• IMMEDIATE FIRE EFFECT ON PLANT
• DISCUSSION AND QUALIFICATION OF FIRE EFFECT
• PLANT RESPONSE TO FIRE
• DISCUSSION AND QUALIFICATION OF PLANT RESPONSE
• FIRE MANAGEMENT CONSIDERATIONS

IMMEDIATE FIRE EFFECT ON PLANT:

Fire often kills aboveground chokecherry stems and foliage, but it quickly resprouts, either the same year following a spring burn, or by the next growing season [97,105,162,166,177]. In the South Dakota Black Hills chokecherry sprouts were double the preburn numbers within 2 months of an early May burn [51]. Conversely, in an early May prescribed burn in central Alberta quaking aspen parkland, chokecherry shrubs did not resprout within the first 3 months following burning [63]. Fire intensity was not described for either study.

A prescribed fire study was conducted in northern Idaho to test the effect of spring versus fall burning on elk browse. Measurements were made of crown diameter, crown height, number of basal sprouts, and sprout height before and after each burn. Postfire measurements were made on 11 shrubs the first growing season after the fall burns. Seasonal fire effects were similar for chokecherry crown diameter, crown height, and sprout height. Though not statistically significant (at P = 0.05), the number of chokecherry basal sprouts was somewhat higher after the spring burn, suggesting that spring burning may be more conducive to the rapid recovery of chokecherry than fall burning [97].

DISCUSSION AND QUALIFICATION OF FIRE EFFECT:

No entry

PLANT RESPONSE TO FIRE:

Most studies report either an increase in chokecherry in the years following fire, or an increase followed by a return to prefire numbers. After wildfires in the oakbrush zone in Utah, McKell [105] reported twice as many chokecherry stems sprouting from root crowns on 1-year-old burns than on adjacent unburned sites. A reduction to prefire densities occurred within 18 years.

Following wildfires in Rocky Mountain Douglas-fir/Rocky Mountain juniper/Wyoming big sagebrush associations in the Missouri Breaks area of central Montana, chokecherry canopy cover increased consistently for 13 years, then stabilized [46].

Bock and Bock [22] compared data from prescribed October burns in 1974 and 1979 in the South Dakota Black Hills. The 1974 burn escaped and became a crown fire, killing ponderosa pines of all sizes. The 1979 fire remained a controlled understory fire. When measured in 1981, the 1974 burn site supported higher densities of all woody taxa except chokecherry and western poison-ivy (Toxicodendron rydbergii). There was no significant difference (P = 0.71) in numbers of chokecherry plants between the 2 burn sites. Measurements taken within the 1979 surface fire site (prefire, postfire yr 1, and postfire yr 2) showed that chokecherry stems were not significantly (P = 0.75) reduced by the fire.

Geier-Hayes [53] included chokecherry in a study of vegetation response to helicopter logging and broadcast burning in an Idaho Douglas-fir forest. Data were collected in 3 cutting units prior to burning and 1,2,5 and 10 years after. Fire severity was higher in 2 of the units and altered the vegetation from the original. Fires classed at a severity level of 2M [126] were less severe and had little or no impact on chokecherry percent cover and root frequency. 2M fires are characterized as having a flame length of 2 to 4 feet (0.6-1.2 m) and a corresponding crown scorch height of 9 to 24 feet (2.7-7.3 m), with moderate ground charring. The units that burned hotter, having a severity rating of 3M had markedly less chokecherry cover and root frequency during all postburn years measured. 3M fires have flame lengths of 8 to 12 feet (2.4-3.7 m), corresponding crown scorch to 64 feet (20 m), with moderate ground charring.

Following a September prescribed burn in a quaking aspen stand in Idaho, chokecherry biomass exceeded preburn biomass within 2 seasons and was double preburn biomass after 5 seasons [29]. Biomass was computed using weight versus stem diameter relationships [28]. Details of fuel conditions are provided: litter and woody material moisture content was 8 to 9% and herbaceous vegetation was 40 to 50% cured. Fire severity was rated as moderate to high [126].

After 24 years of annual early spring burning in quaking aspen parklands in Alberta, chokecherry percent cover had decreased but the number of stems increased in density from 6% to 15% [5].

In a 20-year study of the effects of fire frequency on Minnesota oak savanna herbs and shrubs, Tester [150,151] determined that increased fire frequency tended to increase the density of native, true prairie shrubs and decrease the density of native, non-prairie shrubs (including chokecherry). Chokecherry cover estimates were negatively correlated with burn frequency (r = -0.51, P = 0.09).

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:

No entry

FIRE MANAGEMENT CONSIDERATIONS:

Chokecherry is a component of persistent, fire-maintained seral shrubfields on steep slopes in Northern Idaho. Fuels in shrubfields differ in quantity and distribution from those on forested sites. Herbaceous and large woody fuels are relatively light. Live and dead shrub biomass, which includes chokecherry, can reach nearly 20 tons per acre. After fires, which are severe during summer drought conditions, dense shrub cover regenerates within 10 years. Trees regenerate slowly or not at all on these dry sites, because of erosion, depleted soil organic matter, high soil temperatures, and lack of seed [138].

Arno [7] hypothesized that relatively frequent fires set by Native Americans in western grassland and sagebrush communities, where chokecherry occurs, favored expansion of grasslands into adjacent shrub or tree communities. In recent times shrub and tree communities have developed in former grasslands due to fire exclusion and grazing. Arno argues that baseline information on Native American use of fire will aid land managers in predicting vegetative development under different fire regimes.

Morber and Miyanishi [112] studied fire as a tool for controlling chokecherry and black cherry in Ontario oak savanna. A controlled spring burn had no effect on chokecherry seedlings. Postfire seedling emergence was concluded to be largely dependent on postfire seed production or seed influx from adjacent unburned areas, because there was no viable soil seedbank.

Related categories for SPECIES: Prunus virginana | Chokecherry