quantifying effects of quaking aspen silvicultural
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Undergraduate Theses and Professional Papers
2016
Quantifying Effects of Quaking Aspen Silvicultural Treatments on Quantifying Effects of Quaking Aspen Silvicultural Treatments on
Aspen Regeneration and Residual Growth Aspen Regeneration and Residual Growth
Philip W. Williams University of Montana, [email protected]
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Undergraduate Senior Thesis
QUANTIFYING EFFECTS OF QUAKING ASPEN SILVICULTURAL TREATMENTS ON
ASPEN REGENERATION AND RESIDUAL GROWTH
BY:
Philip W. Williams
Bachelor of Science in Forestry Candidate
The University of Montana
Davidson Honors College
College of Forestry and Conservation
Thesis Supervisor: Dr. Andrew J. Larson
Approved by:
Dr. Andrew J. Larson
College of Forestry and Conservation
THE UNIVERSITY OF MONTANA
MISSOULA, MONTANA
9TH
OF MAY 2016
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ABSTRACT
Williams, Philip W., B.S., May 2016 Forestry
Quantifying Effects of Quaking Aspen Silvicultural Treatments on Aspen Regeneration and
Residual Growth
Faculty Mentor: Andrew J. Larson
Many quaking aspen (Populus tremuloides) populations are in decline across the western United
States, a trend likely driven by ongoing climate change and past management that has led to
increased competition with conifers. Restoration of aspen is a management goal potentially
achievable through active forest management, but treatment effects on regeneration and residual
growth have not been comprehensively studied. This project examined if removal of competing
conifers altered aspen regeneration density, ungulate browsing, and residual adult aspen diameter
growth using a control-impact study design. Sampling occurred at the Burnt Fork (ten
treatments, four controls) and Bandy (seven treatments, four controls) sites. Nested plot-centric
circles with a common center point were used for sampling. Regeneration was counted in 0.004-
hectare plots and examined for ungulate browsing. Adult trees were surveyed in 0.04-hectare
plots; diameters and increment cores were taken on the most vigorous tree to represent growth
before and after harvest. Ungulate browsing (percent of regeneration browsed) means were
higher in treated units (23% and 46% browsed at the Burnt Fork and Bandy, respectively) than in
control units (3% and 2% browsed at Burnt Fork and Bandy, respectively). Aspen regeneration
was higher in treated units than controls: regeneration at the Burnt Fork site averaged 10743
stems/ha in treated units and 7054 stems/ha in controls, while the Bandy site averaged 13438
stems/ha in the treated units and 6824 stems/ha in controls. Average adult aspen diameter growth
rates were stable or increased from pre- to post-treatment in treated units, while diameter growth
rates were stable or decreased from pre- to post-treatment in controls. This study demonstrates
that silvicultural treatments to remove competing conifer trees can increase aspen regeneration
density and maintain or increase adult aspen growth rates. Managers seeking to regenerate
declining aspen stands can use conifer removal treatments to promote aspen regeneration.
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CONTENTS
LIST OF FIGURES & APPENDICES ............................................……………………………...4
Sections
1. ABSTRACT ..........................................................................................................................2
2. ACKNOWLEDGEMENTS ..................................................................................................5
3. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5. RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6. DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
7. CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
8. LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
9. APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4
FIGURES
1. Bandy Ranch understory results. ...........................................................................23
2. Bandy Ranch overstory results. .............................................................................24
3. Burnt Fork understory results. ...............................................................................25
4. Burnt Fork overstory results. .................................................................................26
5. Bandy control regeneration stems per acre by unit and control average ...............26
6. Bandy treatment regeneration stems per acre by unit and treatment average. .......27
7. Burnt Fork control regeneration stems per acre by unit and control average. .......27
8. Burnt Fork treatment regeneration stems per acre by unit and treatment average.28
APPENDICES
A. Prescription for the Bandy Ranch Jumpstart Project ....................................... 38-40
B. Map of the Bandy Ranch Jumpstart silvicultural operation and various silvicultural
treatments: summer 2009. ......................................................................................41
C. Research equipment and travel costs ............................................................... 42-43
D. Map of the Burnt Fork Ranch aspen study units....................................................44
E. Map of the Bandy Ranch aspen study units ...........................................................45
F. Burnt Fork Ranch raw data. ............................................................................. 46-49
G. Bandy Ranch raw data. .................................................................................... 50-51
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ACKNOWLEDGEMENTS
I would like to express my gratitude to my undergraduate thesis supervisor, Dr. Andrew J.
Larson, for his insightful guidance in helping me develop scientific thinking skills and for
introducing me to the challenging but rewarding realm of independent study.
I wish to thank Dr. Elizabeth Dodson for introducing me to the University of Montana’s Bandy
Ranch Jumpstart Project and its relevance to quaking aspen management. I am also grateful to
Dr. Carl Seielstad and Mr. Kevin McManigal for their assistance with geospatial aspects of
natural resource data collection. In addition, Dr. John Goodburn offered excellent silvicultural
expertise that I am very thankful for.
Mr. and Mrs. Randy Creech of the Burnt Fork Ranch deserve a special thank-you for permitting
me to perform my study on their property. I also appreciate the logistical and research-design
advice from Mr. Mike Bradt and Mr. Mark Lewing. I am very thankful to Mr. Bill Bradt for
introducing me to the Burnt Fork Ranch aspen treatment and opening my eyes to the wonders of
quaking aspen ecology.
A very special thanks goes to my family for their unceasing support and encouragement as I
completed this project. I am also very grateful to my brother, Michael, for assisting me with data
collection on long summer afternoons.
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INTRODUCTION
Quaking aspen (Populus tremuloides) spans the widest range of any tree species on the
North American continent (Worrall et al. 2013, Perala n.d.). Not surprisingly, humans have
found a wide array of uses for this diverse poplar from ice cream sticks to particleboard (Rook
2006). While it is used to make many wood products, quaking aspen also has significant value as
wildlife habitat. Many wildlife species (especially deer and beaver) utilize the watersheds filtered
by quaking aspen stands to satisfy essential life functions (Howard 1996). The moist, lush, and
camouflaging quaking aspen stands also attract ungulates that, in turn, browse available
understory graminoids (grasses) and shrubs (Perry et al. 1999). Quaking aspen clearly provides
many services to people and wildlife. However, contemporary research shows a general decline
in quaking aspen across the United States that seems related to climate change; this is largely due
to quaking aspen’s inability to tolerate hot temperatures that are becoming more widespread
during summer and late winter months (Worrall et al. 2013). Diminishing quaking aspen
translates to reduced wildlife habitat, fewer ecosystem services, and a decreased wood supply.
Restoring quaking aspen is a valid restorative and financial goal that may achievable through
timber harvests. But, the implications of timber harvests on residual tree growth (both aspens and
conifers) and on understory aspen regeneration have not been comprehensively studied. This
undergraduate-level research project was undertaken to examine each of the just-mentioned
variables and their relationships to a variety of timber harvests in western Montana.
Specific silvicultural treatments have been used throughout the western United States to
encourage aspen regeneration and learn how different treatments influence the regeneration
process. Thinning quaking aspen stands by removing vegetative competition is a silvicultural
method used to increase residual tree growth and productivity. This information is valuable to
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managers and other scientists interested in how to use silvicultural prescriptions as a multi-
purpose tool to achieve management objectives while restoring critical quaking aspen habitat
through regeneration. One author describes clearcutting residual aspens as one of the most
efficient ways to regenerate an aspen stand in the northern Rocky Mountains (Doucet 1989).
While it seems much regeneration can be created from clearcutting aspen, clearcutting also
temporarily destroys wildlife habitat, shelter, and moist areas that are not re-gained until
regeneration matures to dominant overstory trees.
In addition, quaking aspen suffers from a wide-ranging disease – hypoxylon
canker (Anderson 1979). Most cankers form in dense, moisture-deficient stands (Bagga and
Smalley 1974). On the other hand, insects such as the large aspen tortrix are particularly
prevalent in thinned stands when residual trees have been damaged by a logging operation
(Stewardship 2011.). Understanding dynamics between silvicultural treatments and aspen
insects/diseases can give crucial information to forest managers responsible for restoring quaking
aspen and the multitude of services they provide.
According to several scientists (Bradt 2015, Lewing 2015, Howard 1996) deer
browse aspen regeneration heavily and rely on it for spring fawning and summer water sources.
Deer also browse bunchgrasses found in the understory; removing encroaching conifer from
aspen stands may lead to an increased abundance of graminoid species, and thus restore deer to
an aspen stand (Lewing 2015). Graminoids often respond only in the third year after a partial cut,
which may occur when encroaching conifer species are removed from an aspen stand (Perry et
al. 1999).
Quaking aspen is an extremely diverse tree that provides a wide range of habitats,
wildlife cover, and ecosystem services that many people take for granted. The pure water many
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Americans enjoy largely comes from mountain watersheds filtered by quaking aspen stands.
While some studies have been dedicated solely to understanding the mechanisms that promote
aspen regeneration, few have investigated how aspen growth rates respond to thinning
treatments. Literature exists on wildlife uses of aspen, but fewer studies associate this with
silvicultural treatments. Because decades of research highlight the importance of quaking aspen
stands to wildlife, watersheds, and humans, knowing how the multiple features of aspen stands
respond to forest management practices becomes a necessity in an era of increased natural
resource use. Still, much of the existing information concerning quaking aspen regeneration
through silvicultural treatments is outdated and/or insufficient when considered separately. This
research will help fill knowledge gaps by providing a practical, methodical examination and
synthesis of various aspen silvicultural treatments performed in the Rocky Mountains of western
Montana. Relevant information produced by this research project will be particularly valuable to
wildlife and forest managers in the western United States. Quaking aspen is a significant mesic
species with potent impacts on other tree species, understory grasses, insects/diseases, and a wide
array of wildlife. Because the tree species is currently in decline across much of its native and
introduced ranges, knowing what silvicultural methods encourage overall stand restoration will
lead to informed and effective quaking aspen management that both sustains humans and the
natural realm.
This research project used a control-impact (CI) study to determine effects of silvicultural
treatments on quaking aspen stand responses. The research occurred on the privately-owned
Burnt Fork Ranch (Bitterroot Valley, MT) and on the University-of-Montana-owned Bandy
Ranch (Blackfoot River Valley, MT); both areas contain forestland that was subjected to various
silvicultural treatments two years before the study at the Burnt Fork Ranch and six years pre-
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study at the Bandy Ranch. Study sites at both locations were used to introduce a variety of spatial
locations and timber harvest types. All timber harvests studied were performed to increase the
abundance and health of residual quaking aspen and of any existing/ensuing regeneration.
Browsing impacts were measured by intensity (percentage of aspen regeneration displaying
browsing on current year’s growth) in control and treatment units. It was not possible to
differentiate between livestock and cattle grazing because no wildlife or livestock-proof fences
were built for this study (Lewing 2015).
The overall objective of this research project was to examine how removing encroaching
conifers from quaking aspen stands altered residual aspen growth and aspen regeneration
(browsed vs. un-browsed). The primary metrics used to determine any change in the variables
was frequency, abundance, density, browsing intensity, and annual growth of the residual aspen
and conifers. The following specific research questions were addressed:
Does conifer removal in quaking aspen increase, decrease, or not affect aspen
regeneration?
Does conifer removal in quaking aspen increase, decrease, or not affect aspen
regeneration browsing by ungulates?
Does conifer removal in quaking aspen increase, decrease or not affect residual growth?
What differences exist between variables at larger spatial scales (Bandy Ranch vs. Burnt
Fork)?
This author hypothesized that residual overstory aspens will have experienced an increase
in average annual radial growth since treatments. Also, aspen regeneration was expected to be
greater in treated than in untreated stands due to increased resource availability (Lewing 2015).
There may also be far more regeneration in treated stands where 1 or 2 stems were removed per
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stand, as apical dominance of the residual tree has been suppressed (Sandberg and Schneider
1953).
All treatment measurements were compared to duplicated measurements made in no-
treatment control units. Comparing measurements allowed inferences to be made as to the
magnitude of effects (if any) implementations had on treated sites in a control-impact research
setting.
METHODS
Study Design
Burnt Fork Ranch Silvicultural Methods:
In the winter of 2013-14, the Burnt Fork Ranch released 23.82 acres of quaking aspen stands in
the Ambrose Creek area of the Sapphire Mountains. Conifers were marked for removal and
aspen stands were delineated based on the extent of the overstory aspen dripline. Ten aspen
stands of varying sizes (see Figure 1) were delineated, located on flat to north-facing slopes. A
dirt road, running east-west through the area, was used to split the aspen stands into northern and
southern units. Montana Fish, Wildlife, and Parks holds a conservation easement on the former
Bolin Ranch immediately east of the Burnt Fork Ranch property. There are two separate aspen
stands, both split by the same road that runs through the Burnt Fork units. Those areas feature
mostly flat to slightly north-facing topography. As no silvicultural treatment occurred on the
Bolin Ranch Conservation Easement, those four units (each of the two stands, like the treatment
areas, were divided into north and south units on account of their location to the road) were used
as control areas. Overall, there are 10 treatment units and 4 control units. All the treatment units
experienced the same treatment of complete conifer removal within the aspen stands by a
fellerbuncher and rubber-tired skidder whole-tree logging system. Slash was burnt on-site in
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designated slash piles. Mature, overstory quaking aspen were only cut if they prevented the
fellerbuncher operator or skidder from removing conifers. As noted in the results section, some
conifers were left inside only one aspen clone (unit T3-N) at the discretion of the Burnt Fork
Ranch forester (Bradt 2015). All other stands had every conifer removed from within the clone.
Bandy Ranch Silvicultural Methods:
In the summer of 2009, the University of Montana launched its “Jumpstart” silvicultural
treatment at its Bandy Ranch in order to determine various effects of different forest treatments
on overstory and understory responses (Dodson 2015). Quaking aspen was a specific species of
interest and received three different treatments and a control to help measure those effects
(Dodson 2015). All harvest units were treated with a mechanical whole-tree logging system
using a fellerbuncher and rubber-tired skidders. Treatments were implemented by codes red,
blue, yellow and white; please see Appendix A for a complete description of all the treatments
and of the control. As far as quaking aspen was concerned, the red treatment did not remove any
conifers from within the aspen stands but did clear conifers within a 50-foot radius of the aspen
clone itself (Dodson 2015); the blue treatment also cleared 50 feet around the clones and
removed all conifer encroachment; and the yellow treatment cleared 50 feet around the clone,
removed all conifer encroachment, and cut 1-2 mature overstory aspen trees in each clone. The
white treatments were control areas and thus experienced no treatments. See Appendix B for a
map of treatment and control locations.
Burnt Fork Ranch Sample Design:
Dividing the quaking aspen stands into observable units was done based on the parameters
described in the introduction. Namely, this entailed using the main access road (which runs east
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to west) as a break dividing aspen clones into northern and southern portions. The boundaries
and areas of each quaking aspen stand were delineated on the ground by walking the stand
borders. Borders were defined by the overstory canopy dripline. The boundaries of all control
and treatment units were delineated with a Samsung ® Galaxy S5 ® smartphone using the
Avenza Systems Inc. ® PDF Maps for Android application, version 1.4.9 Build(115). Yellow
ribbons were labeled for each unit and hung at the four vertices of each aspen clone. After each
aspen grove was defined geographically, they were named in the following way. Control units
were all given the prefix “C” for control, immediately followed by a number in increasing order
from east to west. “N” for north or “S” for south followed a hyphen to denote the location of the
unit in relation to the management road intersecting the stand. Treatment units were labeled in a
similar fashion, with the notable difference that “T” was used for treatment with the following
numbers in increasing order from west to east. The same road (although now on Burnt Fork
Ranch land) differentiated each stand into north and south units.
Because this study was a control impact observation of a past silvicultural manipulation,
the control and treatment units were measured in exactly the same fashion. Each treatment and
control unit would serve as a replication within the study, thus eliminating the need to perform
multiple samples within each unit. Measurements taken in the treatment areas would be
compared to duplicated measurements in the control areas. A diagonal line running from the
northeast to southwest corners of the stand was created in the Avenza ® environment and
measured in feet. The northeast-to-southwest trajectory was chosen based on the overall north-
south orientation of the aspen units. A diagonal line was chosen over a north-south or east-west
line because a diagonal may most likely incorporate varying differences in stand structure
resulting in north-facing topography (Bradt 2015). In other words, merely using a north-south
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trajectory on north-facing topography would likely be biased toward sampling plants reacting to
that north aspect. This was undesirable as the control sites, and the majority of the treatment
sites, were flat to slightly north-facing.
Once the diagonal lines of each control and treatment unit were measured in feet, a
random number was generated by starting a countdown timer at 100 seconds and then randomly
stopping it. The resulting number was used as a percentage to multiply the total distance of the
diagonal line by, and that value was the distance of the sample point from the southwest corner
of the northern units and the northeast corner of the southern units. A nested sampling design of
plot-centric circles with a common center point was used to sample the overstory and understory
variables, inspired by a method used by Fowler (2014). An interior, 100th
-acre circular plot (11.7
ft. radius) was employed to sample quaking aspen regeneration, while an exterior, larger 10th
-
acre circular plot (37.2 ft. radius) was used to sample residual aspen growth and the number of
mature overstory quaking aspen and/or conifers. If a plot lacked all variables (both in the
overstory and understory), it was rejected and a new plot was subsequently established by
proceeding one chain (66 feet) down the diagonal sample line. If this led outside the clone, the
new sample area was located by pacing one chain in the opposite direction. Each treatment and
control unit only had one sample per unit, meaning that 14 total nested plots (4 controls and 10
treatments) were sampled at the Burnt Fork Ranch.
Bandy Ranch Sample Design: All observable quaking aspen stands were located first as they had
never been officially delineated at the Bandy Ranch before. Once all stands were located, all
were assigned numbers and two stands within each silvicultural treatment type were randomly
selected. Please note that Bandy aspen stands will be described by the color-coded silvicultural
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system that they were treated with. For instance, “yellow clones” or “yellow groves” denote
aspen stands that were within the yellow, or 3rd
treatment, type (please refer to Appendix A).
This author only discovered three quaking aspen clones within the control units, so all three
control groves were selected for sampling. In addition, three blue groves were considered for the
study because each blue grove contained relatively little area. All aspen groves selected for the
study were delineated with the same Avenza ® PDF Maps application used at the Burnt Fork
Ranch. No flags were hung at the Bandy Ranch and, just as with the Burnt Fork sample design,
only one sample area per unit was done at the Bandy Ranch. Aspen clones were named based on
the pre-named Jumpstart unit in which they occurred. For instance, the control site occurring in
Jumpstart management area E(4) was named unit E(4). If more than one unit occurred in a
management area, an alphabetic suffix was added (for instance, E(4).a, E(4).b, etc.).
All aspen clones occurred on flat to nearly-flat terrain, so there was no special adjustment
needed for aspect biases. Sample location was determined by generating a random number
between one and four. The north side of a unit was represented by the numeral one, the east by
two, the south by three, and the west by four. It was necessary to sample a side of the unit, rather
than somewhere along a bisecting diagonal as at the Burnt Fork, because the Bandy aspen clones
were nearly all located around small seasonal wetlands and prairie-type potholes. In other words,
the aspen were usually formed in an outer ring around an interior, circular area with no
vegetation other than grasses. Once the randomly-selected side of a unit was selected, its length
was measured in the Avenza ® environment. Just as at the Burnt Fork Ranch, a random number
was generated by starting a countdown timer at 100 seconds and then randomly stopping it. The
resulting number was used as a percentage to multiply the total distance of the diagonal line by,
and that value was the distance of the sample point from one end of the unit. The end of the unit
15
to start measuring from was determined by assigning each end a number and randomly selecting
it.
Again, a nested sampling design of plot-centric circles with a common center point was
used to sample the overstory and understory variables. An interior, 100th
-acre circular plot (11.7
ft. radius) was employed to sample quaking aspen regeneration, while an exterior, larger 10th
-
acre circular plot (37.2 ft. radius) was used to sample residual aspen growth and the number of
mature overstory quaking aspen and/or conifers. If a plot lacked all variables (both in the
overstory and understory), it was rejected and a new plot was subsequently established by
proceeding one chain (66 feet) down the diagonal sample line in the original direction. If this led
outside the clone, the new sample area was located by pacing one chain in the opposite direction.
Each treatment and control unit only had one sample per unit, meaning that 10 total nested plots
(3 controls and 7 treatments) were sampled at the Bandy Ranch.
Measurements
The following measurements were taken within each sample plot for both the Burnt Fork and
Bandy Ranches. Measurements were identical in all control and treatment units.
100th
-acre Plots (Understory)
The plot center was established with a metal pin at the pre-determined location along the transect
line. A cloth tape measure was attached to the pin to delineate a radius of 1/100th
of an acre (11.
7 feet radius). Regeneration was counted by starting at a marked location on the plot
circumference and sweeping the cloth tape around the pivot point, keeping it tight at all times to
ensure distance accuracy. Any regeneration growing directly on the border of the plot was
included in the plot. As each individual aspen sprout was encountered, a graduated ruler using
16
tenths of centimeters was placed next to the stem of each individual aspen sprout just above
ground level. The stem was measured in centimeters and placed in the following categories: less
than 1 centimeter, 1-2 centimeters, 2-3 centimeters, and greater than 3 centimeters. All data was
recorded on a voice recorder and later transferred to an understory Excel spreadsheet (see
Appendices F and G). Regeneration tallies were further subdivided in each diameter class based
on whether the current year’s growth had been browsed or not by an ungulate. Current year’s
growth was determined based on leaf scars; any removal of current year’s growth, whether by
ungulate biting or tearing, placed that particular sprout into the browsed category in its respective
diameter class.
10th
-acre Plots (Overstory)
The 1/10th
-acre sampling plots were established with the same central pin, location, and cloth
tape used for the smaller 1/100th
-acre plots. These plots all had a 37.2-foot radius. Mature,
overstory trees were counted by starting at a marked location on the plot circumference and
sweeping the cloth tape around the pivot point, keeping it tight at all times to ensure distance
accuracy. If any trees touched the border of the sample plot, at least half the tree diameter at
breast height must be included in the plot for that tree to be sampled. The diameter at breast
height (DBH) was measured on every “in tree” with a standard logging diameter tape in tenths of
inches and recorded on a voice recorder. The data was later transferred to the overstory sample
sheet (see Appendix F). Next, an increment borer was used to retrieve cores from the most
vigorous and/or most dominant aspen and/or conifer tree in the canopy. Because the treatment
occurred two growing seasons ago at the Burnt Fork Ranch and six growing seasons ago at the
Bandy Ranch, increment corings were taken to display the last four years of growth at the Burnt
Fork and the last twelve years of growth at the Bandy Ranch. The total number of overstory
17
aspen and/or conifer trees were tallied and recorded in each sample plot. However, at the Bandy
Ranch, units G2 and P2.b contained nearly the same area as the 10th
-acre sample plots. In these
cases, a complete tallying census of the overstory was done. However, the most vigorous and/or
most dominant aspen and/or conifer tree in the canopy was still cored.
Analysis
Geospatial Analysis at Bandy and Burnt Fork Locations:
Geospatial track data was exported from the Avenza ® environment in .kml format. The “From
KML” Conversion tool found inside of ArcToolbox ® translated the .kml data into shapefiles
readable by ESRI’s ® ArcMap ® v. 10.2.2. A standard USA topographic basemap, courtesy of
National Geographic, was uploaded and projected into NAD 83 UTM Zone 12N. Avenza ®
described its datum as being in NAD 27; however, the tracks were in the wrong location when
the projection was changed to NAD 27. Eventually, it was discovered that Avenza ® had made
an error and its datum was actually NAD 83 (McManigal 2015). Unit labels, a scale bar, north
arrow, coordinate system description, and National Geographic credit was added to each map
(see Appendices D and E). The Avenza ® application determined areas of each unit’s track
polygon. These values were later transferred to an Excel spreadsheet.
Regeneration Analysis
After raw data was entered into Excel, the total number of sprout stems were multiplied by 100
to attain a per acre estimate of regeneration in the control and treatment sites at the Burnt Fork
and Bandy Ranches. This was done in the three census areas of the Bandy Ranch in order to
normalize the data and reduce ensuing bias. Per-acre calculations were performed for each aspen
sprout size class; the per-acre estimates of sprouts per size class were then summed in order to
18
understand the overall density of all sprouts across the unit. Utilization was measured for each
unit as the total number of browsed sprouts out of the grand total of sprouts in that unit; this was
expressed as a percentage and showed the amount of use by ungulate species (Holechek et al.
2003). The total acreages of the control and treatment units were summed, and control and
treatment sums were taken of number of regeneration in each size class. Averages were also
calculated for total stems per acre and utilization.
Overstory Analysis
Quaking aspen cores were allowed to dry for one month and then examined with a hand lens for
growth rings. However, the growth rings were extremely faint and nearly impossible to detect
with such a low level of magnification. Eventually, using a portable dissecting scope from the
College of Forestry and Conservation on low-to-medium power sufficiently revealed early and
late wood cells so growth could be determined. At the Bandy Ranch, the past twelve years of
radial growth were broken into two distinct segments and measured separately. The newest six
years showed growth since the treatment (post-treatment), and the older six years displayed
growth before the treatment (pre-treatment). An equal number of years were needed for pre-
treatment analysis in order to compare a consistent number of years before and after the
silvicultural manipulation of the quaking aspen stand. At the Burnt Fork Ranch, the past four
years of radial growth were broken into two segments and measured separately for the same
reasons. A standard dissecting probe was used to prick and mark the boundary delineating pre
and post-treatment growth and the termination of pre-treatment growth. The segments were
measured in centimeters with the same tenth-centimeter graduated ruler used to measure aspen
sprout diameters in the field. Results for the Bandy Ranch were divided by six years in order to
determine average annual growth in centimeters for post- and pre-treatment radial growth. The
19
number of trees within the 10th
acre plots was multiplied by 10 in order to arrive at per-acre
estimates. This was also done for the three Bandy units where a census was taken in order to
normalize data and reduce any ensuing bias. Averages of radial growth for post- and pre-
treatment were taken for the control and treatment sites of both the Bandy and Burnt Fork
ranches. Trees per acre were also averaged for the control and treatment locations at both
ranches.
In addition, the Bandy and Burnt Fork data was compared at the treatment and control
levels for average regeneration per acre (by size class and total), utilization, trees per acre (both
conifer and aspen), and average annual growth for post and pre-treatment time periods.
RESULTS
Burnt Fork Ranch
Regeneration
For the control location, C2-S contained the most regeneration per acre (7100 stems) while C1-N
contained the least (1200). Most regeneration occurred in the less-than-1 cm class and the least
occurred in the greater-than-3 cm class for the treatment area; the control area contained the most
regeneration in the greater-than-3 cm class and the least in the less-than-1 cm class. For the
treatment location, T1-S contained the most regeneration per acre (8700) while T3-S contained
the least (1900). Figures 7 and 8 illustrate this information graphically.
Utilization
The only ungulate utilization of quaking aspen regeneration in the control location occurred on
unit C2-N, which had 12.5% utilization of all aspen regeneration. Utilization was very poor in
the control overall with only 0.03% of the entire available regeneration being browsed, which
20
stood in sharp contrast to the 23.28% utilization of all available regeneration in the average
treatment unit. All but two treatment areas experienced utilization (T2-N and T5-S), with the
highest utilization occurring in T2-S (60.87%) and the lowest utilization in T5-N (4.55%).
Overstory
The greatest control growth pre-treatment occurred in C2-N (0.15 cm/year), while the
least control growth pre-treatment occurred in C1-S and C2-S (0.05 cm/year). The greatest
control growth post-treatment again occurred in C2-N (0.125 cm/year), while the least control
growth post-treatment occurred in C2-S (0.05 cm/year). The average control post-treatment
growth was 0.088 cm/year and the average control pre-treatment growth was 0.081 cm/year.
The greatest treatment growth pre-treatment occurred in T3-S and T4-S (0.25 cm/year),
while the least treatment growth pre-treatment occurred in T2-N, T5-N and T5-S (0.05 cm/year).
The greatest treatment growth post-treatment occurred in T1-S (0.275 cm/year), while the least
treatment growth post-treatment occurred in T2-N (0.05 cm/year). The only conifer measured
experienced 0.05 cm/year of growth after the treatment and 0.075 cm/year before it. It was
located in the treatment area in unit T3-N. The average treatment post-treatment growth was
0.153 cm/year and the average treatment pre-treatment growth was 0.119 cm/year. The average
mature trees per acre in the control location was 70 aspen with the most trees per acre existing in
C2-S (110 trees per acre); the least trees per acre occurred in C1-N (30 trees per acre). The
treatment location contained an average of 78 aspen per acre and 20 conifers per acre, with the
most aspen trees per acre existing in T1-S (130 trees per acre); the least trees least trees per acre
occurred in T5-N (30 trees per acre). These results are shown in tabular form in Figure 4.
21
Bandy Ranch
Regeneration
Control unit E4.a contained the most regeneration per acre (5050 stems) while E4.b contained
the least (1020 stems). Most regeneration occurred in the 1-2 cm class and the least occurred in
the greater-than-3 cm class for the treatment area; the control area contained the most
regeneration in the 2-3 cm class and the least in the less-than-1 cm class, as can be seen in
Figures 1 and 5. For the treatment location, P2.a contained the most regeneration per acre (9800)
while P2.b contained the least (1000). Please see Figure 6.
Utilization
As Figure 1 shows, the only ungulate utilization of quaking aspen regeneration in the control
location occurred on unit E4.a, of all aspen regeneration. Utilization was very poor in the control
overall with only 1.83% of the entire available regeneration being browsed, which stood in sharp
contrast to the 46.46% utilization of all available regeneration in the average treatment unit. All
treatment areas experienced utilization, with the highest utilization occurring in P2.a (71.43%)
and the lowest utilization in Q1.b (5%).
Overstory
The greatest control growth pre-treatment occurred in A4 (0.1 cm/year), while the least
control growth pre-treatment occurred in E4.b (0.05 cm/year). The greatest control growth post-
treatment again occurred in A4 (0.125 cm/year), while the least control growth post-treatment
again occurred in E4.b (0.05 cm/year). The average control post-treatment growth was 0.072
cm/year and the average control pre-treatment growth was 0.081 cm/year, as can be seen in
Figure 2.
22
The greatest treatment growth pre-treatment occurred in Q1.a (0.133 cm/year), while the
least treatment growth pre-treatment occurred in P2.a and H3 (0.075 cm/year). The greatest
treatment growth post-treatment occurred in P2.b (0.117 cm/year), while the least treatment
growth post-treatment occurred in D3 (0.075 cm/year). The only conifer measured experienced
0.05 cm/year of growth after the treatment and 0.075 cm/year before it. The conifer was located
in the treatment area in unit H3. The average treatment for both pre and post-treatment growth
was 0.086cm/year. The average mature trees per acre in the control location was 7 aspen with the
most trees per acre existing in A4 (14 trees per acre); the least trees per acre occurred in C1-N
(30 trees per acre). The treatment location contained an average of 49 aspen per acre and 30
conifers per acre, with the most aspen trees per acre existing in D3 (130 trees per acre); the least
trees least trees per acre occurred in T5-N (30 trees per acre).
Please see Figures 1-4 for a visual explanation of the above-mentioned results; figures 5-
8 give a graphical interpretation.
At the Burnt Fork Ranch, the average treatment unit contained 2672 more aspen
regeneration stems per acre than the average control unit. Similarly, the average treatment unit at
the Bandy Ranch contained 1490 more aspen than the average control unit. The average
treatment unit at the Bandy Ranch also experienced greater average annual radial growth both
post-and-pre-treatment, but only by 0.005 cm/year and 0.011 cm/year, respectively. In addition,
the average Burnt Fork overstory unit experienced greater average annual radial growth both
post-and-pre-treatment, by 0.065 cm/year and 0.037 cm/year, respectively.
23
Figure 1: Bandy Ranch understory results.
CONT
ROL
REGE
NERA
TION
(ste
ms p
er ac
re)
Unit
Area
(ac)
< 1 cm
coun
t1-
2 cm
coun
t2-
3 cm
coun
t> 3
cm co
unt
Tota
l Cou
ntut
iliza
tion
(%)
A40.
330
1300
600
300
2200
0
E4.a
0.2
025
035
0013
0050
505.
48
E4.b
0.24
100
220
400
300
1020
0
Cont
rol T
otal
s0.
77
Cont
rol A
vera
ges
33.3
359
0.00
1500
.00
633.
3327
56.6
71.
83
TREA
TMEN
TRE
GENE
RATI
ON (s
tem
s per
acre
)
Unit
Area
(ac)
< 1 cm
coun
t1-
2 cm
coun
t2-
3 cm
coun
t> 3
cm co
unt
Tota
l Cou
ntut
iliza
tion
(%)
Blue
P2.a
0.15
1700
4500
3300
300
9800
71.4
3
P2.b
0.1
500
500
00
1000
100
G20.
0935
0036
0060
010
078
008.
54
Red
Q1.a
0.34
400
1000
200
016
0031
.25
Q1.b
0.55
013
0010
060
020
005
Yello
w
H32.
7516
0031
0044
0030
094
0057
.45
D30.
9729
0017
0018
000
6400
51.5
6
Trea
tmen
t Tot
als
4.95
Trea
tmen
t Ave
rage
s15
14.2
922
42.8
614
85.7
118
5.71
5428
.57
46.4
6
24
Figure 2: Bandy Ranch overstory results.
cm/yr cm/yr OVERSTORY
Avg. ann. growth post-T: Avg. ann. growth pre-T: Species: # aspen/ac # conifers/ac
0.108 0.100 aspen 14
0.083 0.067 aspen 5
0.05 0.05 aspen 1
0.081 0.072 7
cm/yr cm/yr OVERSTORY
Avg. ann. growth post-T: Avg. ann. growth pre-T: Species: # aspen/ac # conifers/ac
0.092 0.075 aspen 7
0.117 0.083 aspen 6
0.058 0.042 aspen 1
0.100 0.133 aspen 50
0.083 0.108 aspen 30
0.12 (con); .08 aspen 0.13 (con); 0.075 aspen con/aspen 120 30
0.075 0.083 aspen 130
.086 aspen 0.086 aspen 49 30
25
Figure 3: Burnt Fork understory results.
CO
NTR
OL
REG
ENER
ATI
ON
(st
em
s p
er
acre
)
Un
itA
rea
(ac)
< 1
cm c
ou
nt
1-2
cm c
ou
nt
2-3
cm c
ou
nt
> 3
cm c
ou
nt
Tota
l co
un
tu
tili
zati
on
(%
)
C1
- N
2.65
200
00
1000
1200
0
C1
- S
1.6
300
400
400
400
1500
0
C2
- N
2.36
800
600
020
016
0012
.50%
C2
- S
2.32
060
048
0017
0071
000
Co
ntr
ol T
ota
ls8.
93
Co
ntr
ol A
vera
ges
325.
0040
0.00
1300
.00
825.
0028
50.0
00.
03
TREA
TMEN
TR
EGEN
ERA
TIO
N
Un
itA
rea
(ac)
< 1
cm c
ou
nt
1-2
cm c
ou
nt
2-3
cm c
ou
nt
> 3
cm c
ou
nt
Tota
l co
un
tu
tili
zati
on
(%
)
T1 -
N1.
551
0012
0020
00
6500
13.8
5
T1 -
S2.
678
0080
010
00
8700
51.7
2
T2 -
N1.
0546
0030
00
200
5100
0
T2 -
S1.
4537
0080
010
00
4600
60.8
7
T3 -
N4.
810
019
0030
010
024
006.
06
T3 -
S1.
8490
020
060
020
019
0010
.53
T4 -
N1.
5138
0016
0010
050
060
0031
.67
T4 -
S6.
418
0030
010
060
028
0053
.57
T5 -
N0.
820
1600
400
200
2200
4.55
T5 -
S1.
8525
0050
010
010
032
000
Tre
atm
en
t To
tals
23.8
2
Tre
atm
en
t A
vera
ges
3030
920
200
190
4340
23.2
82
26
Figure 4: Burnt Fork overstory results.
Figure 5: Bandy control regeneration stems per acre by unit and control average.
cm/yr cm/yr OVERSTORY
Avg. ann. growth post-T: Avg. ann. growth pre-T: Species: # aspen/ac # conifers/ac
0.075 0.075 aspen 30
0.1 0.05 aspen 50
0.125 0.15 aspen 90
0.05 0.05 aspen 110
0.088 0.081 70
cm/yr cm/yr OVERSTORY
Avg. ann. growth post-T: Avg. ann. growth pre-T: Species: # aspen/ac # conifers/ac
0.175 0.15 aspen 90
0.275 0.175 aspen 130
0.075 0.05 aspen 70
0.125 0.1 aspen 100
0.05 (con); 0.125 (aspen) 0.075 (con); 0.1 (aspen) con, aspen 70 20
0.15 0.25 aspen 70
0.15 0.1 aspen 120
0.25 0.25 aspen 60
0.1 0.05 aspen 30
0.1 0.05 aspen 40
0.153 0.119 78 20
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
A4 E4.a E4.b Control Average
Ste
ms
pe
r ac
re
Bandy Control Regeneration
27
Figure 6: Bandy treatment regeneration stems per acre by unit and treatment average.
Figure 7: Burnt Fork control regeneration stems per acre by unit and control average.
0100020003000400050006000700080009000
10000
Ste
ms
pe
r ac
re
Bandy Treatment Regeneration
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
C1 - N C1 - S C2 - N C2 - S Control Avg.
Ste
ms
pe
r ac
re
Burnt Fork Control Regeneration
28
Figure 8: Burnt Fork treatment regeneration stems per acre by unit and treatment average.
DISCUSSION
Please note that the research questions are reiterated in italics. The fourth research question
(investigating differences between variables at the Bandy Ranch and Burnt Fork ranches) is
considered within each of the research question discussions below.
Does conifer removal in quaking aspen increase, decrease, or not affect aspen regeneration?
Aspen regeneration was greater on average than treatment at both the Bandy and Burnt
Fork Ranches. As hypothesized, this increase in regenerative growth was most likely due to the
removal of conifers that competed for water, sunlight, and nutrients. In addition to an increased
abundance of resources, quaking aspen regeneration was probably also influenced by the
disturbance of ground (stimulating shallow aspen root systems) (Doucet 1989, Howard 1996,
Sandberg and Schneider 1953, Perry et al. 1999), and from winter (Burnt Fork) and summer
(Bandy) logging activities that utilized tracked and chained-tire equipment. Doucet (1989) stated
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Ste
ms
pe
r ac
re
Burnt Fork Treatment Regeneration
29
that seasonality of timber harvests within quaking aspen stands do not have any significant effect
on clonal aspen regeneration productivity. The sprouts measured in this study were most likely
clonal sprouts, as fire is often one of the only naturally-occurring mechanisms that can trigger
viable quaking aspen seed production (Shinneman et al. 2013). No prescribed fire has occurred
within the Burnt Fork or Bandy Ranch aspen stands in the past twenty years at least. Therefore,
the timing of release treatments was probably not a significant factor in determining aspen
regeneration responses between the Burnt Fork and Bandy ranches.
Both locations offered specific evidence that removal of encroaching conifers increases
quaking aspen regeneration. Bandy Ranch units with 1-2 mature quaking aspen stems removed
per clone (units H3 and D3) experienced the second-highest regeneration densities per acre.
Several foresters mention how mature quaking aspen trees regularly secrete a hormonal chemical
to their root systems that keeps clonal reproduction relatively in check (Rook 2006, Bradt 2015).
Removing mature aspen stems, even if a partial removal, removes this stem-based inhibitory
chemical and should increase the probability of regeneration success. Although more factors
could be at play, the removal of 1-2 quaking aspen stems per clone seems a very probable cause
of the dramatic increase in quaking aspen regeneration in units H3 and D3 at the Bandy Ranch
(Williams, personal observation 2015).
The aspen release treatment at both locations seems to have resulted in an increase in
regeneration in the lower sprout-diameter classes, which likely means the roots are continuing to
produce regeneration until a threshold is reached. This would accord with existing aspen
silviculture literature, as aspen sprout age is usually correlated with diameter (Bradt 2015,
Lewing 2015, Howard 1996). The Burnt Fork Ranch was the best illustration of this relationship
as the most aspen regeneration occurred in the less-than-1 cm class at and the least occurred in
30
the greater-than-3 cm class. And, the Burnt Fork control area exhibited an opposite relationship
with the most regeneration in the greater-than-3 cm class and the least in the less-than-1 cm
class. The Bandy Ranch treatment units exhibited the densest regeneration in the 1-2 cm class
and the least in the greater-than-3 cm class, with the control area showing densest regeneration in
the 2-3 cm class and the least in the less-than-1 cm class. It seems that regeneration is older in
the control units at both the Bandy and Burnt Fork ranches when compared to the treatments
units, therefore implying that the silvicultural treatment of the stand directly influenced aspen
regeneration production because the regeneration was much younger than that in the control
units (Williams, personal observation 2015).
An interesting follow-up study might investigate the numbers of new regeneration
through time and determine when the released aspen clone stopped producing regeneration.
Answering that question, however, is beyond the scope of this current investigation and is best
left to future scientists.
Does conifer removal in quaking aspen increase, decrease, or not affect aspen
regeneration browsing by ungulates?
Quaking aspen regeneration utilization by ungulates (measured as percent of regeneration
browsed) was extremely poor in all control sites at both the Bandy and Burnt Fork ranches. The
low percentage of total regeneration browsed (1.83%) at the Bandy control sites was most likely
due to the majority of regenerative stems (77%) occurring in the 2-greater-than-3 cm classes.
These thicker stems were observed to have far less browsing than stems in smaller diameter
classes, which contained most of the meager control utilization. This stark difference is most
likely due to younger stems containing more succulent and nutritious current year’s growth than
older stems in larger diameter classes (Williams, personal observation 2015). On average, the
31
Bandy Ranch regeneration occurring in treated areas experienced 46.46% more utilization than
the average control area. Again, this difference is most likely due to differences in size class
densities (69% of all regeneration occurred in the less-than-1 to 2 cm size classes). As noted in
section one of this discussion, conifer removal in quaking aspen stands seems to result in a pulse
of regeneration recruitment into the smaller size classes because increasing light availability
stimulates sprout growth (Sandberg and Schneider 1953).
Moreover, it is also likely that ungulates prefer tenderer current year’s growth which is
found in younger, and thus usually smaller, diameter classes (Bradt 2015, Howard 1996, Lewing
2015). Those factors would influence herbivores to selectively graze smaller diameter classes,
and this overall trend was observed at the Bandy and Burnt Fork ranches. Because conifer
removal (and especially the cutting of some overstory aspen) recruits more regeneration into
smaller diameter classes than a no-cut control unit, it makes sense that treatment units would
experience the greatest amount of utilization (Williams, personal observation 2015).
The Burnt Fork ranch utilization data showed a similar trend between control and
treatment sites. Only one control location experienced utilization (12.5%) to give an average of
.03% total control utilization. The treatment average utilization, however, showed a dramatic
increase to 23.28% of total regeneration. It is very likely that similar factors were at play at the
Burnt Fork and Bandy ranches, namely, that silvicultural manipulation of the aspen stands
resulted in more regeneration (Williams, personal observation 2015). Because 75% of Burnt
Fork control regeneration occurred in the 2-greater-than-3 cm classes and 25% in the less than 2
cm classes, the little regeneration that did occur was clustered in the less-than-1 diameter class.
The Burnt Fork treatment units, however, showed 91% of all regeneration grouped in the 2-
greater-than-3 cm classes and only 8% in the less than 2 cm classes. As palatable browsing
32
material was more abundant in treatment areas than in controls, selective browsing resulted in
higher ungulate utilization of treatment units (Williams, personal observation 2015).
Overall, then, the data trends and relationships suggest that removing encroaching
conifers from quaking aspen clones does seem to result in greater ungulate utilization of young
regeneration, mostly because there is simply denser, younger forage available in treated stands
due to an increased production of regeneration post-treatment (Williams, personal observation
2015).
Does conifer removal in quaking aspen increase, decrease or not affect residual growth?
Average annual growth of residual trees either increased or stayed the same post-harvest
for all but one location at the Bandy and Burnt Fork ranches, which showed a decrease in
residual growth. Both instances of decrease in average annual growth were found in treatment
units. The Bandy unit showing decreased radial growth (D3) contained the most overstory trees,
which could at least partially explain why growth decreased post-treatment. The Burnt Fork unit
with decreased radial growth (T3-S), however, did not contain the most trees per acre.
On the other hand, 45% of regeneration in unit D3 occurred in the less-than-1 cm
diameter class (which is the youngest diameter class), implying that its growth was stimulated by
the timber harvest. Unit T3-S at the Burnt Fork also showed a comparatively large (47%) portion
of its regeneration occurring in the youngest diameter class. Where conifer removal was
incomplete at the Bandy and Burnt Fork ranches, radial conifer growth declined from pre-
treatment to post-treatment. The overstory trees at both ranches may have experienced a decrease
in residual growth because resource consumption was switched post-treatment from radial
growth to clonal reproduction (Williams, personal observation 2015).
33
Any change, whether positive or negative, in average annual residual growth was very
small and only discernable with a dissecting microscope at both ranches. The average difference
between treatment and control at the Bandy Ranch was a positive growth but very small: only
0.005 cm/year post-treatment and only .011 cm/year pre-treatment. The Burnt Fork Ranch also
showed positive but nearly non-significant growth changes: 0.065 cm/year post-treatment and
only 0.073 cm/year pre-treatment. Still, the Burnt Fork Ranch showed a greater average annual
growth increase over a shorter time period (four years) than the 12-year time period at the Bandy
Ranch. This may indicate that the Burnt Fork overstory aspen trees are more responsive to
treatments than the Bandy Ranch aspen trees, most likely because the Burnt Fork trees are much
younger than those at the Bandy (Williams, personal observation 2015).
Overall, removing encroaching conifers from quaking aspen seems to increase the radial
growth of residual overstory aspen but only by a small amount. While there were instances
where overstory aspen radial growth decreased post-treatment, the overall trend suggests that
conifer removal has the ability to increase residual growth. In addition, time-scales make a
difference: if this study were repeated in ten years and regeneration production has slowed, then
the overstory stems may have more resources available to continue radial growth (Williams,
personal observation 2015).
34
CONCLUSION
This control-impact study quantified how releasing quaking aspen stands from conifer
encroachment affected aspen regeneration and residual radial growth. Releasing quaking aspen
stands at a large spatial scale shows similar results, giving implications for effective management
techniques across the wide ecological spectrum of western Montana. When quaking aspen stands
were released, regeneration increased abundantly in treatment units and was clustered in lower
diameter classes. Because of this regeneration concentration of smaller, more palatable stems,
ungulate utilization of current year’s growth was greater in all treatment units than in all control
units. Thus, while the goal of increasing aspen regeneration was met through silvicultural
manipulation of aspen clones, the ensuing regeneration was heavily grazed by ungulates at both
study locations. Average annual radial growth increased overall in both control and treatment
location, but only by very small amounts. There were two instances in treatment units where
annual radial growth actually decreased following a treatment, but this coincided with a large
percentage of regeneration occurring in small diameter classes. Overstory trees were most likely
devoting resources to the pulse of clonal reproduction following the treatment; this would help
explain the reason why overstory trees were only increasing (and sometimes decreasing) annual
radial growth following the conifer removal. The above-mentioned trends occurred at both the
Bandy and Burnt Fork ranches, implying similarity between silvicultural effects at a larger
spatial scale.
Results and relationships brought out in this study may be of help to managers who want
to restore quaking aspen stands without clearcutting. While clearcutting has been shown to
drastically increase regeneration (Doucet 1989), many landowners may wish to retain the myriad
of benefits (wildlife and bird cover, snag habitat, cooler soil temperatures and less water
35
evaporation, less erosion from spring runoff events) from leaving an aspen overstory (Bradt
2015, Howard 1996, Lewing 2015, Perry et al. 1999). This study has hopefully added to
previous, although scant, information on partially cutting quaking aspen stands to achieve
multiple objectives while retaining vertical structural diversity. Land managers should now have
more information, and therefore more options than clearcutting, about how to increase aspen
regeneration and ensure the future presence of aspen on a site.
This study would benefit from a future investigator determining the site-specific
relationships between Burnt Fork and Bandy aspen regeneration diameter and age. While
reviewed sources do state that smaller-diameter aspen regeneration usually implies younger
sprouts (Bradt 2015, Howard 1996), having site-specific correlations with regeneration and age
would help bolster assertions made in this study. In addition, an interesting follow-up study
might mark the browsed aspen stems now and then re-examine them a decade or so later to
determine if browsing had any detrimental effects on regeneration mortality. At the time this
study was carried out, no aspen regeneration had died from over-browsing. Monitoring overstory
aspen after a longer period (say a decade or two) would help researchers find if a longer time
period is necessary to notice a meaningful increase in residual overstory radial growth. As
mentioned earlier, the age of overstory trees is likely a significant factor in determining radial
growth responses.
Anyone interested in ensuring the future of quaking aspen and its many ecological, and in
turn monetary, benefits should be able to practice partial cuts in their quaking aspen stands,
remove encroaching conifers, and achieve abundant regeneration. Ungulates do browse the
ensuing regeneration, but browsed regeneration is still alive and thriving after four to six years
post-treatment. Overall, quaking aspen stands can be regenerated successfully by selective partial
36
cuts in order to meet stand objectives at the Burnt Fork and Bandy ranches. Managers may
hopefully apply principles explored and relationships found in this study to quaking aspen stands
throughout western Montana in order to ensure a future of a tree crucial to nature and society.
37
LITERATURE CITED
Anderson, R. L. 1979. Hypoxylon canker of aspen. Washington : Dept. of Agriculture, Forest
Service, Washington.
Bagga, D. K., and E. B. Smalley. 1974. The development of hypoxylon canker of populus
tremuloides: role of interacting environmental factors. American Phytopathological Society.
64.5:March 23 2015.-658-662.
Bradt, W. 2015. Personal Communication.
Dodson, E. 2015. Personal Communication.
Doucet, R. 1989. REGENERATION SILVICULTURE OF ASPEN. Forestry Chronicle;
For.Chron. 65:23-27.
Holechek, J., R. Pieper, and H. Carlton. 2003.
Howard, J. L. 1996. Populus tremuloides. Fire Effects Information System, [Online]. U.S.
Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences
Laboratory (Producer). March 18 2015.
Lewing, M. 2015. Personal Communication.
McManigal, K. 2015. Personal Communication.
Perala, D. A. n.d. Quaking aspen. U.S. Department of Agriculture, Forest Service. 2015.
Perry, R. W., R. E. Thill, D. G. Peitz, and P. A. Tappe. 1999. Effects of Different Silvicultural
Systems on Initial Soft Mast Production. Wildlife Society Bulletin 27:915-923.
Rook, E. 2006. Populus tremuloides: quaking aspen. Rook.org March 18 2015.
Sandberg, D., and A. E. Schneider. 1953. The regeneration of aspen by suckering. School of
Forestry, University of Minnesota. March 23 2015.
Shinneman, D., W. Baker, P. C. Rogers, and D. Kulakowski. 2013. Fire regimes of quaking
aspen in the Mountain West. Forest Ecology and Management; For.Ecol.Manage. 299:22-
34.
Stewardship, W. 2011. Forest Types: Aspen, University of Minnesota collaboration. March 18
2015.
Worrall, J., G. Rehfeldt, A. Hamann, E. Hogg, S. B. Marchetti, M. Michaelian, and L. Gray.
2013. Recent declines of Populus tremuloides in North America linked to climate. Forest
Ecology and Management; For.Ecol.Manage. 299:35-51.
38
APPENDICES
Appendix A: Bandy Ranch Jumpstart Prescription
The following four treatments will be implemented:
Treatment 1 - Red
This is a wildlife-focused treatment that leaves naturally-occurring clumps of trees and creates
clearings around these clumps. This treatment would break up fuels horizontally, minimizing
risk of continuous crown fire.
- Leave clumps should vary in size from a few trees to 1/4 acre in size.
- Leave clumps may be a mixture of species, sizes, and age classes.
- 50-80% open (no trees), with the remainder of the area in clumps.
- No thinning of clumps.
- Clumps will be arranged so as to minimize sight distance through the stand.
- When practical, lodgepole pine that has been hit by bark beetles or is of a susceptible size
(mature) should be favored for removal.
- Species preference for retention is: aspen, cottonwood, larch, ponderosa pine, spruce,
Douglas-fir, lodgepole pine.
Aspen: clear around aspen clones approximately 50 feet. No cutting within aspen.
Treatment 1 applies to Units B, J, L, and Q. Unit boundaries are marked with red flagging at
road intersections and along boundaries not formed by roads.
Treatment 2 - Blue
Same as 1 but with thinning of clumps to remove less-desired species and ladder fuels. This
treatment breaks up fuels both horizontally and vertically and also provides for increased browse
and some disruption of sight distance.
- Leave clumps should vary in size from a few trees to 1/4 acre in size.
- Leave clumps may be a mixture of species, sizes, and age classes.
- 50-80% open (no trees), with the remainder of the area in clumps.
- Clumps will be thinned to retain the most vigorous, best form trees (sanitation thinning). A
range of residual age and size classes is desired, when possible.
- Clumps will be arranged so as to minimize sight distance through the stand.
- When practical, lodgepole pine that has been hit by bark beetles or is of a susceptible
(mature) size should be favored for removal.
- Species preference for retention is: aspen, cottonwood, larch, ponderosa pine, spruce,
Douglas-fir, lodgepole pine.
39
Aspen: Clear around aspen clones approximately 50 feet and remove conifer encroachment.
Unit G: This unit has a large volume of dead or dying lodgepole pine from an ongoing mountain
pine beetle outbreak. All dead, dying, and susceptible lodgepole pine will be removed from this
unit. This will create patch openings. In portions of the stand that are currently mixed conifer,
the above treatment will be applied.
Treatment 2 applies to Units F, G, O, and P. Unit boundaries are marked with blue flagging at
road intersections and along boundaries not formed by roads.
Treatment 3: Yellow
This treatment will thin by species preference, retaining the naturally-occurring clumpy stand
structure.
- Target species composition is 40-60% larch, 20-40% Douglas-fir, 20-40% ponderosa pine,
20% other.
- On average retain 50-70 sq. ft. basal area per acre (1/2 to 2/3 the pre-treatment basal area).
- Retain the most vigorous, best form trees in a variety of age and size classes.
- Species preference for retention is: aspen, cottonwood, larch, ponderosa pine, spruce,
Douglas-fir, lodgepole pine.
Aspen: Clear around aspen clones approximately 50 feet. Remove conifer encroachment from
within each clone. Additionally, cut 1 to 2 mature aspen stems per clone to promote
regeneration.
Treatment 3 includes Units C, D, H, I, and K. Unit boundaries are marked with yellow flagging
at road intersections and along boundaries not formed by roads.
Treatment 4: White
Control (no treatment). No cutting is to occur within these units except where necessary for road
relocation.
Treatment 4 includes Units A, E, M, N. Unit boundaries are marked with white flagging at road
intersections and along boundaries not formed by roads.
40
Unit acreages:
Unit Acres Treatment Treated
A 20.1 4 no
B 11 1 yes
C 25.2 3 yes
D 22.1 3 yes
E 15.1 4 no
F 23.7 2 yes
G 26.6 2 yes
H 10.5 3 yes
I 14.7 3 yes
J 8.9 1 yes
K 11.1 3 yes
L 10.1 1 yes
M 13.8 4 no
N 26.8 4 no
O 18.5 2 yes
P 27.8 2 yes
Q 29.4 1 yes
Appendix A: Prescription for the Bandy Ranch Jumpstart Project (courtesy of Dr. Elizabeth
Dodson, University of Montana, Missoula).
41
Appendix B: Map of the Bandy Ranch Jumpstart silvicultural operation and various
silvicultural treatments: summer 2009 (courtesy of Dr. Elizabeth Dodson, University of
Montana, Missoula).
42
Equipment Cost
($)
Flagging Tape 5
50' Spencer Diameter Tape ft./10ths
(950DC)
57.98
Lufkin Fiberglass Tape - 3/4-inch X
100-foot
56.44
Haglöf 3-Thread Increment Borers 269.55
(16"L x 0.200 (5.15mm) Dia.)
Silva Ranger Orienteering Compass 50
Equipment Total Costs 438.97
Burnt Fork Ranch Travel
Date Miles Gal
used
Cost
($)
6/1/2015 31.8 2.54 6.56
6/4/2015 31.8 2.54 6.56
6/15/2015 31.8 2.54 6.56
6/17/2015 32.5 2.60 6.71
6/26/2015 29.2 2.34 6.03
7/16/2015 31.2 2.50 6.44
7/17/2015 31.2 2.50 6.44
7/21/2015 32.6 2.61 6.73
7/22/2015 23 1.84 4.75
7/23/2015 17 1.36 3.51
7/27/2015 30.1 1.00 2.59
7/31/2015 17 1.36 3.51
8/18/2015 26 2.08 5.37
9/12/2015 34 1.13 2.92
9/19/2015 29 0.97 2.49
Burnt Fork Ranch Total Costs ($) 77.17
43
Bandy Ranch Travel
Date Miles Gal
used
Cost ($)
6/22/2015 71 2.37 6.11
8/22/2015 160 7.27 18.04
9/11/2015 104.6 8.37 21.59
Bandy Ranch Total
Costs ($)
45.73
GRAND TOTAL
COSTS ($)
561.87
Notes
Price/Gal (Unlead) MPG
(truck)
MPG
(car)
MPG
(Diesel)
Price/Gal
(Diesel)
$2.58 12.5 30 22 $2.48
Appendix C: Research equipment and travel costs.
44
Appendix D: Map of the Burnt Fork Ranch aspen study units.
45
Appendix E: Map of the Bandy Ranch aspen study units.
46
Appendix F.1: Burnt Fork Ranch control raw data.
Un
it:
C1
- N
Un
it:
C2
- N
100t
h a
cre
100t
h a
cre
Dia
me
ter
Cla
sse
s (c
m)
Dia
me
ter
Cla
sse
s (c
m)
< 1
1-2
2-3
> 3
< 1
1-2
2-3
> 3
Bro
wse
dB
row
sed
2
Un
bro
wse
d2
10U
nb
row
sed
66
2
10th
acr
eN
ote
s10
th a
cre
No
tes
Mo
st V
igo
rou
sM
ost
Vig
oro
us
DB
H:
13.2
Tota
l gro
wth
DB
H:
8.3
Avg
. gro
wth
po
st-T
:0.
075
0.15
Tota
l gro
wth
Avg
. gro
wth
pre
-T:
0.07
50.
15A
vg. g
row
th p
ost
-T:
0.12
50.
25
# o
vers
tory
tre
es:
3Sa
mp
leA
vg. g
row
th p
re-T
:0.
150.
3
# o
vers
tory
tre
es:
9Sa
mp
le
Un
it:
C1
- S
100t
h a
cre
Un
it:
C2
- S
Dia
me
ter
Cla
sse
s (c
m)
100t
h a
cre
< 1
1-2
2-3
> 3
Dia
me
ter
Cla
sse
s (c
m)
Bro
wse
d<
11-
22-
3>
3
Un
bro
wse
d3
44
4B
row
sed
Un
bro
wse
d6
4817
10th
acr
eN
ote
s
Mo
st V
igo
rou
s10
th a
cre
No
tes
DB
H:
9.9
Tota
l gro
wth
Mo
st V
igo
rou
s
Avg
. gro
wth
po
st-T
:0.
10.
2D
BH
:0.
8To
tal g
row
th
Avg
. gro
wth
pre
-T:
0.05
0.1
Avg
. gro
wth
po
st-T
:0.
050.
1
# o
vers
tory
tre
es:
5Sa
mp
leA
vg. g
row
th p
re-T
:0.
050.
1
# o
vers
tory
tre
es:
11Sa
mp
le9
de
ad
47
Appendix F.2: Burnt Fork Ranch treatment raw data, units 1 & 2.
Un
it:
T1 -
NU
nit
:T2
- N
100t
h a
cre
100t
h a
cre
Dia
me
ter
Cla
sse
s (c
m)
Dia
me
ter
Cla
sse
s (c
m)
< 1
1-2
2-3
> 3
< 1
1-2
2-3
> 3
Bro
wse
d8
1B
row
sed
Un
bro
wse
d43
112
Un
bro
wse
d46
32
10th
acr
eN
ote
s10
th a
cre
No
tes
Mo
st V
igo
rou
sM
ost
Vig
oro
us
DB
H:
7.4
Tota
l Gro
wth
DB
H:
4.3
Tota
l Gro
wth
Avg
. gro
wth
po
st-T
:0.
175
0.35
Avg
. gro
wth
po
st-T
:0.
075
0.15
Avg
. gro
wth
pre
-T:
0.15
0.3
Avg
. gro
wth
pre
-T:
0.05
0.1
# o
vers
tory
tre
es:
9Sa
mp
le#
ove
rsto
ry t
ree
s:7
Sam
ple
smal
l, a
bo
ut
30 f
ee
t.
Un
it:
T1 -
SU
nit
:T2
- S
100t
h a
cre
100t
h a
cre
Dia
me
ter
Cla
sse
s (c
m)
Dia
me
ter
Cla
sse
s (c
m)
< 1
1-2
2-3
> 3
< 1
1-2
2-3
> 3
Bro
wse
d44
1B
row
sed
244
Un
bro
wse
d34
71
Un
bro
wse
d13
41
10th
acr
eN
ote
s10
th a
cre
No
tes
Mo
st V
igo
rou
sM
ost
Vig
oro
us
DB
H:
5.9
Tota
l Gro
wth
DB
H:
6.7
Tota
l Gro
wth
Avg
. gro
wth
po
st-T
:0.
275
0.55
Avg
. gro
wth
po
st-T
:0.
125
0.25
Avg
. gro
wth
pre
-T:
0.17
50.
35A
vg. g
row
th p
re-T
:0.
10.
2
# o
vers
tory
tre
es:
13Sa
mp
le#
ove
rsto
ry t
ree
s:10
Sam
ple
2 ar
e d
ead
sn
ags
48
Appendix F.3: Burnt Fork treatment raw data, units 3 & 4.
Un
it:
T3 -
NU
nit
:T4
- N
100t
h a
cre
100t
h a
cre
Dia
me
ter
Cla
sse
s (c
m)
Dia
me
ter
Cla
sse
s (c
m)
< 1
1-2
2-3
> 3
< 1
1-2
2-3
> 3
Bro
wse
d2
Bro
wse
d19
Un
bro
wse
d8
193
1U
nb
row
sed
1916
15
10th
acr
eN
ote
s10
th a
cre
No
tes
Mo
st V
igo
rou
s C
on
ifer
Mo
st V
igo
rou
s
DB
H: (
PP
)15
.5To
tal G
row
thD
BH
:5.
9To
tal G
row
th
Avg
. gro
wth
po
st-T
:0.
050.
1A
vg. g
row
th p
ost
-T:
0.15
0.3
Avg
. gro
wth
pre
-T:
0.07
50.
15A
vg. g
row
th p
re-T
:0.
10.
2
Mo
st V
igo
rou
s A
spen
# o
vers
tory
tre
es:
12Sa
mp
le
DB
H:
4.6
Tota
l Gro
wth
Avg
. gro
wth
po
st-T
:0.
125
0.25
Avg
. gro
wth
pre
-T:
0.1
0.2
Un
it:
T4 -
S
# o
vers
tory
tre
es:
9Sa
mp
le7
asp
en
, 2 p
on
do
s.10
0th
acr
e
Dia
me
ter
Cla
sse
s (c
m)
< 1
1-2
2-3
> 3
Un
it:
T3 -
SB
row
sed
122
1
100t
h a
cre
Un
bro
wse
d6
16
Dia
me
ter
Cla
sse
s (c
m)
< 1
1-2
2-3
> 3
10th
acr
eN
ote
s
Bro
wse
d2
Mo
st V
igo
rou
s
Un
bro
wse
d7
26
2D
BH
:9.
6To
tal G
row
th
Avg
. gro
wth
po
st-T
:0.
250.
5
10th
acr
eN
ote
sA
vg. g
row
th p
re-T
:0.
250.
5
Mo
st V
igo
rou
s#
ove
rsto
ry t
ree
s:6
Sam
ple
DB
H:
5.8
Tota
l Gro
wth
Avg
. gro
wth
po
st-T
:0.
150.
3
Avg
. gro
wth
pre
-T:
0.25
0.5
# o
vers
tory
tre
es:
7Sa
mp
leve
ry s
mal
l, 2
0-25
fe
et.
49
Appendix F.4: Burnt Fork Ranch treatment raw data, unit 5.
Unit: T5-N
100th acre
Diameter Classes (cm)
< 1 1-2 2-3 > 3
Browsed 1
Unbrowsed 16 3 2
10th acre Notes
Most Vigorous
DBH: 8.1 Total Growth
Avg. growth post-T: 0.1 0.2
Avg. growth pre-T: 0.05 0.1
# overstory trees: 3 Sample
Unit: T5 - S
100th acre
Diameter Classes (cm)
< 1 1-2 2-3 > 3
Browsed
Unbrowsed 25 5 1 1
10th acre Notes
Most Vigorous
DBH: 4.3 Total Growth
Avg. growth post-T: 0.1 0.2
Avg. growth pre-T: 0.05 0.1
# overstory trees: 4 Sample
50
Appendix G.1: Bandy Ranch control raw data.
Unit: A4
100th acre
Diameter Classes (cm)
< 1 1-2 2-3 > 3
Browsed
Unbrowsed 0 13 6 3
10th acre Notes
Most Vigorous
DBH: 24.5
Avg. growth post-T: 0.108333333 0.65
Avg. growth pre-T: 0.1 0.6
# overstory trees: 14 Census
Unit: E4.a
100th acre
Diameter Classes (cm)
< 1 1-2 2-3 > 3
Browsed 2 2
Unbrowsed 23 33 13
10th acre Notes
Most Vigorous
DBH: 25
Avg. growth post-T: 0.083333333 0.5
Avg. growth pre-T: 0.066666667 0.4
# overstory trees: 5 Census
Unit: E4.b
100th acre
Diameter Classes (cm)
< 1 1-2 2-3 > 3
Browsed 2 2
Unbrowsed 1 20 2 3
10th acre Notes
Most Vigorous
DBH: 13.2
Avg. growth post-T: 0.05 0.3
Avg. growth pre-T: 0.05 0.3
# overstory trees: 1 Sample
51
Appendix G.2: Bandy Ranch treatment raw data.
Un
it:
P2.
aU
nit
:Q
1.a
Un
it:
H3
100t
h a
cre
100t
h a
cre
100t
h a
cre
Dia
me
ter
Cla
sse
s (c
m)
Dia
me
ter
Cla
sse
s (c
m)
Dia
me
ter
Cla
sse
s (c
m)
< 1
1-2
2-3
> 3
< 1
1-2
2-3
> 3
< 1
1-2
2-3
> 3
Bro
wse
d13
3024
3B
row
sed
23
Bro
wse
d11
1921
3
Un
bro
wse
d4
159
Un
bro
wse
d2
72
Un
bro
wse
d5
1223
10th
acr
eN
ote
s10
th a
cre
No
tes
10th
acr
eN
ote
s
Mo
st V
igo
rou
sM
ost
Vig
oro
us
Mo
st V
igo
rou
s C
on
ifer
DB
H:
12.8
Tota
l Gro
wth
DB
H:
17To
tal G
row
thD
BH
:22
D-f
Avg
. gro
wth
po
st-T
:0.
0916
670.
55A
vg. g
row
th p
ost
-T:
0.1
0.6
Avg
. gro
wth
po
st-T
:0.
1166
670.
7
Avg
. gro
wth
pre
-T:
0.07
50.
45A
vg. g
row
th p
re-T
:0.
1333
330.
8A
vg. g
row
th p
re-T
:0.
125
0.75
# o
vers
tory
tre
es:
7C
en
sus
# o
vers
tory
tre
es:
5Sa
mp
le1
snag
Mo
st V
igo
rou
s A
spen
DB
H:
21.7
Tota
l Gro
wth
Avg
. gro
wth
po
st-T
:0.
0833
330.
5
Un
it:
P2.
bU
nit
:Q
1.b
Avg
. gro
wth
pre
-T:
0.07
50.
45
100t
h a
cre
100t
h a
cre
# o
vers
tory
tre
es:
15Sa
mp
le3
con
ife
rs: 2
D-f
, 1 W
L.
Dia
me
ter
Cla
sse
s (c
m)
Dia
me
ter
Cla
sse
s (c
m)
12 a
spe
n
< 1
1-2
2-3
> 3
< 1
1-2
2-3
> 3
Bro
wse
d5
5B
row
sed
1
Un
bro
wse
dU
nb
row
sed
121
6U
nit
:D
3
100t
h a
cre
10th
acr
eN
ote
s10
th a
cre
No
tes
Dia
me
ter
Cla
sse
s (c
m)
Mo
st V
igo
rou
sM
ost
Vig
oro
us
< 1
1-2
2-3
> 3
DB
H:
14.6
Tota
l Gro
wth
DB
H:
19.8
Tota
l Gro
wth
Bro
wse
d23
10
Avg
. gro
wth
po
st-T
:0.
1166
670.
7A
vg. g
row
th p
ost
-T:
0.08
3333
0.5
Un
bro
wse
d6
718
Avg
. gro
wth
pre
-T:
0.08
3333
0.5
Avg
. gro
wth
pre
-T:
0.10
8333
0.65
# o
vers
tory
tre
es:
6C
en
sus
# o
vers
tory
tre
es:
3Sa
mp
le10
th a
cre
No
tes
Mo
st V
igo
rou
s
DB
H:
11.6
Tota
l Gro
wth
Un
it:
G2
Avg
. gro
wth
po
st-T
:0.
075
0.45
100t
h a
cre
Avg
. gro
wth
pre
-T:
0.08
3333
0.5
Dia
me
ter
Cla
sse
s (c
m)
# o
vers
tory
tre
es:
13Sa
mp
le
< 1
1-2
2-3
> 3
Bro
wse
d3
4
Un
bro
wse
d32
366
1
10th
acr
eN
ote
s
Mo
st V
igo
rou
s
DB
H:
15.3
Tota
l Gro
wth
Avg
. gro
wth
po
st-T
:0.
0583
330.
35
Avg
. gro
wth
pre
-T:
0.04
1667
0.25
# o
vers
tory
tre
es:
1C
en
sus