FIRE EFFECTS
SPECIES: Rubus idaeus | Red Raspberry 



IMMEDIATE FIRE EFFECT ON PLANT : 
Red raspberry is described as "resistant" to fire [39,103].  However,
foliage is extremely susceptible to fire-induced mortality [52].  In an
Alberta study, all aboveground stems were completely killed wherever
supplemental fuels contributed to relatively intense fires [52].  Where
fuels were reduced and fires less intense, the stems of many plants were
only partially killed [52].  However, all aerial stems experienced at
least partial mortality, regardless of fire intensity.

Belowground regenerative structures appear to be relatively resistant to
fire [39].  Johnston and Woodard [52] observed belowground mortality
only on plots with high surface fuel loadings (3.94 or 9.65 kg/m sq).
Here, tissue mortality extended as far as 0.4 to 1.2 inches (1-3 cm)
below the duff surface.  Raspberry is capable of sprouting from lateral
buds on relatively shallow roots.  These roots, which are small and
succulent, are poorly protected by duff and can be damaged by fires of
high intensity and severity [52].  However, at least some regenerative
structures typically grow to 2 inches (5 cm) below the soil surface, and
many are apparently unharmed by fires of even high intensity and
severity [52].  In general, the effects of fire on red raspberry are
much less pronounced wherever nutrients and water are abundant [39].
The long-lived seed of red raspberry is generally unharmed by fire when
protected by overlying soil [39,78,94].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
In an Alberta study, both dead and live woody stems remained where fuel
loadings of 0.00, 0.17, and 0.87 kg/m sq were recorded [52].  However,
all foliage was completely consumed on plots with fuel loadings of 3.94
and 9.65 kg/m sq [52].


PLANT RESPONSE TO FIRE : 
Red raspberry is well adapted to reoccupy a site quickly after fire.
This common "fire follower" is favored by increased amounts of nitrates
present on burned sites and generally exhibits rapid and vigorous
postfire growth through sprouting and/or seedling establishment [4,95].

Vegetative response:  Red raspberry typically sprouts readily after fire
wherever present in preburn communities [18,95].  Most belowground
regenerative structures appear to be well protected from the damaging
effects of heat [52].  Postfire sprouting of root buds is commonly
observed.  Although more shallow root buds may be damaged or killed by
heat, root bud depths can range from 1.9 to 2.4 inches (5-6 cm) or
greater [28,52] and many escape serious damage.  Postfire sprouting from
rhizomes may also occur [39], although a number of researchers have
reported no evidence of any rhizomes with regenerative capabilities in
the red raspberry [28].  Where light fires damage but do not kill the
aboveground foliage, aerial stems generally resprout and quickly resume
growth [52].  Consequently, red raspberry is reported to be
"rejuvenated" by fire [103].

Johnston and Woodard [52] reported that fire intensity and severity had
little effect on the sprouting ability of red raspberry in aspen
communities of east-central Alberta.  Both the number of sprouts
produced per plant and total biomass appeared unaffected by fire
intensity and severity.  However, the height growth of individual
sprouts was greatest after fires of low severity.  Thus, although high
severity fires reduced the rate of sprout growth, they did not affect
the number of sprouts produced by each plant [52].

Seedling establishment:  Rapid postfire establishment through on-site
seed is common in the red raspberry [95].  Long-lived seed, which is
produced in abundance, accumulates in seedbanks in the soil or duff
[35,38].  Germination is enhanced by exposure to heat [78,94], and large
numbers of seed germinate soon after disturbance [100].  Mineral soil
creates a favorable seedbed [26] and elevated nitrate levels enhance
early seedling growth.  Most germination occurs within the first year
after fire [38].  

Limited evidence suggests that fires of high intensity and severity may
promote red raspberry seedling establishment more than light fires.
Bock and Bock [6] observed vigorous seedling establishment after crown
fires in ponderosa pine forest of the southern Black Hills.  However,
large increases in red raspberry did not occur after lighter, cooler
ground fires in the same area [6,7].  Extremely light fires may provide
insufficient heat scarification and do little to prepare a seedbed.

Postfire recovery:  Postfire recovery of red raspberry is generally
rapid, with vigorous expansion in cover during early seral stages.  This
shade-intolerant species [95,100] declines as tree cover increases [29].
In many communities, red raspberry begins to decline within only 3 or 4
years after fire [18,103].  It is important to note that many variables
can significantly influence the speed of postfire recovery and
subsequent persistence within the community.  Such variables may include
season of burn, fire intensity and severity, site characteristics,
genetic variation, and climatic factors.  Specific postfire response of
red raspberry by community is discussed in the 'Successional Status'
slot.


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
In some areas, significant differences in postfire recovery of red
raspberry have been noted after fires of varying intensity and severity.
The following data document postfire recovery in ponderosa pine stands
of the southern Black Hills of South Dakota [7,6]:

                  # of stems per subplot
fire type       preburn     1st year     2nd year      5th year 

  light burn       0            0          0.07         ---
  crown fire      ---          ---         0.01        116.8

                       # of individuals
fire type               1st year     2nd year     3rd year     5th year

  cool ground fire          0            0           3           ---
  hot crown fire           ---          ---         ---         4,672
    


FIRE MANAGEMENT CONSIDERATIONS : 
Fire generally benefits animals that consume the fruits of species
within the genus Rubus [58].

Related categories for Species: Rubus idaeus | Red Raspberry