FIRE CASE STUDIES
SPECIES: Dactylis glomerata | Orchardgrass 



CASE NAME : 
Vegetation response to spring and fall burning for wildlife habitat improvement


REFERENCE : 
Noste, N. V. 1982 [51]


SEASON/SEVERITY CLASSIFICATION : 
Spring- moderate severity
Fall -extreme severity


STUDY LOCATION : 
Ten miles (16 km) north of Missoula, Montana, on a generally southeast
aspect below 4,920 feet (1,500 m).


PREFIRE VEGETATIVE COMMUNITY : 
The study site had been previously burned by wildfire in 1945, which set
back the successional stage to a seral shrub community.  The habitat
type is Douglas-fir/ninebark (Pseudotsuga menziesii/Physocarpus
malvaceus).  This area remained unburned until 1979 (the year of the
prescribed burns), and the shrub species important for wildlife had
become decadent.

Herbaceous vegetation aerial crown cover averaged 19 percent prior to
the fall burn, and 24 percent prior to the spring burn.

Species present on the site prior to the spring burn were serviceberry
(Amelanchier alnifolia), evergreen ceanothus (Ceanothus velutinus,
creeping Oregon grape (Berberis repens), ninebark (Physocarpus
malvaceus), chokecherry (Prunus virginiana), Scouler willow (Salix
scouleriana), snowberry (Symphoricarpus albus), spreading dogbane
(Apocynum androsaemifolium), kinnikinnick (Arctostaphylos uva-ursi),
arrowleaf balsamroot (Balsamorhiza sagittata), pinegrass (calamogrostis
rubescens), elk sedge (Carex geyeri), orchardgrass (Dactylis glomerata),
and timothy (Phleum pratense).  Species present present prior to the
fall burned site included all of the above, except creeping Oregon
grape, spreading dogbane, arrowleaf balsamroot, kinnikinnick, and
timothy, but did include Douglas hawthorn (Crataegus douglasii) and
spotted knapweed (Centaurea maculosa).


TARGET SPECIES PHENOLOGICAL STATE : 
The target species for this study was evergreen ceanothus (Ceanothus
velutinus), selected for its importance to wildlife.  A number of
species were monitored preburn and postburn.  Orchardgrass on the spring
burn site was in a green growing stage, not yet in flower.  On the fall
burn site, orchardgrass was generally dormant (tall dead material with a
green basal rosette).


SITE DESCRIPTION : 
Both burned sites occurred on generally southeast aspect below 4,920
feet (1,500 m).  The slope averages 30 percent with a maximum of 50
percent.


FIRE DESCRIPTION : 
Fuel loadings on the fall burn were greater than on the spring burn, but
fuel loadings on both sites were low.  The amount of fine fuel was
marginal for carrying the fire.

The fall fire prescription called for a "hot fire moving fast enough to
consume all grasses and forbs and kill the cambium at the stems of most
of the shrubs."  For the fall fire, rate of spread ranged from 40 chains
per hour on the lower slope to 56 chains per hour on the upper slope.
On the spring fire, rate of spread ranged from 10 chains per hour on the
mid-slope, 11 chains per hour on the upper slope to 18 chains per hour
on the lower slope.

Weather and fuel moisture conditions during the burn are shown in the
tables below:

Fine fuel moisture contents:

---------------------------------------
Transect                   Fuel
                    Dead          Live
---------------------------------------
                    ----(percent)-----
Fall fire             6             55
F1-4 upper slope      8             62
F1-2 mid slope        8             53
F1-1 lower slope

Spring fire 
S1-2 upper slope      8             67
S1-3 mid slope        9            156
S1-1 lower slope     12            149
---------------------------------------


Weather conditions during the burn:

-----------------------------------------------------------------------
                                        Observations
                        -----------------------------------------------
                          Dry bulb      Relative            Wind
                         temperature    humidity          velocity
    Transect
------------------------------------------------------------------------
                       (deg F(deg C))   (percent)    (Mi/h)       (km/h)

Fall fire
F1-4 upper slope          59 (15)          30       6/gusts to 8    (10)
F1-2 mid slope            69 (20)          23       8               (13)
F1-1 lower slope          70 (21)          18       7/gusts to 12   (11)

Spring fire
S1-2 upper slope          65 (18)          36       5/gusts to 7    (8)
S1-3 mid slope            57 (14)          30       6/gusts to 10   (10) 
S1-1 lower slope          62 (17)          37       6/gusts to 8    (10)
-------------------------------------------------------------------------


FIRE EFFECTS ON TARGET SPECIES : 
In the 2 years following the spring burn, herbaceous aerial crown cover
averaged 21 to 22 percent.  In the 2 years following the fall burn,
average herbaceous aerial crown cover was 28 percent. Orchardgrass was
considered an important component of the preburn vegetation that
reproduced well.

Prior to the spring burn, orchardgrass provided 253 cubic feet per acre
(2.9 m3/ha) and in the following 2 years provided 45 cubic feet per acre
(0.52 m3/ha) and 654 cubic feet per acre (7.5 m3/ha) respectively.

Prior to the fall burn, orchardgrass is reported as 554 cubic feet per
acre (6.35 m3/ha), and in the years following the burn is reported as 30
and 134 cubic feet per acre (0.34 and 1.54 m3/ha), respectively.


FIRE MANAGEMENT IMPLICATIONS : 
The fall burn was hotter and faster moving than the spring burn, and
apparently caused more damage to orchardgrass plants than did the spring
burn.  But even the greater severity of the fall burn did not result in
a complete removal of orchardgrass.  As is true of most perennial grass
species, orchardgrass is well adapted to recover after even severe
fires, although recovery is slower after severe burns or hot fires.  If
the management objective is to increase orchardgrass specifically (as
this study was not intended), then a less severe treatment, such as the
spring burn, would be recommended.

Related categories for Species: Dactylis glomerata | Orchardgrass