I

@

United States

Department of

Agriculture

Forest Service

Southern Forest

Research Note

SO-320

Experiment Station December 1985

Sprouting of Slash, Loblolly, and Shortleaf Pines

Following a Simulated Precommercial Thinning

T. E. Campbell

SUMMARY

To prevent cut stumps of 4- to 7-year-old slash (finus

elliotiii Engelm.) and loblolly (f. taeda L.) pines from

resprouting, precommercial thinnings should be done in

late summer at 6 inches or less above the groundline.

For shortleaf pine (P. echinata Mill.), late summer and 6

inches or less appears safe but should be delayed at

least until age 5 years.

INTRODUCTION

Natural or direct-seeded stands of southern pines are

often overstocked and need precommercial thinning to

prevent a serious reduction in growth of crop trees. But

some species, notably shortleaf (Pinus echinata Mill.)

and Virginia (P. virginiana Mill.), are prolific sprouters

when cut above the groundline. Such a situation can

easily negate a thinning operation. Numerous inquiries

on the problem in the early 1970’s prompted an investigation on how best to prevent resprouting following precommercial thinning. A study was initiated to determine

the effects of age at cutting, season of cutting, and height

of cutting on resprouting of three principle Midsouth species.

PROCEDURES

Slash (f. elliottii Engelm.), loblolly (f. taeda L.), and

shortleaf pines were direct-seeded in rows to make the

evaluation. Three replications were sown in successive

years, beginning in March 1975, 1976, and 1977 for

blocks 1,2, and 3 respectively. Sowing within each replication was done in 5 successive years so that several

age classes could be cut at the same time. Thus, the last

sowing would be done on the third replication in March

1981. Plans were to cut at ages 2, 3, 4, 5, and 6 years

from seed, to cut in September and February, and to cut

all three species at 2 and 6 inches above the groundline

plus cutting shortleaf at the groundline. The five age

classes on block 1 would be cut in September 1980 and

February 1981, on block 2 in September 1981 and

February 1982, and on block 3 In September 1982 and

February 1983. Statistical analysis would determine the

effects of age, season, and height of cutting on sprouting, and any interactions that might occur. Species

would be analyzed separately and not be compared.

Plans were rendered statistically invalid by an incendiary fire on December 25, 1980. All of the first replication

and more than half the second replication were destroyed. However, because the remaining portion of the

study could produce some general information that

might be useful, all of block 3 and the remaining portion

of block 2 were cut to specifications in September 1982

and February 1983. The trees available for cutting in

block 2 were 1 year older than the planned cutting age.

This note reports the results.

RESULTS AND DISCUSSION

Slash Pine

Precommercially thinning 4-to -I-year-old slash pine in

September and cutting it up to 6 inches in height did not

result in any substantial amounts of sprouting (table 1).

Southern Forest Experlment Station/T-10210 U.S. Postal Services Bldg., 701 Loyola Avenue, New Orleans, La. 7Oll3

Forest Service, U.S. Department of Agriculture.

Serving Alabama, Arkansas, Louisiana, Mlsslsslppl, E. Oklahoma, Tennessee, E. Texas, Puerto Rico, U.S. Virgin Islands
Table 1 .-Living sprouts on slash pine at five observations following a simulated precommercial thinning by age, season, and height of cutting

Age

from

Date

of

Height

of Sprouting observed on

seed cutting cutting 2/l 6163 4/l 6163 6/l 4163 2/l I64 6/l 3165

years mo/yr

4 9162

2163

5 9162

2163

6 9162

2l63

7 9162

2l63

inches

2

6

2

6

2

6

2

6

2

6

2

6

2

6

2

6

0

0

. . . . . . 2

0

. . . . . .

. . . .

0

0

. . . . . .

. . . . . .

0

0

. . . . . .

. . . . . .

._________ percent _______________________

0 0 0 0

0 0 0 0

30 23 15 15

56 56 14 14

0 0 0 0

0 0 0 0

10 6 0 0

24 16 4 4

0 0 0 0

0 0 0 0

3 3 0 0

11 3 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

However, sprouting is likely to occur from cutting in

February under the age of 6 years, and a substantial

surviving, and no sprouting at age 7. But about one-third

proportion of the sprouts can be expected to survive.

of the 6-inch cuts sprouted in both years, and half the

sprouts survived.

Mann and Lohreyl recommend thinning at about age

3 years when trees are large enough to be easily seen

but small enough to be cut with light machinery. The

results of this study indicate that such an early thinning

should be made before the beginning of fall dormancy.

Though cutting at age 3 was not possible here, the data

suggest that the younger the slash pine, the more susceptible to sprouting when cut in the dormant season.

Cutting at age 4 in February at 2 and 6 inches resulted

in 30 and 58 percent sprouting, respectively, within 8

weeks after cutting. Half the sprouts from 2 inches and

a third from 6 inches were still alive and healthy 2 years

later.

Shortleaf Pine

Precommercially thinning 4-year-old shortleaf should

be done late in the active growing season, and it should

be cut as close to the ground as possible (table 3). Even

then, 48 percent in this study sprouted, but none survived. All the 4-year-olds cut at 2 and 6 inches sprouted,

with 40 and 60 percent surviving. For 5 and 6-year-olds,

it appears that a precommercial thinning should also be

done late in the growing season, but cut at a height of 6

inches. Although sprouting was prolific, none survived

longer than 7 months.

Loblolly Pine SUMMARY

This species responded much the same as did slash

pine-no sprouting from a September cut and a trend to

decrease sprouting as age increased for a February cut

(table 2). The most surprising occurrence with loblolly,

however, was the difference in sprouting response between 2- and 6-inch cuts in February at ages 6 and 7. At

2 inches, there was minimal sproutng at age 6 with none

‘Mann, W. F., Jr; and Lohrey, R. E. Precommercial thinning of southern pines. J. For. 72 (9): 557-560; 1974.

Results garnered from the remnants of this study were

not surprising, with the possible exception of the sprouting response in 4-year-old slash pine. It was generally

believed that slash sprouting was not a problem. Loblolly

was known to sprout to some degree but was not thought

to be troublesome. Though there was some sprouting

from February cutting at all ages, the only ones surviving

2 years were from 6-inch cuts. Precommercially thinning

shortleaf late in the active growing season at age 5 or 6

years and cutting at 6 inches in height presents the best

possibility for success.

T. E. Campbell is Principal Silviculturist, USDA Forest Service, Southern Forest Experiment Station, Pineville, LA 71360.

2
Table 2.-Living sprouts on loblolly pine at five observations folowing a simulated precommercial

thinning by age, season, and height of cutting

Age Date

from of

seed cutting

Height

of

cutting 2/l 6183

Sprouting observed on

416l83 6/i 4183 2/l/84 6/13/85

years mo/yr inches ---___---______-----___ percent ----_-__--_-----_------

4 9182 2 0 0 0 0 0

6 0 0 0 0 0

2183 2 . . . . . . 5 4 17 0 0

6 . . . . . . 5 5 3 2 2 3 2 0

5 9182 2 0 0 0 0 0

6 0 0 0 0 0

2183 2 . . . . . . 2 9 2 5 0 0

6 . . . . . . 2 2 12 2 2

6 9182 2 0 0 0 0 0

6 0 0 0 0 0

2183 2 . . . . . . 7 7 0 0

6 . . . . . . 2 9 2 4 14 14

7 9182 2 0 0 0 0 0

6 0 0 0 0 0

2l83 2 ..*... 0 0 0 0

6 . . . . . . 3 5 2 9 18 18

Table 3.-living sprouts on shortleaf pine at five observations following a simulated precommercial

thinning by age, season, and height of cuffing

Age

from

seed

Date

of

cutting

Height

of

cutting 2M6l83

Sprouting observed on

4/l 6183 6/l 4183 2/l/84 6/l 3185

years mo/yr inches _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ percent _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

4 9182 0

2

6

2/83 0

2

6

5 9182 0

2

6

2183 0

2

6

6 9182 0

2

6

2183 0

2

6

4 8

100

100

. . . .

. . . .

. . . .

5 4

9 0

8 7

. . . .

. . . .

. . . .

4 6

6 4

8 5

. . . .

. . . .

3 0 0 0 0

4 0 4 0 4 0 4 0

6 0 6 0 6 0 6 0

7 8 7 0 6 1 6 1

100 9 5 9 5 9 5

100 100 9 2 9 2

8 8 4 0

2 5 5 5 5

8 0 0 0

7 2 9 6 7 6 7 6

9 6 9 6 6 4 6 4

100 100 8 4 8 4

15 15 15 8

7 0 0 0

0 0 0 0

5 5 5 5 6 4 6 4

6 9 6 9 4 6 4 6

100 100 6 9 6 9