FIRE CASE STUDIES
SPECIES: Ribes lacustre | Bristly Black Currant 



CASE NAME : 
Neal Canyon Prescribed Fire/Vegetation Development Study


REFERENCE : 
Lyon, J. L. 1971 [42]


SEASON/SEVERITY CLASSIFICATION : 
Summer/severe


STUDY LOCATION : 
The study site is located in Neal Canyon, 6 miles (9.6 km) north of
Ketchum, Idaho, in the Sawtooth National Forest.


PREFIRE VEGETATIVE COMMUNITY : 
The study site was selectively logged in 1950 and 1960.  The remaining
trees were primarily pole and sapling Douglas-fir (Pseudotsuga
menziesii), many of which were diseased.  Minor tree species included
lodgepole pine (Pinus contorta), subalpine fir (Abies lasiocarpa),
Englemann spruce (Picea engelmannii), and quaking aspen (Populus
tremuloides).  Understory vegetation was dominated by Rocky Mountain
maple (Acer glabrum) and mountain snowberry (Symphoricarpos oreophilus).
Bristly black currant was a minor species.

Vegetation layers over and under 18 inches (46 cm) in height were
sampled and described separately.  Bristly black currant under 18 inches
occurred on 20 percent of the study quadrats.  Bristly black currant
abundance of plants over 18 inches in height was:

density                     0.9 plant/1,000 sq feet
canopy cover                0.67 percent
aerial crown volume        16.8 cubic feet/1,000 sq feet


TARGET SPECIES PHENOLOGICAL STATE : 
Bristly black currant was probably in flowering and fruiting stages on
August 1, the day of the fire.  


SITE DESCRIPTION : 
The mountainous study site is at 6,500 feet (1,980 m) elevation.  Annual
precipitation is from 14 to 17 inches (360-430 mm), most occurring in the
winter as snow.  The slope averages 64 percent and the aspect is 10 to
20 degrees.  The soils are rocky, averaging 50 percent gravel.


FIRE DESCRIPTION : 
The fire was started at 8 a.m. on August 1, 1963 and burned until 5 p.m.
Air temperature was 50 degrees Fahrenheit (10 deg C) in the morning and
nearly 80 degrees Fahrenheit (27 deg C) in the afternoon.  Relative
humidity declined from 50 percent in the morning to 10 percent in the
afternoon.  Fuel moisture sticks indicated 5 to 6 percent moisture.
Surface winds were less than 5 miles per hour, but fire-induced gusts up
to 30 miles per hour were recorded.

The fire was severe and crowned.  All litter, herbaceous plants, dead
woody stems less than 3 inches (7.6 cm) in diameter, and live woody
stems less than 2 inches (5.1) in diameter were consumed.  The
Douglas-fir overstory was killed.  The mean heat flux, measured using
water-can integrating devices, was 200 calories per second for 45
seconds.


FIRE EFFECTS ON TARGET SPECIES : 
Bristly black currant was killed by the fire.  Bristly black currant was
observed on the study site beginning in postfire year 2.  However, no
bristly black currant less than 18 inches in height was detected during
the 7 postfire years in 2- by 2-foot quadrats.  Density, height, and
crown volume for bristly black currant over 18 inches in height was
originally recorded using quarter-point sampling [79], but this
technique was eventually deemed inadequate because of low plant
densities.  Beginning in 1966 (postfire year 3), 0.04 acre (0.016 ha)
plots were sampled, both in the original quarter-point sampling area and
in three additional subplots located at lower, middle, and upper slope
sites; measurable quantities of bristly black currant occurred only on
the lower and upper slope subplots.  Bristly black currant over 18
inches in height was first recorded in postfire year 3, presumably
growing from seed in the first or second postfire year.  The following
data should be interpreted with caution because of very low sample
numbers for bristly black currant.

                                           Postfire year
                      
                           1      2      3      4      5      6     7

plants/1,000 sq ft
  original study area:     -      -      T      T      -     0.3   0.1
  subplots (lower slopes): *      *     0.2    0.2    1.0    1.3   1.8
  subplots (upper slopes): *      *     0.1    0.5    0.2    0.2   0.5

canopy cover (%)            
  original study area:     -      -      T     0.01    -    0.05    T

aerial crown volume  
  (cu ft/1,000 sq ft)    
  original study area:     -      -     0.1    0.1     -     1.1    T    
  subplots (lower slopes): *      *     0.2    0.4    2.6    7.4   4.4
  subplots (upper slopes): *      *     0.7    2.0    1.4    1.8   2.5

*Data were not collected


Height and crown volume were measured and averaged for the first four
bristly black currants on the burn to reach 18 inches in height.

                                           Postfire year

                           1      2      3      4      5      6     7

average height (ft)        -      -     1.7    1.6    1.5    2.4   1.9

Average volume (cu ft)     -      -     2.6    3.1    4.4   11.5   6.2

A wildfire site which burned in 1950 was located near the Neal Canyon
study site.  Twenty years after the wildfire, bristly black currant
averaged 2.6 plants per 1,000 square feet, 0.6 percent cover , and 12.2
cubic feet aerial crown volume per 1,000 square feet.  Based on the Neal
Canyon prescribed fire and the wildfire, Lyon [42] projects that bristly
black currant will reach prefire crown volumes 30 to 40 years after
fire.


FIRE MANAGEMENT IMPLICATIONS : 
NO-ENTRY

Related categories for Species: Ribes lacustre | Bristly Black Currant