United States

Department of Agriculture

Forest Service Intermountain Forest and Range

Experiment Station,

Ogden, UT 84401

Research Note INT-333

July 1983

# Harvesting Strategies for

## Management of

#### Mountain Pine Beetle Infestations

## in Lodgepole Pine:

##### Preliminary Evaluation, East Long Creek

Demonstration Area, Shoshone National

###### Forest, Wyoming

Walter E. Cole,’ Donn B. Cahill,? and Gene D.

ABSTRACT

Diameter-limit and leave-tree cuts were tested as ways to reduce or minimize lodgepole pine losses to the mountain pine beetle. In the first year after treatment, loss reductions were proportional to the intensity

of cut. According to the Rate of Loss Model, the 100-leave-tree cut was the best deterrent of recurring infestation, measured as amount of losses and length of

time. The 100-leave-tree cut also should provide the best regeneration and has the added benefit of reducing dwarf mistletoe infection.

KEYWORDS: mountain pine beetle, Dendroctonus

ponderosae, lodgepole pine, Pinus contorta var. latifolia, harvest strategies

“Principal Entomologist, Population Dynamics of the Mountain Pine

Beetle Research Work Unit, Intermountain Forest and Range Experiment Station, Ogden, Utah. Entomologist, Forest Pest Management, Boise Zone Office,

Intermountain Region, USDA Forest Service, Boise, Idaho.

Entomologist, Forest Pest Management, Rocky Mountain Region,

USDA Forest Service, Lakewood, Colo.

East Long Creek in the Shoshone National Forest is

one of a series of demonstration area projects that used management alternatives derived from research

(Cole and Cahill 1976 and small-scale tests (Cahill 1978; McGregor and Cole, in press) in an attempt to reduce or minimize lodgepole pine (Pinus contorta var.

latifolia Engelm.) losses to the mountain pine beetle

(Dendroctonus ponderosae Hopkins).

The objective of this initial large-scale application of

management alternatives was to prevent undue losses of lodgepole pine by changing or reducing the food supply of the mountain pine beetle, and also to manipulate the stand to grow at or near optimum site capacity with continued prevention of large losses to

the beetle.

Some constraints on the project were to protect or

enhance key resource values, remove merchantable material through a commercial timber sale, develop permanent access roads for general land use and management, improve forest cover growing conditions through

disease control and stocking to attain timber production potentials on regulated lands, and develop a costbenefit analysis for each strategy. This report is limited to the reaction of the mountain pine beetle and tree

growth response the first year after cutting.

Future efforts to manage stands to prevent losses to the beetle must be made before the beetle epidemic cycle. East Long Creek Demonstration Area provided this opportunity.

-----

STUDY AREA

The East Long Creek Demonstration Area lies between 7,600 and 8,800 ft 2 317 and 2 683 m) elevation, which is the lower half of the forested zone in the Wind River Drainage. The climate is cool and dry; moisture

availability is the most limiting growth factor during the

season

Soils are derived from sedimentary formations and glacial moraines derived from the Wiggins formation. The clay content of the soils and seasonal distribution

of precipitation make natural regeneration difficult on

southerly and westerly aspects and flats, especially

below 8,500 ft 2 591 m).

Cover types change with aspect and elevation; coniferous trees grow only on favorable aspects below

7,600 ft 2 317 m), and seldom occur on more adverse aspects at higher elevations.

Reestablishment of conifers following fire is extremely slow on adverse aspects. Recovery from any drastic disturbance on this area can be expected to be slow unless seedlings are planted as the regeneration method. On some of the adverse aspects, the scattered limber pine (P. flexilis James) and lodgepole pine trees appear to be pioneers of a first generation forest.

The lower part of the coniferous cover could be

classed as Abies lasiocarpa-Arnica cordifolia habitat

type, milk vetch phase. This habitat type on the Wind

River District has almost no potential to be dominated by Abies lasiocarpa because the development of the climax community requires more time than is permitted

by the natural fire cycle. Inland Douglas-fir (Pseudotsuga menziesii [Mirb.]

Franco) predominates in an alternative seral community

on this habitat type where soils are basic. At this elevation, the inland snowberry habitat

is present on soils derived from limestone formations.

Aspen (Populus tremuloides Michx.) is a short-lived

seral community replaced by limber pine or lodgepole

pine in the first generation. Retention of aspen as a

cover type requires reduction in competition for

a

moisture and cutting the live aspen to break the auxin

flow so sprouting can occur.

In most of the stands in this zone, the lodgepole pine

component of the stand is 150 to 200 years old and dying out rapidly. Younger stands are still dominated by lodgepole pine and have a manageable pole and smallsize sawtimber component. This zone of the coniferous

forest is an Abies lasiocarpa-Vaccinium scoparium

habitat type.

Regeneration following disturbance is more rapid in

this habitat and will tend to be mixed aged, with some tolerant species seedlings and saplings present in the first 50 years of stand development. The number of spruce and fir trees present during early stand development probably depends on seed source, once the lodgepole pine component accomplishes the necessary

site modification. In some cases, competition by density stocked lodgepole pine may reduce spruce and fir

regeneration.

Site index values for lodgepole pine are 30 to 35 ft 9.1 to 10.7 m) in 50 years in the Abies lasiocarpa-Arnica cordifolia-milk vetch phase habitat, increasing to 45 to 50 ft 13.7 to 15.2 m) in 50 years in the Abies lasiocarpa-

Vaccinium scoparium habitats.

Throughout this area of the forest, basal area in natural stands follows the site index values, with basal areas as low as 65 ft¥/acre 14.4 on the lower site index areas and increasing to 140 ft\*/acre 31.1 m\*/ha) on the most productive sites. Total live conifer trees over 2 inches 5.08 cm diameter at breast height) (d.b.h.) on the

1,789 acres 724 ha) cruised rarely exceeded 400 per acre 988 per ha).

The demonstration area contained approximately 1,898

768 ha). Before harvesting, the area contained

acres

3,777 board feet (bd.ft.) of gross green volume per acre

and 1,664 bd.ft. of dead standing volume per acre. Net

volumes were 3,397 bd ft. of green volume per acre and 1,332 bd.ft. of dead volume per acre, or 4,729 bd.ft. total

net volume per acre.

STAND PRESCRIPTIONS

Three general prescriptions were applied: 1 cutting

levels based on diameters, 2 leave-tree cuts, and 3

clearcuts. In each case, the primary purpose was to remove the food supply from the beetle; the larger diameter trees generally contain the thicker phloem. However, other criteria were considered in each case. Each prescription required retention of adequate forest

cover to promote natural regeneration, wildlife needs,

and visual qualities, and was designed to fit the condition of the stand and its ecology to promote future

development under natural conditions.

The prescriptions and their applications were:

1. Diameter cuts.

a. Cut all lodgepole pine 7 inches 17.78 cm) d.b.h.

and larger and salvage dead trees 8 inches 20.32 cm) d.b.h. and larger. This prescription

was applied to three different stand conditions:

1 Late transitional stands that had converted

to the spruce-fir type. The lodgepole pine

component was decadent or dying rapidly.

In this case, adequate lodgepole pine growing stock was to be retained. Lodgepole pine regeneration could be expected to fill in openings created by logging. @ Two-aged lodgepole pine stands that contained very few tolerant trees. The

understory was primarily lodgepole pine,

and the residual stand of seedlings and saplings would be understocked. Trees less

than 7 inches 17.78 cm) d.b.h. down to the seedling-sapling understory were not

suitable growing stock because of disease—dwarf mistletoe (Arceuthobium

americanum) and comandra blister rust (Cronartium comandrae). It was necessary

on these sites to retain the undesirable pole timber to protect the site until natural

regeneration occurs to bring the seedlingsapling stand up to 300 per acre 121 per ha). Timely removal of mistletoe-infected

trees will be required.

-----

In some cases where stocking inadewas

quate and residual trees were than 100 per acre 40 per ha)—planting

would be necessary. Lodgepole pine or inland Douglas-fir containerized stock should be planted at 200 to 400 trees 81

per acre to 162 per ha) depending on the number and

size of residual growing stock trees. (&) Heavily stocked lodgepole pine pole timber

stands where the age and disease conditions made regeneration of the stand desirable, and enough trees less than 7 inches 17.78 cm) d.b.h. were present to furnish adequate cover to meet forest cover

objectives, including site protection. Adequate natural regeneration was expected in

these stands.

b. Cut all lodgepole pine trees 10 inches 25.40 cm)

d.b.h. and larger and salvage all dead or attacked trees 8 inches 20.32 cm) d.b.h. and

larger. This prescription was applied to isolated

stands in the unthinned component where

forest cover was not maintained for production

of wood products, but primarily where lodgepole pine was the principal component and

cover objectives required retaining forest cover

to protect other values. Site potential was low in these stands, ecosystems were exceptionally fragile, and values

other than timber were paramount. The prescription was applied to stands that were sparsely

stocked and on adverse aspects. These stands

were suspected to be first-generation coniferous forests, hence were fragile ecotones, and

disruption could reverse ecologic trends. Subsequent treatments on regulated lands will be overstory removal in one or two steps, depending on disease conditions, regeneration success, and visual quality needs.

| c. | Cut all | lodgepole pine trees 12 inches 30.48 cm) |
|---|---|---|
|  | d.b.h. | and larger and salvage all dead or at- |

tacked trees 8 inches 20.32 cm) and larger. This

prescription was applied to stands where lodgepole pine was the principal component, site potential was extremely low, stands were sparsely stocked, aspects were adverse, and

stands contained trees exceeding this diameter limit.

2. Leave-tree cuts.

The leave-tree prescription was applied to two

stands and required leaving 100 trees per acre 40 trees per ha), while removing the balance of the

lodgepole pine component of the stand. All

selected leave trees were the largest, most desirable lodgepole pine, growing stock, and sufficient desirable growing stock trees of other species were retained to result in an average stocking of 100 trees per acre 40 per ha) over 7 inches

17.78 cm) d.b.h.

Because of small islands of old lodgepole pine that

escaped the fire that regenerated these two stands,

and because these stands contained mistletoe infection centers, small clearcuts also were required. Natural regeneration could be expected in 5 years if these clearcuts did not exceed 5 acres 2 ha).

3. Clearcuts. Six areas, averaging 14 acres 5.7 ha) each, were

clearcut. These were in fire-regenerated pole timber

stands. There were small islands of old-aged, larger diameter lodgepole pine trees that were diseased and decadent. Some of these islands had lodgepole pine andlor spruce-fir understories. Because of the heavy fuel accumulations in the pockets of old growth, bulldozer piling and slash burning were

desirable to meet fuel management objectives.

METHODS

A total of 37 cutting units and one check block unit were laid out in the demonstration area: 10 units in the 7-inch (17.78-cm) cutting block

17 units in the 10-inch (25.40-cm) cutting

block

2 units in the 12-inch (30.48-cm) cutting

block 2 units in the 100-leave-tree cutting block 6 units in the clearcut block 1 check block unit

Harvesting began in January 1979 and was completed in February 1981, well before the 1981 beetle flight. A summary of the pretreatment stand structure and proposed cuts is shown in table 1.

A survey of the demonstration area was made in the spring of 1982 to determine tree loss to the mountain

pine beetle. A 20-percent survey was conducted in 22 of

the 38 units: 6 of 10 units in the 7-inch (17.78-cm) cutting

block 11 of 27 units in the 10-inch (25.40-cm) cutting

block

2 of 2 units in the 12-inch (30.48-cm) cutting

block 2 of 2 units in the 100-leave-tree block 1 check block unit The 20-percent survey used a 1-chain-wide strip 20 m) every 5 chains 100 m) and recorded beetle-killed trees in

1979, 1980, and 1981, other causes of death, and

diameter.

Tree growth data were collected during the loss surveys. Basal area and radial growth measurements were taken at 5-chain 100 m) intervals along the cruise strip, using a 10 BAF gage. Unfortunately, similar data were not taken before the harvest for comparison.

-----

Table 1.—Summary of stand data and proposed cuts for East Long Creek Demonstration Area

Treatment

Stand structure and volumes T-inch 10-inch 12-inch 100-leave-tree Clearcut

Acres

| Total | 1,132.0 | 581.0 | 60.0 | 39.0 | 86.0 |
|---|---|---|---|---|---|
| Mean | 113.2 | 342 | 30.0 | 195 | 143 |
| Live lodgepolelacre |  |  |  |  |  |
| Total | 1,633.0 | 3,668.0 | 686.0 | 428.0 |  |
| Mean | 163.3 | 215.7 | 343.0 | 2140 | 2458 |
| < 7-inch | 864.0 | 1,925.0 | 458.0 | 2420 | 769.0 |
| Mean | 86.4 | 132 | 2290 | 121.0 | 1282 |
| > 7-inch | 769.0 | 1,743.0 | 2280 | 186.0 | 706.0 |
| Mean | 76.9 | 1025 | 1140 | 93.0 | 17.7 |
|  | 3520 | 656.0 | 88.0 | 62.0 | 271.0 |
| Mean | 35.2 | 386 | 44.0 | 31.0 | 452 |
| >12-inch | 166.0 | 282.0 | 140 | 240 | 156.0 |
| Mean | 166 | 16.6 | 7 | 120 | 260 |
| Live species/acre |  |  |  |  |  |
| Subalpine fir and other | 768.0 | 699.0 | 66.0 | 30.0 | 1,006.0 |
| Mean | 76.8 | 41.1 | 33.0 | 15.0 | 167.7 |
| Engelmann spruce | 194.0 | 47.2 | 0 | 24 | 248.0 |
| Mean | 19.4 | 28 | 0 | 12 |  |
|  |  |  |  |  | 413 |
| Aspen | 1,683.0 | 232.0 | 0 | 64.0 | 340 |
| Mean | 168.3 | 136 | 0 | 320 | 57 |
| Proposed cut |  |  |  |  |  |
| TIA | 769.0 | 656.0 | 14.0 | 2280 | 1,475.0 |
| Mean | 76.9 | 38.6 | 70 | 114.0 |  |
|  |  |  |  |  | 245.8 |
| Gross volumelacre |  |  |  |  |  |
| Live cut | 4,468.0 | 3,518.0 | 3,683.0 | 3,205.0 | 4,093.0 |
| Mean | 4,468.0 | 3,518.0 | 3,683.0 | 3,205.0 | 4,093.0 |
| Salvage cut | 2,290.0 | 1,480.0 | 1,583.0 | 1,231.0 | 2,337.0 |
| Mean | 2,290.0 | 1,480.0 | 1,583.0 | 1,231.0 | 2,337.0 |
| Gross volume (M) |  |  |  |  |  |
| Green | 5,058.0 | 2,044.0 | 2210 |  |  |
|  |  |  |  | 1250 | 3520 |
| Mean | 505.8 | 120.2 | 1105 | 625 |  |
|  |  |  |  |  | 58.7 |
| Dead (=8") | 2,592.0 | 860.0 | 95.0 | 48.0 |  |
|  |  |  |  |  | 201.0 |
| Mean | 259.2 | 50.6 | 475 | 240 |  |
|  |  |  |  |  | 335 |
| Uncut per acre |  |  |  |  |  |
| Lodgepole pine (=2") | 891.0 | 2916.0 | 558.0 | 39.0 | 877.0 |
| Mean | 89.1 | 1715 | 279.0 |  |  |
|  |  |  |  | 195 | 146.2 |
| Total trees (>2") | 1,602.0 | 3,661.0 | 624.0 |  |  |
|  |  |  |  | 43.0 | 2,1320 |
| Mean | 160.2 | 215.4 | 3120 |  |  |
|  |  |  |  | 215 | 355.3 |

Average gross volume

per acre (M) Green 4.468 3518 3.683 3.205 4.093

Dead 2.290 1.480

1.583 1.231 2.337

Average net volume

per acre (M)

| Green | 4.023 | 3.166 | 3.315 | 2.885 |
|---|---|---|---|---|
| Dead | 1.832 | 1.184 | 1.267 | 985 |

Total adjusted net volume

| Volume per acre | 5.855 | 4.350 | 4.582 | 3.870 |
|---|---|---|---|---|
| Net volume | 6.628 | 2528 | 275, | 151 |

-----

RESULTS

The stand structure changed tensity of harvest cut used in each block average diameter (d.b.h.)

Treatment

7-inch (17.78<m) cut

10-inch (25.40-cm) cut 124nch (30.48-cm) cut 100-eave-tree cut proportionally to the inchanges were:

Original

diameter Inches

78 77 74 75 cm

19.81 19.56 18.80 19.05

(table 2). Stand

Diameter after harvest Inches

7.0 70 73 80 cm

17.78 17.78 18.54 20.32

Considering only the kill by the mountain pine beetle,

the trend for the 3 years 2 years before the cut was completed and 1 year after completed cuts) is rather dramatic (table 3 and fig. 1). In all cutting blocks, the

number of trees infested dropped considerably after

harvesting; the check block continued to lose trees to

the beetle at about the same rate.

It is evident that tree loss to secondary insects, such

as Ips, Pityophthorus, Pityogenes, and Pityokteines, and

rust lessened after treatment (table 4). However, this apparent reduction of loss may be an artificial

effect of sampling, because the check areas also showed no loss due to these factors in 1981 (the year

after cutting was completed).

Table 2.—Stand structure before and after cutting

Live lodgepole pine per acre by diameter class

Treatment Before cut After cut

Trees

| <7 | 7-9 | 10-11 | >12 | cut per | <7 | 7-9 | 10-11 | >12 |
|---|---|---|---|---|---|---|---|---|
| inches | inches | inches | inches | acre | inches | inches | inches | inches |

| 7-inch cut | 163.3 | 86.4 | a7 | 186 | 16.6 | 76.9 | 86.4 | 86.4 | 0 | 0 | 0 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 10-inch cut | 215.7 | 113.2 | 63.9 | 220 | 16.6 | 386 | 1774 | 113.2 | 63.9 | 0 | 0 |
| 12-inch cut 100-leave-tree cut | 343.0 2140 | 2290 1210 | 70.0 62.0 | 37.0 19.0 | 70 12.0 | 70 114.0 | 336.0 1100.0 | 229.0 | 70.0 - | 37.0 —_ | 0 — |
| Clearcut | 2458 | 128.2 | 725 | 19.2 | 26.0 | 245.0 | 0 | 0 | 9 | 0 |  |
| Check area | 251.0 | 265.0 | 196.0 | 91.0 | 420 | 0 | 2510 | *55.0 | 196.0 | 91.0 | 42 |

"Data not available on distribution. “Include only 4- to trees.

Table 3.—Tree mortality due to the mountain pine beetle

Treatment

7-inch cut 10-inch cut 12-inch cut

100-leave-tree cut Check area

Number of trees killed per acre

1979 1980 1981

| 072 35 | 051 6 | g | 009 07 |
|---|---|---|---|
| 19 | 5.00 | g | 1.15 |
| 20 253 | 10 577 | 3S 3 | 0 423 |

-----

= H

7 INCH CUT

1

| A : | 10 | INCH | CUT |
|---|---|---|---|
| 5 | 12 | INCH | CUT |

##### a 1 NN

H 100-LEAVE-TREECUT

= H Bl

check AREA

= 1

i

> a

>

2

o

a (&]

##### Sih mi

| wi | o {nd |
|---|---|
| a | 2 o |
| = | 1 |

A =

=

:

- 1 = 1 S ] 2

1

=

1 1 1 1 1

=

1979 1980 1981

Figure 1.—Tree loss due to the mountain beetle within the demonstration

areas.

-----

Table 4.—Trees killed per acre by cutting block,

year, cause, and diameter

Treat.

ment

Year of kill

Cause of death 6

Diameter of tree killed (inches) 7 8 9 10 11 12 13 14 15 16 >17

Total trees killed

Trees killed peracre

1979 aE

cut Pity's? 1 1 1

Total 3 3 4

4 4 1 1 1980 MPB EEE

Pity's A

Comandra 1

Total

1 20 1981 MPB 1

Total

1 All years 4 5 8% 8

1 1 1

1 1 1

24 orn 3 09

27 81 17 51

2 06 1 03

20 60

5 09 3 09 50 151

10-inch 1979 MPB 21 35

cut Ips spp. 1 3 2 6 10

6 8 a 5 22 36

Comandra

|  | Total | 1 8 15 | 1 9 | 15 | 2 | 2 |  |  |  |  | 2 51 | 03 84 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1980 | MPB Pity's | 16 | 12 aly | 9 | 4 | 3 | 2 | 1 | 1 | 1 | 40 12 | 66 20 |
|  | Comandra | 2 | 2 | 1 |  |  |  |  |  |  | 5 | 08 |

Total 5 11 1B NN 4 3 2 1 1 1 57 94

1981

MPB 1 1 1 4 07

Total 1 1 1

| 1 | 4 | 07 |
|---|---|---|
| 1 | 112 | 1.78 |

1979 MPB cut Comandra 2 1 1

| Total | 2 | 1 | 1 |
|---|---|---|---|
| MPB Pity's | 1 | 4 | 5 1 |

Comandra 1

Total 1 2 4 5 6 7 3 1981 MPB 12 3

Total 1 2 3

All years 3 3 7 5 7 10 3

| 1 | 1 | 19 |
|---|---|---|
| 1 | 4 | ar |
| 1 | 5 | 96 |
|  | 26 | 5.00 |
|  | 1 | 19 |
| 1 | 1 | 19 |
|  | 28 | 5.38 |
|  | 6 6 | 1.15 1.15 |
| 1 | 39 | 7.50 |

100-leave 1979 MPB 1 1 2 20

tree cut Ips spp. 1 1 1 3 30

Total 2 1 1 1

5 50

1980 MPB 1

10

Ips spp. A 2 20

Total 1 3

30

1981 MPB 1

1 10

Total 1

1 10 All years 4 2 1 1 1 9 90

Check 1979 MPB 4 9 5 9 1 5 1 1 36 253

area Pity’s 3 3 21

| Total | 4 | 3 | 9 | 5 | 9 | 1 | 5 | 1 | 1 | 39 | 274 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| MPB Pity’s | 1 | 4 | 1 1 | 14 | 18 | 10 | 8 | 6 | 1 | 82 1 | 5.77 07 |
| Comandra |  |  |  | i |  |  |  |  |  | 1 | 07 |
| Total | 1 | 4 | 12 | 15 | 18 | 10 | 8 | 6 | 1 | 84 | 591 |

1981 MPB 6 5 13 6 5 4 1 60 423

Total 6 5 9 1 13 6 5 4 1 60 423

All years 1 5 13 26 29 38 24 19 12 2 6 7 183 12.88

=

Mountain pine beetle.

3Pityophthorus, Pityogenes, and Pityokteines.

-----

Adding the loss due to the mountain pine beetle,

90

secondary insects, and comandra rust to the trees cut

per acre gives the gross number of trees removed and

thus the residual trees per acre (table 5). All cutting blocks now contain almost the same number of trees per acre, which is about one-half the number per acre now in the check area, although the average stand diameter is

70

different.

Residual basal area followed the level of cut POSTHARVEST

as would

be expected (fig. 2). Using the check blocks as a base, then 66 percent of the basal area was removed in the 7-inch (17.78-cm) blocks; 55 percent in the 10-inch

(25.40-cm) blocks; 45 percent in the 12-inch (30.48-cm) BLOCK,

blocks; and 63 percent in the 100-leave-tree blocks. 50

There was an apparent and slightly greater radial

CUTTING

growth, of those residual trees measured, in the 12-inch

(30.48-cm), 100-leave-tree, and check blocks as compared

to the 7-inch (17.78-cm) and 10-inch (25.40-cm) blocks PER

(fig. 3). This does not necessarily reflect release by cut- AREA

ting, because only 1 to 2 years of growth occurred since

cutting BASAL

was started.

20 Table 5.—Net effects to the stands from cutting levels and mortality factors

Trees per acre

by

Trees Killed

Before Number

Treatment Residual

cut cut MPB' Comandra

7inchcut

12inchcut

1633 769 2157 1132 3430 2290

132 1108 634

0 0.10 0

015

56

19 treecut Checkarea

2140 1140 1960 0

30 60 1253 0

=

Mountain pine beetle.

Pityogenes, and Pityokteines

50 28

0.03

11

9%

0 07

84.90 90.76 88.66

99.70 183.12

7 inch 12inch 100 leave- check

tree

CUTTING BLOCKS Figure 2.— Residual basal area of cutting blocks.

0.06

0.05

100- leave- tree (IN) 10 inch

+

#### GROWTH

RADIAL

7 inch

AVERAGE

| i | 1 | 1 | \| | \| | \| |
|---|---|---|---|---|---|
| 1972 | RES | 74 | 75 | ‘76 | mn |

YEAR

Figure 3.—Average radial growth of stand per year for last 10 years by cutting block.

-----

DISCUSSION

Having seen the immediate results

levels, the question

now is of the future of

with respect to the activity of the beetle development. The harvest

level of loss somewhat proportionally,

resume killing trees at the

ment or has a change been induced

infestation? To project

mortality trend data were used in the Rate of

(Cole and McGregor, in press) to

future tree loss and number of tion (fig. 4).

50 — of the cutting

these stands, and stand levels reduced the current but will the beetle

same ratio as before treatin the course of the

to

an answer this question, these

Loss Model

predict the rate of

years of such an infesta-

KILLED

ACRE

PER

TREES

PREDICTED

1980 1990 2010

YEAR OF KILL

Figure trees per acre killed by mountain pine

beetle, postharvest by cutting levels.

-----

This projection showed that the infestation within the check area should peak in 1981, with 46.9 trees killed per

acre 19 per ha), and subside to 1.1 trees per acre 0.44

per ha) by 1989, tailing to 0.02 tree per acre 0.008 per ha) by 1993. The diameter-limit cuts reduced the peak loss

rather proportionally to the extent of cutting; for example, peak kill was greater in the 12-inch (30.48-cm) cuts

than in the 7-inch (17.78-cm) cuts. The expected length of infestation changed accordingly, with the longest period of outbreak expected for the 7-inch (17.78-cm) cut. The

exception was the 100-leave-tree cut. This cut extended

the predicted life of the infestation to the year 2012, with

peak tree loss of only 1.5 trees per acre 0.61 per ha) in

the year 1993 (table 6).

Table 6.—Predicted peak loss, length of infestation, and annual

drain from the mountain pine beetle by cutting level

(trees per acre)

Peak Peak Years of Total Annual

Treatment

loss infestation loss drain

year

| Check area | 46.9 | 1981 | 14 | 180.5 | 129 |
|---|---|---|---|---|---|
| 12-inch cut | 21 | 1981 | 18 | 80.1 | 4.4 |
| 10-inch cut | 103 | 1982 | 26 | 62.5 | 24 |
| 7-inch cut | 123 | 1882 | 13 | 328 | 25 |

100-leavetree cut 15 1993 33 236 7

The 100-leave-tree cut, according to these predictions, would reduce tree loss from the mountain pine beetle to alow amount. This cut would also be advantageous in

reducing or minimizing dwarf mistletoe occurrence (Wicker 1967; Wicker and Shaw 1967). Once the area is

reseeded and the regeneration height exceeds snow

depth, the leave trees should be removed. The small target area of the regeneration, the washing action of the snow in removing dwarf mistletoe seeds, and the young

stand being immune to the mountain pine beetle may well be the keys to producing a healthy new stand of

lodgepole pine.

SUMMARY

The demonstration area on which diameter-limit and leave-tree cuts were applied to reduce or minimize lodgepole pine losses to the mountain pine beetle was evaluated the first year after cutting. First-year losses were reduced proportionally to the intensity of cut. Projected losses and continuation of the mountain pine

beetle infestation were derived from the predictive Rate of Loss Model. The best deterrent of recurring infestation—amount of losses and length of time—was the 100-leave-tree cut. The 100-leave-tree cut also was the best in encouraging regeneration and reducing dwarf mistletoe infection.

-----

PUBLICATIONS CITED

Cahill, Donn B. Cutting strategies as control measures

of the mountain pine beetle in lodgepole pine in Colorado. In: Berryman, Alan A; Amman, Gene D.; Stark, Ronald W., tech. eds. Theory and practice of mountain

pine beetle management in lodgepole pine forests: symposium proceedings; 1978 April 25-27; Pullman,

WA. Moscow, ID: University of Idaho, Forest, Wildlife and Range Experiment Station; 1978: 188-191.

Cole, Walter E.; Cahill, Donn B. Cutting strategies can

reduce probabilities of mountain pine beetle epidemics in lodgepole pine. J. For. 74: 294-297; 1976.

Cole, Walter E.; McGregor, Mark D. Estimating the rate

and amount of tree loss from a mountain pine beetle infestation. In press.

McGregor, Mark D.; Cole, Walter E. Harvesting strategies for management of mountain pine beetle infestations in lodgepole pine. In press.

Wicker, Ed F. Seed destiny as a klendusic factor of infection and its impact upon propagation of

Arceuthobium spp. Phytopathology. 57(11): 1164-1168;

1967.

Wicker, Ed F.; Shaw, C. Gardner. Target a

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The Intermountain Station, headquartered in Ogden, Utah, is one of eight regional experiment stations charged with providing scientific knowledge to help resource managers meet human needs and

protect forest and range ecosystems.

The Intermountain Station includes the States of Montana, Idaho, Utah, Nevada, and western Wyoming. About 231 million acres, or 85 percent, of the land area in the Station territory are classified as forest and rangeland. These lands include grasslands, deserts, shrublands, alpine areas, and well-stocked forests. They supply fiber for forest industries; minerals for energy and industrial development; and water for domestic and industrial consumption. They also provide recreation opportunities for millions

of visitors each year. Field programs and research work units of the Station are maintained in:

Boise, Idaho

Bozeman, Montana (in cooperation with Montana State

University)

Logan, Utah (in cooperation with Utah State University)

Missoula, Montana (in cooperation with the University

of Montana)

Moscow, Idaho (in cooperation with the University of

Idaho)

Provo, Utah (in cooperation with Brigham Young University)

Reno, Nevada (in cooperation with the University of

Nevada)

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77 US GOVERNMENT PRINTING OFFICE: REGIONNO.