with a decreased fire frequency in this prairie region [240].

Eastern deciduous forests: Most researchers indicate that fire is rare in moist eastern deciduous forest habitats. In hardwood forests of the Great Lakes States, Frelich [97] described fires as uncommon in presettlement time and at present. The Big Woods of Minnesota are densely shaded and dominated by elm, basswood, sugar maple, and ash. It supports a sparse understory, maintains an open canopy, and experiences high humidity levels. This environment does not carry fire well and "limits the destructive potential of fires that may occur" in the Big Woods [125]. Extensive studies of the vegetation, environmental site characteristics, and past disturbances in Riding Mountain National Park, Manitoba, revealed that the green ash-American elm-boxelder eastern deciduous forest type occurred almost exclusively in infrequently burned areas [53]. The sugarberry-American elm-green ash forest cover type that occupies floodplain habitats in the southeastern and south-central United States reportedly experiences mixed or stand-replacing fires at frequencies of less than 35 to 200 years. The low fuel loads and moist, humid conditions associated with this forest type suggest that low-severity fires are most typical [298].

Bottomland hardwood forests: The following studies indicate that the fire ecology of bottomland hardwood forests changed with the level of anthropogenic influence. After studying landscape and environmental factors together with historical records and fire scar data, Frost [98] estimated that seasonally wet southeastern bottomland forests where baldcypress, sweetgum, red maple, swamp tupelo, swamp chestnut oak, and green ash occur burned at 100- to 300-year intervals in presettlement time. Fire severity was likely low, but fires may have damaged exposed roots and scarred adult trees. Green ash may also inhabit forests with relatively fire-proof characteristics that include saturated soils, standing water, and an absence of understory vegetation. In these fire-protected forests, any evidence of past fire is completely lacking [98]. After settlement of the Mississippi River Delta, however, Hepting [140] claimed that hardwood forests often burned. In dry years in this area, fires were recorded in 1899 to 1900; 1910 to 1911; 1916 to 1917; 1917 to 1918; and 1924 to 1925. From 1900 to 1930, at least some part of the Mississippi River Delta burned each year. Fire fuel was leaf litter that, when present in a 1-year accumulation, was sufficient to produce "hot" fires in dry weather conditions. However, the ignition source of these fires was primarily anthropogenic. Ignition sources included hunters using fire to flush game animals, farmers clearing land with fires that often escaped, and woodsmen leaving fires unattended.

The following table provides fire return intervals for plant communities and ecosystems where green ash is important. For further information, see the FEIS review of the dominant species listed below.

Community or Ecosystem Dominant Species Fire Return Interval Range (years)
maple-beech-birch Acer-Fagus-Betula spp. >1,000
silver maple-American elm A. saccharinum-Ulmus americana <5 to 200
sugar maple A. saccharum >1,000
sugar maple-basswood A. saccharum-Tilia americana >1,000
sugarberry-America elm-green ash Celtis laevigata-U. americana-Fraxinus pennsylvanica <35 to 200
Atlantic white-cedar Chamaecyparis thyoides 35 to >200
beech-sugar maple Fagus spp.-A. saccharum >1,000
black ash Fraxinus nigra <35 to 200 [298]
green ash F. pennsylvanica <35 to >300 [98,298]
Rocky Mountain juniper Juniperus scopulorum <35 [220]
yellow-poplar Liriodendron tulipifera <35 [298]
shortleaf pine Pinus echinata 2-15
shortleaf pine-oak P. echinata-Quercus spp. <10
eastern white pine-northern red oak-red maple P. strobus-Q. rubra-A. rubrum 35-200
loblolly-shortleaf pine P. taeda-P. echinata 10 to <35
sycamore-sweetgum-American elm Platanus occidentalis-Liquidambar styraciflua-U. americana <35 to 200 [298]
eastern cottonwood Populus deltoides <35 to 200 [220]
aspen-birch P. tremuloides-Betula papyrifera 35-200 [83,298]
quaking aspen (west of the Great Plains) P. tremuloides 7-120 [16,127,200]
black cherry-sugar maple Prunus serotina-A. saccharum >1,000
oak-hickory Quercus-Carya spp. <35
northeastern oak-pine Quercus-Pinus spp. 10 to <35 [298]
oak-gum-cypress Quercus-Nyssa spp.-Taxodium distichum 35 to >200 [210]
southeastern oak-pine Quercus-Pinus spp. <10
white oak-black oak-northern red oak Q. alba-Q. velutina-Q. rubra <35
northern pin oak Q. ellipsoidalis <35
bur oak Q. macrocarpa <10 [298]
oak savanna Q. macrocarpa/Andropogon gerardii-Schizachyrium scoparium 2-14 [220,298]
chestnut oak Q. prinus 3-8
northern red oak Q. rubra 10 to <35
black oak Q. velutina <35 [298]
baldcypress T. distichum var. distichum 100 to >300
pondcypress T. distichum var. nutans <35 [210]
elm-ash-cottonwood Ulmus-Fraxinus-Populus spp. <35 to 200 [83,298]

POSTFIRE REGENERATION STRATEGY [270]:
Tree with adventitious bud/root crown/soboliferous species root sucker
Initial off-site colonizer (off-site, initial community)

FIRE EFFECTS

SPECIES: Fraxinus pennsylvanica
IMMEDIATE FIRE EFFECT ON PLANT:
The fate of burned green ash trees varies from main stem survival to complete kill. Likely site conditions, season, and fire severity play a role in green ash survival following fire. Some green ash trees have survived fire. Fire-scarred green ash trees were studied in the Mississippi River Delta by Hepting [140] and Toole [283], and mangers and biologists from Wind Cave National Park, South Dakota, suggested that fire-scarred green ash trees there may be useful in reconstructing the fire history of the area. In a review, Wasser [301] indicates that green ash is fire tolerant when dormant.

However, in burned riparian areas of eastern Montana, Lesica [185] reported green ash tree (all size classes except seedling) mortality as high as 80%. In oak-hardwood woodlands of the central and eastern United States, Kennedy and Nowacki [168] report that green ash is "adversely affected" by fire.

DISCUSSION AND QUALIFICATION OF FIRE EFFECT:
Green ash trees scarred by fire are vulnerable to postfire fungal infection and decay. From 8 locations on the Mississippi River floodplain of Louisiana and Mississippi, researchers located 122 fire-scarred green ash trees. Fire scars were between 6 and 54 years old, and 113 of the 122 trees surveyed had heart rot. The decay rate calculated from 5 trees was 3.5 to 3.7 inches (8.9-9.4 cm)/year. Decay progressed up from the fire-damaged area [283].

PLANT RESPONSE TO FIRE:
While some green ash trees may survive fire, those that are top-killed are capable of "prolific" root crown sprouting following fire [183,247,248]. The high seed production potential [38,308], wind-dispersed seed [22,167], and wide ecological tolerance of seedlings [63,162] make green ash a likely candidate for off-site colonization of burned sites. Seedling recruitment, however, may require a nearby seed-producing tree, as green ash seed on or near the soil surface likely does not survive fire [185].

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:
The majority of literature regarding green ash and fire reports on just early postfire responses. Based on these short-term studies, it is generally true that the density of green ash trees, saplings, and/or seedlings is lower on burned than unburned sites but that the number of green ash sprouts is greater on burned than unburned sites. More information is needed on the long-term recovery of green ash following fire.

Fires in bur oak woodlands: Many have studied the recovery of green ash following fire in bur oak-dominated woodland habitats. In the following studies, green ash recovered from fire by vegetative sprouting and perhaps seedling growth, but typically green ash density was greater on unburned than burned plots. In eastern Kansas, the pre- and postfire densities of green ash saplings and seedlings* were compared following 2 spring prescription fires. Fires burned in late April 1984 and early April 1985. At the time of the 1984 fire, air temperature was 61 F (16 C), wind speed was 11 feet/s (3.3 m/s), and relative humidity was 21%. During the 1985 fire, the air temperature was 70 F (21 C), wind speed was 7.2 feet/s (2.2 m/s), and relative humidity was 44%. Both fires moved slowly, rarely exceeding 3 to 7 feet/min (1-2 m/min), and had low flame heights, typically below 1.6 feet (0.5 m). The fires burned over 90% of the area but did not reach into the canopy. Fires killed all green ash saplings, but seedlings quickly emerged on burned sites. The 1984 fire encouraged green ash seedling growth. The pre- and early postfire green ash sapling and seedling densities (number/ha) are summarized below [2,3].

  Prefire (1983) Postfire (1984) Postfire (1985)
saplings 100 0 0
seedlings* 250 900 150
*"Seedlings" represents a small stem size class. Term does not imply or dispute origin from seed.

In mid-April of 1987, bur oak-dominated woodlands were burned in the foothills of South Dakota's Black Hills. Livestock grazing was excluded a year before burning. Bur oak density before the fire was 1,097 trees/ha and basal area was 39 m/ha. The prefire density and basal area of other overstory species including fireberry hawthorn (Crataegus rotundifolia), green ash, and hophornbeam were 200 to 245 trees/ha and less than 1 m/ha, respectively. The fine fuel load was 589.6 kg/ha, fine fuel moisture was 14.6%, heavy (100-hour) fuel moisture was 11.2%, and soil moisture was 37.8% before burning. Temperatures were from 61 to 70 F (16-21 C), relative humidity ranged from 10% and 25%, and wind speeds ranged from 6 to 10 miles/hour (9-16 km/h) at the time of the fire. Fire spread was slow, between 0.01 and 0.09 m/s. Researchers noted that fewer than 5% of any tree species were top-killed. The number of green ash sprouts produced on burned sites was significantly greater than that on unburned plots (p≤0.1), but green ash density was greater on unburned than burned plots. The number of sprouts produced per green ash tree increased with increasing scorch height, but sprout density decreased with increasing slope [256].

Fires in a red and white pine plantation: Single and biennial fires in the W. K. Kellogg Experimental Forest of Kalamazoo County, Michigan, killed all large seedlings and saplings, but small seedlings* were present on singly and biennially burned sites. Prescription fires burned on 2 sites, one burned just once and the other burned biennially (2 fires in 2 years), in a mixed red and white pine plantation. The single fire burned in May 1991, and the biennial fires burned in May 1991 and May 1993. Postfire vegetation was measured in the 1994 and 1995 growing seasons. All fires were strip fires that produced flame lengths less than 3 feet (1 m), and fewer than 10 conifers lost over 80% of their needles to scorching. The understory was almost completely top-killed, with only a few small unburned portions. In even the most severely burned areas, nothing beyond the top 0.59 inch (1.5 cm) litter layer was consumed. No downed woody fuels greater than 0.98 inch (2.5 cm) were consumed either. The single fire and biennial fires killed all green ash saplings and large seedlings. However, small green ash seedlings appeared on both treatment sites. Researchers burned biennial plots again in 1995 and reported that no green ash seedlings or sprouts survived the 3rd fire. The coverage of small green ash seedlings, and density of large seedlings and saplings following fire, are reported below [215]. See the Effects of surface fires in a mixed red and eastern white pine stand in Michigan Research Project Summary for a more detailed description of this study.

Size class Measurement Unburned Single fire Biennial fires
Large seedlings*
(>1 m tall, ≤1.9 cm dbh)
density (number/ha) 333 0 ----
Saplings
(2 to 5.9 cm dbh)
density (number/ha) 56 0 ----
Small ash (Fraxinus spp.) seedlings*
(<1 m)
cover
(%)
0.23 0.28 0.24
*"Seedlings" represents a small stem size class. Term does not imply or dispute origin from seed.
Density counts made in 1995.
Coverage assessed in 1994.

Fires in woody draws: The following studies indicate that green ash recovers from fire chiefly through vegetative sprouting, and that this regenerating strategy allows green ash to survive even multiple fires. Green ash recovery following fire was studied in 7 eastern Montana green ash woodland sites. Sites had burned in August and September from 1988 to 1998 and were assessed in 2001. Tree mortality was as high as 80%. There were more, larger sprouts but fewer seedlings and a greater number of dead green ash trees on burned than unburned sites. There was also a positive relationship between burn severity and the number of sprouts produced; however, burn severity was not reported by site in this report. The low number of seedlings on burned sites suggests that fire killed green ash seed on or near the soil surface, making seedling recruitment dependent on seed producing trees, a lot of which were killed by fire. The average number of sprouts, seedlings, and dead trees on unburned and burned sites is presented below. Postburn data were collected 3 to 13 years after fire [185].

Status Burned Unburned
Sprouts/0.25-ha plot 4.3 1.3
Diameter of sprouts (mm) 1.56 0.84
Seedlings/plot 1.8 8.1
Dead trees/plot 1.43 0.14

In southwestern Minnesota's Pipestone National Monument, spring prescription fires burned each year from 1983 to 1987. Fires were ignited once grasses had "initiated good growth." Most fires burned in early to late April, except the 1987 fire that burned in early May. Fires were considered low or moderate severity. The 1983 fire burned when fuel loads were highest. The burned area was dissected by a woody draw dominated by green ash, Tatarian honeysuckle (Lonicera tatarica), and common buckthorn. Upslope from the woody draw was a mixed short- and mid-grass prairie, and downslope was a tallgrass prairie. The coverage of green ash increased as time since fire increased, to a maximum of 4.9% [29].

Green ash density was greater on burned than unburned sites after an October 1976 wildfire that burned approximately 6,000 acres (2,000 ha) of southwestern North Dakota's Little Missouri Badlands. Green ash occurred in lower portions of a drainage that was bordered by a mixed-grass prairie of western wheatgrass, blue grama, and little bluestem. Dry conditions were reported for 1976, but no other data regarding fire behavior or severity were provided. Green ash tree density was 0.05 stem/m on unburned sites. On burned sites the 1st postfire year, green ash averaged 0.1 stem/m and 0.3 stem/m the 2nd postfire year [318].

Fires in bottomland forests: In bottomland forests, fire typically top-kills green ash trees. In Marshall County, Oklahoma, a prescription fire burned a little bluestem-dominated grassland invaded by woody vegetation from the bordering green ash-black willow-eastern cottonwood bottomland forest community. The fire burned on 14 July 1979 when winds were 15 inches/s (37cm/s), air temperature was 95 F (35 C), and relative humidity was 58%. The prefire density of green ash was 167 stems/ha. No green ash stems were present in the 1st postfire year [5].

Managers in Cutoff Creek Wildlife Management Area in Drew County, Arkansas, compared unburned, once burned, and multiple-burn sites in bottomland hardwood forest openings. The objective of burning was to maintain open wildlife habitat. Sites burned multiple times experienced fire up to 6 times in 14 years. Fire conditions, severity, or behavior were not described. The authors report that the last fire in all openings occurred in 1997, and the data provided below were published in 1999 [276]. Likely, postfire measurements occurred in the 1st postfire year. There were fewer green ash seedlings in burned areas, but seedlings in burned areas produced more sprouts than those in unburned areas. The single fire killed most green ash trees, and multiple fires killed all green ash trees. Interestingly, the number of green ash seedlings 1 to 3 feet (0.3-0.9 m) tall was greater on sites burned in multiple fires than on sites burned only once. However, some sites burned in multiple fires may have had greater recovery time than sites burned just once. The study results are summarized below [276].

  Unburned Burned once Burned multiple times
Seedlings (<1 foot tall)/acre 22 0 0
Seedlings (1-3 feet tall)/acre 134 25 120
Seedlings (>3 feet tall, 0.5 inch dbh)/acre 431 34 145
Trees (>0.5 inch dbh tall)/acre 231 3 0
Mean seedling height (cm) 109 100 106
Mean number of sprouts per seedling 1.4 5 6.6

Fires in deciduous forests: Based on the following research, green ash may not recover following multiple fires, and recovery from fires burned in drought conditions may be slow in temperate deciduous forests. Researchers indicate that green ash was eliminated from sites burned 3 times in a deciduous forest in east-central Minnesota's Cedar Creek Natural History Area. Fires burned in 1992, 1997, and 2000. As of 2001, green ash was no longer present on burned sites. No information regarding fire seasonality or severity was provided [75].

In the Turtle Mountains of North Dakota, researchers compared burned and adjacent unburned sites 72 years following a stand-replacing fire that burned during drought conditions. Green ash density, basal area, and importance values were greater on unburned than burned sites. The number and size of postfire green ash trees differed by site. Burned site 1 had more green ash trees and undulating topography and loam soils, but trees were larger on burned site 2, which had level terrain and clay soils. Data from the study are provided below [224].

Site Unburned Burn 1
silty-clay loam
Burn 2
heavy silt, clay
Relative frequency (%) 16.4 17 12.3
Relative density (%) 13.5 9.8 5.1
Relative basal area (%) 8.2 2.6 3.5
Importance (%)* 12.7 9.8 7
*Average of the relative frequency, density, and basal area

FIRE MANAGEMENT CONSIDERATIONS:
The information on green ash and fire concentrates heavily on only early postfire effects. Very few studies have investigated both early and later postfire recovery of green ash. The above information, however, does suggest that green ash is fire sensitive. An evaluation of the utility or harm of prescribed fire in green ash communities requires more site and condition specific information than is currently available. The wide range occupied by green ash is not matched with a wide range of fire studies, and likely fire effects depend on sites occupied, fire season, fire severity, and time since last fire.

Myers and Buchman [209] recommend against the use of prescribed fire as a tool in elm-ash-cottonwood forests of the north-central United States if managing stands for timber production. They suggest that the genera are fire sensitive. Surface fires easily kill seedlings and saplings and wound mature elm, ash, and cottonwood trees.

MANAGEMENT CONSIDERATIONS

SPECIES: Fraxinus pennsylvanica
IMPORTANCE TO LIVESTOCK AND WILDLIFE:
Green ash trees and habitats provide food and/or cover for game and nongame birds, American beavers, other small mammals, deer, bison, livestock, insects, and aquatic species. The riparian habitat in Nebraska's Scotts Bluff National Monument, dominated by eastern cottonwood, willow, boxelder, American elm, and green ash, occupied just 4% of the area but was habitat for 57% of the total vertebrate species (amphibians, reptiles, mammals, and birds) surveyed [68]. However, the number of wildlife species supported by green ash habitats may change with condition of the habitat. Bjugstad [34] found that the green ash/chokecherry habitat type in an early seral stage supported approximately half the number of birds, and fewer small mammals, compared to a later seral stage.

Livestock: Livestock browse green ash stems. In studies along an 80-mile (100 km) stretch of North Dakota's Missouri river, Johnson [162] considered green ash one of the most grazing-tolerant species. In the Little Missouri National Grasslands, cattle exclusion grazing experiments were monitored for 7 years. The stocking rate on grazed sites was 1.07 AUM/ha from 15 May to 30 October, and forage utilization averaged 35% by late August or early September. Green ash heights were significantly greater (p= 0.04) on ungrazed sites in the 3rd, 4th, and 6th postexclusion years, suggesting that cattle fed on green ash stems [291]. The effect of grazing on green ash seedlings was also assessed. Survival of green ash seedlings averaged 72% on ungrazed and 38% on grazed sites. Seedling height averaged 17 inches (42 cm) on ungrazed and 12 inches (30 cm) on grazed sites 5 years following planting. The density of green ash seedlings was greater on grazed than ungrazed sites during the 4th, 5th, and 6th posttreatment years. The majority of seedlings in a given year were 1st-year seedlings [292].

Wooded draws dominated by green ash, western snowberry, and chokecherry in the Little Missouri Badlands were grazed at light, moderate, or heavy levels. Grazing pressure was evaluated by the number of animal trails, extensiveness of lounge areas, and distance to water. Green ash coverage, frequency, and density decreased with increased grazing. Results are summarized below [50,51].

Livestock use Light Moderate Heavy
Cover (%) 0.77 0.55 0.27
Frequency 6.5 4.8 2
Sapling density (stems/ha)
(1.8-7.5 cm dbh)
1,159 709 634
Tree density (stems/ha)
(>7.5 cm dbh)
429 411 354

Extensive livestock use of green ash habitats likely does more damage than browsing. Many have highlighted the use or overuse of green ash/chokecherry habitats by livestock in the northern Great Plains. Green ash habitats provide shade, palatable forage, water sources, protection from severe weather, and shelter during the calving season. Livestock also utilize green ash habitats to avoid insects, especially horn flies in the northern Great Plains, and trees are often used as rubbing posts to remove insect pests [35,133]. Not surprisingly, the same habitat qualities attractive to livestock are attractive to wildlife in the area. The potential for livestock/wildlife management conflicts is considerable [133]. Severson and Boldt [248] suggest several management techniques and grazing systems that may reduce grazing impacts on woody draw vegetation of the northern Great Plains.

Bison: In Oklahoma's Tallgrass Prairie Preserve, rubbing and horning activities of 100 or more bison were monitored. Green ash was used significantly (p<0.001) more than expected based on its availability. Bison moderately damaged green ash bark, but overall damage to the area's woody vegetation was not great. However, a number of miscellaneous man-made or artificial objects in the area were used extensively for horning and rubbing. Without these objects, woody vegetation damage may have been greater. Researchers suggest that bison activity may have acted to restrict woody vegetation from the prairie [67].

Deer: The literature suggests that deer utilize green ash habitats extensively, but that browsing of green ash may be limited. Vines [294] reports that white-tailed deer browse green ash twigs. Rayburn and Barkalow [229] monitored damage to trees in a logged tupelo-cypress forest in eastern North Carolina and found that white-tailed deer fed on green ash leaves only in May.

Monitoring white-tailed deer through aerial surveys, radio collars, and markings revealed selective use of eastern Montana's riparian habitats. On the north side of the Yellowstone-Missouri River in Montana's Dawson and Richland counties, riparian habitats dominated by green ash, eastern cottonwood, western snowberry, and chokecherry occupied 7% of the research area but received 86% of annual white-tailed deer use. Use levels significantly (p<0.001) exceeded availability [86]. Aerial surveys in the winters from 1976 to 1979 in southeastern Montana showed heavy deer use of creek riparian habitats. About 40% of 1,727 mule deer and 39% of 1,675 white-tailed deer wintered in riparian habitats. Creek riparian habitats were either eastern cottonwood or hardwood dominated. Important species included green ash, boxelder, and/or American elm [274].

American beaver: Reports of American beavers feeding on green ash come from North Dakota, Wisconsin, and Mississippi. In a review, Allen [9] indicated that green ash was a major winter food for North Dakota's American beavers. On a river island in the Chippewa River near Eau Claire, Wisconsin, American beavers preferentially fed on green ash stems and maintained shrub-like green ash trees. The researcher was uncertain as to green ash's survival and growth with heavy American beaver browsing [22]. A later report on the same area indicated that decreased green and black ash density was likely with continued American beaver feeding [23].

Hardwood seedlings planted on a batture (land between a river bank and the water's edge when water level is below normal) of the Mississippi River in Issaquena County, Mississippi, were preyed on heavily by American beavers. American beavers uprooted seedlings during flooded periods and consumed the root system and part of the root crown, but discarded the rest of the plant. Fifteen to eighteen percent of green ash seedlings were destroyed during the 2-year monitoring period. This type of feeding is considered much more destructive than browsing aboveground stems, since green ash sprouts readily following aboveground damage [174].

Small mammals: Green ash seeds, stems, and foliage provide important cover and food for a diversity of rabbit and other small mammal species. A study of habitat use by small mammals in Pipestone National Monument, Minnesota, conducted in 1984 and 1985, found that white-footed mouse abundance was significantly (p<0.05) greater in the bur oak-green ash woodland habitat than in any other grassland, prairie, or riparian area studied [261]. In southeastern Montana, researchers found that dwarf shrew abundance was significantly (p<0.05) correlated with green ash cover [190]. In old fields of north-central New Jersey, researchers studied microhabitat's effect on rodent seed feeding behavior. White-footed mice, the predominant seed predators in the area, consumed green ash seeds by gnawing the end of the seed coat and splitting the seeds. A total of 1,920 feeding trials were monitored, and an average 14.2% of green ash seed was removed by predators. More seed was removed at night, 17.9%, than in the daytime, 10.5%. Coverage of ground level vegetation explained most of the variation in green ash seed predation [193].

Wildlife, chiefly cottontail rabbits and white-tailed jackrabbits, browsed green ash in shelterbelts of eastern South Dakota. In 1-year-old plantings, 4.8% of the overwinter mortality of 736 green ash trees was attributable to wildlife browsing [21]. Researchers compared the use of closed-canopy and open-canopy green ash-dominated drainages in the Slim Buttes of Harding County, South Dakota. Nineteen total mammal species were observed during the 2-year study, and significantly more small mammals (p≤0.05) were found in closed-canopy than open-canopy forests. Only white-tailed jackrabbits preferred open-canopy woodlands and for just 1 year of the study [143].

Game birds: Wood ducks, grouse, northern bobwhites, and wild turkeys utilize green ash habitats. In Wyoming, green ash is considered important food and cover for sharp-tailed grouse [214]. Twedt and Best [287] also report that grouse commonly feed on ash seeds. In the Slim Buttes, researchers found that sharp-tailed grouse preferred open-canopy green ash woodlands on gentle slopes [143]. Sharp-tailed grouse utilized hardwood draws of eastern Montana in the fall and winter. Twelve percent of fall and winter observations were in hardwood draws where boxelder, silver buffaloberry (Shepherdia argentea), American plum, green ash, and American elm were common. Hardwood draws were likely used for berry foraging in the fall and for bud feeding in the winter [275].

In the Duck Creek Wildlife Management Area of southeastern Missouri, the esophageal contents of 20 male and 20 female wood ducks contained green ash in the fall of 1975 and 1976. The occurrence of green ash was 30% in males and 15% in females [81].

The movements of 88 male and 52 female northern bobwhites were monitored by radio collars in an old-field habitat of Oktibbeha County, Mississippi. Boxelder and green ash were the prominent woody species in low-lying, poorly drained sites, and brooding northern bobwhites selected woody vegetation in a greater proportion than was available. The researchers suggest that forested areas may have provided display areas for males, cover for escape, and/or corridors for movement between habitats [279].

Wild turkeys studied in Gregory County, South Dakota, selected woodland sites over grassland sites for nesting. Woodlands in the study area were bur oak-dominated, but green ash, American elm, and basswood were typical on mesic sites [305].

Nongame birds: Green ash provides food, nesting sites, and roosts for numerous nongame bird species. Twedt and Best [287] report that blackbirds, finches, grosbeaks, and cardinals feed on ash fruits.

A large number of birds occupy green ash habitats in North Dakota. In the Little Missouri National Grasslands, Hopkins [148] found that green ash-dominated woodlands supported 531 nesting bird pairs/40 ha. Green ash woodlands had the highest density of bark foraging and ground nesting birds. Three, Cooper's hawk, mountain bluebird, and a 3rd unidentified species, of the 50 species studied nested only in ash woodlands. A total of 49 bird species, 23% of North Dakota's known nesting avifauna, were encountered in wooded draws of western North Dakota where green ash dominates. Common birds included rufous-sided towhees, brown-headed cowbirds, house wrens, American goldfinches, and several species of sparrows, warblers, blackbirds, and flycatchers [148].

In South Dakota, studies compared the canopy and seral condition of communities as they relate to bird species richness. In the Slim Buttes, researchers compared bird use of closed-canopy and open-canopy drainages dominated by green ash. A total of 82 bird species was observed in the woodlands, and significantly more (p=0.002) occurred in closed-canopy sites. Mountain bluebird and western meadowlark were the only nongame birds that preferred open-canopy woodlands [143]. Researchers surveyed bird populations in 40 early to late seral green ash/chokecherry vegetation stands of central South Dakota. Bird censuses occurred in the summers of 1990, 1991, and 1992 near the Missouri River. A total of 81 bird species was found in green ash woodlands. Tree and shrub nesting birds preferred late-seral and ground nesting species preferred early seral communities [242].

Two studies report that green ash trees are typical in habitats used by eastern screech-owls. The Souris River of southern Saskatchewan represents the northwestern limit of the eastern screech-owl's range. Here eastern screech-owls occur predominantly in river bottom woodlands dominated by boxelder, green ash, and American elm. These woodlands likely support no more than 50 eastern screech-owl pairs [4]. In and near the Central Kentucky Wildlife Management Area, radio-tagged eastern screech-owls were monitored from late May 1985 to early July 1986. Monitoring revealed that woodlot and woodlot edge habitats were important to eastern screech-owls during the breeding, predispersal, and nonbreeding periods. Woodlot habitats had an overstory dominated by shagbark hickory, sweetgum, American elm, and green ash. Trees likely provided important perching areas for hunting [264].

Researchers observed 2,576 trees with fall blackbird roosts in Columbus, Ohio, and indicated that 13% of them were green ash. The study area included forested tracts scattered within agricultural, residential, and industrial areas [203].

Insects: Ash trees are hosts for tiger swallowtails, ash and waved sphinxes, and polyphemus moths [287].

Aquatic species: The green ash/chokecherry habitat type in central and eastern Montana is important in maintaining streambank stability and thermal cover for aquatic organisms [133].

Palatability/nutritional value: Green ash is considered moderately palatable forage for cattle, domestic sheep, and horses [133].

In a review, Blinn and Buckner [37] report the mean foliar nutrient levels of green ash in Minnesota as:

Nutrient N P K Ca Mg
% oven-dry weight 2.13 0.37 1.64 1.46 0.36

  Al B Cu Fe Mn Mo Zn
ppm 49 48 17 105 71 8 22

The foliar nutrient content of green ash saplings based on a percentage of dry weight was assessed from samples collected from 1978 to 1982 in different-aged stands on the Atlantic Coast and east Gulf Coast plains. Findings are summarized below [201]:

Stand age (years) N P K Ca Mg
20 1.47 0.09 0.32 0.73 0.21
40 2.35 0.25 0.98 0.9 0.26
40 1.56 0.3 0.68 0.9 0.21
60 1.5 0.13 0.41 0.64 0.39

The caloric content of green ash stump sprouts between 6 and 15 years of age is provided below. Sprouts were collected mid-summer from "fertile" bottomland sites along the Oconee River in Greene County, Georgia. Calorie measurements are based on oven-dry weights [212].

Sprout component Wood Bark Branches Twigs Leaves
Calories/g 4,768 4,618 4,857 4,818 5,119

Pardo and others [218] provide a searchable database with information on above ground nutrient content of many northeastern U.S. tree species including green ash. Information contained in the database comes from numerous references.

Cover value: Green ash provides important cover for livestock and a diversity of wildlife species. Likely the usage or reliance on green ash habitats depends on the relative environmental conditions in neighboring communities. Use may also change with season. Hansen and others [133] categorized Montana's green ash/chokecherry habitat type as providing fair cover for elk, mule deer, game birds, and waterfowl. Fair cover value was defined as habitat that was moderately utilized when available. The green ash/chokecherry habitat was considered good cover for white-tailed deer, small nongame birds, and small mammals. Good cover was habitat that was readily utilized when available [133].

Other cover value information has been integrated into Importance to livestock and wildlife above. See the species of interest in that section for more information.

VALUE FOR REHABILITATION OF DISTURBED SITES:
Green ash is widely used in revegetation, reclamation, and protection plantings. There is abundant literature on the multistaged revegetation process of green ash from seed collection to monitoring success.

Seed collection/storage: Green ash seed is available commercially [288], and many guidelines are available for the successful collection, storage, and germination of green ash seed. Cunningham [73] provides delineated seed collection zones where soils, precipitation, and temperature regimes are similar within the Great Plains. Zones are designed to be matched with the area being revegetated or restored. Cram and Worden [71] suggest collecting green ash seed only when its moisture content is below 49%, as seed moisture content is likely related to seed maturity. Bonner and Turner [43] suggest ways to rapidly measure the moisture content of green ash seeds. If stored properly, green ash seed retains its viability for over 8 years of storage. Cram [69] reports 80% germination of green ash seed after 8 years of storage at 0 F (-20 C). Another researcher provides a green ash viability equation based on 5 years of seed storage [42]. Comprehensive information on green ash seed collection, seed storage, and planting is available [308].

Revegetation methods: Researchers have tested a variety of green ash planting methods. Researchers found that water level was most important to green ash survival on wetland sites from Louisiana to South Carolina. Green ash survival was 85% to 100% for moderately root-pruned seedlings on sites with shallow water (0-10 inches (0-30 cm)) and tree shelter. Survival was less, 45% to 65%, on shallow water sites without tree shelter. In deep water (10-20 inches (30-60 cm)), survival ranged from 0% to 100% [66].

Researchers used an underplanting method to regenerate degraded bottomland hardwood forests on the Atchafalya River basin of south-central Louisiana. Green ash seedlings were planted before harvesting the "overmature" eastern cottonwood and black willow overstory. Bareroot forest nursery seedlings were planted in the winter of 1983 to 1984, and sites were harvested from April through September of 1985. Green ash survival before harvesting (1985) was 98.2% (n=589), and in the 1st postharvest year (1986) survival was 74.2%. An estimated 9.2% of the mortality was attributed to natural causes, chiefly animal damage, and 16.7% of the mortality was logging related. Green ash seedlings grew rapidly. Two years after logging, green ash seedling height averaged 2.8 feet (0.85 m), and 38.7% of seedlings were over 3 feet (1 m) tall [59].

Some literature provides comprehensive information on the initiation and care of revegetation projects. Manci [192] provides a thorough review on the planning, implementing, sustaining, and monitoring of riparian restoration projects, and Houston and Buckner [152] compare cultural, mechanical, and chemical treatment effects on the growth of green ash in reforestations and plantations.

Plantations: Green ash is often successful in managed plantations. Typically survival does not require the control of weeds or other understory vegetation. However, vines can decrease green ash growth [157]. Baker and Broadfoot [20] provide a site suitability chart for green ash plantations based on soil and hydrologic characteristics. Best green ash soils are typically deep, medium-textured, noncompacted, silts or loams with a pH of 5.5 to 7.5. Floodplains or stream bottoms with a 2- to 6-foot (0.6-2 m) water table that experience winter or spring flooding are considered ideal green ash sites [20]. Seeds of select trees growing in the National Environmental Research Park of New Ellenton, South Carolina, were collected in the fall of 1992 and grown in nursery beds until February 1994. Seedlings were transplanted into a cleared pine plantation in the Crackerneck Wildlife Management Area of South Carolina's Savannah River Research Park. As of 1998, green ash seedling survival was 100% although 1997 and 1998 experienced drought conditions, and seedlings were browsed by deer. Six seedlings produced seed in 1998 [170].

Ten years after planting green ash seedlings on a cleared forest site, an abandoned field, and a previous plantation in eastern Texas, survival ranged from 95% to 98%. Seedlings were grown from seed collected in 5 eastern Texas locations, and weeds and sprouts of other species were controlled mechanically [267].

For 20 years, researchers monitored survival and growth of green ash planted in a cleared hardwood-pine forest along a minor stream bottom in southeastern Arkansas. When the plantation was 6 years old, green ash was among the fastest growing of the 8 planted species. However, by age 20, green ash height growth was negligible or none. Soil tests revealed it was infertile for hardwood trees and likely explains the poor green ash growth [54].

Abandoned agricultural lands: Green ash commonly invades and is often actively planted on old fields. Newling [216] described green ash as a typical volunteer species on old fields that were previously bottomland hardwood communities. Based on soils information, Groninger and others [126] suggest that green ash would be valuable in reforesting poorly drained sites in the Mississippi Delta region of Arkansas, Mississippi, and Louisiana cleared for soybean crop production.

Green ash survival was 98% three years following its planting on a recently abandoned soybean field of southwestern Tennessee. Early green ash height growth was greatest when weedy species were mechanically controlled [299]. On an abandoned agricultural field in Catahoula Parish, Louisiana, green ash survival was approximately 60%. Seedlings were used in the afforestation effort, and over the 5-year monitoring period, the study area was inundated by 2 flooding events per year. The maximum consecutive number of flooded days was 116, and the maximum flood level was 10.3 feet (3.13 m) above flood stage [219]. Green ash survival was nearly 100% on an improved grass pasture in Poteau, Oklahoma. The large-scale cultivation methods, site preparation, maintenance, and hand-planting methods tested are described in the original reference together with costs involved [260].

Shelterbelts: The use of green ash in shelterbelts or other protective plantings is extensive. Often times shelterbelts are needed on sites that would not naturally support green ash. George [100] followed the successes and failures of shelterbelt plantings across the northern Great Plains. He found overall that green ash growth was good and survival was consistently high. Trees grown in deep shade frequently died back, but growth was generally good in dry conditions [101]. However, green ash suffered slightly increased winterkill with age, injury with late spring frosts, and occasional broken stems from drifting snow [100]. Winter damage was greatest during severe drought years [101]. In the northern Great Plains, winters and summers can be severe. Within a 6-month period, 2 North Dakota weather stations located less than 100 miles (200 km) apart reported a temperature range of 181 F (100 C). Average precipitation in northern and southern zones from 1914 to 1946 ranged from 13.6 to 16.2 inches (34.6-41.1 cm), and the frost-free period lasted 127 to 139 days [100].

Johnson [160] reported poor green ash survival on dry sites. The potential use of green ash in fuel breaks was evaluated near conifer plantations with high fire frequencies. Study sites in Wexford County, Michigan, and Bayfield County, Wisconsin, were dry and sandy. Six years after planting green ash, survival ranged from 37% to 42%.

Surveys from private landowners and operators have also provided information on the use and success of green ash in windbreaks. Thirty-five percent of respondents rated green ash performance as excellent, 42% rated it as good, 14% rated it fair, and 6% as poor. Those who planted green ash by machine rated performance significantly (p≤0.05) higher than those who hand planted [286].

Abandoned mining sites: Green ash has been successfully used in mine reclamations from Wyoming to Pennsylvania. The Minkers Run Mine of southeastern Ohio was deep mined from 1878 to 1924, surface mined from 1948 to 1950, and revegetated 15 years following abandonment in 1966. Green ash density was 110/ha in 1966, and 79/ha in 1997 [56]. Green ash survival ranged from 98% to 83% on other Ohio coal mine spoils that were abandoned from 1 to 7 years prior. The pH of spoils ranged from 3 to 7 or more. A number of "toxic patches" were noted on some sites, and rabbit browsing was common to severe [186]. In southeastern Kansas green ash was 1 of several species evaluated on a coal strip-mine site that was mined in 1946 and planted in 1950. Green ash survival averaged 94% after 10 years, but most trees were bent with multiple branches, lowering timber value [245]. On a lignite coal strip in eastern Texas, green ash survival was an estimated 81% on sites planted 3 to 10 years earlier [119]. Green ash survival on a coal mine spoil in Campbell County, Wyoming, was 40% to 80%. Spoils were slightly more saline than surrounding soils. Survival rates were higher for bare root than container seedlings, and interestingly irrigated seedlings grew slower than nonirrigated seedlings [36].

Green ash survival was evaluated on several surface mined reclamation sites in Colorado and Wyoming. Seedlings were planted in 1975 on overburden covered with 6 to 18 inches (20-46 cm) of topsoil. Green ash seedling survival on coal mine sites ranged from 42% to 100% in 1977. Survival was 100% on Colorado mine sites at 7,500 feet (2,300 m) elevation that received an average annual precipitation of 40.2 inches (1,020 mm). The low 42% survival was on sites in Wyoming at 6,000 feet (1,800 m) that averaged 33.8 inches (858 mm) of annual precipitation. No green ash seedlings planted on a uranium mine site in Wyoming survived [153].

Green ash growth and survival were evaluated on mine spoils of Missouri, Kansas, Oklahoma, Illinois, Indiana, and Pennsylvania. From this study, Vogel [295] reported a lower pH limit of 4 and an upper elevation limit of 2,500 feet (760 m) for green ash seedlings on mine sites. Growth was considered best on soils with a high proportion of soil particles greater than 2 mm in size. Presented below are the average survival percentages and growth characteristics of green ash on 30-year-old mine spoils [295].

Location Number of sites Survival (%) Dbh (inches) Height (feet) Basal area (ft/acre)
MO, KS, OK 9 33 3.8 28 23.0
IL, IN 11 53 4.7 ---- 56.8
OH 4 55 4.0 27 42.7
PA* 2 69 2.5 15 ----
*Revegetated mine areas were 10 years old in Pennsylvania.

Landfills: Researchers have also planted green ash on backfilled landfill sites in East Brunswick, New Jersey. Root growth was stunted compared to control plots when just 20 inches (60 cm) of soil was spread over a 30-foot (9-m)-deep former refuse landfill [104].

OTHER USES:
Native people of the Great Plains utilized green ash. Bows, arrows, drums, tent poles, teepee pegs, and meat-drying racks were often constructed of green ash [136]. It was believed that green ash had beneficial natural powers and was often used to carry and/or display ceremonial or symbolic objects of the Omaha and Pawnee tribes [105]. The Cheyenne built portions of their Sun Dance Lodge with green ash, as they too believed in green ash's powers [136]. The Cheyenne Contrary Warriors reportedly wore whistles made of green ash around their necks [137].

Wood Products: Green ash wood is course grained, heavy, hard, and strong [269,294]. Sapwood is white [269]. Green ash is used to make tool handles, furniture, and interior furnishings [294].

OTHER MANAGEMENT CONSIDERATIONS:
Urban landscapes: Green ash's salt and pollution tolerances make it a likely choice in urban landscapes. Heisler and others [139] suggest using green ash in parking lot plantings. Lait and others [178] have researched the growth and survival of green ash cultivars under a variety of urban conditions. 'Summit' tolerated ozone, sulfur dioxide, and a combination of both pollutants [164]. 'Summit' and 'Marshall's Seedless' both had high survival in street plantings in Wisconsin cities [205]. 'Cardan' was best adapted to the northern Great Plains, and would likely do well in windbreaks, mining reclamations, floodplains, and disturbed areas [290]. In a study conducted in Logan, Utah, 1-year-old green ash seedlings were watered with an excess-of-salt solution for an entire growing season. Salt solutions provided a known salinity level without build up. Green ash survived levels of salt up to 8,000 ppm [207].

Invasive species: Native ungulate use of green ash-chokecherry habitat in Theodore Roosevelt National Park, North Dakota was reduced by 32% when sites were infested with leafy spurge (Euphorbia esula) [284].

Diseases/damaging agents: Green ash is susceptible to a number of diseases and damaging agents. Ash dieback is common; for a description of symptoms, causes, and control see Hibben and Silverborg [141]. The emerald ash borer, an exotic insect pest identified in Michigan, primarily attacks green ash trees. For more information on the potential control and means for mitigating the spread of this species see [121,122,310]. Riffle and Peterson [236] and Solomon and others [262] provide information on green ash tree diseases, their symptoms, causes, damaging agents, and potential controls. Chlorosis, foliar fungi, and wood, root, and stem rots that infect naturally occurring and managed populations are described and discussed.

Lesica and others [182] revealed a relationship between decreased annual precipitation and increased incident of green ash infected with a common stem decay pathogen. Trees sampled in 17 stands in east-central Montana, together with precipitation data, suggested that drought conditions may increase the incident of green ash heartwood decay [182].

Growth relationships: Many researchers report relationships between growth aspects of green ash that are used in regression equations and models to gain additional information. Below is a table summarizing the system of equations and where they are most likely useful:

Data collection area Related parameters Additional information
Dependent variable Independent variable
AR, LA, MO, OK, and TX potential relative increment and optimal annual dbh growth min, max, and mean dbh n=3,058 [46]
Gulf and Atlantic Coastal Plain nutrient content dbh and provided regression coefficients hardwood forests [223]
IN projected basal area and tree number initial basal area and number of trees model for growth and yield in elm-ash-cottonwood vegetation type, used trees with >5 inch dbh [253]
KS site index rating age and height of dominant and codominant trees 3 to 5 uniformly shaped, dominant and codominant trees [102]
TX, Lewisville Lake Wildlife Restoration Area age dbh bottomland hardwood forests, n=9 [24]
Mississippi, Missouri, Illinois, and Des Moines rivers in MO, IA, and IL height dbh bottomland hardwood forests, n=110 [64]
MS crown radius dbh equations for dominant, codominant, and intermediate trees [96]
Mississippi River Delta crown radius dbh open-grown trees [113]
West-central MS volume and weight A variety including: age, dbh, height, wood and bark moisture contents, specific gravity, and density [244] ----

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