Should ponderosa pine be planted on lodgepole pine sites?

Historic, archived document

Do not assume content reflects current
scientific knowledge, policies, or practices.

SS
faniny United States
‘x2, Department of
Aa) Agriculture

7,
See

Forest Service

Pacific Northwest
Forest and Range
Experiment Station

Research Note
PNW-419
December 1984

STAI

‘Abstract

Introduction

Should Ponderosa Pine
Be Planted on
Lodgepole Pine Sites?

7 P. H. Cochran

Repeated radiation frosts caused no apparent harm to the
majority of lodgepole pine (Pinus contorta Dougl.) seedlings
planted on a pumice flat in south-central Oregon. For most but
not all of the ponderosa pine (Pinus ponderosa Dougl.)
seedlings planted with the lodgepole pine, however, damage from
radiation frost resulted in reduced height growth.

Keywords: Radiation frost, pumice soil, lodgepole pine, Pinus
contorta, ponderosa pine, Pinus ponderosa.

In the pumice soil region of south-central Oregon, lodgepole
pine (Pinus contorta Dougl.) usually occurs in pure stands on
flats and basins, where cold air accumulates at night, whereas
ponderosa pine (Pinus ponderosa Laws.) dominates the adjacent
higher ground. Stand boundaries are often abrupt, coinciding
with slight changes in topography. Reasons for this distri-
bution pattern include superior frost tolerance of developing
lodgepole pine cones (Sorenson and Miles 1974) and germinants
(Cochran and Berntsen 1973) over ponderosa pine cones and
germinants.

Occasionally lodgepole pine stands on level topography have an
understory of younger ponderosa pine. Modification of the low
temperature extremes at the soil surface by the lodgepole
canopy probably allowed the ponderosa pine to become estab-
lished. A few scattered mature ponderosa pines do exist in
some lodgepole pine flats. These ponderosa pine trees are much
Older and taller than the lodgepole pine and may have started
as understory trees beneath an earlier lodgepole pine stand.

P. H. COCHRAN iS a soil scientist, Silviculture Laboratory,
Pacific Northwest Forest and Range Experiment Station,
1027 N. W. Trenton Ave., Bend, Oregon 97701.

Further Comparisons

Table 1--Differences in height of lodgepole and ponderosa
pines in four “frost pocket” locations in south-central Oregon,
fall 1974

Range in height

Year

ponderosa Planted Natural
pine ponderosa lodgepole
Site Location Elevation planted pine pine
Feet Feet Feet
Snow Creek Sl/2 sec. 10,
Vo 440 Sos Ro f3 1B. 4,545 1934 8.0-15.0 26.0-33.0
Pipeline flat Sl/2 sec. 2,
Vo 25 Sog Ro 13 fe. 4,460 1963 1.5- 5.0 8.0-15.0
Shevlin well NW1/4 sec. 20,
Wo 23 Sog Rho 9 [Eo 5,025 1955 6.5-10.0 20.0-33.0
Shevlin yard NW1/4 sec. 20,
Vo 43 Sag Wo ©) les 5,150 1955 2.5- 6.5 11.5-13.0

planting dates for ponderosa pine were obtained from USDA Forest Service records or
estimated from ring counts of tree sections taken at ground line. Lodgepole pine at each
site was 2 or 3 years younger than the ponderosa pine, indicating that 2-0 or 3-0
ponderosa pine stock was planted.

Planted seedlings do not germinate on the site or need to
produce cones. Further, the frost resistance of 2-0 or larger
seedlings of either species is thougnt to be high, provided the
dormancy cycle has been correctly managed in the nursery (Cleary
and others 1978). Therefore, practicing foresters periodically
inquire about the possibility of planting ponderosa pine
seedlings in clearcuts on flats and basins previously occupied
by lodgepole pine. Such plantings have been attempted in
several locations, but lodgepole pine has seeded in, overtopping
the ponderosa pine (table 1). Where ponderosa pine seedlings
Survive, they are deformed or severely suppressed; frost damage
to the needles is apparent during some growing seasons.

This paper presents further exploratory comparisons of the early
development of ponderosa and lodgepole pine seedlings planted
together on soils developing from Mazama pumice. Care should

be taken in extrapolating the results to other soils and areas.

For the locations shown in table 1, the ponderosa seed source
is unknown and may not be adapted to the site. Would the
performance of ponderosa pine from appropriate seed sources be
satisfactory? To partially answer this question, we planted
100 ponderosa pine and 100 lodgepole pine seedlings inter-
changeably at a 12- by 12-foot spacing on a "pumice flat"
surrounded by lodgepole pine (NW1/4 sec. 31, T. 22 S., R. 11
E., Willamette meridian). Elevation of the area is 4,120
feet. The soil is an ashy over loamy, mixed Typic Cryorthent.

Early juvenile growth of lodgepole pine has been considered
superior to that of ponderosa pine on comparable sites. We
decided to compare differences in growth rates on the pumice
flat with growth rates of the two species planted earlier on
sloping topography nearby. Seed collected from the plantation
Site, 7.3 air miles west of tne flat, was germinated in the
greenhouse in the spring. The seedlings were kept in the
greenhouse until mid-winter when the greenhouse temperature was
slowly lowered to match outside temperatures. Next the seed-
lings were taken outside, then planted interchangeably in April
on a 6-percent slope with a west-southwest aspect. The soil at
this plantation is very similar to the soil of the pumice flat.

After six growing seasons in the plantation, over 300 undamaged
seedlings of each species remained. The lodgepole pine seed-
lings averaged 2.7 feet in height, and the ponderosa pine
seedlings averaged 2 feet. For the seedlings surviving after
Six growing seasons on the pumice flat at the end of 1983,
average heights were:

First planting Second planting
Lodgepole pine Lodgepole pine
2.4 feet 2.4 feet
Ponderosa pine Ponderosa pine
1.2 feet 0.96 feet

At the end of 1983, 8 of the 27 surviving ponderosa pine from
the first planting and 8 of the 35 surviving from the second
planting in the pumice flat resembled stunted bushes and
appeared damaged from repeated radiation frosts. None of the
lodgepole pine trees displayed reduced height growth that
seemed related to radiation frost damage. Two of the ponderosa
pines from the first planting were over 6.6 feet tall, and an
additional nine trees appeared to be healthy and have been
growing over 8 inches a year. Eight of the 35 ponderosa pines
from the second planting also appeared fairly resistant to
frost damage and may grow to size suitable for harvest.

Most of the mortality for both plantings on the flat has been
Caused by pocket gophers (Thomomys spp.). A few trees have
also been destroyed by porcupines (Erethizon dorsatum Linn.).
There is no indication that pocket gophers or porcupines prefer
one species over the other. Crouch (1971) also noted no differ-
ence in the susceptibility of ponderosa and lodgepole pines to
pocket gophers. Some of the trees, primarily lodgepole pine,
have been attacked by the lodgepole pine terminal weevil
(Pissodes terminalis Hopping); but in every case, a lateral
branch replaced the destroyed terminal, and the height develop-
ment of the tree appeared to be reduced slightly, if at all.

20

Lodgepole pine

95%-percent

Confidence limit

Height growth, cm/yr
Height growth, in./yr

a Ponderosa pine

as :

0
1976 1977 1978 1979 1980 1981 1982 1983 1984

Year

Figure 2.--Height growth per year for
lodgepole and ponderosa pine seedlings
planted in April 1975.

To obtain another comparison of species performance, we
alternately planted 100 2-0 seedlings of each species at a

12- by 12-foot spacing in the spring 1975, on the pumice flat
adjacent to the plantation established 4 years earlier. The
seed came from zones compatible with this planting site; the
seedlings were raised in the Bend Pine Nursery. A severe frost
(17 °F minimum temperature in a standard weather shelter at the
site) on June 19, 1975, caused no apparent harm to lodgepole
pine seedlings, but there was obvious damage to 52 of the
ponderosa pine seedlings. Height growth for 1975 was not
measured. At the end ot 1983, only 35 ponderosa and 40
lodgepole pine seedlings remained. Average heights of the
Surviving lodgepole and ponderosa pine seedlings were 5.2 feet
and 1.9 feet, respectively, in the fall 1983, and height growth
rates for this second planting have been significantly
different since 1976 (fig. 2).

20

Lodgepole pine

Height growth, cm/yr
Height growth, in./yr

95%-percent Ponderosa pine
Confidence limit

iy

0
1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984
Year
Figure 1.--Height growth per year for
lodgepole and ponderosa pine seedlings
planted in April 1971.

The 3-0 ponderosa pine stock was raised in the Bend Pine Nursery
of tne USDA Forest Service, 28 air miles from the planting site;
seed had been collected at the 4,000-foot elevation within 18
miles of the planting site. Lodgepole pine seedlings were
obtained from roadsides within 10 miles of the planting site
because nursery seedlings were not available. The planting was
done over a 2-day period in April 1971. Average height growth
for the first growing season (fig. 1) was slightly greater for
ponderosa pine, possibly because of the nursery fertilization
program. From 1972 through 1983, however, height growth of
lodgepole pine was superior. At the end of 1983, the 60
Surviving pee enove pines averaged y feet in height,
Significantly’ taller than the 3.9-foot average for the 27
Surviving ponderosa pines. Of the surviving ponderosa pine
trees, none was taller than tne average height of the lodgepole
pine trees. Height growth rates, however, have accelerated
with time: 11 of the 27 ponderosa pine trees grew more than 8
inches in 1983, although the best height growth of ponderosa
pine was not equal to the average height growth of the

lodgepole pine.

lUse of the word "Significantly" in
this note means that a t test has been
applied using a 5-percent level of
probability to accept or reject
differences as real.

Conclusions Ponderosa pine planted on flats and basins in the pumice soil
region of south-central Oregon will suffer varying degrees of
radiation frost damage. Some of the trees will be so severely
damaged they will not grow to salable size in a reasonable
length of time. Most ponderosa pine trees will exhibit reduced
growth rates because of repeated frost damage, but some of the
trees may grow normally.

The data and observations presented nere indicate that pumice-
mantled flats and basins should be managed for lodgepole pine.
Because a small percentage of ponderosa pine seems to be
resistant to radiation frost, some seedlings could be planted
on flats and basins. The scattered ponderosa pine trees
existing in some of the flats might provide a seed source for
tne planting stock. These plantings could establish a
potential future source of seed for geneticists to use in
developing ponderosa pine that is more resistant to low

temperatures.
Metric Equivalents 1] inch = 2.54 centimeters
1 foot = 0.30 meter
| mile = 1.61 kilometers
HE Slee) (SC) a 32
Literature Cited Cleary, Brian D.; Greaves, Robert D.; Owston, Peyton W.

Seedlings. In: Cleary, Brian D.; Greaves, Robert D.; Hermann,
Richard K., comps., eds. Regenerating Oregon's forests: a
guide for the regeneration forester. Corvallis, OR: Oregon
State University Extension Service; 1978: 63-98.

Cochran, P. H.; Berntsen, Carl M. Tolerance of lodgepole and
ponderosa pine seedlings to low night temperatures. Forest
Science. 19(4): 272-280; 1973.

Crouch, Glenn L. Susceptibility of ponderosa, Jeffrey, and
lodgepole pines to pocket gophers. Northwest Science. 45(4):
252-256; 1971.

Sorensen, Frank C.; Miles, Richard S. Differential frost
tolerance of ponderosa and lodgepole pine megasporangiate
strobili. Forest Science. 20(4): 377-378; 1974.