FIRE CASE STUDIES
SPECIES: Vaccinium angustifolium | Low Sweet Blueberry 



CASE NAME : 
Minnesota burn pruning, low sweet blueberry


REFERENCE : 
Shubat, D. J. 1983 [132]


SEASON/SEVERITY CLASSIFICATION : 
May/not reported.


STUDY LOCATION : 
Sites are located along Highway 1 in northeastern Minnesota, south of the Ely
Airport, and 2 miles north of Silver Bay on Lake Superior.  Specific locations
are as follows:

     (1) Palisades Site:  located 2.5 miles (4 km) northeast of Silver Bay on
            Highway 61. (SW 1/4 Sec 22, T56N, R7W).
     (2) Isabella Tracks:  cleared area north of Ely on Highway 1,
            approximately 0.5 mile (0.8 km) west of Forest Service
            Headquarters at Isabella, Minnesota.  (NE 1/4, SE 1/4, Sec 1,
            T59N, R9W).
     (3) Isabella Sawbill: 12 miles (19 km) east of Isabella, Minnesota, just
            west of Sawbill Landing (NE 1/4 Sec 1, T60N, R8W). 
     (4) Ely North:  2 miles (3 km) south of Ely Airport on Highway 120 and
            Highway 1 (W 1/2, NE 1/4, SW 1/4, Sec 35, T62N, R12W).
     (5) Ely South:  located near Ely, Minnesota (SW 1/4, NW 1/4, NW 1/4, Sec
            11, T61N, R12W).


PREFIRE VEGETATIVE COMMUNITY : 
The preburn vegetative community consisted of pure open stands of low
sweet blueberry (Vaccinium angustifolium), or stands made up of both low
sweet blueberry and velvetleaf blueberry (V. myrtilloides).

     (1) Palisade Site:  Low sweet blueberry plants were short and "stunted."
     (2) Isabella Tracks:  Velvetleaf blueberry was the primary lowbush
           blueberry at this site.
     (3) Isabella Sawbill:  This stand was made up of young, vigorous low
            sweet blueberry plants.
     (4) Ely North:  Many weedy species were intermixed with low sweet
            blueberry. 
     (5) Ely South:  This stand exhibited few weedy plants.  The soil surface
            was cover with decomposing branches and small logs.  Low sweet
            blueberry plants were described as vigorous.


TARGET SPECIES PHENOLOGICAL STATE : 
not reported


SITE DESCRIPTION : 
Paired plots, burned and unburned, were located at four of the location.
The fifth site (Palisade) had only the unburned plot.  All plots were on
level ground in full sun.  Soils were as follows:

           P         IT           IS           EN           ES
                  a      b      a     b      a      b      a     b
pH        4.5    5.3    5.3    5.3   5.4    5.0    5.4    5.0   4.1
organic
 matter   high   low    low    low    med.  low    low    low   med.
nitrogen  low    low    low    low    low   low    low    low   low 
texture   loam  loamy  sandy  loamy  loamy  loamy  sand  loamy  sand
                 sand   loam   sand   sand   sand         sand  

a unburned plot   P  Palisade site     IS Isabella Sawbill site
b burn plot       ES  Ely South site   IT Isabella Tracks site
                  EN  Ely North site 


FIRE DESCRIPTION : 
      Palisades Site - not burned.
      Isabella Tracks - mechanically pruned and burn-pruned plots.
      Isabella Sawbill - mechanically pruned and burn-pruned plots.
      Ely North - mechanically pruned and burn-pruned plots.
      Ely South - mechanically pruned and burn-pruned plots.

Dried straw was spread across the burn-pruned plots prior to ignition. 


FIRE EFFECTS ON TARGET SPECIES : 
             stems/     flower buds/      stem length       stand
             0.1 m sq.  plant                 (cm)          age (yrs)
Isabella
Tracks-
  unburned     2.3          6                 22               3
  burned       2            8                 24               3

Isabella
Sawbill
  unburned     3           2.3                22               2.6
  burned       5           2.4                22               2

Ely North     
  unburned     2           2                  23               4
  burned       2.3         1                  23               4

Ely South 
  unburned     3          11.6                35               4
  burned       2           5.5                25               5


FIRE MANAGEMENT IMPLICATIONS : 
Both burning and mechanical pruning increased stem numbers.  However,
mechanically pruned plants produced more flower buds than the
burn-pruned plants.  Tests indicated that mulch should not be applied to
recently pruned plants.  Fertilizers proved to be most effective on
mechanically pruned and untreated plants.  They had little effect on
recently burned plants.  Best results were observed when plants were
mechicanically clipped or fire pruned in April or November.  This
experiment suggests that semicultivated stands of low sweet blueberry in
Minnesota may need to be pruned every 4 to 5 years rather than every
other year as is most common in parts of the Northeast.

Related categories for Species: Vaccinium angustifolium | Low Sweet Blueberry