• GENERAL BOTANICAL CHARACTERISTICS
• RAUNKIAER LIFE FORM
• REGENERATION PROCESSES
• SITE CHARACTERISTICS
• SUCCESSIONAL STATUS
• SEASONAL DEVELOPMENT

GENERAL BOTANICAL CHARACTERISTICS:

Chokecherry is a native, deciduous, thicket-forming erect shrub or small tree. Stems are numerous and slender, either branching from the base or with main branches upright and spreading [166]. Heights vary considerably according to variety and site quality, ranging from 3 to 19.5 feet (1-6 m) [73]. In the Great Basin, chokecherry may grow to almost 40 feet (12 m) with trunk diameters of approximately 8 inches (20 cm) [92]. Perfect flowers are borne on leafy twigs of the season. Fruits are drupes, each containing a small stone [73]. Chokecherries have a network of rhizomes and a deep root system established at intervals along the rhizomes [129,140,175]. Roots may extend laterally more than 35 feet (10.6 m) and vertically more than 6 feet (1.8 m) [175]. Rhizomes range from 0.4 to 0.8 inch (1-2 cm) in diameter [129].

RAUNKIAER LIFE FORM:

Phanerophyte

REGENERATION PROCESSES:

Chokecherry reproduces sexually and vegetatively. In laboratory experiments involving excised rhizomes which were approximately 11 years of age, Schier [129] observed that chokecherry rhizomes sprouted at a faster rate and had higher sprouting percentages than Gambel oak (Quercus gambelii) rhizomes.

Seed crops are typically regular and viable [111], with seed-producing capacity higher in plants on open sites [166]. Seeds are surrounded by a stony endocarp that may offer some resistance to germination but is permeable to moisture. Chokecherry has seed dormancy; an after-ripening period in the presence of oxygen and moisture is necessary for adequate germination [60].

Rogers and Applegate [124] reported significantly (P <0.01) enhanced germination in chokecherry seeds ingested by black bears in Minnesota and attributed this to acid and mechanical scarification of seeds in the digestive tract.

Although large numbers of chokecherry seeds may be deposited beneath parent plants, long-distance dispersal also occurs via frugivorous birds and mammals [86,167,170,172]. Meyer and Witmer [107] studied the effect of gut-scarification on chokecherry seeds fed to captive frugivorous birds. Removal of fruit pulp was critical for germination, but they found no differences in germination success between seeds manually cleaned of pulp and bird-passed seeds lacking pulp. Seeds of chokecherry that were defecated and planted with feces, mimicking natural deposition, had reduced germination relative to manually cleaned seeds. Artificial seed treatments to enhance germination are discussed in the Value and Use section of this report.

Viable seed persists in the soil seedbank. In a closed-canopy forest in northern Idaho, chokecherry seeds were found in soil samples taken at depths of up to 4 inches (10 cm); overall seed viability equaled approximately 27% [86].

SITE CHARACTERISTICS:

In the western United States, chokecherry grows at low to mid-elevations in positions in the landscape where combinations of soil and topography permit greater than average accumulation of moisture. These sites include riparian areas, wooded draws, and steep ravines [43,64,65,66,149,163]. Soils supporting chokecherry are variable, ranging from Entisols to Mollisols, and soil texture ranges from silt to sandy loam. Chokecherry can tolerate weakly saline soils but is intolerant of poor drainage and prolonged flooding [66].

Chokecherry grows in very acid to moderately alkaline soils. In the green ash/chokecherry habitat type in the northern Great Plains, pH ranged from 6.0 to 7.6 in loam, clay, and clay loam [65,163]. In deciduous forests in Vermont, glacial till soils supporting chokecherry had a pH ranging from 3.5 to 5.5 [136]. Where chokecherry occurred in forests growing on coastal Lake Michigan sand dunes, pH ranged from approximately 4.0 to 6.0 [99]. In Pennsylvania, soils in oak-pine supporting chokecherry grew on well-drained limestone residuum soil and had a pH range from 4.8 to 5.4 [2].

Elevational ranges for chokecherry are:

Idaho: 3,100 to 8,000 feet (945-2440 m) [143,173]
Michigan: 580 to 738 feet (177-225 m) [99]
Montana: 580 to 738 feet (177-225 m) [46,66,119]
Nevada and Utah: 4,986 to 10,170 feet (1520-3100 m) [11,33,79,90]
North Dakota: 1,023 to 1,095 feet (312-334 m) [171]
South Dakota: 3,002 to 3,494 feet (915-1065 m) [77]
Vermont: 1,797 to 2,798 feet (548-853 m) [136]

SUCCESSIONAL STATUS:

Because chokecherry occurs so widely, it is reported in numerous habitat types and plant associations that range from post-disturbance invaders to early-successional to climax or stable. It grows in sparse stands, dense thickets, and under open forest canopies [64,66,116,119]. It is shade tolerant [31,64,99,100], but reaches its greatest density near forest edges [64,65]. Plant association descriptions for most the studies discussed below appear in the Distribution and Occurrence section of this species report.

EASTERN AND CENTRAL REGION

In the eastern and central region of the U.S. and Canada, chokecherry occurs in a broad range of successional habitats. It been studied in both seral and climax or stable communities. It resprouts readily and also persists under open and closed forest canopies.

Chokecherry was characterized as early-successional following logging and (or) burning in northern white-cedar and jack pine forests in Michigan [1]. Chokecherry was mid-successional in coastal Lake Michigan chronosequences that focused on long-term vegetation succession on sand dunes, reaching its greatest abundance after pine and oak cover was well developed [99,117].

In Pennsylvania mixed-oak forests chokecherry was described as a later-successional understory species where the overstory is dominated by oak and pine [2].

In a 1924 study of succession in northwestern Minnesota chokecherry was prominent in non-climax brush stands in ecotones between prairie and deciduous forests [47]. In a 1951 study in northern Minnesota chokecherry was noted as a major component in the sparse shrub layer of a climax maple-basswood forest. The maple-basswood forest was characterized as having light penetration of less than 5%, indicating shade tolerance, at least in mature chokecherry [31].

In a 1964 study in Vermont, chokecherry was one of 14 shrub species documented in the understory of an old, undisturbed remnant of northern hardwood forest. Sugar maple, beech, and white ash were overstory dominants. The authors predicted that this assemblage replaces itself in forest succession, creating a stable overstory community [23].

In Ontario, following forest clearcutting and brush removal for a utility right-of-way, chokecherry was a prominent initial colonizer. The original forest cover was dominated by sugar maple, white ash, quaking aspen and black cherry. In addition to abundant chokecherry seedlings, raspberry (Rubus spp.) seedlings and sprouts, and sprouts from quaking aspen were also prolific initial colonizers. After 6 years chokecherry and quaking aspen stems had declined and white ash stems had become most numerous. The author indicated that rapid invasion by chokecherry and raspberry, followed by replacement with more shade-tolerant species was a common pattern of secondary succession [27].

In southern and western North Dakota chokecherry is an indicator species for the green ash/chokecherry woodland habitat type [64,65]. This habitat type is characterized as a topographic climax. Where disturbance from livestock grazing is heavy, shrub cover is greatly reduced and unpalatable western snowberry becomes dominant. Tree seedlings and saplings decline, leaving only older trees and an open understory [65]. In southern North Dakota chokecherry is an indicator species for the interior ponderosa pine/chokecherry habitat type, determined to be an edaphic climax. In undisturbed vegetation of this type, ponderosa pine forms a closed overstory and chokecherry shrubs reach about 3.28 feet (1 m) in height. Chokecherry responds to fire in these stands by resprouting vegetatively, and as succession advances following fire, chokecherry gradually increases while other shrubs decrease [64]. The green ash/chokecherry and interior ponderosa pine/chokecherry habitat types also occur in South Dakota and eastern Montana [64,66,77,119].

WESTERN STATES

In the western United States, chokecherry is usually identified as seral but persists under closed canopies in mature conifer forests and in riparian areas. Central Rocky Mountain quaking aspen stands, where chokecherry is prevalent in the tall shrub layer, are thought to be a regional transition zone between sporadic groves and extensive forests. The quaking aspen/chokecherry community is categorized as seral [114].

In a classification of forest habitats of Montana [119], chokecherry is documented in numerous habitat types within forest climax series for limber pine, ponderosa pine, Douglas-fir, and Engelmann spruce. In that classification it is also an indicator species for a ponderosa pine/chokecherry type present in eastern Montana (see discussion in North Dakota section above). In river drainages of central Montana, Eichorn and Watts [46] studied succession following wildfire. In burned north-slope sites characterized by a Douglas-fir/common juniper association, chokecherry, snowberry (Symphoricarpos spp.) and rose (Rosa spp.) were predominant among shrubs that increased significantly (P<0.05) in years 5 through 28 following burning. In Douglas-fir habitat types in western Montana, chokecherry becomes common after stand-replacing wildfires and clearcuts with or without subsequent broadcast burns [8].

In central Idaho chokecherry is classified by Steele and Geier-Hayes [143] as mid-seral in 7 Douglas-fir habitat types. Though seral to Douglas-fir climax forests, these sites may be dominated by open-canopy stands of fire-maintained ponderosa pine. Chokecherry may regenerate vegetatively or by seed following logging or burning, depending on the type and severity of the disturbance.

In a central Utah study, Christensen [33] reported that although mountain brush stands are often interpreted as stable, chokecherry was among 10 shrub species in a mountain brush stand undergoing transition to a conifer stand dominated by white fir and Douglas-fir. The author interpreted the transition as primary succession because no evidence was found of disturbance by livestock use, fire or logging. Chokecherry is common in Gambel oak communities in Utah, which Kunzler and others [90] predicted might succeed to ponderosa pine, bigtooth maple (Acer grandidentatum), or white fir and Douglas-fir, depending on site conditions. Chokecherry is common in northern Utah quaking aspen stands, which are reported to succeed to conifer stands [14]. In a study of early succession following clearcutting of quaking aspen, chokecherry and snowberry were "by far" the most dominant shrubs in uncut control plots. In the 4 years following clearcutting, percent composition of chokecherry in the undergrowth increased by much as 5 times over that in the control plots. The authors did not indicate the method of chokecherry regeneration in the clearcuts [14].

SEASONAL DEVELOPMENT:

Generally chokecherry plants leaf out in spring to early summer and flower 1 to 3 weeks later, with fruits maturing in late summer to fall [166]. Fruits dehisce soon after maturity [59]. Average date of phenological stages for chokecherry east and west of the Continental Divide in Montana from 1928 to 1937 are presented below [130]:

                           East Divide      West Divide
leaf buds burst            May 2            April 29
leaves full grown          June 11          May 17
flowers start              June 4           May 19  
flowers end                June 17          June 11
fruits ripe                August 22        August 14
leaves start to color      August 31        September 15
leaves begin to fall       September 10     September 28
seed fall starts           September 12     September 19 
leaves fallen/withered     September 30     October 14

Related categories for SPECIES: Prunus virginiana | Chokecherry