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Wildlife, Animals, and Plants
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Introductory
SPECIES: Juniperus pinchotii | Pinchot Juniper
ABBREVIATION :
JUNPIN
SYNONYMS :
Juniperus monosperma var. pinchotii (Sudw.) Van Melle
Juniperus texensis Van Melle
Sabina pinchotii (Sudw.) Lewis
SCS PLANT CODE :
JUPI
COMMON NAMES :
Pinchot juniper
redberry juniper
Texas juniper
Christmas berry juniper
cedar
TAXONOMY :
The accepted scientific name for Pinchot juniper is Juniperus pinchotii
Sudworth. There are no recognized subspecies, varieties, or forms
[20,43,50,56].
Pinchot juniper is probably a stabilized hybrid between alligator
juniper (J. deppeana) and oneseed juniper (J. monosperma) [16]. Reports
of hybridization between Pinchot juniper and oneseed juniper were not
substantiated by chemosystematic analysis [1,2,57]. Pinchot juniper
does appear to hybridize with redberry juniper (J. erythrocarpa) in an
area of sympatry in the Chisos Mountains Basin, Texas. It also appears
to hybridize with Ashe juniper (J. ashei) [1,2,27].
LIFE FORM :
Tree, Shrub
FEDERAL LEGAL STATUS :
No special status
OTHER STATUS :
NO-ENTRY
COMPILED BY AND DATE :
Janet Sullivan, February 1993
LAST REVISED BY AND DATE :
NO-ENTRY
AUTHORSHIP AND CITATION :
Sullivan, Janet. 1993. Juniperus pinchotii. In: Remainder of Citation
DISTRIBUTION AND OCCURRENCE
SPECIES: Juniperus pinchotii | Pinchot Juniper
GENERAL DISTRIBUTION :
Pinchot juniper has a limited distribution in southwestern North
America. It occurs in disjunct populations in west-central Texas,
southeastern Oklahoma, eastern New Mexico, and Coahuila, Mexico
[46,47,59,60,62]
ECOSYSTEMS :
FRES15 Oak - hickory
FRES31 Shinnery
FRES32 Texas savanna
FRES38 Plains grasslands
STATES :
OK NM TX MEXICO
ADMINISTRATIVE UNITS :
BIBE CACA GUMO
BLM PHYSIOGRAPHIC REGIONS :
13 Rocky Mountain Piedmont
14 Great Plains
KUCHLER PLANT ASSOCIATIONS :
K054 Grama - tobosa prairie
K059 Trans-Pecos shrub savanna
K060 Mesquite savanna
K065 Grama - buffalograss
K071 Shinnery
K076 Blackland prairie
K085 Mesquite - buffalograss
K088 Fayette prairie
SAF COVER TYPES :
66 Ashe juniper - redberry (Pinchot) juniper
67 Mohr ("shin") oak
68 Mesquite
SRM (RANGELAND) COVER TYPES :
NO-ENTRY
HABITAT TYPES AND PLANT COMMUNITIES :
Pinchot juniper forms dense thickets that can largely or entirely
exclude herbaceous understory vegetation [50]. It is often found with
honey mesquite (Prosopis glandulosa var. glandulosa), live oak (Quercus
virginiana), Mohrs oak (Q. mohriana), prickly-pear (Opuntia spp.),
Acacia spp., and with Ashe juniper where their ranges overlap [13].
Pinchot juniper was named as dominant in the following publication:
Ecological survey and elevational gradient implications of the flora and
vertebrate fauna in the northern Del Norte Mountains, Brewster Co.,
Texas [11].
VALUE AND USE
SPECIES: Juniperus pinchotii | Pinchot Juniper
WOOD PRODUCTS VALUE :
Pinchot juniper wood is reddish brown to white, soft, and moderately
durable in soil [55]. The wood is used locally for fenceposts and fuel
but is not commercially important [55].
Pinchot juniper wood was used for bows and arrow shafts by the Kiowa,
Commanche, Cheyenne, and Apache [18].
IMPORTANCE TO LIVESTOCK AND WILDLIFE :
Pinchot juniper berries are eaten by many species of birds and small
mammals. Foliage and twigs are consumed by white-tailed deer, but
Pinchot juniper is a low preference browse. Pinchot juniper is browsed
more in poor growing seasons than in productive years [24,54].
PALATABILITY :
NO-ENTRY
NUTRITIONAL VALUE :
Nutritional values of Pinchot juniper leaves are as follows [21]:
% of dry weight
ash 4-6
cell wall components 34-37
phosphorus 0.08-0.17
crude protein 6-9
digestible organic matter 57-66
COVER VALUE :
Pinchot juniper has high escape and thermal cover value for white-tailed
deer [9]. Many species of birds use Pinchot juniper for nesting and
roosting cover [54,55].
VALUE FOR REHABILITATION OF DISTURBED SITES :
NO-ENTRY
OTHER USES AND VALUES :
Pinchot juniper has been used as parental stock for breeding ornamental
junipers [17].
MANAGEMENT CONSIDERATIONS :
The range of Pinchot juniper has grown since the late nineteenth
century, largely through encroachment onto adjacent grasslands. It was
estimated to occupy about 6 million acres (2.4 million ha) in western
and central Texas in 1972 [1,12]. Dense stands of Pinchot juniper
suppress the growth of forage plants and create difficulty in the
handling of livestock, and thus are detrimental to rangeland
productivity [51]. Pinchot juniper cover negatively influences grass
production on both grazed and ungrazed sites [34]. Where Pinchot
juniper is controlled or eradicated, forage production increases [17].
On some range sites Pinchot juniper serves as a soil stabilizer and
furnishes cover for wildlife. Rangeland managers must take these
factors into account when determining on which sites Pinchot juniper
should be controlled [45].
The amount of Pinchot juniper encroachment differs between grazed and
ungrazed sites, and with the amount of grazing. As range conditions
improve and grass cover increases, Pinchot juniper germination and
seedling survival decrease [38].
Control: Ueckert and Whisenant [52] conducted a study to determine the
efficacy of a number of herbicides and compared the costs of chemical
control and hand or mechanical control of Pinchot juniper seedlings
(average 13 inches [34 cm] tall, up to 964 seedlings per acre
[2,409/ha]). They determined that the least expensive-most effective
treatment was hand grubbing/ground level cutting of seedlings, costing
$9.26 per acre ($23.14/ha) based on a 1979 labor cost of $3.00 per hour.
This method resulted in complete control of seedlings. Complete control
within 3 months was also achieved with the least expensive chemical
control: a foliar spray of dicamba at 1.1 pounds active ingredient per
acre (0.5 kg ai/ha).
Control of mature juniper is more difficult and expensive. The most
effective chemical controls are wetting sprays of picloram in an
oil/water carrier, achieving 74 to 99 percent canopy reduction, and
wetting sprays of picloram plus 2,4,5-T (1:1) in an oil/water carrier,
achieving 82 to 100 percent canopy reduction. Spring or fall treatments
are more effective than midsummer treatments [46]. Soil-applied
herbicides are relatively ineffective [44].
Mechanical methods for removing or controlling Pinchot juniper include
hand grubbing, chaining, tree-dozing or the use of a Jacques-saw [7].
The most effective treatments uproot trees so that they cannot sprout.
These methods can lower the Pinchot juniper canopy and increase grass
production, but residual stems, sprouts, and debris will build up over
time, and new Pinchot juniper seedlings can become established [51].
These methods are usually fairly costly. In the past, some managers
recouped some control costs by harvesting fenceposts and fuelwood [7].
Sites on which Pinchot juniper is mechanically killed (by chaining or
tree-dozing) will be infested with Pinchot juniper seedlings rapidly.
These sites should be burned by prescription 3 to 5 years after the
mechanical treatment. Grazed sites, because of the increased frequency
of Pinchot juniper establishment, need to be burned every 7 to 10 years
to maintain high grass production and kill Pinchot juniper seedlings
before the basal bud zone is protected by soil [33].
In areas where Pinchot juniper is considered a problem, ranchers
estimated that they achieved a 40 to 50 percent increase in stocking
capacity and a 50 percent reduction in labor costs where they controlled
Pinchot juniper (any means of control) [12].
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Juniperus pinchotii | Pinchot Juniper
GENERAL BOTANICAL CHARACTERISTICS :
Pinchot juniper is a native, evergreen large shrub or small tree, not
usually over 25 feet (8 m) tall, more often not over 18 feet (5.5 m)
tall [20,47,55]. It usually has lengthy lateral stems and spreads
considerably, with a broad, flattened to dish-shaped crown [20]. The
bark is gray to reddish brown and peels off in shaggy strips [55].
Pinchot juniper forms a berrylike "fruit" that contains one or rarely
two seeds [55].
RAUNKIAER LIFE FORM :
Phanerophyte
REGENERATION PROCESSES :
Sexual reproduction: Pinchot juniper is typically dioecious, though
most populations have a small percentage of monoecious individuals
[47,55]. Pinchot juniper reproductive maturity is correlated more
strongly with tree height (r = 0.59) than with age (r = 0.35 or r = 0.50
site dependent) [35]. Average height at reproductive maturity is 3 to 4
feet (1-1.2 m); average age at maturity is 25 years. Height and age
were found to be highly correlated (r = 0.93); however, a few
individuals produce strobili as young as 12 years if they are tall
enough [35]. Seeds are dispersed by mammals and birds. Rabbits can
carry seed up to one mile. Some seed is carried by rainfall runoff
[17].
Pinchot juniper requires 2 years of above average precipitation for good
seedling establishment; the first year for good seed production and the
second for good germination [48]. Germination of Pinchot juniper seeds
declines with a decrease in moisture availability. Optimal soil
temperature for germination is 64 degrees Fahrenheit (18 deg C), with no
emergence at 50 degrees Fahrenheit (10 deg C) and limited emergence at
81 degrees Fahrenheit (27 deg C) [48]. Seedling densities of more than
800 per acre (2,000/ha) were found on sites where mature Pinchot juniper
had been tree-dozed. Seedling densities can also be high beneath
canopies of live oak and honey mesquite trees, due to dispersal of seed
by birds [39,52].
Asexual reproduction: Pinchot juniper sprouts from meristematic tissue
at the base of the stem following injury or top removal [48].
SITE CHARACTERISTICS :
Pinchot juniper occurs on open flats, on dry hillsides, in canyons,
caprock regions, and talus slopes. It is usually found on limestone or
gypsiferous soils [18,47,55]. Pinchot juniper-mixed grass habitats are
most widely developed on rough breaks and shallow range sites along the
high plains escarpment and adjacent rolling plains of western Texas
[51]. On the redbed soils of the Permian formation, Pinchot juniper
forms dense clumped stands 15 to 20 feet (4.6-6 m) in height. On gypsum
soils it can form thickets of very low (3 feet [0.9 m] tall) shrubs that
cover hundreds of acres [47]. Pinchot juniper is drought resistant; its
range extends into the Chihuahuan Desert region, and it is associated
there with xeric shrubs such as creosotebush (Larrea tridentata),
lecheguilla (Agave lecheguilla), sotol (Dasylirion leiophyllum), catclaw
acacia (Acacia greggii), and mariola (Parthenuim incanum) [56,57].
Overstory or shrub associates not previously mentioned include Texas
persimmon (Diospyros texana), Shumard oak (Quercus shumardii), lotebush
(Ziziphus obtusifolia), catclaw mimosa (Mimosa biuncifera), yucca (Yucca
spp.), netleaf hackberry (Celtis reticulata), algerita (Mahonia
trifoliolata), littleleaf sumac (Rhus microphylla), skunkbush (R.
aromatica), feather dalea (Dalea formosa), and elbowbush (Forestiera
pubescens) [33,36,39,51].
Understory/herbaceous associates not previously mentioned include common
curlymesquite (Hilaria belangeri), buffalograss (Buchloe dactyloides),
little bluestem (Schizachyrium scoparium), silver bluestem (Bothriochloa
saccharoides), perennial threeawn (Aristida wrightii, A. purpurea, A.
longiseta), sideoats grama (Bouteloua curtipendula), red grama (B.
trifida), hairy grama (B. hirsuta), hairy tridens (Erioneuron pilosum),
slim tridens (Tridens muticus), Texas wintergrass (Stipa leucotricha),
sedges (Carex spp.), Arizona cottontop (Trichachne californica), chloris
(Chloris spp.), tumblegrass (Schedonnardus paniculatus), and fall
witchgrass (Leptoloma cognatum) [33,36,51].
SUCCESSIONAL STATUS :
Facultative Seral Species
Following top removal, Pinchot juniper sprouts are only slightly
affected by competition from herbaceous species in terms of reproductive
succcess, growth rate, and survival. Competition from neighboring
herbaceous plants has a greater effect on the growth and survival of
seedlings, and may delay reproductive maturity [35,36]. Shrub density
and cover, however, have no effect on reproductive maturity [35].
The encroachment of Pinchot juniper onto adjacent grasslands is
attributed to disturbances such as grazing, reduced fire frequency, and
climatic changes over the last 50 to 300 years [6]. Grazing thins or
removes the grass cover, providing Pinchot juniper seeds a "safe spot"
to become established. Blue grama (Bouteloua gracilis) will suppress
Pinchot juniper seedling growth [48]. Johnsen [63], however, found that
in years of above normal moisture, Pinchot juniper seedlings may become
established in even the best stands of grass.
The maintenance of continuous Pinchot juniper stands depends on at least
2 consecutive years of cooler and wetter than average weather occurring
during the lifespan of the trees in a stand. This is not usually an
obstacle, since Pinchot juniper can live more than 100 years [38].
In closed-canopy stands, Pinchot juniper can exclude essentially all
herbaceous vegetation [37]. The litter and foliage extracts of some
juniper species have allelopathic effects on some associated grasses and
browse [22]. Some woody species were present only in the shade of large
Pinchot juniper plants; shrub densities may increase as Pinchot juniper
approaches reproductive maturity [35]. Pinchot juniper significantly (p
< 0.01) affected total production and grass production on both grazed
and ungrazed sites, with a linear inverse relationship on ungrazed sites
and a inverse logarithmic relationship on grazed sites [37]. McPherson
and Wright [37] determined that herbaceous composition and productivity
are altered for at least 5 years following cessation of grazing, from
which they inferred that succession following grazing will proceed
slowly or be unpredictable.
Pinchot juniper is apparently tolerant of some shade, as it can
establish under the canopies of live oak and honey mesquite [39,51].
The relationship is not reciprocal; honey mesquite does not establish
under Pinchot juniper canopies. Pinchot juniper does, however,
facilitate the establishment of algerita, littleleaf sumac, and catclaw
mimosa [39].
SEASONAL DEVELOPMENT :
Pollination occurs in September and October, and the fruiting cones
mature the following fall [4].
FIRE ECOLOGY
SPECIES: Juniperus pinchotii | Pinchot Juniper
FIRE ECOLOGY OR ADAPTATIONS :
Pinchot juniper was historically restricted to "cedar brakes"--upland
areas of dissected limestone or gypsiferous soils that were protected
from fire and in which juniper species formed dense thickets. The
estimated natural fire regime for the adjacent grasslands is 20 to 30
years [59]. Such frequent fires kill most young Pinchot juniper
seedlings and saplings, and, coupled with a slow rate of seed
germination in vigorous stands of grass, would be sufficient to restrict
Pinchot juniper establishment. As a result of reduced vigor of grass
stands due to grazing and suppression of fire, Pinchot juniper is
encroaching onto adjacent grasslands [12,59]. The ability to sprout
after fire coupled with the reduction of understory vegetation makes
mature Pinchot juniper stands somewhat resistant to fire [48,59].
POSTFIRE REGENERATION STRATEGY :
Tree with adventitious-bud root crown/root sucker
Ground residual colonizer (on-site, initial community)
Secondary colonizer - off-site seed
FIRE EFFECTS
SPECIES: Juniperus pinchotii | Pinchot Juniper
IMMEDIATE FIRE EFFECT ON PLANT :
Moderate- and low-severity fires can kill Pinchot juniper seedlings and
saplings if the basal bud zone is unprotected by soil. Mature Pinchot
juniper with a soil-protected basal bud zone is top-killed by fire
[49,50].
Considerable heat is required for ignition, but once ignited, the plant
burns so vigorously that usually all the branches are killed [5].
DISCUSSION AND QUALIFICATION OF FIRE EFFECT :
NO-ENTRY
PLANT RESPONSE TO FIRE :
Pinchot juniper will sprout from a basal bud zone when top-killed by
fire [5,25].
Ahlstrand [5] reported that 50 percent of the mature height was regained
during a 3- to 7-year recovery period after a fire. Kittams [25]
reported that 25 to 50 years may be required for attainment of mature
height, which agrees with Ahlstrand's estimate for attaining the mature
height of the original stand.
Pinchot juniper sprouts were not producing seed after 3 years of
postfire growth [51].
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE :
NO-ENTRY
FIRE MANAGEMENT CONSIDERATIONS :
Prescribed fire can be used to eradicate Pinchot juniper seedlings on
grasslands not already infested with mature Pinchot juniper.
Established or mature Pinchot juniper can be controlled by a combination
of mechanical treatments and prescribed fire [41,42].
Pinchot juniper is difficult to kill with fire unless the basal bud
zones are above the soil, which is usually only true for seedlings and
saplings (not sprouts). If the bud zones are exposed, prescribed fire
can result in 70 to 75 percent mortality [41,50]. Percent mortality
increases in dry years: 90 percent of Pinchot juniper plants less than
20 inches tall were killed by a prescribed fire when precipitation was
32 percent below normal. Pinchot juniper fire mortality decreases with
increased precipitation, and plots would need to be burned again sooner
than if originally burned in a dry year [50]. Pinchot juniper sprouts
do not produce seed right away, which decreases the amount of seedling
recruitment on the site [51]. Prescribed fires should be limited to
gently to moderately sloping sites (3 to 12 percent grade) to minimize
potential soil loss [50,51].
Areas burned to remove Pinchot juniper are usually not invaded by other
woody species following fire [41]. Herbaceous plant recovery after
prescribed fire depends on the season of burn and postburn moisture
availability [50]. The benefit of increased mortality of Pinchot
juniper from burning in a dry year is offset by the loss of forage;
productivity can be decreased by 50 percent after prescribed burning in
a dry year. Most Pinchot juniper-invaded pastures recover to noninvaded
productivity levels within 3 years of a prescribed fire (after earlier
mechanical treatment) [50]. After early spring fires, managers are
advised to wait until mid-June before stocking [41]. A 10- to 20-year
burning cycle can keep pasture in a productive state for both wildlife
and livestock, reducing the need for chemical or mechanical control
[41,50].
Rangeland sites with shallow loamy soils over limestone will respond
differently than sites with deep or clay soils. On deep, heavy soil
sites, tobosa grass (Hilaria mutica) may be the dominant grass.
Following burning, sites with deep soil tend to be more stable with
regard to production and species composition [41]. Pinchot juniper may
become more fire resistant earlier (i.e. the basal bud zone buried
sooner) on sites with deep soil. On deep-soil sites, a shorter fire
interval (7 to 10 years) may be needed to maintain control of Pinchot
juniper [41,49,50].
Control methods: Mechanical treatment kills large plants and
concentrates fuels. Prescribed fire following such treatment removes
woody debris (cover reduction from 25 percent to less than 2 percent)
and kills Pinchot juniper seedlings and plants that escaped mechanical
treatment [51].
Treatment of mature juniper involves chaining or using bulldozers to
push over and pile large trees to concentrate Pinchot juniper fuels and
allow an increase of fine fuels (pastures should be rested or undergo
light grazing only). The prescribed fire should be conducted 3 to 5
years after the chaining treatment to allow fuels to dry and to allow
Pinchot juniper seeds to germinate so that the seedlings can be killed.
Managers can expect reductions in woody debris cover to below 2 percent
[51]. Follow-up treatments should not be necessary, except that the
area should be burned again before any Pinchot juniper plants are 4 feet
(1.2 m) tall [41,50].
The ignition time needed to burn green Pinchot juniper foliage is most
closely related to foliage moisture content and average mean daily
temperature (r = 0.73 and r=0.48 respectively). During dry periods, the
most significant factors are moisture content (r = 0.83) and relative
humidity (r = 0.77). During wetter than average periods, no significant
correlations occur, making fire behavior less predictable [10].
Chained, dead juniper is a highly volatile fuel [41,55]. The prepared
sites can be burned with a headfire into 400 to 500 foot (120-150 m)
firelines prepared earlier in the spring [41,50,59]. The green juniper
seedlings can be burned with a foliage moisture content of between 60
and 80 percent [58]. It is recommended that there be 2,000 pounds per
acre (2,250 kg/ha) of fine fuels present to carry the fire into juniper
piles and to completely burn over the surrounding grasses and Pinchot
juniper seedlings. It should be noted that if the area is populated by
widely separated bunchgrasses, the fire may achieve only 50 percent
coverage, even with 2,500 pounds per acre (2,800 kg/ha) fine fuels. If
the area is covered with a sod-type grass, such as buffalograss, 1,000
pounds per acre (1,125 kg/ha) of fine fuels may be sufficient to achieve
70 percent burn coverage [41]. Wright and others [60] have developed an
"expert system" for burning large pastures of dozed Pinchot juniper,
with inputs of windspeed, time of day, air temperature, topography,
green juniper moisture content, fuel type, and nearness of cold front.
Large, mature Pinchot juniper with little understory is difficult and
expensive to control with fire. It is hazardous to burn because extreme
conditions are needed to achieve moderately complete burns. There has
been limited success with windrowing techniques; conditions for success
are particular and there is a risk of spot fires. Cover has to be at
least 35 percent to form a relatively continuous fuel bed. Crown fires
tend to stop when the distance between trees is greater than 26 feet [41].
Prescribed fire for control of Pinchot juniper can be conducted with
ground ignition for small, easily traversed areas. Ground ignition can
be difficult on large, rough and dissected areas because of increased
fuel breaks. Aerial ignition, with a helitorch can be safer and give
more control over the ignition pattern [32,58]. When compared for cost
and efficiency, the helitorch method was found to have an economy of
size, that is, as the size of units to be burned increases or the number
of smaller units to be burned increases, the cost per acre decreases.
Such economy does not occur with ground ignition, the cost per acre
decreases only to a limit of approximately 2,500 acres (1,000 ha), above
which the cost per acre remains the same. Therefore, it is recommended
that aerial ignition be employed for large units (approximately over
5,000 acres [2,000 ha]) or for the equivalent area of smaller units
[42].
FIRE CASE STUDIES
SPECIES: Juniperus pinchotii | Pinchot Juniper
CASE NAME :
Fire-induced mortality of redberry juniper [Juniperus pinchotii Sudw.]
2. Wright, H. A.; Bunting, S. C. Neuenschwander 1976 [2622]
SEASON/SEVERITY CLASSIFICATION :
Spring, 1979
Spring, 1980
Spring, 1981
STUDY LOCATION :
Masterson Ranch, King County, Texas; Potts Ranch, Motley County, Texas
PREFIRE VEGETATIVE COMMUNITY :
The preburn community was a Pinchot juniper-mixed grass type. Pinchot
juniper was the dominant woody species. Associated shrubs included
skunkbush (Rhus aromatica), littleleaf sumac (R. microphylla), algerita
(Mahonia trifoliolata), lotebush (Ziziphus obtusifolia), catclaw acacia
(Acacia greggii), feather dalea (Dalea formosa), honey mesquite
(Prosopis glandulosa var. glandulosa), catclaw mimosa (Mimosa
biuncifera), and elbowbush (Forestiera pubescens). Dominant grasses
were sideoats grama (Bouteloua curtipendula), perennial threeawn
(Aristida wrightii, A. purpurea, A. longiseta, little bluestem
(Schizachyrium scoparium), silver bluestem (Bothriochloa saccharoides),
tall dropseed (Sporobolus asper var. asper), slim tridens (Tridens
muticus), hairy tridens (Erioneuron pilosum), and fall witchgrass
(Leptoloma cognatum).
TARGET SPECIES PHENOLOGICAL STATE :
NO-ENTRY
SITE DESCRIPTION :
Long-term mean annual precipitation is 23 inches (590 mm), of which 90
percent occurs during the growing season.
Soils on the King County area are shallow, rock Mollisols of the Talpa
series, while those on the Motley County area are deep Alfisols of the
Miles series.
FIRE DESCRIPTION :
1979 broadcast burn on 2,000 acres (800 ha) in mid-March
1980 broadcast burn on 700 acres (280 ha) in mid-March.
Relative humidity: 25 percent
Air temperature: 68 to 79 degrees Fahrenheit (20 to 26 deg C)
Wind speed: 7 to 14 miles per hour (12-24 km/h)
Fine fuel load: 1,607 to 3,125 pounds per acre (1,800-3,500 kg/ha)
The separate 1981 study involved burning Pinchot juniper plants with an
individual plant burner. Plants in three size classes were randomly
assigned to one of four treatments consisting of a control, light,
moderate, and heavy fine fuel simulated fires. The burner was
calibrated using time/temperature curves developed for mixed grass fuels
by Wright and others [1976]. Treatments were applied in early April
with air temperatures from 68 to 79 degrees Fahrenheit (20 to 26 deg C)
and relative humidity from 60 to 75 percent.
Pinchot juniper plants on the two broadcast burns (1979,1980) were
seedlings from 3 to 32 inches tall (7-80 cm), residual live stems that
escaped the chaining treatment, and 5- to 6-year-old basal sprouts from
plants that were top-killed by chaining.
FIRE EFFECTS ON TARGET SPECIES :
Mortality was assessed 6, 18, and 30 months after the prescribed fires
in 1979 and 1980. Mortality of young Pinchot juniper was 42 percent 6
months after the 1979 fire, 49 percent 18 months after the fire, and 50
percent 30 months after the fire. This indicates that disease, insects,
and rodents do not interact with fire injury to increase mortality.
Postfire growing conditions appear to affect mortality following a
prescribed fire. Following the 1979 fire, precipitation was 18 percent
above the long-term average during the growing season. In 1980,
precipitation was 32 percent below average and summer temperatures were
higher than normal in the growing season following fire treatments.
Mortality following the 1980 fire was higher; there was some effect of a
higher fine fuel load, but this did not appear to have as great an
effect as the drought conditions.
In the 1981 simulated fire study Pinchot juniper mortality increased
across size classes with increased heat treatment.
Location of the bud zone relative to the soil surface was the dominant
variable associated with mortality of Pinchot juniper plants. Only 1 of
100 marked mature plants (with buried bud zones) was killed by broadcast
burning in 1979, and the bud zone of this plant had been mostly exposed
by the chaining operation 4 years earlier. In the drought year of 1980,
burning killed approximately 5 percent of the mature plants. The plants
that were killed typically had a large amount of woody debris from the
caining operation lodged around the base, increasing fire intensity.
FIRE MANAGEMENT IMPLICATIONS :
Pinchot juniper can be killed by fire if it is burned before the
majority of young plants have their bud zones covered by soil. On
shallow rocky sites, mortality of Pinchot juniper plants less than 13
years old and 20 inches (50 cm) tall ranged from 33 to 100 percent,
depending on the size of the plants and the conditions of the following
growing season. Continuing control of Pinchot juniper can be achieved
with a prescribed fire treatment only; chaining is needed only if the
Pinchot juniper on the site is allowed to reach mature heights.
Intervals between prescribed fire treatments should be approximately 7
to 20 years, or when Pinchot juniper on the site reaches 20 inches (50
cm) in height and the bud zone is still exposed. The age at which the
bud zone is covered with soil varies with site. On deep soil sites with
gentle slopes the bud zones are protected earlier. On such sites, the
interval between fires should be shorter to obtain satisfactory control
of Pinchot juniper.
Development of fine fuel loads of 2,680 pounds per acre (3,000 kg/ha)
will improve fire control of Pinchot juniper. Fires conducted in dry
years will also achieve higher mortality rates, but these conditions
negatively affect herbaceous plant yield. Good soil moisture reserves
at the time of the fire are recommended to minimize herbaceous plant
yield loss.
REFERENCES
SPECIES: Juniperus pinchotii | Pinchot Juniper
REFERENCES :
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Index
Related categories for Species: Juniperus pinchotii
| Pinchot Juniper
|
 |
