FIRE EFFECTS
SPECIES: Rubus ursinus | Trailing Blackberry 



IMMEDIATE FIRE EFFECT ON PLANT : 
Trailing blackberry is described as "rather tolerant" of fire [25].
Although it may be top-killed [52], underground regenerative portions of
this shrub generally survive [9,52,61].  Fires of relatively high
severity or intensity, with the potential to harm belowground
regenerative structures, appear to be the most damaging to trailing
blackberry [52].

Most trailing blackberry seed stored on-site in the soil or duff is
probably unharmed by fire [52].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 



PLANT RESPONSE TO FIRE : 
Vegetative response:  Trailing blackberry is capable of vegetative
regeneration following fire through nonrhizomatous basal sprouts or root
"suckers" [9,52].  Basal sprouting is believed to be of primary
importance, and often results in a large number of sprouts [51].  This
low-growing shrub can also root at the stem nodes [37,65] and can
presumably spread quickly where portions of the aboveground stem remain
undamaged.  Vegetative spread is generally both vigorous and rapid.
Stewart [61] observed an average of approximately 1,520 sprouts (plus
some surviving original stems) per acre (3,762/ha) within 2 year after
fire.  Prior to the fire, an average of only 40 original trailing
blackberry stems had been counted within the same area.  Evidence
suggests that all forms of sprouting may be favored after fires of
relatively low severity or intensity which are unlikely to damage
belowground regenerative structures [52].  Expansion of trailing
blackberry may be delayed on heavily burned sites [25,50].  Comparative
cover and density values of sprouts on a 2-year-old burn in western
redcedar/pachistima and western redcedar/queencup beadlily habitat types
in northern Idaho are as follows [50]:
            
           low severity              high severity
        
  % cover     32.5                        16.0
  density      1.7                         1.8


Seedling establishment:  Seedbanking is reportedly an important means of
postfire reestablishment for the trailing blackberry [50].
High-severity fires, which burn to mineral soil, frequently create a
favorable seedbed for buried blackberry seed, and seedlings sometimes
germinate in abundance [52].  However in several instances, researchers
have observed decreased seedling establishment after unusually hot fires
with "much fuel consumption" [52,64].  Other factors, such as site
characteristics or climatic conditions, may have contributed to the
variable responses.  Seedling establishment of trailing blackberry can
also occur through seed transported from off-site by birds and mammals.

Rate of postfire recovery:  Sprouting produces the most rapid early
growth, as plants draw upon portions of previously established root
systems [52].  In many locations trailing blackberry has exhibited the
most rapid postfire expansion of any residual species [25].  This shrub
can dominate the herbaceous layer within 2 to 5 years after fire
[25,53,66].  Peak cover values have been reported from 0 to 5 years
after fire [25,51].  Trailing blackberry is characterized by a
relatively long (> 5 years) period of postfire abundance and generally
persists until suppressed by canopy closure [25].  Trailing blackberry
cover occasionally exhibits a temporary decline after rapid early growth
as one or a few stems attain dominance over many initial sprouts [50].
In western redcedar habitat types of northern Idaho, Morgan and
Neuenschwander [52] observed highest cover values in the third and fifth
years after fire, with trailing blackberry disappearing by the fifteenth
year.  However, trailing blackberry frequently remains abundant for 11
to 16 years or more after fire in the Cascade Mountains of western
Oregon [59,60].  Halpern [25] reported that it remained prominent for at
least 20 years after fire in seral Douglas-fir forests of western
Oregon.


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
Fire severity and intensity can influence the rate of postfire recovery
in trailing blackberry regardless of whether regeneration occurs
vegetatively or through seedling establishment.  The following response
has been observed in western redcedar/queencup beadlily habitat types of
Idaho [52]:

              mean frequency of occurrence 
              burn age in years
        
severity        1        2        3        4        5        15
  low          33       82       71       74       98         0
  high         71       80       68       74      100         0


FIRE MANAGEMENT CONSIDERATIONS : 
Timber harvest and slash burns:  Trailing blackberry commonly invades
logged and slash burned sites in the Douglas-fir zone of the Pacific
Northwest [39,61].  Reestablishment is rapid and can occur by the second
season after treatment [53].  In early postfire years, cover of trailing
blackberry is frequently as much as 3 times higher on slash burned sites
than in adjacent undisturbed stands [15].  Trailing blackberry remains
prominent until suppressed by the closure of the forest canopy [25].
Schoonmaker and McKee [59] reported the following cover values after
clearcutting and broadcast burning in the Cascades of western Oregon:

yrs. since
 tmt.       2       5       10      15     20      30      40  old growth 
        
cover(%)  2.28    2.18    1.11     9.7   20.52    7.35    0.66   0.18

Stewart [61] observed similar increases after clearcutting and broadcast
burns in Coastal Oregon:

years         preburn         1         3         4
        
cover (%)       .20          .90      2.40       .20

Competition:  Trailing blackberry is favored by fire and can
aggressively compete with conifer seedlings in some postfire
communities.

Wildlife:  Species which consume large amounts of blackberries are often
benefited by fire [45].

Related categories for Species: Rubus ursinus | Trailing Blackberry