THE HEALTH OF COLORADO'S FORESTS - 2018 REPORT ON - PROTECTING - Colorado State ...
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2018 REPORT ON
THE HEALTH OF
COLORADO’S FORESTS
SPECIAL SECTION:
PROTECTING
OUR COMMUNITIES
Director’s Message
December 2018
settings. We demonstrate how our efforts successful in our efforts, we also need to
can also protect property, infrastructure, work together. The CSFS can best achieve
water supplies, and even forests and its mission by working with landowners and
trees themselves, to ensure the benefits communities and through collaborations
they provide. with our many partners, including the U.S.
There are significant economic and health Forest Service, Colorado Division of Fire
implications to utilizing forest management Prevention and Control, water providers,
to protect our communities, and Coloradans local governments and many other federal,
in general. We all suffer when tourism, air state and local partners.
and water quality, wildlife habitat and other I hope you find the information contained
values are negatively impacted by poor forest in this year’s report useful, so you can
health and wildfires. Record-breaking fires or effectively participate in conversations with
Michael B. Lester, State Forester insect outbreaks drive away tourists, fill the others regarding the health, management and
and Director. Photo: Ryan air for weeks with noxious smoke and impact future of our forests. We are your Colorado
Lockwood, CSFS other values. The economic implications of State Forest Service and our staff are available
unhealthy forests also are very real. The State to assist you in your efforts.
I
of Colorado alone spent an estimated $40 The management activities we perform
t’s been another year of large wildfires in million for fire suppression efforts in 2018 – in the coming decades will have profound
the West, and in Colorado. What does and this figure does not include what federal consequences for Colorado’s forests, and the
this mean for the future of our state and and other agencies spent, nor add in vastly communities within them, for generations
the forests that sustain our way of life? When greater financial impacts due to property to come.
we think about community protection, the losses, reduced tourism and potential future
first people who may come to mind are damage to water supplies and infrastructure.
the dedicated firefighters, police officers Of note is that these suppression figures
and other emergency services personnel also far exceed what was spent in 2018 on Michael B. Lester
who are always there when we need them. proactive forest management work across State Forester and Director
But foresters and land managers are also Colorado, including to reduce wildfire risk. Colorado State Forest Service
ensuring our protection – by addressing In addition to our special focus this
potential disasters before they ever happen. year, as always we offer a snapshot of the
The focus of this year’s report is on the use conditions of our forestlands around the
of forest management actions and programs state. Spruce beetle continues to be the
to protect our communities. Just as building most destructive insect impacting our forest Table of Contents
a levee far in advance of a storm can help resources, and for the seventh year in a row
Executive Summary............................................ 2
protect a neighborhood from flooding years an outbreak of roundheaded pine beetle
later, proactive forest management work has continues to expand in southwest Colorado. Statewide Insect and Disease Update........... 4
very real implications when a catastrophic Proactive forest management treatments Special Section: Protecting Our
event occurs. By constantly working to continue to be utilized to address insect Communities..................................................... 13
reduce future risks from wildfire, insects and and disease threats, as well as wildfires and Managing Forests, Protecting
other concerns, we have the opportunity to other threats. Communities Requires a Team Effort......... 21
proactively enhance public health and safety. We all need to remember that healthy
Citing examples from 2018, we address forests are not free. We need to invest in
the protection of human life from dangers forest management, fuels mitigation and On the cover: The Buffalo Fire burning
such as catastrophic wildfire and hazard our forest products industry to help protect near Silverthorne, Colo., June 2018. Photo:
trees prone to coming down in community ourselves and our resources. And to be Andrew Bottomley
The Role of the Colorado State Forest Service
Forester Kelsey Lesniak (second from left) and Supervisory CSFS foresters use various tools to gather data on forest
Forester Jodi Rist (right), CSFS Southwest Area, provide a tour of inventory, such as this wedge prism that helps to estimate
a Good Neighbor Authority project in Gunnison County to State timber volume within a given area. Photo: Kelsey Lesniak, CSFS
Rep. Marc Catlin and his wife, Kerri. Photo: Joe Duda, CSFS
The mission of the Colorado State Forest Service (CSFS) is “to trees for conservation purposes. From its headquarters in Fort
achieve stewardship of Colorado’s diverse forest environments Collins, the CSFS offers a statewide reach through 18 field
for the benefit of present and future generations.” Each year, offices and more than 100 full-time staff.
the CSFS assists thousands of landowners and hundreds CSFS funding sources are diverse, with approximately 40
of communities throughout the state. The agency offers percent of its budget coming from the U.S. Forest Service; the
leadership, resources and guidance to accomplish forest state supporting another 30 percent; and the remainder being
management; wildfire mitigation and community planning; self-generated or other revenues, or coming from severance
wood utilization and marketing; outreach and education; and taxes. Without this range of funding, the agency’s broad annual
insect and disease detection, surveys and response. accomplishments would not be possible.
As a service and outreach agency of the Warner College of Starting in January 2018, the agency underwent an
Natural Resources at Colorado State University, the CSFS also organizational restructure designed to best translate its Five-
fulfills the responsibilities of the Division of Forestry within the Year Strategic Plan into focused actions; prioritize work to
Colorado Department of Natural Resources. For more than 60 increase impact; create a more integrated agency; and better
years, CSFS accomplishments have only been possible through serve Colorado’s citizens. The most significant changes include
strong partnerships and collaborative relationships with a field reorganization into four areas covering the quadrants
landowners, communities, nonprofits, local governments, state of the state, rather than having more numerous districts, and
and federal agencies, and many others. adding a new Science and Data Division to keep current on
As demonstrated in this year’s report, the CSFS provides forestry-related research; best communicate applied forestry
guidance on creating effective fuelbreaks and other forest science and data needs both internally and externally; and
management treatments that reduce wildfire risk and help ensure that management actions taken are science and data-
protect people, property and water supplies. The agency also driven. The agency remains committed to providing timely,
offers professional forestry services in urban and community relevant forestry information and education to the citizens of
settings, and serves as Colorado’s primary provider of seedling Colorado to achieve resilient forests and communities.
PROTECTING OUR COMMUNITIES 1
Executive Summary
A
nnual reports on the health of For the seventh consecutive year,
Colorado’s forests summarize Colorado’s most widespread and destructive
the current health and condition forest insect pest was the spruce beetle.
of forests across the state. The primary This insect has now affected more than 1.8
measures for assessing broad forest health million cumulative acres since 2000, with a
conditions are the severity and scope of total of 178,000 acres of active infestations
insect and disease issues impacting forest occurring in high-elevation Engelmann
ecosystems. For this reason, the backbone spruce forests in 2018. A four-year trend
of this report offers a detailed summary of of tens of thousands of new acres being
2018 insect and disease activity in Colorado. infested annually indicates a continuing
This year’s report also offers a special focus spread of spruce beetle into previously
on how the Colorado State Forest Service uninfested forests.
(CSFS), working with key partners, is able Another native bark beetle – roundhead-
to help protect communities from wildfires ed pine beetle, along with closely associated
and other threats, through the use of bark beetles – continues to affect ponderosa
forest management. pine forests in Dolores County, with 27,000
Colorado’s 24.4 million acres of acres impacted in 2018. Impacts from this
forestland provide immeasurable social, “bark beetle complex” have significantly
economic and ecological benefits. These increased since 2012. For the past several
forests offer a sustainable wood products years, Douglas-fir beetle also has continued
industry, diverse wildlife, fresh water and to attack and kill mature Douglas-fir trees
ample recreation opportunities. But they in the central and southern portions of
face numerous threats, and can present the state. In 2018, approximately 14,000
risks to both residents and visitors. As total acres were impacted statewide, with
a service and outreach agency of the Gunnison, Hinsdale and Saguache counties
Warner College of Natural Resources heavily affected. Though less destructive than
at Colorado State University, the CSFS these bark beetles, western spruce budworm
works with partners, communities and defoliated 131,000 acres of spruce and fir,
landowners to address these threats and primarily in central and southwest Colorado,
achieve stewardship of Colorado’s forests. in 2018. Western balsam bark beetle and
Every year, the CSFS assists thousands of associated root disease fungi also persisted
landowners and hundreds of communities throughout Colorado’s spruce-fir forests.
throughout the state, providing leadership, In addition to insect impacts in to life and property. The 2018 fire season
resources and guidance to accomplish forest Colorado’s native forests, introduced exotic saw more acres burned in Colorado than
management; wildfire mitigation; wood pests continued to impact trees in urban any other year except 2002. Many of these
utilization and marketing; outreach and and community areas. The CSFS and its burned acres were within the wildland-
education; and insect and disease detection partners are working to slow the spread and urban interface (WUI) – any area where
and response. mitigate impacts of the highly destructive human improvements are built close to,
A key aspect of forest management is emerald ash borer (EAB), which has caused or within, natural terrain and flammable
the regular monitoring for damage caused billions of dollars in damage in North vegetation. The historic wildfire season was
by forest pests. In Colorado, the primary America. Although this pest still has not due to factors that include overly dense
source of information on forest insect and been detected outside of Boulder County, and unhealthy forest conditions; ongoing
disease conditions is an annual aerial forest new EAB detections in 2018 occurred in drought; and increasingly warmer weather
health survey conducted by the CSFS and the communities of Lyons and Superior. linked to climate change. A recent update to
U.S. Forest Service (USFS), Rocky Mountain Infestations from another significant the CSFS-administered Colorado Wildfire
Region. This year’s survey was conducted community forest pest – Japanese beetle – Risk Assessment Portal (CO-WRAP)
as Colorado was experiencing the warmest were at the highest levels ever reported in indicated that the population living in areas
annual temperatures on record, and also Colorado, primarily impacting Boulder, at risk to wildland fire in Colorado increased
historically low precipitation levels. These Denver and Pueblo. approximately 50 percent from 2012 to 2017,
dramatic climatic deviations played a Besides damage from insects and disease, surpassing 2.9 million people.
powerful role in shaping forest insect and destructive wildfires represent an ever- In 2018, several wildfire incidents
disease activity in 2018. present threat to Colorado’s forests, and also demonstrated the effectiveness of the
2 2018 REPORT ON THE HEALTH OF COLORADO’S FORESTS
CSFS Northwest Area Manager Ron
Cousineau describes the value of
interagency fuels mitigation work to
reduce wildfire risk, utilized by firefighters
on the Buffalo Fire (pictured on the cover),
in an August 2018 tour for U.S. Sen.
Michael Bennet. Photo: U.S. Forest Service
they eventually fail, putting neighborhood
residents at risk. One of the key steps to
protecting community trees, and those
who benefit from them, is conducting a
tree inventory. Inventories, including those
completed by CSFS staff, help city foresters
and others determine which trees pose
potential risks to people and property.
Agencies including the CSFS, USFS and
Bureau of Land Management are largely
responsible for addressing forest health
and wildfire risk at a larger scale, but these
agencies cannot be successful working
alone. Besides joining together to address
cross-boundary concerns through use of
the Good Neighbor Authority – a program
utilized for a 2018 project near Steamboat
Springs featured in this report – they rely
on the insights and assistance of numerous
other partners, from water providers and
local governments to other state and federal
agencies, local fire protection districts, the
wood products industry and nonprofits.
CSFS’s broader efforts to reduce wildfire life or destruction of property. Homeowners and communities also must
risk to communities. Two wildfires burning Two communities in southern Colorado, take steps to reduce wildfire risk to help
toward Colorado subdivisions provided also impacted by the 2018 fires, benefited protect life and property, and provide safer
a perfect example of how proactive from prior engagement with the CSFS conditions for firefighters during a wildfire.
forest management can work in tandem in the form of becoming Firewise USA® The CSFS works closely with landowners
with suppression efforts to minimize communities, and working together to and communities around the state to not only
the impacts of fire. Firefighters made take action to reduce wildfire risk. Work provide resources and assistance, but also
clear that a key reason they were able to completed by a neighborhood northwest to determine needs and concerns to better
protect communities in Grand Lake and of Durango paid off during the 416 Fire, inform broader forest management priorities.
Silverthorne from these fires was prior when the incident management team took Also guiding CSFS efforts is Colorado’s Forest
mitigation work by the CSFS and partners, advantage of prior efforts to make structures Health Advisory Council, created in 2016 to
which include the U.S. Forest Service more defensible. And another Firewise advise the state forester on how to effectively
(USFS), Denver Water, Northern Colorado USA community in the Sangre de Cristo respond to forest health challenges.
Water and Grand and Summit counties. Mountains, though not as fortunate in the The Colorado General Assembly and
Fire management teams halted the progress face of the massive 108,000-acre Spring other decision-makers likewise play a key
of the Buffalo and Golf Course fires in Creek Fire, likely lost fewer homes than it role in enabling forest managers to have the
fuelbreaks where vegetation had previously could have if the community had not taken greatest positive impacts toward the health
been thinned or removed to alter fire steps to help protect homes. of Colorado forests, and the protection of
behavior and make fires less intense. As a Trees in urban and community forests its communities.
result, these fires did not result in the loss of present a different sort of threat when
PROTECTING OUR COMMUNITIES 3
Statewide Insect and Disease Update
F Highlights for 2018
orest insects and diseases are primary enough sap to resist insects attempting to
natural drivers in the dynamics of According to the National Oceanic and enter through the bark.
forest ecology. A primary example Atmospheric Administration, Colorado The warmer temperatures and drought
in Colorado is tree-killing bark beetles. experienced the warmest annual conditions in 2018 thus played a powerful
During outbreaks, these beetles attack trees temperatures on record (spanning the last role in shaping forest insect and disease
in mature, often overly dense forests, setting 124 years) during the water year of October activity in the state, which included the
the stage for the replacement of older, less 2017 through September 2018. During that following impacts:
healthy trees with younger, more vigorous same period, precipitation levels statewide • For the seventh consecutive year,
ones. These outbreaks, on the other hand, plummeted to the second driest on record, Colorado’s most widespread and
also can affect many of the values that dating back to 1895. The southwest quadrant destructive forest insect pest was the
humans place on forests, including timber of the state was the warmest and driest spruce beetle. This insect has now affected
production, wildlife habitat, recreation and region, while precipitation in the northeast more than 1.8 million cumulative acres
watershed protection. quadrant of the state was near average. The since 2000, or approximately 40 percent
A key part of forest management is the Western Slope saw a record number of days of the state's spruce-fir forests. A total
regular monitoring for damage caused by with highs exceeding 90 degrees F, and of 178,000 acres of active infestations
forest pests. In Colorado, the primary source record-low precipitation values. occurred in high-elevation Engelmann
of information on forest pest conditions is an These dramatic shifts in annual spruce forests throughout the state in
annual aerial forest health survey. This is a temperature and precipitation levels have 2018. Of those, a total of 59,000 new, or
cooperative program that involves specialists real implications for forest insect and previously uninfested, acres were affected.
from the U.S. Forest Service (USFS), Rocky disease activity. Forest disturbance from An ongoing four-year trend of a high
Mountain Region and the Colorado State epidemic bark beetle populations tracks number of newly infested acres indicates
Forest Service (CSFS). Trained aerial closely with long-term precipitation a continuing spread of spruce beetle into
observers from both agencies fly over the levels and temperature patterns. Warmer previously uninfested forests. Susceptible
majority of the state’s 24.4 million acres of temperatures during the winter months Engelmann spruce forests exist in the
native forests in small aircraft, to map and also reduce over-winter beetle and larvae northern and central portions of the
classify the intensity of the current year’s mortality, while lower than average state, indicating that this insect has the
damage. When necessary, some areas flown precipitation may reduce one important potential to affect more new areas in the
also are ground-checked to verify the agent line of tree defense: the ability to produce upcoming year.
(i.e., insect) responsible for the damage and/
or the severity of damage.
Another important source of
information for this report is field visits
made by CSFS foresters. These experts
identify and assess forest pest activity, while
advising private landowners – who together
own 30 percent of the state’s forests – on
how to best manage their forests. CSFS
foresters also are directly responsible for
management of state-owned forestlands,
including State Trust Lands, and for
conducting statewide forest inventories.
Additionally, in cooperation with other
agencies such as the Colorado Department
of Agriculture, USDA Animal and Plant
Health Inspection Service (APHIS) and
USFS, the CSFS is involved in the design
and implementation of special surveys
to ensure early detection of exotic insect
species that threaten both urban and
native forests. Colorado experienced the warmest annual temperatures on record during the water year from
October 2017 through September 2018. Image: Western Regional Climate Center
4 2018 REPORT ON THE HEALTH OF COLORADO’S FORESTS
• Roundheaded pine beetle and associated
native bark beetles continue to affect
more acres of ponderosa pine in Dolores
County, with 27,000 acres impacted in
2018. Although not all acres are intensely
infested, impacts in affected acres have
significantly increased since 2012. Record-
low precipitation values in the county
have weakened tree defenses, providing an
environmental window favoring increased
beetle populations in the coming year.
• For the past several years, Douglas-fir
beetle has continued to attack and kill
mature Douglas-fir trees in the central
and southern portions of the state. In
2018, Gunnison, Hinsdale and Saguache
counties were heavily affected in the
south-central portion of the state, while
Eagle, Mineral and Pitkin counties also
were heavily affected. Approximately
14,000 total acres were impacted
Spruce beetle-caused mortality of high-elevation Engelmann spruce in the San Juan National
statewide, with 11,000 acres being new.
Forest. Photo: Dan West, CSFS
• Western spruce budworm defoliated
131,000 acres of Douglas-fir, white fir and
spruce in central and southern Colorado. • Japanese beetle infestations in Boulder, and fly to seek new host trees from late May
Chaffee, Dolores, Freemont, Gunnison, Denver and Pueblo were at the highest through July, preferring large-diameter trees
Park and Saguache counties experienced levels ever reported in Colorado. Most until these have been depleted from the
heavy and widespread defoliation. Pocket communities from Fort Collins and forest. As the spruce beetle moves through
activity also occurred in many other Greeley south to Pueblo, along the Front contiguous stands of Engelmann spruce, its
southern Colorado counties. Range, are now affected. host type is depleted, which has resulted in
• White fir mortality declined across less actively affected acreage since 2014.
all affected areas, and for the fourth Indigenous Pests In 2018, severe outbreaks continued in
consecutive year, mortality from the fir Conifer Forests portions of the San Juan Mountains, West
engraver beetle declined in and around Spruce Beetle Elk Mountains and Sawatch Range; the
Ouray. Localized activity occurred in (Dendroctonus rufipennis) southern reaches of the Sangre de Cristo
Archuleta County and continues to be Spruce beetle is the most damaging pest of Mountains through the Culebra Range;
at only background levels elsewhere. mature spruce forests in North America, and portions of north-central Colorado
Tree mortality occurred on 1,400 acres and was the most damaging forest pest in west of the Continental Divide, in and
statewide. Colorado for the seventh consecutive year. around Rocky Mountain National Park, in
• Western balsam bark beetle and associated These small, native bark beetles infest the Grand and Larimer counties. Susceptible
root disease fungi persisted throughout state’s high-elevation Engelmann spruce, contiguous Engelmann spruce forests
Colorado’s spruce-fir forests, causing usually above 9,000 feet in elevation, and exist between expanding outbreaks in
tree mortality over 24,000 acres of high- occasionally Colorado blue spruce. They live the northern and central portions of the
elevation subalpine fir. and develop in a thin layer of inner bark, state, indicating that the spruce beetle has
• Emerald ash borer, an exotic pest, still between the thicker sapwood and outer bark. the potential to affect new areas in the
has not been detected outside of Boulder Feeding by developing larvae girdles the tree, upcoming year.
County, where it was first confirmed in causing spruce needles to fade in color from • Spruce beetle has affected 1.84 million
2013. Early detection of this invasive green to light yellow, and eventually to an off cumulative acres in Colorado from 2000
remains challenging, but new detections reddish-brown color. to 2018.
in 2018 occurred in the communities of Spruce beetles typically produce another • Although some acres are more intensely
Lyons and Superior. generation within two years. Adults emerge affected than others, approximately 40
PROTECTING OUR COMMUNITIES 5
• Counties affected by the most cumulative • 2018 saw the lowest acreage impacted by
acres through 2018: mountain pine beetle statewide in two
1996-2018 decades.
Colorado 2017 Acres 2018 Acres
County Affected Affected
Cumulative • Notable counties with mountain pine
Acres Affected
Hinsdale 22,000 19,000 275,000 beetle-caused mortality in 2018:
Mineral 590 1,400 236,000
1996-2018
Saguache 18,000 4,400 217,000 Colorado 2017 Acres 2018 Acres
Cumulative
Gunnison 40,000 20,000 140,000 County Affected Affected
Acres Affected
Conejos 18,000 19,000 104,000 Saguache 100 180 43,000
Rio Grande 18,000 9,900 95,000 Jefferson 90 140 36,000
For data on all counties, go to: Custer 50 70 36,000
csfs.colostate.edu/forest-insects-diseases
Roundheaded Pine Beetle
Mountain Pine Beetle (Dendroctonus adjunctus)
(Dendroctonus ponderosae) The roundheaded pine beetle is also native
Another native bark beetle, mountain pine to Colorado, being a bark beetle closely
beetle, infests all pine species naturally related to mountain pine beetle, spruce
found in Colorado. Populations reproduce beetle and Douglas-fir beetle. The range
once every year, requiring new, live trees to of this bark beetle extends north into
complete development. Adults fly to green Colorado from as far south as Guatemala;
trees typically from late June into early southern Colorado is the northernmost
August in Colorado. extent of its range. Ponderosa pine is
Aside from localized spot activity, the only primary host tree species in the
populations remain at endemic – or United States, though other pine species
background – levels statewide. Infestations are attacked throughout Mexico and into
in ponderosa, limber and bristlecone pines Central America.
continued at low levels in the northern In Colorado, trees are attacked later in the
Boring dust on a downed Engelmann spruce and central Sangre de Cristo Mountains. year than with other Colorado bark beetles,
tree on the Alpine Plateau, Gunnison County.
Localized spot activity occurred throughout from late August through November. With
The dust results from spruce beetles entering
the Front Range, impacting ponderosa only one generation flying per year, these
the tree. Photo: Kelsey Lesniak, CSFS
and lodgepole pines, although other native beetles attack a wide range of tree sizes and
bark beetles in the Ips genus may also have ages, typically after a prolonged drought
percent of the state’s spruce-fir forest contributed to some localized impacts. period. Outbreaks south of Colorado’s border
ecosystems have been affected since 2000. • Less than 500 acres of native pine forests are typically short in duration, though
• 178,000 actively affected acres of were affected in 2018. contiguous ponderosa pine forests in Dolores
Engelmann spruce forest were observed
in 2018, compared with 206,000 acres in
2017. Forested Acreage Affected by Spruce Beetle in Colorado, 2000-2018
• 59,000 “new,” or previously uninfested,
acres were detected statewide in 2018,
compared to 67,000 new acres in 2017. 600
• Infestations intensified in 2018 in Rocky
Mountain National Park and in the 500
Sawatch Range, Culebra Mountains and
Thousands of acres
400
San Juan Mountains.
• Notable counties affected by new acres in
300
2018:
1996-2018
Previously 200
Colorado 2017 Acres 2018 Acres Cumulative
Uninfested
County Affected Affected Acres
Acres
Affected
Costilla 4,800 8,900 16,000 6,300 100
Park 5,300 8,700 13,000 6,100
Gunnison 40,000 20,000 140,000 6,000
0
La Plata 9,200 13,000 41,000 6,000
2000
2005
2006
2009
2002
2008
2003
2004
2007
2001
2010
2015
2016
2012
2018
2013
2014
2017
2011
Larimer 9,500 18,000 92,000 5,000
Grand 5,800 17,000 70,000 5,000
Hinsdale 22,000 19,000 275,000 3,000
6 2018 REPORT ON THE HEALTH OF COLORADO’S FORESTS
County have sustained increased mortality an important native bark beetle of mature 1996-2018
Previously
Colorado 2017 Acres 2018 Acres Cumulative
for the seventh consecutive year. Douglas-fir forests across most of the West. County Affected Affected Acres
Uninfested
Acres
Roundheaded pine bark beetles are often Outbreaks tend to be associated with overly Affected
Saguache 2,500 2,700 42,000 2,700
associated with several other species of bark dense forests containing mature Douglas-fir, Gunnison 1,900 2,600 37,000 2,600
beetles, typically western pine beetle (D. during extended periods of below-normal Hinsdale 1,100 1,800 16,000 1,000
Eagle 500 1,500 12,000 1,000
brevicomis), pine engraver beetles (Ips spp.) precipitation. Adults typically seek new trees Pitkin 590 1,400 13,000 1,000
and mountain pine beetle (D. ponderosae). to attack from May through September.
These associated bark beetles, working in Widespread groupings of tree mortality
Western Balsam Bark Beetle/
conjunction with one another, produce a occurred in 2018, in portions of the northern
Root Disease Complex
“bark beetle complex” that results in tree Sawatch Range near the community of
Disturbance caused by western balsam bark
injury and death. Carbondale; northern areas of the La Garita
beetle (Dryocoetes confusus) and several
Approximately 27,000 acres were affected Mountains, south of the community of
species of fungi that cause root decay has
in 2018, compared to 11,000 acres in 2017, as Gunnison; the Needle Mountains near Lake
remained persistent for many years now,
the infestation intensified in Dolores County. City; and the San Miguel River drainage
in Colorado’s high-elevation subalpine fir.
However, many of those acres were of low around the community of Telluride in the
Actively affected acres from western balsam
intensity, where the complex affected only San Juan Mountains.
bark beetle decreased by approximately 50
small groups of trees. • 14,000 acres of forests comprising
percent in 2018. This is not highly significant,
Douglas-fir were impacted in 2018.
Douglas-fir Beetle however, as the area affected may vary from
• 11,000 new, previously uninfested acres of
(Dendroctonus pseudotsugae) year to year, though is typically relatively
Douglas-fir were impacted statewide.
Douglas-fir beetle, another close relative of low in intensity in the absence of localized
• Notable counties with the most newly
spruce beetle and mountain pine beetle, is drought conditions.
infested acres in 2018:
A grouping of ponderosa pines killed by roundheaded pine beetle/associated native bark beetles in San Juan National Forest, Dolores County.
Photo: Dan West, CSFS
PROTECTING OUR COMMUNITIES 7
Several areas of significant damage Intensity of Roundheaded Pine Beetle/Bark Beetle Complex, 2018
occurred in the Flat Tops Wilderness and
Mount Zirkel Wilderness near Steamboat
Springs; the Sawatch Range near the town of
Aspen; and along the northern portion of the
Front Range in 2018.
• 24,000 acres of high-elevation, mixed-
conifer forests comprising subalpine fir
were affected in 2018, compared to 50,000
acres in 2017.
• Notable counties affected in 2018:
Colorado County 2017 Acres Affected 2018 Acres Affected
Gunnison 6,400 3,600
Grand 4,400 2,800
Summit 1,900 2,700
Larimer 4,400 2,600
Routt 2,400 2,500
Rio Blanco 2,500 1,900
Fir Engraver Beetle
(Scolytus ventralis)
Fir engraver beetle is a native bark beetle that
primarily impacts white fir, and occasionally
subalpine fir, Douglas-fir and Engelmann
spruce. Outbreaks often are associated with
below-normal precipitation or defoliation.
Adults typically disperse to seek new trees
in which to lay eggs under the bark during a
peak time of July and August. In 2018, tree
mortality continued to decrease statewide,
and occurred in southern and central
Colorado where white fir grows in mixed-
species forests, often alongside Douglas-fir.
• 1,400 acres of white fir in southern
Colorado were affected in 2018, whereas
2,500 acres were impacted in 2017 and Roundheaded pine beetle and associated native bark beetle-caused mortality has increased
exponentially in total area in Dolores County over the past six years.
6,300 acres in 2016.
• Portions of the Sangre de Cristo
Mountains were impacted in localized Roundheaded Pine Beetle and Associated Bark Beetle-Caused
areas in 2018. Mortality in Colorado, 2012-2018
• Archuleta County, within the San Juan 30000
National Forest, continues to see low-level,
localized fir mortality.
Acres Impacted (Aerial Survey Data)
25000
• Infestations near the mountain town of
Ouray declined, but continue to affect the
few remaining white firs in the area, in an 20000
infestation that is ongoing for the sixth
straight year. 15000
• Notable counties affected in 2018:
Colorado County 2017 Acres Affected 2018 Acres Affected 10000
Ouray 1,600 950
Gunnison – 150
Archuleta 400 70
5000
Hinsdale 380 60
0
2012 2013 2014 2015 2016 2017 2018
8 2018 REPORT ON THE HEALTH OF COLORADO’S FORESTSWestern Spruce Budworm • Notable counties affected in 2018:
(Choristoneura freemani) Colorado County 2017 Acres Affected 2018 Acres Affected
Larvae of the western spruce budworm feed Saguache 75,000 30,000
Park 12,000 14,000
in the buds and on new shoots of Douglas-fir, Dolores 5,000 13,000
true firs (Abies spp.) and spruce. Feeding on Freemont 11,000 12,000
the needles causes a reddish-brown color in Gunnison 42,000 11,000
San Miguel 3,900 11,000
the branch tips and terminal ends of affected Chaffee 7,700 7,000
trees. Larval damage occurs from early in the Custer 11,000 5,900
spring through mid-summer, at which time
the insects pupate and emerge as adult moths. Piñon Engraver Beetle
Adults are typically active in July and August. (Ips confusus)
This moth has been Colorado’s most Piñon pines typically grow in harsh, low-
damaging and widespread forest defoliator elevation sites below the mixed-conifer/
for a number of consecutive years. Heavy ponderosa pine forests of Colorado. Piñons
damage occurred in 2018 in most of the often grow in proximity to juniper trees
Douglas-fir forests in the southern portion of and shrubs, where conditions are dry and
the state. precipitation fluctuations are the norm.
• 131,000 acres of Douglas-fir, true firs and During prolonged periods of below-average
spruce were impacted statewide in 2018. precipitation, populations of the piñon
• Significant areas affected included the engraver beetle can build in already-stressed
southern Front Range; the Sawatch Range piñon trees.
and West Elk Wilderness in the central Isolated or localized tree mortality was
portion of Colorado; the Culebra Range in observed in 2018 near the Colorado National
A late-stage caterpillar of the large aspen
the southern Sangre de Cristo Mountains; Monument around Glade Park; and along
tortrix, which is responsible for defoliating
the Mosquito Range and Tarryall the I-70 corridor near Rifle, Carbondale and
aspens in Colorado. Photo: Dan West, CSFS
Mountains surrounding South Park; along Grand Junction. Record-warm temperatures
the southern portions of the Rampart and record-low precipitation along the
Range; and the western edge of the San Western Slope and in the southwest corner of Colorado are likely to produce continued
Juan Mountains. dieback/die-off of piñon pines in these areas
in the coming year.
Deciduous Forests
Defoliating Insects/Leaf
Diseases of Aspen
Two insect species, western tent caterpillar
(Malacosoma californicum) and large aspen
tortrix (Choristoneura conflictana), can
defoliate Colorado’s aspen forests when
at higher population levels. Western tent
caterpillars produce and live within silken
tents, typically in the crowns of affected
aspen and cottonwood trees, although
mountain mahogany, chokecherry and plums
also are occasionally affected. The caterpillars
are typically present in spring, though can be
seen as late as September. Large aspen tortrix
also feed upon the leaves of aspen, and roll
the leaves into shelters in which they pupate.
Adult tortrix are typically present in July and
August.
• 12,000 acres of aspen forests were
defoliated statewide in 2018, compared to
A piñon pine expressing symptoms of attack from piñon engraver beetle, Chaffee County. 38,000 acres the prior year.
Photo: Dan West, CSFS
PROTECTING OUR COMMUNITIES 9fungi (Geosmithia morbida). Most insects have a primary feeding stage,
Black walnut trees continue being either larvae or adults. However, the
to die off along the Front challenge with Japanese beetles is that both
Range and Eastern Plains of larvae and adults cause significant damage to
Colorado. The most recent affected trees or plants. The larvae are white,
new detection occurred in C-shaped grubs that feed underground
2017 in the community of on the roots of grasses. Upon completing
Brush, in Morgan County. their development, adult beetles feed on the
No additional detections foliage and flowers of a wide range of plants.
occurred across the state Foliage damage appears “skeletonized” as the
in 2018. adults typically feed between, but not on, the
structural leaf veins.
Exotic Pests In Colorado, linden, apple, crabapple,
The introduction and cherry, plum and peach trees are most
establishment of exotic – and affected. Grape, Virginia creeper, rose,
potentially invasive – insects, raspberry, hollyhock and Rose of Sharon
fungi, plants and other are plants that are also heavily affected.
organisms threatens forests In 2018, Boulder, Denver and Pueblo had
worldwide. Invasive species high Japanese beetle populations, while the
can cause severe damage remainder of Front Range communities
in their new habitats, as experienced varying degrees of infestation,
unfamiliar host trees may ranging from moderate to low. No new
At a workshop in Montezuma County, Dr. Dan West, CSFS have little or no resistance detections in 2018 occurred north of Fort
forest entomologist, describes to stakeholders and private to the introduced pest, and Collins and Greeley, nor south of Pueblo.
landowners how bark beetles attack and kill ponderosa pines. natural enemies may not
Photo: Amy Lockner, U.S. Forest Service Emerald Ash Borer
be present to help keep
(Agrilus planipennis)
invasive populations in
Emerald ash borer (EAB) is an insect native
• Notable counties affected by aspen- check. Once established, invasive pests can
to Asia, introduced into North America
defoliating insects in 2018: be inadvertently spread by humans over
sometime during the 1990s. Since its
long distances, via the transport of firewood,
Colorado County 2017 Acres Affected 2018 Acres Affected initial discovery in Michigan in 2002, this
Archuleta 3,400 2,300 nursery stock and other plant material.
Conejos 2,300 1,400 insect has killed millions of true ash trees
Several exotic, invasive insects and diseases
La Plata 1,600 1,200 (Fraxinus spp.) throughout the central and
Gunnison 4,400 1,000 pose a threat to both native and urban forests
Mineral 1,600 1,000
northeastern U.S. and eastern Canada. EAB
in Colorado; two of primary significance are
is now considered the most destructive
described below.
Several species of leaf fungi are responsible tree insect ever to be introduced into
in some years for the thinning or discoloration Japanese Beetle North America.
of aspens, poplars and cottonwoods in
(Popillia japonica) Infestations were first detected in
Japanese beetle is an invasive pest that affects Colorado in the City of Boulder, in 2013.
Colorado; in severe cases this damage forces
hundreds of species of trees, grasses and Approximately 15 percent of all trees in
affected trees to drop their leaves early.
plants in North America. The adult beetles Colorado’s urban and community forests
However, record-dry conditions in 2018 were
damage flora by feeding on leaves, flowers are ash, making EAB a major threat to these
not conducive to these fungal pathogens
and fruit, with larvae feeding on roots. This forests statewide. New detections in 2018
in the summer months, and no significant
beetle was first detected in the U.S. more occurred in the towns of Lyons and Superior,
damage was observed in the aerial survey.
than a century ago. Although first detected still within an established quarantine that
in Colorado in the mid-1990s, populations primarily encompasses the generally infested
Other Broadleaf Disturbance
had not established until 2003, initially County of Boulder. No additional detections
Thousand Cankers Disease/ in the Palisade, Colo., area. Eradication in Colorado were reported outside of the
Walnut Twig Beetle attempts there were successful after a county, though early detection of this pest
(Pityophthorus juglandis)
seven-year effort. Meanwhile, discoveries of remains difficult.
Thousand cankers disease is native to the
the beetle occurred in Denver in 2005 and A collaborative Colorado EAB
Western United States and is the result of
subsequently in Pueblo in 2009. Response Team has been working
small twig beetles (Pityophthorus juglandis)
Japanese beetles are a metallic-green together to coordinate surveys and pest
feeding on primarily black walnut trees, and
color with copper-colored wing covers. management activities designed to limit
in the process spreading a canker-causing
10 2018 REPORT ON THE HEALTH OF COLORADO’S FORESTSspp.), the black-horned juniper size, from small saplings to mature trees, can
borer (Callidium texanum) and be heavily infested during outbreaks.
the juniper twig pruner (Styloxus Pine needle scale has been active in many
bicolor) are typically associated areas of the Fraser Valley and Vail Valley
with dead and declining juniper for the past several years. Activity declined
trees. in 2018 throughout Grand County, where
Extreme springtime the scale had caused significant tree damage
temperature fluctuations, from 2015 through 2017, though remained
coupled with numerous years persistent in the communities of Grand
of below-average precipitation, Lake, Granby, Fraser, Winter Park and
have resulted in some juniper portions of Summit County. Communities
dieback and die-off in the Four along the I-70 corridor (including Empire,
Corners region. No other causal Vail, Breckenridge and Frisco) also had
agent has been associated with noticeable insect populations in both native
The invasive Japanese beetle infests a wide variety observed damage. and transplanted spruce, likely a result
of flora in Colorado. The highest populations of this Pine Needle Scale of prior heavy and sustained chemical
pest are in Boulder, Denver and Pueblo. Photo: David (Chionaspis pinifoliae) preventive spraying for bark beetles. While
Cappaert, Bugwood.org Pine needle scale feeds on the chemical use to protect trees from bark
needles of most pine species, beetles is effective, prolonged spraying
the spread and reduce the impact of this Douglas-fir, Engelmann spruce and Colorado also diminishes populations of beneficial
extremely destructive insect. Agencies blue spruce. During outbreaks, insects insects that naturally keep scale infestations
and organizations represented on this can settle on every surface of the needles, in check.
team include the CSFS, Boulder County, robbing the affected tree of nutrients. Dwarf and Leafy Mistletoes
City of Boulder, Colorado Department Heavy infestations can cause premature Five species of dwarf mistletoe
of Agriculture, Colorado State University needle drop, branch dieback, increased (Arceuthobium spp.) and one leafy mistletoe
Extension, Colorado Tree Coalition, Green susceptibility to other insects or disease, or occur in Colorado. Dwarf mistletoes
Industries of Colorado, USFS, University of even tree death. Lodgepole pines of every are leafless “holoparasites,” deriving
Colorado, USDA Animal and Plant Health
Inspection Service (APHIS) and various
municipalities. Representatives of this team
have been instrumental in: evaluating traps
designed to attract flying adult beetles for
early detection of infestations; the release
of four species of parasitic wasps that prey
on EAB; maintenance of the quarantine
for Boulder County and adjoining areas,
intended to help restrict movement of
infested plant materials; and providing up-
to-date information on the insect’s status and
the most effective ways to protect trees.
Other Damaging Agents
Juniper Die-Back/Die-Off
The piñon pine-juniper forest cover type
occupies more area than any other forest
type in Colorado, at approximately 5.1
million acres of the state’s 24.4 million
forested acres. Below-average precipitation
for numerous years in southern Colorado
has predisposed Rocky Mountain juniper,
one-seed juniper and Utah juniper to branch
die-off and dieback. Cedar bark beetles
(Phloeosinus spp.), juniper borers (Atimia An adult emerald ash borer on an ash leaf, Boulder County. Photo: Dan West, CSFS
PROTECTING OUR COMMUNITIES 11both necessary carbohydrates and water
exclusively from their host trees by sinking
roots down into tree branches and stems.
Shoots develop and produce flowers and
seeds within five to six years. Seeds are
dispersed locally from shoots, while long-
range dispersal occurs via animals and birds.
All native pines and Douglas-fir trees in the
state are susceptible to dwarf mistletoe.
Dwarf mistletoes cause branches to
swell at the infection site, subsequently
forming large “witches brooms” that appear
as densely clumped twigs, and eventually
cause trees to become stunted and deformed.
Infections can result in loss of tree growth
and vigor, and susceptibility to other insects
and diseases. Infested trees often are targeted
for removal to improve overall stand health.
A range of infection severity regularly
occurs across the state, from localized
pockets and stand-level occurrence to severe
infections that impact entire drainages and
forests. Dwarf mistletoes continue to be a
persistent problem for communities and
forests statewide.
The only leafy mistletoe in Colorado,
commonly known as the juniper mistletoe Juniper die-off and die-back in the Four Corners region,
(Phoradendron juniperinum), occurs Montezuma County. Photo: Dan West, CSFS
in the southwest corner of the state on
several juniper varieties. This mistletoe
is considered less aggressive than dwarf
mistletoes, though is still impactful in harsh
conditions where many junipers occur. Leafy
mistletoes are “hemiparasites,” deriving
water and only partial carbohydrate needs
from their tree hosts. Infection rates for this
mistletoe are low in southwest Colorado;
however, affects are noticeable in areas
throughout Dolores, Montezuma and La
Plata counties.
Lodgepole Pine Needle Cast
Lodgepole pine forests along I-70 over Vail
Pass, and over Monarch Pass in Saguache
County, were discolored by a needle cast
disease in 2017. Premature needle drop of
older needles and discoloration of older
and new needles was caused by two species
of fungi of the genus Lophodermella due to
above-average precipitation in the spring
of that year. Environmental conditions
were unfavorable to these and other fungi
throughout Colorado in 2018, and no new
reports of incidence were recorded. A juniper tree infected with juniper mistletoe, Dolores County. Photo: Dan West, CSFS
12 2018 REPORT ON THE HEALTH OF COLORADO’S FORESTS2018 Insect and Disease Activity in Colorado Forests
Aerial Survey Data
Due to the nature of aerial surveys, the data on this map only provide
rough estimates of location, intensity and the resulting trend information
for agents detectable from the air. Some destructive diseases are not
represented on the map because these agents are not detectable from
aerial surveys. The data presented on this map should only be used as an
indicator of insect and disease activity, and should be validated on the
ground for actual location and causal agent. Shaded areas show locations
where tree mortality or defoliation were apparent from the air. Intensity of
damage is variable, and not all trees in shaded areas are dead or defoliated.
The insect and disease data represented on this map are available
digitally from the USDA Forest Service, Region 2 Forest Health
Management group. The cooperators reserve the right to correct, update,
modify or replace GIS products. Using this map for purposes other than
those for which it was intended may yield inaccurate or misleading results.
Caution should be used when comparing this year’s data to prior years,
due to slightly differing sampling tools and variability between observers.
Map created December 2018
For more information:
www.csfs.colostate.edu
© CSFS
Data Source: United States Department of Agriculture (USDA) Forest
Health Assessment & Applied Sciences Team (FHAAST)Spruce Beetle Activity in Colorado Forests, 2000-2018
Spruce beetle intensity percent classes denote the number of
dead trees relative to the total forested area within the polygon.
Contiguous spruce forests susceptible to spruce beetle exist in the
central part of the state, between the advancing fronts of separate
ongoing outbreaks in the north and south.
Aerial Survey Data
Due to the nature of aerial surveys, the data on this map only provide rough
estimates of location, intensity and the resulting trend information for agents
detectable from the air. The data presented on this map should only be used as an
indicator of insect and disease activity, and should be validated on the ground for
actual location and causal agent. Shaded areas show locations where tree mortality
or defoliation were apparent from the air. Intensity of damage is variable, and not all
trees in shaded areas are dead or defoliated.
The insect and disease data represented on this map are available digitally
from the USDA Forest Service, Region 2 Forest Health Management group. The
cooperators reserve the right to correct, update, modify or replace GIS products.
Using this map for purposes other than those for which it was intended may yield
inaccurate or misleading results.
Caution should be used when comparing this year’s data to prior years, due to
slightly differing sampling tools and variability between observers.
Spruce-fir type represents Engelmann and/or blue spruce occurrence with basal
area >1 (based on basal area data FHAAST*).
Map created December 2018
For more information:
www.csfs.colostate.edu
© CSFS
*Data Source: United States Department of Agriculture (USDA) Forest
Health Assessment & Applied Sciences Team (FHAAST)Special Section: Protecting Our Communities
T Risk Reduction Efforts Prove
hroughout Colorado and the West, and communities/ landowners are able to
2018 proved to be another year Successful in 2018 Wildfires proactively address forest conditions with
of historical wildfires, expanding The 2018 fire season saw more acres burned goals that include reducing forest stand
insect and disease challenges – including in Colorado than any other year except densities to decrease insect and disease risk
in urban and community settings – and 2002. The state also witnessed five of the 20 and the risk of intense wildfire, through
increasing risks to water supplies and largest wildland fires in recorded history. targeted treatments.
other benefits forests provide. For decades, Many of the burned acres were within the To meet these goals, one of the best
forest management has played a key role in wildland-urban interface (WUI) – any area approaches is engaging landowners with
addressing these types of challenges by pre- where human improvements are built close information and resources that inform
emptively implementing actions that reduce to, or within, natural terrain and flammable and enable them to implement the most
negative impacts when a wildfire ignites vegetation. effective treatments. The Colorado State
or an invasive pest arrives in a new area. The reasons for a historic wildfire Forest Service (CSFS), which is the lead state
Many success stories related to proactive year were complex, and included factors agency for providing fuels reduction and
forest management can be demonstrated such as overly dense and unhealthy forest wildfire mitigation assistance, offers many
in any year, and 2018 was no exception. In conditions; ongoing drought; wind and resources and programs to help address
this section are several examples of how weather events that coincided with ignitions; risk to communities and ensure they are
actions taken by the Colorado State Forest and increasingly warmer weather linked increasingly fire-adapted. These include
Service and its partners are achieving safer to climate change. Of these factors, only guidance in developing Community Wildfire
communities and healthier forests. one can be directly addressed by land Protection Plans (CWPPs) and targeted
managers. Working together, foresters fuelbreaks, leadership for the Firewise USA®
The blackened aftermath of the 2018 Buffalo Fire, which was halted in fuelbreaks buffering adjacent subdivisions. Photo: U.S. Forest Service
PROTECTING OUR COMMUNITIES 13program in Colorado, and through creating
and updating the Colorado Wildfire Risk
Assessment Portal. But in 2018, a year of
major wildfires in the state, these programs
and efforts would be tested.
Fuelbreaks Help Save
Mountain Subdivisions
In June of 2018, two fires burned perilously
close to Colorado subdivisions in Grand
and Summit counties, but did not result in
the loss of life or destruction of property.
One thing the Golf Course and Buffalo fires
had in common was that besides highly
capable fire management teams, they both
encountered forests previously managed
to alter fire behavior – and both fires were
prevented from being highly destructive as
a result.
The 20-acre Golf Course Fire, despite
causing the evacuation of 300 homes as
it burned west of Grand Lake, provided a
perfect example of how proactive forest
management can work in tandem with Firefighters were able to control the Buffalo Fire (footprint in red), before it destroyed any
suppression efforts to minimize the impacts homes, within fuelbreaks (green and blue) created previously through proactive, interagency
forest management efforts. Image: Zach Wehr, CSFS
of wildfire. Firefighters and emergency
responders made clear that a key reason
they were able to protect the community was Not far to the south, forest management possible through a partnership between the
mitigation work by the CSFS intended to work near Silverthorne, largely to create a CSFS, U.S. Forest Service, Denver Water and
reduce wildfire risk. 900-acre fuelbreak around subdivisions, also Summit County.
“The forestry work and fuels mitigation was attributed by fire managers as a major
the Colorado State Forest Service has reason homes did not burn in the Buffalo
Firewise USA® Sites Benefit
Fire. Firefighters were able to stop the 81-acre
from Awareness, Actions
administered in the Grand Lake community
Firewise USA® is a national recognition
without a doubt saved the Columbine fire within the fuelbreak, before it burned
program that provides instructional
subdivision,” said Chief Mike Long, Grand into many of the 1,400 evacuated homes and
resources to inform people how to adapt
Lake Fire, immediately after the fire made infrastructure worth nearly $1 billion. The
to living with wildfire, and encourages
its run. fuelbreak also provided a safe and effective
neighbors to work together and take action
Since 2015, the CSFS and its partners – location for the more than 100 firefighters
to reduce their wildfire risk. The CSFS and
which include the Grand County Wildfire on-scene. Again, fire managers indicated that
National Fire Protection Association work
Council, Grand Lake Metropolitan Recreation without the proactive fuels mitigation work,
together to implement the program in
District, Northern Colorado Water and local homes there likely would have been lost.
Colorado, with the CSFS providing technical
forest products businesses – had completed “The fuelbreaks reduced the number
assistance and education to interested
217 acres of targeted fuels treatments adjacent of trees available to burn next to homes,
landowners, homeowners and communities
to subdivisions that were impacted by the fire. gave firefighters safe spots to aggressively
to help them take action and ownership in
Treatments involved removing beetle-killed fight the fire and provided for effective
preparing their homes against the threat
trees and the creation of fuelbreaks to reduce fire-retardant drop zones,” said Bill Jackson,
of wildfire.
wildfire risk. Fuelbreaks are areas 300 or more district ranger, White River National Forest,
The Falls Creek Ranch neighborhood,
feet wide, located near values at risk, where U.S. Forest Service.
northwest of Durango, provides a perfect
vegetation is thinned or removed to alter Similar to the work done at Grand Lake,
example of the benefits of increased
fire behavior and make fires less intense and partnerships were key to completing the
awareness and action via the Firewise USA
more manageable for responders. In this case, forest management work utilized to fight
program. The neighborhood is one of many
the forest was composed chiefly of lodgepole the Buffalo Fire. Proactive, cross-boundary
Colorado communities proactively working
pine trees previously killed by mountain work adjacent to Silverthorne communities
to reduce wildfire risk. A Firewise site since
pine beetles. completed over the past decade was only
14 2018 REPORT ON THE HEALTH OF COLORADO’S FORESTSYou can also read
