Occurrence and Control of Piiion Pine,
Alligator Juniper, and Gray Oak Sprouts
and Seedlings Following Fuelwood Harvest
M. Karl wood' and Roxanne scanlonZ
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Abstract
Three experimental plots (12 x 25 meters) were located in
each of four blocks (12 total plots) on a uniform southwestern exposure.
Four of the plots were left undisturbed as controls. Four of the plots were
clearcut in June 1989 and burned 4 months later in October I989 (Treatment
1). Four of the plots were clearcut in June 1989 and burned 28 months
later in October 1991 (Treatment 2). In July 1992, sprouts and seedlings
were counted and heights measured in each plot. None of the piAon pine
stumps sprouted, 47% of the alligator juniper stumps sprouted, and 90% of
the gray oak stumps sprouted. Treatment 1 resulted in 50% of the alligator
juniper sprouts being killed and none of the gray oak sprouts being killed.
Treatment 2 resulted in only 10% of the alligator juniper sprouts being killed
and 17% of the gray oak sprouts being killed. The control plots gained the
equivalent of eight new alligator juniper seedlings per hectare from seeds
by 1992, while the plots in Treatment 1 had no new alligator juniper
seedlings, and the plots in Treatment 2 had 17 new alligator juniper
seedlings per hectare. The control plots gained the equivalent of 608 new
gray oak seedlings per hectare from seeds by 1992, while the plots in
Treatment I had 133 new gray oak seedlings, and the plots in Treatment
2 had 492 new gray oak seedlings per hectare. Only 50 mature gray oaks
per hectare were found in the control plots, which indicates that most
seedlings do not become mature plants.
INTRODUCTION
Piiion pine and juniper species have similar ecological
requirements and tolerances, which allows them to grow as
dominants on many rangelands of the western United States.
They are usually found as climax species on mky hillsides and
invade downhill onto flood plains, piedmonts, and valley
bottoms and uphill onto mesa tops. Prior to settlement by
Europeans, these invaded lands were burned from wildfiis that
killed most of the invading plants. Occasionally, the wildfires
missed a plant, which resulted in a widely scattered savannah
'
Professor of Rangeland Watershed Management, Range
Improvement Task Force and Department of Animal and Range
Sciences, New Mexico State University, Las Cmces, NM.
Researcher, Department of Entomology, Plant Pathology, and
Weed Science, New Mexico State University, Las Cmces, NM.
With the cessation of fm,these invaded lands experienced
loss of the shrub, grass, and folt, components, which resulted
in accelerated erosion of the deep soils in the interspaces
between trees. Archeological sites are adversely affected by the
erosion and wildlife habitat is lost due to and abundance of tms
and a suppression of understory food sources. F a h g to stop
the invasion or return the lands to a state of sustainability is a
gross violation of the federal Clean Water Act. Programs to
control the invaded piiron pine and juniper trees have included
burning, mechanical, chemical, biological, and fuelwood harvest
methods. Following control, sprouts from stumps and new
seedlings rapidly appear, which give a need for follow-up and
maintenance to prolong the life of the ori@ control treatment.
The objectives of this research project were:
1. To determine the number and height of sprouts
and seedlings following fuelwood harvest of a
piiron pine and juniper dominated mesa top site
Sprout Mortality From Burning
2. To determine the effects of fire for sprout and
seedling control
Site Location
Burning 4 months after clearcutting resulted in 50% of the
alligator juniper sprouts being killed and none of the gray oak
sprouts being killed.
Burning 28 months after clearcutting resulted in only 10% of
the alligator juniper sprouts being killed and 17% of the gray
oak sprouts being killed.
The study was located in a commercial fuelwood harvesting
area of the piiion pine -juniper woodland on the edge of Spring
Sprout Heights Following Burning
METHODS
Mesa adjacent to Corduroy Canyon, which are between Winston
and Beaverhead in the Gila National Forest. Specific location is
Section 36, T9S, R12W, Catron County, New Mexico. The mean
elevation is 2245 meters.
Soils on the study site are Lithic Haplustalfs. The vegetation
of the study area consists of a moderately low tree density of
two-needle piiion (Pinus edulis) (440 trees per hectare), alligator
juniper (Juniperus deppeana) (167 trees per hectare), and gay
oak (Quercus grisea) (69 brees per hectare). The understoxy
herbaceous growth comprises a variety of grass and forb species.
Among grasses, the most plentiful species is blue grams
(Bouteloua gracilis). Mountain muhly (Muhlenbergia montana),
wolftail (Lycurus phleoides), and squimltail (Sitanion hystrix)
are the other commonly found grasses. Goldeneye (Yiquiera
dentata), Bahia spp., and a few chenopods are some of the
eyecatchmg forbs in the area.
Treatments
Three experimental plots (12 x 25 meters) were located in
each of four blocks (12 total plots) on a uniform southwestern
exposure. Four of the plots were left undistuhd as controls.
Four of the plots were clearcut in June 1989 and burned 4
months later in October 1989. These plots had experienced one
growing season to obtain favorable understory response, and the
slash was dxy. Four of the plots were clearcut in June 1989 and
burned 28 months later in October 1991. These plots had
experienced three growing seasons which resulted in much more
favorable understory response but also taller sprouts. The
purpose of the burning was to control stump sprouts. In July
1992, sprouts and s e m were counted and heights measured
in each plot.
RESULTS
Burning at 4 months after clmutting resulted in shorter
alligatorjuniper sprouts at 36 months postclearcut than alligator
juniper sprouts that were allowed to grow for 28 months Qable
n t Gray oak sprout
1). The difference was a ~ i g ~ c a 59%.
heights were not si@cantly different at 36 months when
burned at 4 months after clearcutting and 28 months after
clearcutting.
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Table 1.
Sprout heights (crn) 36 months after clearcutting for
fuelwood.
Control
Burn at 4
months
after clearcut
Burn at 28
months after
clearcut
Pinon pine
0'
0
0
Alligator juniper
0'
22
35
Gray Oak
0'
94
89
' No stumps present
Seedling Density
Most new seedlugs occurred in the control plots (Table 2).
In all three treatments, gray oak seedlings were the most
common Burning at 4 months after clearcutting resulted in no
new piiion pine and alligator juniper seedlings while burning 28
months after clearcutting resulted in sigruficantly more than
burning at 4 months.
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Table 2.
New seedlings (number per hectare) 36 months after
clearcutting for fuelwood.
-
- --
pinon pine
33
Burn at 4
months
after clearcut
0
Alligator juniper
8
o
47
608
133
492
Sprouting
None of the
pine stumps sprouted, 47% of the alligator
juniper stumps sprouted and 90% of the gay oak stumps
sprouted. This experiment was spatially replicated but not
temporally. Because 1989 was a drought year, these percentages
may be lower than sproutmg percentages in wetter years.
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Control
Gray Oak
Burn at 28
months after
clearcut
8
Seedling Heights Following Burning
Piilon pine seedhg heights were 77% greater in the controls
and 64% gmter in the burn at 28 months after clearcut treatment
than alligator juniper seedlug heights ( T ' l e 3). Heights for all
species increased with time to bum, and seedltng heights in the
treatment that was burned 28 months after clearcutbng were
sigmficanfly greater than the controls.
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Table 3.
New seedling heights (cm) 36 months after
clearcutting for fuelwood.
Control
Burn at 4
months
after clearcut
Burn at 28
months after
clearcut
Pinon pine
16
0
46
Alligator juniper
9
0
28
Gray Oak
17
28
37
CONCLUSIONS
Piilon pine did not sprout after clearcutting. Half of the
alligator juniper stumps sprouted, and most of the gray oak
stumps sprouted.
The highest mortality of alligatorjunipers (usually a desirable
goal) and the lowest mortality of the gray oak (also usually a
desirable goal) is best achieved 4 months after clearcutting. But
a companion study showed the understo~yhad not responded
enough in the first growing season to adequately protect the site
from erosion following burning. Therefore, buming to control
sprouts was not found to be favorable.
Burning was not a useful tool for controlling alligator juniper
sprouts. Alligatorjuniper sprouts grew faster than new seedlings.
OTHER CONSIDERATIONS
Re-establishment of piiion pine, if desirable, might be
accomplished by leaving a branch attached to the stump.
Unwanted sprouts and seedling may be individually
controlled with herbicides where permissible.
Or they might be controlled by individual treatment with
flammable liquids when fuel conditions are so wet that gmses
and forb will not burn.