FIRE EFFECTS
SPECIES: Prunus emarginata | Bitter Cherry 



IMMEDIATE FIRE EFFECT ON PLANT : 
Bitter cherry is top-killed or killed by severe fires [70,79,89].
High-severity fires favor bitter cherry [89].  Young [135] stated that
bitter cherry is "unharmed to enhanced" by fire.  However, bitter cherry
mortality can be high when burning occurs while plants are actively
growing.  Approximately 14 percent of 36 mature bitter cherry died after
a single spring (late March/early April) prescribed fire on a seral
brushfield in northern Idaho [73].  Repeated spring burning of similar
sites at 5-year intervals resulted in heavy bitter cherry mortality
[70].  Seven plants sprouted following a fire in late March 1965.  Of
these, four resprouted after a second fire in May 1970, and two remained
alive after a third fire in May 1975.  Total mortality by 1976 was 86
percent.  Leege [70] suggested that the tendency toward fire-induced
mortality in bitter cherry was probably accentuated by the advanced
phenologies of plants during the second and third fires.


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Bitter cherry sprouts from the root crown following fire [47,105].
Since root sprouting has been documented in bitter cherry [28] it
probably also sprouts from roots after fire.  It establishes from buried
seed or seed dispersed onto burned sites [114].  Several studies have
reported rapid recovery and substantial postfire increases in bitter
cherry densities [16,33,112].  In an Oregon coastal brushfield, bitter
cherry sprouted from roots 4 months after fire [138].  In an Oregon red
alder (Alnus rubra)-dominated brushfield burned on August 9, 1974, bitter
cherry started sprouting within 2 to 3 weeks.  By November, bitter
cherry was sprouting vigorously and stems were 3.3 feet (1 m) tall
[106].

In Montana a prescribed fire occurred on April 13, 1988.  Plots were
observed from mid-July to mid-September.  Bitter cherry sprout twig
weights on burned plots exceeded twig weights on unburned plots by a
factor of 4 on southwest-facing forested types and by a factor of 9 on a
southeast-facing forested type [76].

In northern Idaho more bitter cherry sprouts are produced per surviving
plant after spring fires than fall fires; however, sprout height is
usually greater after fall fires.  Bitter cherry recovery trends 1 year
after a prescribed fire in seral brushfields in northern Idaho are
presented below [73]:

                                                time of fire
                                           spring          fall

average # of basal sprouts per plant    
       prefire                              0.4             0.5
       postfire                            18.3            15.2
average height basal sprouts (ft)        
       postfire                             2.0             2.6
average crown diameter (ft)              
       prefire                              5.0             4.7
       postfire                             1.9             2.3
average crown height (ft)
       prefire                             15.1            13.9
       postfire                             3.4             4.1

A seral brushfield in northern Idaho was prescribed burned in 1965,
1970, and 1975.  Bitter cherry sprouted from the root crown and a few
seedlings were observed.  The average prefire crown height and diameter
were 8.4 feet and 1.6 feet, respectively.  Bitter cherry recovery trends
2 years after the prescribed fires are presented below [70]:

                                              year
                                1966          1971          1976

maximum crown height (ft)        5.2           5.5           4.1
maximum crown diameter (ft)      2.2           2.5           2.0

Idaho studies investigating postfire successional patterns in a western
redcedar (Thuja plicata)/queencup beadlily (Clintonia uniflora) habitat
type found that bitter cherry regenerated predominantly from seedbanks.
Seedling establishment was affected by fire severity.  Bitter cherry
seedlings had greatest percent cover on low-severity burns in postfire
years 1 to 3; in postfire years 4 and 5, bitter cherry seedling percent
cover was greatest on high-severity burns [87,89].

A seral brushfield in northern Idaho was prescribed burned on May 2,
1966; all aboveground vegetation was "totally consumed".  In May 1967,
257 bitter cherry seedlings were observed.  By May 1968, 14 bitter
cherry seedlings remained [69].  In northeastern Idaho, on a May 14,
1975 prescribed burn, seven bitter cherry seedlings were observed in
postfire year 2.  By postfire year 4, four seedlings remained [71].  In
Oregon a Douglas-fir (Pseudotsuga menziezii) clearcut was prescribed
burned in late fall.  Bitter cherry seedlings were present postfire year
1 on the burned site but were not present in adjacent virgin forest
[33].

In Oregon 240 acres (96 ha) of a Douglas-fir watershed was harvested
over a 4-year period from the fall of 1962 to the summer of 1966.  It
was broadcast burned in October 1966.  Bitter cherry reached peak
abundance about 10 years after fire [39].  In north-central Idaho in a
grand fir (Abies grandis)/pachistima habitat type, 36 stands
representing 1, 3, 8, 12, and 23 year age classes and 7 near-climax
stands were clearcut and broadcast burned.  Canopy cover and height of
bitter cherry for each age class were as follows [136]:

                     canopy cover                 height 
                         (%)                inches  centimeters 
age class

1                         0.1                 9         22
3                         0.1                 17        44      
8                         0.4                 25        63
12                        0.9                 49        122       
23                        0.3                 38        95          
near-climax               0.0                 --        -- 
      
In the western Cascades bitter cherry was absent from undisturbed
old-growth Douglas-fir stands, but was abundant on Douglas-fir
plantations that were clearcut and broadcast burned 2 to 40 years ago.
Shrub dominance decreases at 20 to 30 years with canopy closure [108].  


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Bitter cherry is a member of the seral brush community in northern
Idaho.  These brushfields provide excellent habitat for elk.  Bitter
cherry is one of the dominant shrubs after fire, but grows out of reach
of browsing animals within several years.  If brushfields are not
maintained by fire, coniferous forest may eventually establish and large
ungulate habitat will be lost [42,45,92,124].  Bitter cherry was found
to have greater frequency and crown cover on single broadcast burned
sites than on unburned and piled-and-burned sites [92].

Related categories for Species: Prunus emarginata | Bitter Cherry