7

United States

G@% Department of

‘?!f& Argriculture

Forest Service

Southern Forest

Experiment Station

Nuttall Oak Direct Seedings Still Successful After 11 Years

Robert L. Johnson

SUMMARY

Forty-five hundred acorns of Nuttall oak (Quercus nut-

&//ii Palmer) were either machine or manually sown at 2-,

4-, or 6-inch depths in a 20-acre, intensively site-prepared

clearing within the Delta Experimental Forest located

near Stoneville, Mississippi. Field germination averaged

36 percent; no significant differences in germination

appeared among seeding methods or sowing depths.

After 11 years, two-thirds of the Nuttall oaks, or 551 per

acre, were free-to-grow: they averaged 2.1 inches dbh

and 16.7 feet tall.

Additional keywords: Quercus nuttallii, sowing,

seeding regeneration.

INTRODUCTION

Direct seeding is an attractive option for artificially

regenerating Nuttall oak (Quercus nutfallii Palmer). Fieldsowing acorns requires less time, effort, and expense

than producing and outplanting seedlings; Most oak

seeding efforts have failed, however, because rodents

dig and destroy the acorns. Rodents were not a major

problem in the successful test reported here.

METHODS

The study area, a Sharkey clay flat located on the Delta

Experimental Forest, was disked in July and August 1970

following a commercial timber harvest and mechanical

clearing. Five separate blocks were delineated within the

20-acre area. Each block contained nine 200-foot-long

rows spaced 10 feet apart. At random, each row was

assigned one combination of three sowing depths, 2, 4,

or 6 inches, with one of three sowing methods, machine

seeding, manual seeding in flat ground, and manual

seeding in mounds. Experimental design was a randomized complete block, with testing at 0.05 level.

Nuttall oak acorns were collected in November 1970

from several parent trees located near the study area.

Defective acorns were discarded following a series of

float tests. Sound acorns were stored dry at 35 to 40°F

until January 1971, then submerged in water until

sowing time.

Machine seeding required one person to operate the

tractor and another to ride a tractor-mounted unit and

drop acorns into rows made wit0 a 2-inch wide subsoiler

blade. Row depth was regulated with gauge wheels.

Simple hand tools, a conduit pipe, a plunger with handle, and an adjustable foot piece, assured uniform sowing depth. Six-inch high mounds were constructed with a

tractor-pulled, two-gang disk ridger.

One hundred acorns per row were sown in April 1971

at approximately 2-foot spacings (2178 acorns per acre).

Ten-foot strips between rows were mowed once during

the lst, 2nd, 9th, lOth, and 11 th years. Above-ground

germination was checked 12 times during the first year,

and seedling heights were taken at the end of the year. In

February 1982, 1 l-year-old Nuttalls were measured for

height, dbh, and classed as dominant (D), codominant

(C), intermediate (I), or suppressed (S). D/C trees of species other than Nuttall were also measured for height and

dbh. For the remainder of this report D/C Nuttall oaks will

be referred to as free-to-grow.

RESULTS

First seedlings appeared in early May from acorns

sown 2 inches deep. Seedlings from 6-inch deep acorns

were delayed about 2 weeks. By mid-June germination

Southern Forest Experiment Station/l-10210 U.S. Postal Services Bldg., 701 Loyola Avenue, New Orleans, La. 70113

Forest Bervice, U.S. Department of Agriculture.

Serving Alabama, Arkansas, Louisiana, Mississippi, E. Oklahoma, Tennessee, E. Texas, Puerto RICO, U.S. Virgin Islands

1
was approximately half complete across all treatments. A

month later three-fourths of the total crop had appeared.

Shallow-sown acorns were most susceptible to rodent

damage that occurred soon after sowing. Although

apparently less than 1 in 10 acorns were destroyed by

rodents, reliable damage estimates were difficult because

clearly visible digging did not always mean loss of seed.

Some seeds were exposed but not injured.

Field germination ranged from 27 to 41 percent,

depending on treatment. Transformed field germination

percentages were not significantly different among treatments and there were no interactions. Averaged over

depths, field germination percentages were 32, 38, and

38 for machine, manual, and manual in mounds, respectively. Combined over sowing methods, field germination

for 2-, 4-, and 6-inch depths were 38,35, and 35 percent.

Overall, 96 percent of the f-year-old trees were still

alive after 11 years, and no significant differences

showed in survival among treatments.

Figure 1 .---Row of 1 l-year-old direct-seeded Nuttall oaks on clay soil

near Sfoneville, Mississippi.

About one-third of the 11 -year-old Nuttalls were o\Jertopped partially or completely; the other 898 trees were

free-to-grow. The latter averaged 2.0 inches dbh, sd 0.6,

and 16.7 feet tall, sd 2.6. Largest free-to-grow trees were

between 3 and 4 inches dbh and 20 and 25 feet tall.

Vines were common to the test site, but few trees were

seriously deformed (fig. 1).

Growth of the Nuttall in this test parallels closely that

from another study on the Delta Experimental Forest

(Johnson 1981). On the same soil type and under similar

environmental conditions, the largest 1 O-year-old directseeded Nuttall, one from each of 162 rows, averaged 1.8

inches dbh and 17.8 feet tall.

Intra-row spacing of free-to-grow Nuttall oaks averaged 7.9 feet, equivalent to 551 trees per acre at lo-foot

spacing between rows. Average dbh of free-to-grow

trees within a row ranged from 1.6 to 2.8 inches; diameter

decreased as total number of trees within a row

increased.

Main non-oak competitors within direct-seeded rows

were green ash (fraxinus pennsylvanica Marsh.), cottonwood (Populus deltoides Bartr. ex Marsh.), sugarberry

(Celtis laevigata Willd.), sweetgum (Liquidambar styraciflua L.), American elm (Ulmus americana L.), persimmon

(Diospyros virginiana L.), and water hickory (Carya aquatica Michx f. Nutt.). Except for two 6-inch dbh, 35-foot tall

cottonwoods, largest non-oaks were about the same size

as the free-to-grow NuttaIls.

DISCUSSION AND CONCLUSIONS

This study and others (Johnson 1981) show Nuttall

oak can be successfully regenerated through direct

seeding of viable acorns selected by a combination of

float tests and visual checks. Seeding depths may vary

from 2 to 6 inches, with the 2-inch depth giving faster

germination and the 6-inch depth a little more protection

from rodents.

Successful seeding can be achieved if severe rodent

damage can be avoided. A relationship seems apparent

between rodent damage and the amount of forest cover.

Where oak seeding has been tried under a forest canopy,

a very high ,percentage of the acorns have been

destroyed. In 2-acre or larger forest openings where

there has been complete stand removal, seeding has

been successful and rodent damage insignificant.

Nuttall direct seeding is recommended on suitable

sites where all commercial trees have been harvested

and the remainder either cut, sheared, or choppedcombinations used on many National Forests and some

Robert L. Johnson is Principal Silviculturist at the Southern Hardwoods Laboratory, maintained at Stoneville, Mississippi, by the Southern Forest Experimen\ Station. Forest Service-USDA, in cooperation with the Mississippi Agricultural and Forestry Experiment Station and the Southern Hardwood

For-Research Group.
industrial lands. The impact of rodents on seeding under

various stocking levels of deadened, but standing, trees

is not yet determined.

Assuming sound acorns, a field germination percentage of between 30 and 40 appears attainable. Although

a high percentage of l-year-old trees should survive

through 10 years, many will be suppressed under sprout

clumps of competing species. Considering acorn germination and subsequent tree survival and growth, a seeding rate of up to 1500 acorns or 500 well-spaced seed

spots per acre should be adequate for most management objectives. Three acorns should be sown about 1

foot apart at each seed spot.

Spring sowing was used in this test, but sowing in the

fall following seed collection has also been successful.

Working conditions normally are much better in the fall

because Nuttall oak sites are frequently very wet in the

spring. Fall sowing avoids storing and stratifying.

Extended flooding from January through April has no

adverse effect on germination of Nuttall oak acorns; in

fact, there is evidence that it will help.

Height growth of Nuttall oak trees starting from seed

appears comparable over the first 10 years to that of 1-O

planted stock or <2-foot tall natural regeneration. On

clay soils all three average about IV2 to 2 feet of annual

height growth when free-to-grow (Johnson 1975,. Krinard

and Kennedy 1981). Such growth is less than that of

some associated species; however, Nuttall appears more

competitive than most associates.

LITERATURE CITED

P

3,‘

\;

Johnson, Robert L. Natural regeneration and $evelopment of Nuttall oak and associated species. Res. Pap.

SO-104, New Orleans, LA: U.S. Department{of Agriculture, Forest Service, Southern Forest Exeeriment

Station; 1975. 12 p.

Johnson, R. L. Oak seeding-it can work. S0uth.k. Appl.

For. 5(l): 28 - 33; 1981.

Krinard, R. M.; Kennedy, H. E., Jr. Growth and yields of

5year-old planted hardwoods on Sharkey day soil.

Res. Note SO-271, New Orleans, LA: U.S. Department

of Agriculture, Forest Service, Southern Forest Experiment Station; 1981.3 p.

*U.S. GOVERNMENT PRINTING OFFICE: 1983-769-oa9:4

3