FIRE EFFECTS
SPECIES: Rumex acetosella | Sheep Sorrel 



IMMEDIATE FIRE EFFECT ON PLANT : 
Sheep sorrel is probably top-killed by fire.


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Sheep sorrel probably sprouts from rhizomes following fire and
establishes from on-site seed [14,21,26].  Several studies describe
establishment or increase of sheep sorrel after fire.  Very severe fire
may kill sheep sorrel.

In New Brunswick a woodlot was clearcut in the fall of 1949 and
prescribed burned in April 1951.  The number of stems of sheep sorrel
per area present in June 1949, 1950, 1951, and 1952 were 0, 0, 18, and
28, respectively [31].  In New Brunswick understory layers of 11 mixed
hardwood stands representing an age sequence of 7 to 57 postfire years
were examined.  Sampling occurred in July and August 1973 and 1974.
Sheep sorrel was found in stands 7, 10, 13, 17, and 25 years old.  It
did not occur in some 7-year-old stands, or in stands 18, 20, 29, and 37
years old [58].

In Idaho seral brushfields in a grand fir/pachistima habitat type were
prescribed burned on May 14, 1975, and a portion was seeded on May 15,
1975.  Sheep sorrel was present on the burn-only area, but did not occur
on the burn-and-seed site.  Frequency (out of 10 possible plots) of
sheep sorrel was as follows [53]:

                    Prefire          Postfire year   
                  July 3, 1974        1    2    4

control                1              2    3    3 
burn only              0              0    5    4
burn and seed          0              0    0    0
 
In Idaho a wildfire burned a ponderosa pine (Pinus ponderosa) forest and
adjacent montane grassland on August 10, 1973 for 43 days.  Fourteen
sites were examined in June 1974 and June 1976.  Percent cover and
frequency of sheep sorrel on burned and unburned sites were as follows
[65]:
                            1974                     1976
                     burned     unburned      burned      unburned

cover +/- SD        t* +/- 1    t +/- t      2 +/- 3      1 +/- 2 
frequency +/- SD    1  +/- t    t +/- 1      2 +/- 4      1 +/- 2

*t = trace

In Washington on the Mount Adams huckleberry (Vaccinium spp.)  fields,
an experimental area was prescribed burned from October 3-7, 1972.
Average understory cover (%) of sheep sorrel from 1972 to 1977 was as
follows [66]:

               1972 (before treatment)    1973    1974    1975    1977

unburned, uncut      0.2                   0.2     0.3     0.3     0.2
thin, underburn      0.2                   0.6     0.9     1.2     1.5
clearcut and burn    0.2                   0.9     1.9     1.0     1.6

In Great Britain severe fires in late summer 1976 killed all surface
vegetation.  Sheep sorrel first appeared in burned areas in October
1985, postfire year 9 [59].  


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
Some research describes no change in cover or frequency in sheep sorrel
after fire.  In California the effects of a late fall burn on a mountain
meadow in Grover Hot Springs State Park were evaluated.  Both wet and
dry meadow plots were prescribed burned by a low- to moderate-intensity
fire in mid-November 1987.  Sheep sorrel was found only on dry plots
before burning and did not increase following fire [8].

In Connecticut experimental tracts were set up in a little bluestem
grassland in 1967.  Tract A was prescribed burned annually from
1968-1976, and in 1978, 1980, 1983, and 1985.  Tract B was prescribed
burned annually from 1968-1975, and in 1978, 1980, 1983, and 1985.
Sheep sorrel percent cover and frequency in two burns and 2 control
plots on each tract were as follows [69]:

                     Tract A                        Tract B
               1967           1985            1967           1985
            cover  freq    cover  freq     cover  freq    cover   freq

treatment
Burn         <1     9        2     6        <1     29      <1      5    
Control      <1     22       0     0         1     65      <1      27

     


FIRE MANAGEMENT CONSIDERATIONS : 
NO-ENTRY

Related categories for Species: Rumex acetosella | Sheep Sorrel