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Species Guide |
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| The following species are discussed in this guide: | |||||||
| Eastern cottonwood Populus deltoides |
bigtooth aspen Populus grandidentata |
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| weeping willow Salix babylonica |
crack willow Salix fragilis |
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| black willow Salix nigra |
shrub willows salix spp. |
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| Species | Eastern cottonwoodPopulus
deltoides |
| Species Name | D-shaped, for the leaves. |
| Sites and Soils | Eastern cottonwood is a bottomland species on alluvial soils. |
| Ecology | Eastern cottonwood is one of the most abundant trees in the flood plains of most major eastern rivers. An extremely intolerant tree, it becomes established only after heavy disturbance, particularly the scouring action of floods. It forms pure stands, or occurs in mixture with tree willows (black and crack), bottomland oaks, American elm, green ash, sycamore and sweetgum. In the coastal plains, it forms pure stands or mixtures with sweetgum on abandoned farm lands. |
| Life History | Eastern cottonwood is an exemplar of the life history of flood plain trees. It is dioecious, bearing catkins before the leaves in early spring, and is wind pollinated. Capsules bearing fluffy seeds, which are widely dispersed on the wind. Seeds must germinate within a few days or they die. Seeds germinate on moist bare mineral soil (not in litter), and seedlings are initially tiny, slow growing and extremely vulnerable to even mild stresses. Only a tiny fraction of seedlings survive, but the prolific seed production of cottonwoods ensures survival of the species.Once established, cottonwoods grow very rapidly, often growing 6' in height and 1' in diameter per year for the first 20 years, reaching a typical maximum of 120'x4' (Champion132'x10'). Cottonwoods also regenerate from stump sprouts, and occasionally from root sprouts; growth of sprouts is very fast. Lifespan rarely exceeds 100 years, though a few individuals may live to 200 years. |
| Interactions | VA- and ectomycorrhizal (a rare trait in trees). Although all Salicaceae are wind pollinated, they are an important source of early spring pollen for honeybees, providing protein required for brood production. The resinous buds of cottonwood also provide the material for propolis, which bees use as a sort of glue to seal the hive. Cottonwood has a number of pests and pathogens, particularly when grown in plantations. Wood is very susceptible to decay, and even minor stem wounds result in extensive decay and, often, breakup of the stem. |
| Status | Abundant; stable. Conversion of bottomland forests to agriculture has reduced habitat, but abandonment of land and disturbance have favored cottonwood; on balance, cottonwood populations are probably increasing slightly. |
| Range | Cottonwood has an unusual range which reflects the distribution of large river valleys. It occurs throughout the Eastern Deciduous Forest except for the Appalachians, New England, the northern Atlantic Coastal Plain, the southern Gulf Coastal Plain and the northern Lake States. It's westward range extends well into the Rocky Mountains as far as Alberta and Montana. |
| Kentucky status | Abundant, stable. |
| Kentucky range | Western Kentucky; nearly absent from the Bluegrass (the author knows of fewer than a dozen trees in the Kentucky River Valley), and absent from the Cumberland Plateau and Cumberland Mountains. |
| Uses | An important species for rough lumber and pulp. Plantations of eastern cottonwood are extremely important for pulp and paper production. |
| Ornamental use | Though often found in the landscape, planting of this species should not be encouraged. Its rapid growth and the weak wood makes cottonwood messy and often a hazard in the landscape. Poplars in general are not good ornamentals, and their only virtue is their fast growth. |
| Notes |
| Species | bigtooth aspenPopulus
grandidentata |
| Species Name | bigtooth |
| Sites and Soils | Bigtooth aspen is an upland tree of well-drained, moderately rich soils. |
| Ecology | Bigtooth aspen, like all members of the Salicaceae, is an intolerant, disturbed site species, forming pure stands or mixed stands with quaking aspen. Aspens are quickly replaced in succession by more tolerant species unless disturbance is repeated. In the Lake States, bigtooth and quaking aspen formed enormous pure stands after the terribly destructive logging of those forests in the 19th and early 20th centuries. These stands now constitute a valuable resource, and are self-perpetuatuing with proper management. In the Appalachians, bigtooth aspen forms mixed stands of pioneer trees with, for example, Virginia pine, black locust and sassafras. |
| Life History | The life history of bigtooth aspen is very similar to that of eastern cottonwood, except that aspen reproduces well from seed, stump and root sprouts, and is less demanding of soil moisture. Pollination is by wind, and the abundant seeds are released to the wind in late spring. Germination is immediate, and seeds which do not become established die within days. Germination occurs on moist, bare mineral soil; seedlings which germinate on leaf litter or other organic matter rarely survive. Growth is exceptionally rapid, and, along with quaking aspen, bigtooth aspen is the most productive tree in Lake States forests. As is typical of pioneer trees, individual trees do not live long, rarely exceeding 120 years. However, clones of bigtooth aspen will maintain indefinitely, as long as disturbance prevents more tolerant trees from establishing. Coppice regeneration is excellent with this species. |
| Interactions | Bigtooth aspen is wind pollinated. It is both ectomycorrhizal and VA mycorrhizal. Buds form an important winter food source for ruffed grouse and other wildlife, and beaver prize aspens (bigtooth and quaking) above all other species. Bigtooth aspen has a huge number of pests and pathogens. The wood is very easily decayed, and basal wounds from fire or logging can lead to rapid decline. |
| Status | Abundant; increased tremendously in the Lake States following destructive logging; increased in the east after logging, but now being replaced by succession, and declining throughout most of its range outside of the Lake States. |
| Range | SE Canada to Virginia, W. to Missouri, Minnesota. Many disjuncts in S and W extremes of range. |
| Kentucky status | uncommon; Kentucky is at the southern extreme of the range. |
| Kentucky range | Cumberland Plateau and Cumberland Mountains. |
| Uses | Bigtooth aspen is an important fiber plant, especially for pulp, pallets, boxes and composite wood products. |
| Ornamental use | Not suitable |
| Notes |
| Species | quaking aspenPopulus
tremuloides |
| Species Name | tremula-like (resembling P. tremula of Europe); tremula means trembling |
| Sites and Soils | Quaking aspen has a huge range and occurs on the widest possible variety of disturbed sites, from bottoms to dry uplands, and from heavy clay to dry sandy or rocky soils |
| Ecology | Quaking aspen, like all members of the Salicaceae, is an intolerant, disturbed site species, forming pure stands or mixed stands with bigtooth aspen. Aspens are quickly replaced in succession by more tolerant species unless disturbance is repeated. In the Lake States, bigtooth and quaking aspen formed enormous pure stands after the terribly destructive logging of those forests in the 19th and early 20th centuries. These stands now constitute a valuable resource, and are self-perpetuatuing with proper management. In Rocky Mountains sites where succession does not occur, aspen stands form enormous clones, covering many square miles. These clones have been present since the glacial retreat about 9,000 years ago. |
| Life History | The life history of quaking aspen is very similar to that of eastern cottonwood, except that aspen reproduces well from seed, stump and root sprouts, and is less demanding of soil moisture. Pollination is by wind, and the abundant seeds are released to the wind in late spring. Germination is immediate, and seeds which do not become established die within days. Germination occurs on moist, bare mineral soil; seedlings which germinate on leaf litter or other organic matter rarely survive. Growth is exceptionally rapid, and, along with bigtooth aspen, quaking aspen is the most productive tree in Lake States forests. As is typical of pioneer trees, individual trees do not live long, rarely exceeding 120 years. However, clones of bigtooth aspen will maintain indefinitely, as long as disturbance prevents more tolerant trees from establishing. Coppice regeneration is excellent with this species. |
| Interactions | Quaking aspen is wind pollinated. It is both ectomycorrhizal and VA mycorrhizal. Buds form an important winter food source for ruffed grouse and other wildlife, and beaver prize aspens (bigtooth and quaking) above all other species. Quaking aspen has a huge number of pests and pathogens. The wood is very easily decayed, and basal wounds from fire or logging can lead to rapid decline. |
| Status | Abundant; increased tremendously in the Lake States following destructive logging; increased in the east after logging, but now being replaced by succession, and declining throughout most of its range outside of the Lake States. |
| Range | Quaking aspen has the largest range of any North American tree. Northern North America: Atlantic to Pacific Coast in Canada, Alaska; N. to treeline in Canada; S. to Ohio, Penn., with disjunct populations in W. Virginia, Virginia; Rocky Mts. S. to Arizona, New Mexico; Cascades; N. Sierra Nevada. |
| Kentucky status | Not native; not known to be planted in state. |
| Kentucky range | |
| Uses | Quaking aspen is an important fiber plant, especially for pulp, pallets, boxes and composite wood products. |
| Ornamental use | Not suitable |
| Notes |
| Species | weeping willowSalix
babylonica |
| Species Name | of Babylon |
| Sites and Soils | Weeping willow is an Asian species of very wet, disturbed sites. |
| Ecology | An intolerant, disturbed site species. |
| Life History | See black willow |
| Interactions | See black willow |
| Status | Planted as an ornamental; Occasional escapes, but does not appear to be naturalized to any extent. |
| Range | Temperate east Asia |
| Kentucky status | Planted as an ornamental; Esapes not known. |
| Kentucky range | not native |
| Uses | Ornamental |
| Ornamental use | Weeping willow is a beautiful ornamental for the banks of lakes and ponds. It performs very poorly on drier sites, and should not be used more than a few feet from a reliable water source. |
| Notes |
| Species | black willow,Salix nigra crack willow, Salix
fragilis
shrub willows, Salix
spp. |
| Species Name | nigra, black
fragilis, fragile |
| Sites and Soils | Willows grow on river bottoms on poorly drained alluvial soils. |
| Ecology | Black and crack willows are very similar, and are the only willows other than ornamentals which reach tree size in the Eastern Deciduous Forest. Black willow is native. Crack willow is an introduced European species which has become naturalized and is found together with black willow. They can be distinguised by the loose branch junctions in crack willow, which cause the branches to pop off with an audible "snap" when tapped gently. Both species occur in heavily disturbed riverine forests. They are extremely intolerant, and occur in pure stands or in mixture with other disturbance tolerant species such as eastern cottonwood, American elm, green ash, red and silver maples , and boxelder. Shrub willows occur on heavily disturbed river bottoms, especially gravel and sand bars, or on creek banks. They usually form pure stands, or may be mixed with other shrubs, especially alders. |
| Life History | Willows flower in early spring, and are largely wind pollinated. Seeds are released to the wind in late spring, and germinate immediately on moist, bare mineral soil. Seeds float well, and may remain viable in water for several days. Seeds which do not land on a moist spot quickly die from desiccation; no seed bank is formed. Willows also reproduce from stump and root sprouts and this is the dominant form of reproduction in some stands. Willow branches break off easily (especially in crack willow), and these branches may take root, forming a new tree either near the parent tree or after floating downstream. Willows grow exceptionally fast, up to 10 ft per year for a few years. They are short lived, rarely exceeding 75 years (less for the shrub species), though clones may be effectively immortal. |
| Interactions | Willows are ectomycorrhizal. Honeybees and other hymenoptera are common spring visitors, and obtain substantial amounts of pollen from the flowers. Pollen provides an important early spring protein source for rearing brood. However, it is not clear that they are important as pollinators. |
| Status | Abundant; stable. Crack willow is increasing in abundance, and exceeds the number of black willows in some areas. |
| Range | River bottoms throughout the Eastern Deciduous Forest, except far north. Disjunct populations in Texas and Mexico. |
| Kentucky status | Abundant; stable. |
| Kentucky range | River bottoms throughout the state; especially abundant in Mississippi river valley |
| Uses | Pulp and rough lumber, combined with other bottomland hardwoods. |
| Ornamental use | Large willows are extremely dangerous, because of their weak branch junctions. Their use should be discouraged. Shrub willows are excellent additions to the landscape, especially in clumps. |
| Notes |