$=-t) United States

$#& Department of

Agriculture

Experiment Station

Research Note

so-343

December 1997

Planted Hardwood Development on Clay Soil

Without Weed Control Through 16 Years

Roger M. Krinard and Harvey E. Kennedy, Jr.

SUMMARY

Average survival at age 16 was determined for five

hardwood species that received no weed control after

planting at lo- by 1 O-foot spacing on cleared Sharkey

clay soil. The average survival rates, in percent, were:

sweetgum (Liquidambar styraciflua L.), 35; cottonwood

(fopulus delfoides Bartr. ex Marsh.), 45; Nuttall oak

(Quercus nuttalli Palmer) and sycamore (Platanus occidentalis L.), 81; and green ash (Fraxinus pennsylvanica Marsh.), 96. Corresponding average heights, in

feet, were: 25, 41, 20, 29, and 27.

Additional keywords: Cottonwood (Populus deltoides), sycamore (Platanus occidentalis), green ash

(Fraxinuspennsylvanica), sweetgum (Liquidambarstyraciflua), Nuttall oak (Quercus nuttallii), sweet pecan

(Carya illinoensis).

INTRODUCTION

General recommendations for hardwood plantings

are to use good seedlings on well-prepared, suitable

sites with at least first-year weed control. What happens to plantings when no weed control is done except

for initial site preparation? Little information is available on such plantation development with minimal

vegetative control. This note presents survival and

d.b.h. and height information for 16-year-old trees on

Sharkey clay soil which never had the benefits of weed

control after planting.

METHODS

This study was located in the Delta Experimental

Forest near Stoneville, Mississippi. The slackwater

area was cleared of trees, raked and disked prior to

planting before the 1971 growing season.

Species planted were cottonwood (CW --Popu/us

deltoides Bartr. ex Marsh.), sycamore (SY -flatanus

occidentalis L.) green ash (GA - Fraxinus pennsylvanica Marsh.) sweetgum (SG - Liquidambar styraciflua L.), Nuttall oak (NO -Quercusnuttallii Palmer),

and sweet pecan (SP -Carya illinoensis (Wangenh.)

K. Koch). One-year-old nursery grown seedlings or

20-inch-long CW cuttings were used.

No weed control was one of three control treatments. The other two treatments were disking and

mowing. All three treatments were in a split-plot design

with six blocks. Species subplots consisted of 4-

column by 6-row plantings (24 trees) on a lo-foot

spacing. Each CW row contained a separate Stoneville

clone: 66,67, 78,82,213, or 244.

Because of interest in possibly increasing tree

growth, all species except SP were thinned in disked

plots and CW, SY, and GA were thinned in mowed

plots after 5 years. Mowing and disking treatments

were maintained through 10 years and trees were

remeasured after 15 years. Those results were published (Krinard and Kennedy 1987). This note presents

the 16-year remeasurement of the study’s check trees,

which had been measured the last previous time at 4

years after planting (Kennedy 1981). Contrasts between means were tested at the 0.05 level using

Duncan’s multiple range test.

RESULTS

At age 2, mean survival without weed control ranged

from 65 percent for SP to 99 percent for GA (table 1).

Two years later survival of SP was down 8 percentage

points, and CW and NO were each down 5 percentage

Southern Forest Experiment Stationn-102lO U.S. Postal Services Bldg., 701 Loyola Avenue, New Orleans, La. 70113

Forest Service, U.S. Department of Agriculture.

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

1
Table l.-Average survival and height at ages 2, 4, and 16 and average d.b.h. at age 16 with

no weed control

Species’

Age 2 Age 4 Age 16

Survival Height Survival Height Silrvival Height D.b.h

% ff % ff % ff i n

CW 76bcdz 6.6a 71 bed 10.3a 45b 41.3a 5.5a

SY a4ab 4.6b a4ab 6.9b ala 29.1 b 3.3b

GA 99a 4.7b 9aa 7.8b 96a 27.3b 3.0b

S G 69cd 2.4~ 69cd 4.4c 35b 25.lb 3.2t.

NO 65bc 1.6cd 80bc 3.0cd ala 19.7c 1.9c

SP 65d 0.8d 57d 1.5d . ..3

- -

’ Species: CW = cottonwood; SY = sycamore; GA= green ash; SG = sweetgum; NO = Nuttall oak; SP

= sweet pecan.

*Means in column followed bv same letter are not significantly different at the 0.05 level by

Duncan’s multiple range test. .

3Not measured.

points; the. other three species were unchanged.

Twelve years later, at age 16, SY, GA, and NO survivals

were essentially unchanged from year 4, and ranged

from 81 to 96 percent. CW and SG survival had greatly

decreased, to 45 and 35 percent, respectively. At the 5

percent level of significance, GA = SY = NO > CW =

SG. SP survival at age 16 could not be reliably

determined because of the number of water hickory

(Carya aquatica (Michx. f.) Nutt.) sprouts in some

situations. However, the SP survival rate was thought

to be very low because of the absence of any Carya

spp. stems in some plots where SP had occurred at age

4. SP was more “off-site”than the other species with an

estimated midrange site index of 80 feet compared to

85 feet for GA, 90 feet for SY, SG and NO, and 95 feet

for CW (Broadfoot 1976).

survival), compared to 54 percent survival at age 4. As

natural regeneration covered the study area these two

plots became mainly a GA thicket in one case and a

water hickory stand in the other. Best SG survival was

71 percent, down from 83 percent at age 4.

The individual NO, SY, and GA plots have had fairly

consistent survival, from 75 to 100 percent, except for

the one SY plot that has maintained 33 percent survival

since the second year.

Survival among CW clones was not significantly

different on the unweeded sites although mean clonal

survival ranged from 38 to 58 percent. From two to four

replications of each clone had only one or no surviving

stem. Stem cankers of Septoria, Phomopsis, and

fusarium spp. were noticeable on some surviving

trees. These cankers had played a part in the mortality

as evidenced by the 15 stems of 4-to-8-inch diameter

that had broken off 3 to 16 feet above the ground. The

best surviving CW plot had 71 percent survival; poorest

surviving plot had 17 percent survival.

Average tree height at age 16, to the nearest foot,

was 41,29,27,25 and 20 feet, for CW > SY = GA = SG

=- NO, at the 5 percent level of significance. At age 4

the relationship was similar except SG was less than

SY and GA. The tallest tree measured per plot varied

from 41 to 60 feet for CW, 31 to 41 feet for SY, 30 to 41

feet for GA, 16 to 34 feet for SG, and 23 to 35 feet for

NO. CW clones did not differ in height even though

clonal means varied from 34 to 48 feet.

In the mixture of planted trees and natural regeneration that developed over the years, there were no

suppressed CW and no dominant SG and NO at age 16

(table 2). While nearly half of the NO were supressed,

the same percentage of SY and GA were dominantcodominant and only 10 percent suppressed. Of the

454 trees planted per acre, 28 percent of CW were

dominant or codominant, 37 percent of SY, 45 percent

of GA and 12 percent of each of SG and NO.

Stem cankers, mainly Botryosphaeria ribis, were On the basis of crown class, all intermediate CW

also noted on SG. Twenty-four percent of the living SG were intermediate to other planted CW. Three-fourths

had brown leaves and nearly dead stems and/or of the stems that were taller than intermediate planted

cankers when measured in the fall after the 16th trees of species other than CW or suppressed planted

growing season. One SG plot had no living stems at trees were some combination of natural GA, natural

age 16, compared to62 percent survival at age4, while CW, water hickory, and the planted species itself.

another plot had only one nearly dead tree (4 percent Other overtopping species included natural NO, natuRoger M. Krinard is mensurationist and Harvey E. Kennedy, Jr., is principal silviculturist at the Southern Hardwoods Laboratory, maintained at

Stoneville, Mississippi, by the Southern Forest Experiment Station, USDA Forest Service, in cooperation with the Mississippi Agricultural and Forestry Experiment Station and the Southern Hardwood Forest Research Group.

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Table 2.-Planted trees per acre, (percent of trees), and average d.6.h. and height by species and crown class at age 16 with no weed control.

Crown Class

Dominant Codominant

.-___-

Intermediate Suppressed

Species’ T/A* (Pct)3 D.b.h. Height T/A (Pet) D.b.h. Height T/A (Pet) D.b.h. Height T/A (Pet) D.b.h. Height

% i n ft % i n ff % i n ft % i n ft

c w 4 8 (24) 7.1 49.5 7 3 (37) 5.2 40.6 7 6 (39) 4.2 34.2 . . . . . . . . . . . .

SY 6 (2) 5.1 38.5 157 3.8 32.4 151 2.7 26.1 3 9 1.8 19.7

GA 1 2 (3) 4.0 33.5 182 ’

(44) (43) (11)

(44) 3.5 29.6 185 (44) 2.8 26.1 3 9 (9) 1.8 18.1

S G . . . . . . . . . . 5 4 (35) 3.8 29.4 8 5 (55) 3.1 24.6 1 5 (10) 2.8 18.7

NO . . . . . . . . 5 4 (15) 2.9 25.9 136 (39) 2.2 22.0 163 (46) 1.3 16.4

1 Species: CW = cottonwood; SY = sycamore; GA = green ash; SG = sweetgum; NO = Nuttall oak.

2 Trees/acre.

3 Percent of trees within a species.

ral SG, American elm (Ulmus americana L.) black

willow (S&ix nigra Marsh.) boxelder (her negundo

L.), honeylocust (Gleditsia triacanthos L.) persimmon

(Diospyros virginiana L.), red maple (Acer rubrum L.),

roughleaf dogwood (Corms drummondii C. A. Meyer),

sugarberry (Celtis laevigata Willd.), and willow oak

- (Quercus phellos L.).

DISCUSSION

When hardwoods are planted without weed control

on cleared clay soils, some species are better able to

survive and compete than others. In this test SY, GA,

and NO survival was 80+ percent, and the trees grew

fairly well through 16 years. A growth comparison may

be made between trees that received weed control

treatments (Krinard and Kennedy 1987) and those that

did not. The 163 SY and 194 GA dominant-codominant

trees per acre averaged 5 and 6 feet shorter, respectively, at age 16 than the 109 trees per acre of the same

species in disk and mow plots at age 15. Unthinned NO,

which was mowed for 5 years and either mowed or

disked for the next 5 years, averaged 83 percent survival

and 24 feet in height at age 15, compared to 81 percent

and 20 feet in 16 years for NO with no weed control.

CW and SG, two species that did not do well without

weed control, had less than 50 percent survival in 16

years and low vigor. Height of lgyear-old dominantcodominant CW was 16 feet shorter than thinned,

disked, or mowed trees after 15 years. Unthinned SG

that received weed control for 10 years averaged 76

percent survival and 28 feet tall at age 15, in contrast to

35 percent and 25 feet at age 16 for SG without weed

control. Neither CW nor SG showed low vigor and

accompanying canker problems where thinned after 5

years and where vegetation was controlled through 10

years.

The planting area for the study was intensively site

prepared prior to planting in preparation for random

assignment of weed control treatments, and thus some

vegetative control was obtained at that time. All planting survival may therefore have fared better than on

sites simply sheared and the debris pushed to one side,

and some sprout development eliminated because of

root-stump destruction. Conversely, disking and resulting bare soil exposure may have been responsible

for the greater than expected natural CW establishment

and the black willow. At age 4 survival ranged from 91

percent for disked plots to 80 percent for mowed plots

to 76 percent for check plots. In spite of the site

preparation, the area has come back to be well stocked

to the expected slackwater site species of mainly GA

and water hickory, along with a mixture of 8 to 10 other

species.

At age 16 there seems to be sufficient numbers of

dominant and codominant planted SY and GA to be

components of the future stand without any management steps required. On these sites GA naturally

reproduces without need for planting. Obviously, the

oaks can sustain themselves and more than sufficient

numbers of codominants and intermediates exist to

assure an oak component in the sawtimber stand.

However, if oaks are to be favored, the option is

available to do some release for better distribution of

free-to-grow trees.

Some hardwood species may be planted on cleared

clay soils without followup weed control, and adequate

survival and growth through 16years may beexpected.

However, it would appear that at least 1 year of weed

control, considering the cost of clearing already invested, would be the prudent thing to do because all the

species can be grown where weeds are controlled. This

information would have no bearing at all on planting old

fields with clay soils without weed control because of

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an entirely different set of grass and weed conditions.

On this study’s cleared site, competition to the planted

trees appears to have mainly come from other tree

species and vines rather than from grass and broadleaved weeds.

LITERATURE CITED

Broadfoot, Walter M. 1976. Hardwood suitability for and

properties of important Midsouth soils. Res. Pap.

SO-127. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment

Station. 84 p.

Kennedy, Harvey E., Jr. 1981. Foliar nutrient concentrations and hardwood growth influenced by cultural

treatments. Plant and Soil. 63: 307-316.

Krinard, Roger M.; Kennedy, Harvey E., Jr. 1987. Fifteenyear growth of six planted hardwood species on

Sharkey clay soil. Res. Note SO-336. New Orleans,

LA: U.S. Department of Agriculture, Forest Service,

Southern Forest Experiment Station. 4 p.