United States 

Department of 

Agriculture

Forest 

Service 

Intermountain 

Region 

Forest Health Protection 

Boise Field Office 

1249 South Vinnell Way, Suite 200 

Boise, ID 83709-1663

 Caring for the Land and Serving People Printed on Recycled Paper 

File Code: 3420 Date: January 27, 2005 

Route To: 

Subject: FHP Report BFO-PR-05-01 

To: Forest Supervisors, Boise and Sawtooth NFs 

 

 

Enclosed is Forest Health Protection project report, BFO-PR-05-01. This report evaluates 

lodgepole pine stands affected by the mountain pine beetle (MPB) outbreak in the Sawtooth 

Valley of the Sawtooth National Recreational Area and susceptible stands in Bear Valley of the 

Boise National Forest. One objective of the report is to document the level of MPB-caused 

mortality of lodgepole pine in the Sawtooth Valley over the course of the current outbreak. An 

additional objective is to report on the establishment of MPB monitoring plots, located in 

susceptible lodgepole pine stands in Bear Valley. 

If you have any questions, please contact Carl Jorgensen at 208-373-4225 or Dayle Bennett at 

208-373-4227 in the Forest Health Protection Boise Field Office. 

For FHP evaluations, project reports, and trip reports on this or other topics visit our Web site at: 

http://fsweb.r4.fs.fed.us/unit/spf/tripreports/bk_beetle.shtml. For more general information on 

FHP programs and services visit our combined Regions 1 and 4 Web site at: 

http://www.fs.fed.us/r1-r4/spf/fhp/ or visit our national FHP Web site at: 

http://www.fs.fed.us/foresthealth/. 

/s/ Dayle D. Bennett (for) 

WILLIAM W. BOETTCHER 

Director, State and Private Forestry 

 

Enclosure 

cc: Carl L Jorgensen, Dayle D Bennett, Joy C Roberts, Barry F Stern, Dave Bassler, Brian 

Ferguson, Karl Fuelling, Sara E Baldwin, Joe Harper, Stephanie L Gripne, Barbara Bentz, Jesse 

Logan 
Monitoring Mountain Pine Beetle-Caused Mortality of Lodgepole Pine 

in the Sawtooth and Bear Valleys of South Central Idaho, 2004 

Report: BFO-PR-05-01 

Prepared by: 

Carl Jorgensen 

Entomologist 

and 

Philip Mocettini 

Biological Technician 

Forest Health Protection-Boise Field Office 

Intermountain Region 

1249 Vinnell Way, Suite 200 

Boise, ID 83709 
INTRODUCTION 

Mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins, is a native insect that plays a 

major ecological role in mature and overmature pine forests of western United States and 

Canada. Having killed millions of pine trees in the past, MPB has a rich history in the 

Intermountain West. MPB outbreaks can cause dramatic tree mortality over extensive areas in 

only a few years often killing the largest host trees (>8 inch diameter) in high density stands 

(>100 sq. ft./acre basal area). These MPB outbreaks reduce average stand density, diameter 

and age of live trees. They also influence such things as canopy closure, stand structure, 

species composition, forage production, wildlife habitat, fuel loading, water yields, and 

aesthetics. Downfall and woody debris following outbreaks can also hamper access and use of 

land by livestock, big game and humans (McGregor and Cole 1985). 

Mountain pine beetle populations have been building to epidemic levels in the Stanley Basin of 

the Sawtooth National Recreation Area (SNRA) since 1996 (Thier 1997). In 1998, the SNRA 

staff began spraying individual lodgepole pines in campgrounds with insecticides to protect 

them from attack by MPB. Other MPB management methods, such as verbenone and 

silvicultural treatments, have also been used on the SNRA to protect trees in some areas. 

Management strategies will not stop an outbreak once it has begun, but may reduce MPB 

impacts in localized areas. Typically, large MPB outbreaks only collapse due to one of two 

factors: a lack of susceptible host trees; or an extreme cold snap (<0  ̊F) in early fall or late 

spring and winter temperatures below –34  ̊F (Amman et al. 1989). 

One objective of this report is to document the level of MPB-caused mortality of lodgepole pine 

in the Sawtooth Valley of the SNRA over the course of the current outbreak. An additional 

objective is to report on the establishment of MPB monitoring plots, located in susceptible 

lodgepole pine stands in Bear Valley on the Boise National Forest, west of the current outbreak. 

Whitebark pine tree mortality from MPB has also been dramatic on the SNRA, but these stands 

were not surveyed due to time constraints and difficulty in accessing these stands. 

METHODS 

During September 26-30, 2004, twelve transects consisting of ten plots each were established 

and sampled for MPB activity. Nine were located in Sawtooth Valley (SNRA) and three were 

located in Bear Valley on the Boise National Forest (Figure 1). Plots within transects were 

spaced 5 chains apart and trees within each plot were identified using a variable radius 10-

factor prism. Surveyed trees were measured by 1-inch diameter at breast height (d.b.h.) size 

classes using a Biltmore stick. Each tree was identified by species and ranked into one of the 

following categories: green, unattacked; pitchout; current strip attack; current successful attack; 

successfully attacked in 2003, successfully attacked in 2002; successfully attacked prior to 

2002. 

Because the forest is always changing, the "snap shot" of average basal area and average 

d.b.h. was estimated for June of each year before the MPB attack period. Assumptions were 

made for "back dating" for the 2003, 2002, and 2001 stand conditions, as well as "projecting" 

the 2005 stand conditions. The first assumption is that the trees remained static from 2001 to 

2005, so all the trees measured on the plot in the fall of 2004 remained the same 1-inch d.b.h. 

size class from 2001 to 2005. The second assumption is that living trees in the fall of 2004 

would still be alive in 2005. Means and percentages were calculated using Microsoft Excel and 

JMP statistical software. 
"

Galena

Sack Ck

Iron Ck

Pole Ck

Elk Mtn

Decker Rd

Pettit Lk

Wyoming Ck

Thatcher Ck

Bruce Meadow

Ranger Station

Hell Roaring Ck

Stanley

1:500,000 {

Mountain Pine Beetle Transect Locations

Pre-MPB

Post-MPB

Current-MPB

2003 MPB infested areas - Aerial Survey

Non-National Forest Lands

National Forest Land

County Boundaries

Figure 1. Location and name of transects for 2004 mountain pine beetle survey in lodgepole 

pine. 

RESULTS AND DISCUSSION 

Previous aerial surveys, the basal area graph (Figure 2), and visual observations of the 

transects were used to classify MPB population levels for each of the transects into the following 

categories: 

• Post-MPB - Transect had substantial MPB activity 2 or more years ago. 

• Current-MPB - Transect had substantial MPB activity in 2004. 

• Pre-MPB -Transect had little or no MPB activity prior to sampling. 

Post-MPB Transects -- Due to MPB caused mortality, the live basal area of trees on the postMPB transects was dramatically reduced from 80-150 square feet per acre to between 50-75 

square feet per acre (Figure 2). 

The average d.b.h. of live lodgepole pine trees was also reduced in these transects. It was 

reduce by approximately 2 inches on the Ranger Station and Pole Creek transects (Figure 3). 

Mortality rates were much higher for the larger trees than the smaller trees. Ninety-six percent 

of the lodgepole pine in 13-inch d.b.h. size class was killed by MPB in these transects (Figure 

4). 
Overstory lodgepole pine, for the purpose of this report, was defined as lodgepole pine trees 

that had a d.b.h. greater than or equal to 7 inches. Overstory lodgepole pine survival on the 

post-MPB transects varied between 31 and 47 percent (Figure 5). 

Understory lodgepole pine, for the purpose of this report, was defined as lodgepole pine that 

had a d.b.h. less than 7 inches. Understory lodgepole pine survival on the post-MPB transects 

varied between 65 and 97 percent (Figure 6). 

Current -MPB Transects -- MPB populations are still building on these transects. Current 

year’s attacks were prevalent, and some reduction in live basal area and average d.b.h. of live 

trees has occurred (Figures 2 and 3). Many live, susceptible lodgepole pines remain and we 

expect continued mortality and resultant changes in stand structure will be similar to that found 

on our post-MPB transects. We plan to continue annually monitoring these transects for the 

duration of this outbreak. 

Pre-MPB Transects -- Little, if any, mortality associated with MPB has occurred on these 

transects. However, many of the lodgepole pine stands within Bear Valley are highly 

susceptible to MPB attack and scattered MPB-caused mortality is evident throughout the area. 

We plan to continue annually monitoring these transects for the duration of the pending 

outbreak. 

CONCLUSION 

The current MPB outbreak on the SNRA has resulted in lodgepole pine survival and mortality 

rates similar to other MPB outbreaks in the Intermountain West. Survival rates of lodgepole 

pine trees greater than 4 inches d.b.h. on the Teton National Forest, Grand Teton National Park, 

and Targhee National Forest following a MPB outbreak resulted in rates of 62-90 percent 

(Amman and Baker 1972). Although many of the dominant lodgepole pine trees have been 

killed in the Sawtooth Valley, a large proportion of the understory lodgepole pines have survived 

(Figure 6). Similar mortality and survival rates can be expected in Bear Valley and in other 

susceptible lodgepole pine stands on the Sawtooth, Boise, and Salmon-Challis National Forests 

as the current outbreak progresses. 

LITERATURE CITED 

Amman, G.D. and B.H. Baker. 1972. Mountain pine beetle influence on lodgepole pine stand 

structure. J. For. 70: 204-209. 

 

Amman, G.D., M.D. McGregor, R.E. Dolph, Jr. 1989. Mountain pine beetle. USDA Forest 

Service Leaflet 2. USDA Forest Service, Washington, DC. 11 p. 

McGregor, M. D.; Cole D. M. 1985. Integrating management strategies for the mountain pine 

beetle with multiple resource management of lodgepole pine forests. General Technical 

Report INT-174. USDA Forest Service, Intermountain Forest and Range Experiment 

Station, Ogden, UT. 68 p. 

Thier, R.W. Memo To Forest Supervisor, Sawtooth NF, dated November 5, 1997. File Code 

3420 Titled, “Mountain Pine Beetle, Riverside and Salmon River Campgrounds, SNRA.” 
Figure 2. Average Basal Area (sq. ft/acre) from 2001 to 2005 at each of the transect locations 

grouped by pre-mountain pine beetle (MPB), current-MPB, and post-MPB population 

categories. 

Figure 3. Average diameter at breast height (d.b.h.) from 2001 to 2005 at each of the transect 

locations grouped by pre-mountain pine beetle (MPB), current-MPB, and post-MPB population 

categories. 

0

20

40

60

80

100

120

140

160

2001 2002 2003 2004 2005

Year

Basal Area (sq.ft./acre)

Pre-MPB Bruce Meadow

Pre-MPB Wyoming Ck

Pre-MPB Sack Ck

Pre-MPB Thatcher Ck

Current-MPB Iron Ck

Current-MPB Elk Mtn

Current-MPB Galena

Current-MPB Pettit Lk

Post-MPB Ranger Station

Post-MPB Hell Roaring Ck

Post-MPB Decker Rd

Post-MPB Pole Ck

5.0

6.0

7.0

8.0

9.0

10.0

11.0

12.0

2001 2002 2003 2004 2005

Year

d.b.h. (in.)

Pre-MPB Bruce Meadow

Pre-MPB Wyoming Ck

Pre-MPB Sack Ck

Pre-MPB Thatcher Ck

Current-MPB Iron Ck

Current-MPB Elk Mtn

Current-MPB Galena

Current-MPB Pettit Lk

Post-MPB Ranger Station

Post-MPB Hell Roaring Ck

Post-MPB Decker Rd

Post-MPB Pole Ck
Figure 4. Percent of lodgepole pine mortality by mountain pine beetle (MPB) between 2001 and 

2005 by 2-inch diameter at breast height size (d.b.h.) classes for the transects at pre-MPB, 

current-MPB, and post-MPB population categories. 

Figure 5. Percent survival of overstory lodgepole pine (greater than 7-inch d.b.h.) between 

2001 and 2005 (projected) at each of the transect locations grouped by pre-mountain pine 

beetle (MPB), current-MPB, and post-MPB population categories. 

0% 0% 2% 6% 6% 7%

3% 3%

31%

62%

86%

0%

22%

63%

86%

96%

0%

53%

16%

78%

35%

0%

20%

40%

60%

80%

100%

<5 5 7 9 11 13 15+

d.b.h. size classes

Percent Mortality

Pre-MPB

Current-MPB

Post-MPB

Overstory Lodgepole pine 97% 97%

66%

81%

43% 44% 47% 45%

31% 31%

96%

92%

0%

20%

40%

60%

80%

100%

Bruce

MeadowWyoming

Ck

Sack CkThatcher

Ck

Iron CkElk MtnGalena Pettit Lk

Station

Ranger

Hell

RoaringDecker

Rd

Pole Ck

Pre-MPB Current-MPB Post-MPB

Transects

Percent Survival
Figure 6. Percent survival of understory lodgepole pine (less than 7-inch d.b.h.) from 2001 to 

2005 at each of the transect locations grouped by pre-mountain pine beetle (MPB), currentMPB, and post-MPB population categories. 

Understory Lodgepole pine

100%100%100%100%100%100%100% 96%

88%

65%

85%

97%

0%

20%

40%

60%

80%

100%

Bruce

MeadowWyoming

Ck

Sack CkThatcher

Ck

Iron CkElk MtnGalena Pettit Lk

Station

Ranger

Hell

RoaringDecker

Rd

Pole Ck

Pre-MPB Current-MPB Post-MPB

Transects

Percent Survival
Appendix 1. Number of live and dead lodgepole pine associated to mountain pine beetle by 2-inch diame

classes per transect.

<5 5 7 9 11 13 

Transect Dead Live Dead Live Dead Live Dead Live Dead Live Dead 

Bruce Meadow 0 17 0 18 0 33 3 36 0 19 0 Wyoming Creek 0 9 0 21 0 28 1 32 3 24 0 Sack Creek 0 16 0 27 0 18 0 16 2 19 0 Thatcher Creek 0 3 0 9 2 14 3 32 1 27 2 

Pre-MPB 

TOTALS 0 45 0 75 2 93 7 116 6 89 2 

Iron Creek 0 9 0 14 3 12 8 25 6 21 7 Elk Mtn 0 7 0 14 1 25 8 23 4 10 2 Galena 0 4 0 14 1 20 15 25 22 4 13 Pettit Lake 0 22 2 24 8 12 5 7 12 4 2 

Current-MPB 

TOTALS 0 42 2 66 13 69 36 80 44 39 24 

Ranger Station 0 12 4 18 14 20 18 11 30 3 11 Hell Roaring Ck 0 4 11 16 9 20 12 10 12 5 4 Decker Road 0 5 4 18 11 14 9 8 5 1 4 Pole Creek 0 11 1 17 2 12 21 7 12 1 8 

Post-MPB 

TOTALS 0 32 20 69 36 66 60 36 59 10 27 

Appendix 2. Number of lodgepole pine by mountain pine beetle attack category per transect.  Transect Unattacked

2004 Strip 

Attack 

2004 

Pitchout 2004 Attack 2003 Attack 2002 Attack

Prior to 20

Attack 

Bruce Meadow 130 0 0 0 2 0 2 Wyoming Creek 123 0 1 0 0 0 4 Sack Creek 106 0 0 0 0 0 2 Pre-MPB 

Thatcher Creek 117 0 0 0 3 3 3 

Iron Creek 80 5 3 6 19 1 7 Elk Mtn 86 1 0 0 7 7 1 Galena 64 6 0 22 19 16 12 Current-MPB 

Pettit Lake 67 0 3 1 16 6 9 

Ranger Station 59 1 3 2 54 16 9 Hell Roaring Ck 52 1 4 5 10 15 23 Decker Road 45 0 2 1 11 7 14 Post-MPB 

Pole Creek 45 4 1 1 14 15 19