J. For. 112(5):484 – 493
http://dx.doi.org/10.5849/jof.13– 092
PRACTICE OF FORESTRY
silviculture
Silviculture of the Colorado Front Range
Landscape Restoration Initiative
Jeffrey L. Underhill, Yvette Dickinson, Alex Rudney, and
Jim Thinnes
We discuss innovative silvicultural practices and implementation methods through 3 years of fuels reduction
and restoration treatments for the Collaborative Forest Landscape Restoration Project, Colorado Front
Range Landscape Restoration Initiative (Front Range Project). The Pike National Forest is implementing
large-scale landscape restoration projects to address the departure of montane forests from historical
conditions and increased susceptibility to uncharacteristic high-severity wildfire. Restoration on approximately 1,600 acres is implemented annually through stewardship contracting. Treatments are shifting from
traditional fuels reduction treatments to restoration treatments designed to achieve heterogeneous
conditions at a variety of scales. Future treatment areas will include more upper montane mixed-forest
types as we transition out of the lower montane ponderosa pine forest. Silvicultural practices include
variable tree spacing, variable densities, and openings. Treatments are implemented via designation by
prescription (DxP), tree marking, and a combination of both methods. We also discuss the status of
monitoring protocols, both established and under development.
Keywords: variable spacing, variable density, openings, designation by prescription, heterogenity
T
he Southern Rocky Mountains
meet the Great Plains at Colorado’s
Front Range. The Front Range includes an urban corridor from Fort Collins
to Denver to Colorado Springs where millions of people live, work, and play. The area’s lower montane forests are dominated by
ponderosa pine (Pinus ponderosa) and
Douglas-fir (Pseudotsuga menziesii), historically largely influenced by a mixed-severity
fire regime (Huckaby et al. 2001, Kaufmann
et al. 2001, 2006). The current landscape is
similar to other portions of the western
United States where fire suppression and
past management have resulted in a departure from historical conditions and an in-
creased susceptibility to uncharacteristic
high-intensity wildfire, insects, and disease
(Fitzgerald 2005, Hood and Miller 2007,
Collins et al. 2011). In recent years, large
wildfires in this wildland-urban interface
have claimed several lives, destroyed more
than 1,100 homes (National Interagency
Coordination Center 2012, 2013), damaged critical watersheds, and created undesirable forest conditions.
The destructive fire season of 2002
highlighted a need for a more proactive and
large-scale response to the growing wildfire
threat, resulting in the establishment of the
Front Range Roundtable in 20031 (Front
Range Fuels Treatment Partnership Round-
table 2006). The partnership includes federal, state, and local agencies, utility providers, conservation groups, private business
representatives, and other stakeholders committed to reducing wildfire hazards through
sustained fuel treatments. These diverse stakeholders identified restoration as a means to
achieve shared goals and objectives.
The Front Range Roundtable developed and proposed the Colorado Front
Range Landscape Restoration Initiative
(Front Range Project) under the Collaborative Forest Landscape Restoration Program
(CFLRP) (Public Law 111-11). The Front
Range Project, which includes portions of
the Arapaho, Roosevelt, and Pike National
Forests, was selected for funding under the
CFLRP in 2010. The CFLRP uses federal
funding to encourage collaborative, sciencebased ecosystem restoration of priority forest
landscapes. CFLRP Projects focus on reducing uncharacteristic wildfire, improving fish
and wildlife habitat, improving water quality and watershed function, controlling invasive species, and utilizing woody biomass
and small diameter trees. Collaboration is a
key component of planning, implementation, and monitoring outcomes.
We discuss the challenges of the Front
Range Project and the innovative silvicultural
techniques employed to resolve these chal-
Received November 25, 2013; accepted July 22, 2014; published online August 21, 2014.
Affiliations: Jeffrey L. Underhill (junderhill@fs.fed.us), USDA Forest Service, Rocky Mountain Region, Golden, CO. Yvette Dickinson (yldickin@mtu.edu),
Michigan Tech University, School of Forest Resources and Environmental Science. Alex Rudney (arudney@fs.fed.us), USDA Forest Service, Pike and San Isabel
National Forests. Jim Thinnes, USDA Forest Service, Rocky Mountain Region, retired.
Acknowledgments: We thank Katherine Mattor and Torsten Lund Snee, Forest and Rangeland Stewardship Department, Colorado State University.
484
Journal of Forestry • September 2014
lenges by focusing on projects implemented in
the Woodland Park area of the Pike National
Forest (Figure 1). Specifically, the Front Range
Project aims to create conditions characteristic
of pre-European settlement conditions with
increased forest heterogeneity across scales
from the substand (⬍1 acre) to the landscape
level (ⱖ10,000 acres). This includes the creation of heterogeneous stand structures that
contain individual trees, clumps of trees, and
interspatial openings and varied stand densities
across the landscape with large openings, ranging from 5 to 40 acres. We also explore the
implications of using tree marking systems,
designation by prescription (DxP), and combinations of these methods to create the desired conditions.
Current Conditions
Existing vegetation on the treatment areas on the Pike National Forest is commonly
grouped into three cover types: ponderosa
pine dominated, dry mixed conifer, and
moist mixed conifer. The distribution of
these cover types across the landscape is correlated with elevation, aspect, and proximity
to riparian areas. Although the project area
ranges from 8,000 to 9,500 ft in elevation,
the lower elevations tend to be more ponderosa pine dominated, with increasing
amounts of Douglas-fir, blue spruce (Picea
pungens), and Engelmann spruce (Picea engelmannii) at higher elevations. Aspen
(Populus tremuloides) is present in all forest
types. Fire, drought, bark beetles, western
spruce budworm (Choristoneura occidentalis), and pathogens such as mistletoe (Arceuthobium spp.) also play important roles in
determining stand structure in these forest
types (Swetnam and Lynch 1993). The majority of the forest vegetation in the project
area is classified as intermediate, closed-canopy structure.
Generally, the productivity of the
Woodland Park treatment areas is relatively
low due to dry conditions. The area receives
just 15–24 in. of precipitation per year, typically from rain during the summer monsoons in July and August and winter snows.
Other factors include a short growing season
of just 70 –125 days and well drained soils
derived from granite with low available water capacity (⬍1 in.). Fire suppression and
past management activities within the project area have resulted in overly dense conditions for the ponderosa pine-dominated and
dry mixed-conifer types and an increased
risk for active crown fires (Veblen et al.
2000).
Ponderosa Pine-Dominated Type
The ponderosa pine-dominated forest
type occupies the lowest elevations within
the project area. Generally, this type exhibits
a mosaic of structural stages with pockets of
regeneration, shrubs, grass, and openings
mixed with forested areas of variable density.
Uneven-aged stand structures dominate
with nearly pure ponderosa pine on the
south and west aspects and higher amounts
of Douglas-fir on north-facing slopes. Limber pine (Pinus flexilis) occurs in groups and
as scattered individuals. Aspen is also present
in small groups and as scattered individuals
on the moister areas of ponderosa pinedominated sites. Ponderosa pine and aspen
will regenerate after fire, whereas Douglas-fir
regeneration occurs both quickly after fires
and in between fires. Ponderosa pine regeneration may be sporadic because average precipitation from March to July in the Colorado Front Range is often insufficient to
establish ponderosa pine seedlings (Shepperd and Battaglia 2002).
The forest structure is greatly influenced by the pattern of fire on a landscape
scale (Huckaby et al. 2001). Historic disturbance regimes for this type include surface,
mixed, and stand replacement fires (Hunter
et al. 2007). Pretreatment densities typically
range from 80 to 120 ft2/acre of live conifer
basal area (Table 1; Figure 2). The species
composition of the lower and mid canopy
has shifted to Douglas-fir. Crown closure
and fuel loading have increased, and fuel
composition has become increasingly litter
composed compared with previous grassy
understories (Huckaby et al. 2001).
Dry Mixed-Conifer Type
Douglas-fir, ponderosa pine, limber
pine, and aspen dominate the dry mixed-
conifer type (Evans et al. 2011). Blue spruce,
Engelmann spruce, and lodgepole pine (Pinus contorta) are also present. The composition and structure of the overstory vary
based on the temperature and moisture relationships of the site, although uneven-aged
stand structures still dominate. Pretreatment densities typically range from 90 to
120 ft2/acre (Figure 3). Because of the lack
of disturbance, understory Douglas-fir and
spruce have increased and ponderosa pine,
aspen, and limber pine have diminished
since European settlement (Evans et al.
2011). Aspen is present as scattered understory individuals.
In general, fire regimes have moved
from mixed severity under historical conditions to stand replacement crown fire under
current conditions. Succession after a replacement fire will depend on the predisturbance species composition. Some ponderosa
pine and Douglas-fir are likely to survive and
provide a seed source for regenerating
stands. In some cases, fire effects may be so
severe that conifer seed sources may be absent, and natural conifer regeneration may
be delayed for decades or longer. Aspen, if
present before a disturbance, will quickly regenerate and expand.
Moist Mixed-Conifer Type
The moist mixed-conifer type occurs in
riparian and moist low-lying areas and on
north aspects with other types at higher elevations. Douglas-fir and Engelmann spruce
are often dominant in canopies with aspen
present in most stands. Ponderosa pine is
present in the moist mixed-conifer type but
at much lower densities than is typical of the
dry mixed-conifer type. Where ponderosa
pine is found, it often occurs in small groups
or isolated pockets, usually in open areas and
Management and Policy Implications
Increasing forest heterogeneity, with an emphasis on structure and pattern at all scales (⬍1 acre–
ⱖ10,000 acres), is a common objective of recent collaborative forest restoration projects throughout the
western United States. Traditional silvicultural treatments intended to increase tree vigor or reduce
hazardous fuels have often reduced heterogeneity. Implementing new restoration treatments using
conventional prescription and implementation methods presents challenges. The Colorado Front Range
Landscape Restoration Initiative (Front Range Project) has taken an adaptive management approach to
these challenges, through monitoring treatment outcomes and iteratively modifying the silviculture
prescriptions and implementation methods based on the outcomes to improve treatment effectiveness. The
most heterogeneous conditions thus far have been achieved through prescriptions that explicitly include
variable residual densities and opening creation through the combined use of designation by prescription
(DxP) and tree marking. We describe the challenges faced by the Front Range Project and the lessons
learned.
Journal of Forestry • September 2014
485
Figure 1. Restoration area, Colorado Front Range Landscape Restoration Initiative (Front
Range Project).
the edges of meadows. Older stands exhibit
high densities, typically 180 ft2/acre or
greater with understories of spruce and
Douglas-fir and an abundance of dead and
downed material. Ponderosa pine regeneration is uncommon, and aspen regeneration
tends to be suppressed. Limber and lodgepole pine tend to be very minor species, occurring as isolated individuals. Infrequent
fire during dry periods is the primary disturbance agent, although insects and disease
also play major roles. Generally, moist
mixed-conifer types are less departed from
the historical fire regimes because presettle486
Journal of Forestry • September 2014
ment stand-replacing crown fires were common (Romme et al. 2009).
Restoration Goals
The Colorado Front Range does not
have extensive models of historic stand
structures similar to those available in other
regions. The Front Range Roundtable is
currently reconstructing historic stand
structures to help guide site-specific desired
stand conditions for restoration treatments. In the absence of site-specific desired
conditions, the general goal includes
increasing forest heterogeneity across all
scales (plot, stand, watershed, and land-
scape). Treatment prescriptions and implementation methods focus on creating conditions characteristic of a mixed-severity
disturbance regime by reducing canopy closure, favoring shade-intolerant species, increasing spacing variability with a mixture of
individual trees, clumps of trees, and interspatial openings, creating persistent
openings, and enhancing the mosaic of successional stages by creating higher levels of
early and late seral structure.
The Front Range roundtable has
strived to identify the goals, scale, pattern,
and location criteria for creating openings.
Traditional metrics such as minimum stocking levels were not considered. The Front
Range Roundtable desired to create
persistent openings located where conditions are less favorable to the establishment
of conifer species. Other treatments would
establish a new cohort of desired species including aspen, ponderosa pine, and limber
pine. These canopy openings are essential
for increasing forest heterogeneity at the
stand scale and greater and are more consistent with fuel loads and distributions that
would be expected with a mixed-severity fire
regime (Kaufmann et al. 2001).
Treatments in the Woodland Park area
(Figure 1) before the Front Range Project
emphasized fuels reduction objectives such
as the removal of ladder fuels and the reduction of canopy bulk density and crown continuity (approximately 9,000 acres, 2004 –
2009). The majority of these treatments were
implemented in ponderosa pine-dominated
stands. Thinning from below to a residual density of 40 – 60 ft2/acre was the standard silvicultural prescription for these treatments.
Treatments that included the creation of
openings were limited. Often small clearcuts
(⬍1 acre) were located to sanitize mistletoe infections and to stimulate aspen sprouting. Although these treatments were considered successful by US Department of Agriculture
(USDA) Forest Service managers in meeting
fuels reduction goals, the Front Range Roundtable was concerned about the low level of spatial and structural variability.
Silvicultural Prescriptions and
Implementation Methods
Since the establishment of the Front
Range Roundtable, fuels reduction silvicultural prescriptions have become more
complex with the incorporation of
CFLRP restoration goals. The primary silvicultural practices that are currently be-
Table 1. Summary of pre- and posttreatment forest inventory data including the number of plots, live and live conifer basal areas, live
conifer canopy cover, and proportion of live ponderosa pine basal area.
1
Project
2
Method
Timing of
data
No. of
plots
Live BA
Live
conifer BA
Live conifer
BA range
. . . . . . . . . . (ft2/ac) . . . . . . . . . .
Phantom Creek 1 (DMC ⫽ 78%, PP ⫽ 7%,
MMC ⫽ 6%)
Phantom Creek 2 (DMC ⫽ 48%, PP ⫽ 41%)
Mech
Mech
Man
Phantom Creek 3 (PP ⫽ 56%, DMC ⫽ 23%,
MMC ⫽ 5%)
Ryan Quinlan (PP ⫽ 61%, DMC ⫽ 36%)
Mech
Phantom Creek 4 (PP ⫽ 50%, DMC ⫽ 30%,
MMC ⫽ 7%)
Long John (PP ⫽ 61%, DMC ⫽ 35%)
Man
Catamount 1 (PP ⫽ 32%, DMC ⫽ 20%,
MMC ⫽ 12%)
Mech
Mech
Mech
Man
Messenger Gulch 2 (PP ⫽ 75%, DMC ⫽ 20%)
Mech
Man
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Conifer canopy
cover (%)
Proportion of
ponderosa
pine BA (%)
. . . . . . . . . (%) . . . . . . . . .
62
46
63
15
15
36
36
.
40
28
28
35
35
33
31
13
13
.
21
47
96.4
56
89.8
78.5
84.1
56.4
.
41.7
93.3
73.3
123.5
55
110.3
54.1
94.5
61.3
.
42.2
42
88.9
52.1
89.7
76.4
80.6
52.9
.
39.6
88.4
69.7
121.3
53.5
98.9
49.1
80
45.4
.
42.2
25–72
60–136
32–107
75–107
53–107
64–88
37–64
.
10–68
60–135
60–110
80–158
52–110
45–130
27–130
20–100
45–60
.
37–46
17.7
37.2
23.7
41.2
32.2
35.6
24.5
.
19.2
35.1
27.6
46.4
20.6
35.3
19.8
29.2
16.8
.
19.2
52.5
59.5
65.8
52.8
66.5
47
53.8
.
64.5
63
62.1
63.3
74.4
55.6
56.3
59.6
58.7
.
91.1
22
63.4
62.7
53–80
28.5
80.2
Pre, pretreatment; post, posttreatment, BA, basal area.
1
Projects are listed in chronological order by contract award year. The percentage of project area by major forest types shown in parentheses: PP, ponderosa pine; DMC, dry mixed conifer; MMC, moist
mixed conifer.
2
Method: Mech, mechanical ground based logging; Man, manual chain saw work or mastication.
Figure 2. Pretreatment (left) and posttreatment (right) comparison, ponderosa pine-dominated site, Long John project. The posttreatment
photo was taken approximately 10 months after implementation.
ing developed to increase heterogeneity
are as follows: variable tree spacing intended to create tree clumps and interspatial openings in a thinning matrix; variable
density thinning by forest type; and creation of openings of 1–5 acres. The transition to more variable tree spacing has
also included a shift from thinning from
below to thinning throughout crown
classes (free thinning).
Since 2009, fuels reduction projects and
CFLRP treatments have been implemented
through a 10-year Integrated Resource Service
Contract. This contract provides USDA Forest Service managers with a range of treatment
options including commercial ground-based
logging with the removal of a range of products
(Table 2) and other treatments2 such as manual chain saw treatments and mastication. The
average project size to date is approximately
500 acres with mechanized logging typically
occurring on 70 – 80% of the treatment footprint. Standard layout practices include the delineation of large treatment units, often ⬎100
acres, composed of multiple stands and different forest types.
Variable Tree Spacing
Projects with variable tree spacing that
have been implemented recently have foJournal of Forestry • September 2014
487
Figure 3. Pretreatment (left) and posttreatment (right) comparison, dry mixed-conifer site, Phantom Creek 2 project. The posttreatment photo
was taken approximately 1 year after implementation.
Table 2. Wood products created from the biomass removed from the Pike National
Forest, 2010 –2013.
Percent of total
material sold
Products created
Product value
2011
2012
Wood shreds (for postfire restoration)
Dimensional lumber
Mulch
Pallets and crates
Compost
Wood chips
Bark fines (landscaping)
Firewood
Soil fertilizer/biochar
Total
Low
High
Medium
Medium
Medium
Low
Low
Low
Low
0
2
23
38
14
21
0
1
1
100
23
4
36
16
10
0
8
3
0
100
cused on retaining small clumps ranging
from 2–3 trees, with larger clumps of up to
10 trees or more. The goal here has been a
limited version of clump retention consistent with the goals of the individuals,
clumps, and openings (ICO) method (Larson and Churchill 2012, Churchill et al.
2013a, 2013b). The ICO method is a prescription development approach that focuses on structure and pattern in terms of
individual trees, clumps, and openings.
Small clumps have typically been designated
for retention with additional individual trees
to meet an average density range (for example, a treatment unit average of 40 – 60
ft2/acre). However, unlike the ICO method,
specific targets such as the proportion of
trees in specific clump sizes have not been
determined. To date, few pretreatment
stands have contained clumps with large
stem counts (ⱖ20 stems/clump) of ponderosa pine with tight spacing and interlocking crowns3; thus, posttreatment variable
488
Journal of Forestry • September 2014
spacing has been somewhat limited. Messenger Gulch 2 (Figure 4) has been the exception. Clumps are designated based on the
closest tree spacing present when the designation of leave clumps with interlocking
crowns is not an option.
USDA Forest Service managers have
experimented with a variety of methods for
implementing variable spacing for the Front
Range Project (Table 3). Tree selection was
implemented in the past via DxP. DxP allows the contractor to select trees to be cut or
retained using outcome-based metrics such
as residual density ranges and distances for
small openings (⬍1 acre), and additional instruction is conveyed through qualitative
criteria such as species preferences, spacing,
tree form, and insect and disease levels. This
method does not incorporate any cut or
leave tree designation in the field unless
demonstration areas are provided. It is the
equivalent of providing a marking guide to a
contractor via contract specifications. DxP
has typically worked well with low-complexity prescriptions composed of one or two residual density ranges, silvicultural methods
such as thinning from below, no openings,
and more homogeneous tree spacing characteristic of traditional fuels treatments. This
method appears to be less effective as prescription complexity has increased, and prescriptions have started incorporating three
or more residual density ranges, large openings, and variable tree spacing.
Leave tree marking has been used to retain clumps in thinning treatments (select
units in Long John and Messenger Gulch 2).
Both leave tree and cut tree methods have
been used to create demonstration areas for
operators and Forest Service marking crews.
Demonstration areas have ranged in size
from 2 to 16 acres. When demonstration
areas are designated for a project, the remaining treatment area is then implemented
via DxP (Phantom Creek 1, Unit 2, Phantom Creek 2 and 3, and Long John). These
methods are applied to the mechanized
treatment areas only. Manual and mastication treatments are less complex and are still
implemented via DxP. The standard prescription for manual and mastication treatments is thin from below in the small size
classes only (⬍10 in. dbh) because of contract limitations.4
Variable Residual Density and Forest
Type
Another factor that has contributed to
increased prescription complexity is greater
forest type variation in restoration project
areas. Early treatments for the Front Range
Project focused on ponderosa pine-domi-
Figure 4. Residual individual trees, variable spacing (left) and residual group (right), Messenger Gulch 2 project. Photos were taken
approximately 2 months after implementation.
Table 3. Description of projects implemented on the Pike National Forest under the Front Range CFLRP, including the project size,
implementation year, and prescription details.
Project1
Year2
Method3
Acres
Prescription density
Phantom Creek 1
Phantom Creek 2
10
11
Phantom Creek 3
Ryan Quinlan
Phantom Creek 4
Long John
11
11
12
12
Mech
Mech
Man
Mech
Mech
Man, Mast
Mech
597
761
110
656
356
507
304
40–60
40–80
60–80
40–80
0–80
40–80
40–60
Catamount 1
12
Messenger Gulch 2
13
Mech
Man
Mech
Man
226
125
263
162
0–120
40–80
40–60
30–50
Openings
X
X
Tree designation
DxP with leave tree marking sample mark (2 acres)
DxP
DxP
DxP
Cut tree marking (saw), DxP (nonsaw)
DxP
Leave tree marking, sample mark on 32 acres for
marking crews
DxP, cut tree marking (openings)
DxP
Leave tree marking
DxP
1
Projects are listed in chronological order by contract award year.
Year: contract award year.
Method: Mech, mechanical ground-based logging; Man, manual chain saw work or mastication (Mast).
2
3
nated areas. Recent activity is located in the
transition zone between the lower and upper
montane ecological zones (8,500 –9,500 ft).
In response to higher forest type variation
within project areas, prescriptions and marking guides have specified different target densities (live conifer basal area) by type such as
40 – 60 ft2/acre in ponderosa pine-dominated
stands, 60 – 80 ft2/acre in dry mixed-conifer
stands, 80 –100 ft2/acre in moist mixed-conifer stands, and 0 – 40 ft2/acre within and adjacent to aspen stands. These aspen stands have a
wider range of specified target densities because of the high level of variability that results
from the removal of conifers both within and
adjacent to these stands. Legacy trees (⬎200
years old) and conifers that would be operationally challenging to remove are retained
with aspen.
Opening Creation
Until recently USDA Forest Service
managers on the Pike National Forest have
not had the ability to incorporate large
Journal of Forestry • September 2014
489
Figure 5. Pretreatment (left) and posttreatment (right) (NAIP) comparison, aerial imagery analysis, Catamount 1 project (mechanized).
Openings were created via cut tree marking. These groups (up to 5 acres) were located to remove Douglas-fir and spruce, stimulate aspen
regeneration, and regenerate ponderosa pine. Posttreatment photos were taken approximately 1 year after implementation.
openings into prescriptions because preexisting forest policies limited low residual
densities. In 2012, the Forest began incorporating patch cuts up to 5 acres in size at a
scale of 20 –25% of the overall treatment
footprint for the Catamount 1 project (Figure 5). These openings were designated with
cut tree marking. Openings were located in
dry mixed-conifer types to encourage ponderosa pine regeneration, stimulate aspen
sprouting, and reduce the density of Douglas-fir. DxP was not considered an appropriate implementation method for this type of
treatment because of the difficulty of conveying clear instructions to the operator regarding opening location criteria, size,
shape, and pattern.
General Prescription Marking
Guidelines
Most prescriptions specify wide density ranges at the plot level such as
10 –100 ft2/acre to increase posttreatment
heterogeneity. Compliance with this guideline can be easily assessed by marking crews,
sale administrators, and operators with
quick point sampling with a prism (sighting
490
Journal of Forestry • September 2014
angle). In addition, small patch cuts are frequently installed around the perimeter of aspen clones. The size of these cuts is often
based on distance criteria such as the 1 1/2–2
times the average height of dominant conifers on site (75–120 ft).
Furthermore, legacy trees (⬎200 years
old) are also retained throughout treatment
areas as much as is feasible. This guideline is
implemented via ocular assessment of the
tree’s morphological characteristics such as
bark texture and color, branch diameters,
and crown shape (Huckaby et al. 2003a,
2003b). The identification of these legacy
trees has worked well with ponderosa pine
but is more difficult to apply to other species
such as Douglas-fir and spruce.
Monitoring Methods
The CFLRP requires multiparty monitoring of restoration activities. Given the uncertainties regarding treatment outcomes,
this monitoring informs the collaborative of
progress and provides opportunities to improve treatments over time. Specifically, the
Front Range Roundtable monitors both the
ecological and socioeconomic outcomes of
the Front Range CFLRP with the assistance
of the Colorado Forest Restoration Institute
(CFRI).5 In addition to this collaborative
monitoring, USDA Forest Service personnel
also monitor active treatments and collect
data to ensure that all contractual obligations are met.
The Front Range Roundtable has
found the writing of the monitoring plan
challenging, and the plan itself is still evolving. Part of this challenge has been reaching consensus on the specific desired future conditions of these forests. Although
there is consensus regarding the desirable
trends for treatment, the collaborative is
still developing the specific evaluation criteria. Meanwhile, monitoring is underway, following an initial monitoring plan
(Clements and Brown 2011). Under the
current monitoring plan, treatments will
be successful if they achieve the following
trends: (1) decreased basal area and trees
per acre; (2) increased quadratic mean diameter; (3) increased ratio of ponderosa
pine to other conifers; (4) increased ratios
Figure 6. Pretreatment (left; NAIP) and posttreatment (right; other USDA Forest Service imagery) comparison, aerial imagery analysis, Ryan
Quinlan project. Posttreatment photos were taken approximately 6 months after implementation.
of old trees (⬎200 years) to transitional
trees (150 –200 years) to younger trees
(⬍150 years); (5) decreased litter and duff
depths; (6) decreased or similar coarse
woody debris; and (7) reduced crown fire
potential at 90% weather as modeled in a
fire behavior model.
Forest inventory data are collected by
contractors using the USDA Forest Service
Common Stand Exam (CSE) protocol analyzed by CFRI, and results are reported to
the Front Range Roundtable. Pretreatment,
posttreatment, and 5–10 years posttreatment tree density, regeneration densities,
basal area, species composition, average tree
size, and surface fuels are measured in permanent plots. Permanent photo points have
also been established at each plot, documenting any visual changes.
The Front Range Roundtable is also developing methods to monitor within-stand
forest heterogeneity, landscape-scale forest
heterogeneity, wildlife values, and understory plant communities, including the
abundance of invasive species. Regarding
heterogeneity, the current monitoring protocol provides comprehensive forest stand
information; however, it does not directly
describe changes to the spatial distribution
of trees within stands nor the distribution of
forest stands across the landscape. The Front
Range Roundtable is currently testing methods for monitoring the within-stand distribution of trees by identifying patches of forest canopy in National Aerial Imagery
Program (NAIP) photographs using multispectral image analysis (Figures 5 and 6).
The size and spatial distribution of these
canopy patches are then compared pre- and
posttreatment using FRAGSTATS (McGarigal et al. 2012). Similarly, methods are
being developed for monitoring the distribution of forest canopies within HUC-12
watersheds using LANDSAT data.
CFRI is monitoring the economic
contribution of restoration activities and
the utilization of harvested wood products
annually. CFRI is also monitoring the
level of collaboration, communication,
and group learning periodically through
interviews with Front Range Roundtable
members.
Project Results
To date pre- and posttreatment CSE
data has been collected and assessed for
trends in three areas: basal area and trees per
acre; quadratic mean diameter; and ratio of
ponderosa pine to other conifers. These results are discussed in the context of desirable
trends only. Preliminary results for withinstand and project scale forest heterogeneity
are also available.
Generally, the treatments have successfully reduced the amount of overstory vegetation and broken up the continuity of the
canopy as desired. Consistent with the desired trends, all the treatments reduced the
live basal area by 42% on average (Table 1).
In Phantom Creek, basal area decreased by
an average 32% (28 ft2/acre), trees per acre
decreased by 46% (79 trees/acre, trees ⱖ5.0
in. dbh), and the mean tree diameter (qua-
dratic mean diameter) increased from 9.9 to
11 in. dbh (Young et al. 2013).
The treatments also increased the prevalence of ponderosa pine, as measured by the
mean proportion of ponderosa pine basal
area, by 7.9%. Although this increase was
consistent with desired trends, it was lower
than anticipated. A greater increase in ponderosa pine may not have been possible
without more intense regeneration treatments, such as clearcutting, seed tree, shelterwood, and selection methods, located to
remove Douglas-fir and spruce and stimulate the regeneration of ponderosa pine. This
is a long-term scenario requiring recurring
stand treatments and decades of stand development. Broadcast burning is under consideration for follow-up treatments to maintain
desired conditions.
Monitoring canopy cover and heterogeneity using aerial imagery confirmed that,
consistent with the desired trends, conifer
canopy cover decreased by 14.2%, and the
average size of a contiguous patch of canopy
declined from 6,098 to 435 ft2 (Phantom
Creek 1 and Ryan Quinlan) (Table 4). The
percentage of the treatment area occupied by
the single largest patch (largest patch index)
also decreased from 27.5 to 1.0% as desired.
In addition, the Euclidean distance between
patches increased by 2.2 ft on average.
The treatments also increased the range
of distances between the nearest neighboring canopy patches by 21.9 ft (Table 4). This
increased distance between canopy patches
and increased range in interpatch distances
reflects the creation of heterogeneous canJournal of Forestry • September 2014
491
Table 4. Summary of pretreatment and posttreatment aerial imagery analysis.
Timing of
data
Project
Phantom Creek 1
Ryan Quinlan
Phantom Creek 2
Phantom Creek 3
Phantom Creek 4
Pre
Post
Pre
Post
Pre
Pre
Pre
Average canopy
patch size
Range of patch
size
. . . . . . . . . . . (%) . . . . . . . . . . .
9,583
6.4 ⫻ 106
435
1.8 ⫻ 105
871
6.4 ⫻ 104
435
7,840
6,969
3.2 ⫻ 106
1,472
7.9 ⫻ 105
10,890
2.9 ⫻ 106
Largest patch
index (%)
45.6
1.6
3.0
0.5
29.9
2.7
56.2
Euclidean distance
to nearest
neighbor
Range of Euclidean
distance to nearest
neighbor
. . . . . . . . . . . . . . (ft) . . . . . . . . . . . . . .
16.7
21.5
17.4
33.0
18.0
28.2
21.2
67.6
17.2
28.2
16.7
44.3
16.7
19.7
Pre, pretreatment; post, posttreatment.
opy gaps as desired. However, counter to the
desired trends, the range of canopy patch
sizes declined by 2.6 ⫻ 106 ft2, indicating
that treatments created a more homogeneous distribution of canopy patches with
the breakup of large contiguous canopy
patches into many similar-sized small canopy patches.
As expected, the manual treatments retained higher than average residual basal areas due to the contractual limitations for upper treatment diameters (Phantom Creek 2,
Phantom Creek 4, and Catamount 1).
Phantom Creek 2 appears to have been the
only manual treatment to date that resulted
in a measurable increase in ponderosa pine
in the residual stand.
The implementation of variable density
prescriptions for the mechanized treatments
in mixed-species projects (Phantom Creek 2
and Catamount 1) resulted in a greater range
of residual densities (32–107 and 27–130
ft2/acre, respectively) than projects dominated by a single forest type that were treated
to a single target range such as Messenger
Gulch 2 (37– 46 ft2/acre) (Table 1). Incorporating larger openings (up to 5 acres) into
these variable density prescriptions, as was
done with Catamount 1, may have resulted
in the highest level of posttreatment structural variability to date. These projects were
also more complex and more challenging to
implement.
A socioeconomic analysis conducted by
the Front Range Roundtable estimated that
restoration activities contributed approximately $1,245,116 (2010 US dollars) in labor income6 and $764,509 (2010 US dollars) in value-added7 (i.e., gross domestic
product [GDP]) contributions to the local
economy in 2012 (K. Mattor and T. Lund
Snee, Colorado State University, pers.
comm., Nov. 22, 2013). In addition, a total
of 26 full- and part-time jobs were created.
492
Journal of Forestry • September 2014
Between 2010 and 2013, a variety of wood
products were produced from the material
removed from the Pike National Forest, including dimensional lumber, posts and
poles, and landscaping materials (K. Mattor
and T. Lund Snee, Colorado State University, pers. comm., Nov. 22, 2013). In 2012,
a large portion (23%) of the material removed from the forest was used to produce
wood shreds for postfire rehabilitation efforts (K. Mattor and T. Lund Snee, Colorado State University, pers. comm., Nov.
22, 2013) (Table 2).
Interviews with Front Range Roundtable members identified high levels of trust
and a strong commitment to work together,
which was attributed to open and frequent
communication among the partners. Although some collaborative members raised
concerns regarding the uncertain roles,
responsibilities, and processes, they were
largely optimistic about the CFLRP and the
opportunity to work collaboratively. Since
these interviews, collaborative leaders have
worked hard to clarify the roles and responsibilities of members in the Front Range
Project and collaborative processes.
Conclusions and Future
Directions
The silvicultural practices of the Front
Range Project are becoming increasingly complex as we transition from thinning from below fuels reduction treatments to restoration
treatments that create a much wider range of
residual densities. Future silvicultural practices
are likely to resemble a free selection system
(Graham et al. 2007) that integrates elements
from both even-aged and uneven-aged silviculture to create and maintain forests that are
heterogeneous in both composition and structure. Prescriptions that incorporate variable
tree spacing with small interspatial openings,
variable residual densities, and a wide range of
openings (from 1 acre up to 40 acres) are expected to increase forest heterogeneity at a variety of scales.
The trend of increasing forest type variability within project areas is expected to
continue as future project areas are designated at higher elevations. Project areas will
also include a higher percentage of steeper
terrain and greater aspect variation than earlier projects. Future variable residual density
prescriptions are expected to be applied not
only by forest type but also within the same
forest type at the stand level, resulting in
even greater project and landscape forest
heterogeneity.
We are currently experimenting with bxdifferent implementation methods. Ultimately, we hope to return to implementation
by DxP for the majority of the treatments because DxP is more efficient; however, this will
require highly skilled operators. Furthermore,
a larger set of demonstration areas implemented via tree marking, and the development
of a photo series field guide will help facilitate
the transition back to DxP.
Finally, opening creation will continue
to be challenging. A higher level of openings
(25– 40% of the treatment footprint) is currently under consideration by the Front
Range Roundtable. This will further increase forest heterogeneity at the project and
landscape scales (ⱖ100 acres). Future openings are expected to continue to be designated with a marking method, either tree
selection or via treatment unit boundary delineation, because of the complexity inherent in describing and implementing this prescription component.
Endnotes
1. For more information on the Front Ridge
Roundtable, see www.frontrangeroundtable.
org.
2. No product utilization occurs. All treated material is processed by hand piling, lop and scatter, or chipping.
3. Tree clumps with interlocking crowns are desirable as nesting and feeding trees for Abert’s
squirrels (Sciurus aberti).
4. Upper diameter limits for manual work and
mastication for the Integrated Resource Service Contract are 9.9 in. dbh for ponderosa
pine, 8.9 in. dbh for Douglas-fir and spruce
spp., and 6.9 in. dbh for lodgepole pine.
These limits were based solely on utilization
specifications.
5. For more information on CFRI, see www.
coloradoforestrestoration.org.
6. These contributions to the local economy
were stimulated by the contractors’ operation
expenditures as well as labor income. Labor
income includes all forms of employment income (wages, benefits, and proprietor income).
7. The value-added contributions consist of (1)
employee compensation—wages and salaries
plus benefits paid by local industries; (2) proprietor income—income from self-employment; (3) other property income— corporate
income, rental income, interest, and corporate
transfer payments; and (4) indirect business
taxes—sales, excise, fees, licenses, and other
taxes paid, including nonincome based payments to the government.
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