United States

.>=$I Department of

w Argriculture

0

cg Forest Service Research Note

XV”- Southern Forest

Experiment Station

so-303

December 1983

Ten-Year Growth of Five Planted Hardwood Species

Mechanical Weed Control on Sharkey Clay Soil

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

SUMMARY METHODS

Five hardwood species planted on Sharkey clay soil

showed little practical difference in growth whether plots

were mowed or disked for weed control in years 6 to 10,

although disking had given better growth in the first 5

years. After 10 years, cottonwood (Populus deltoides

Bartr. ex Marsh.) stem volume was at least three times

greater than other species. Changes in soil nutrient properties were similar for mowing and disking.

Additional keywords: Fraxinus pennsylvanica, Liquidambar styraciflua, Platanus occidentalis, Populus deltoides, Quercus nuttallii.

INTRODUCTION

Clearing and planting hardwoods on slackwater sites

in the Midsouth, though high in initial cost, IS an alternative for rejuvenating cutover and depleted stands and for

introducing desired species on given sites. As production

on these sites is less than on medium-textured sites and

offers poorer economic returns, practices leading to

improvement in tree growth are desirable. Weed control,

along with tree release by thinning, has been suggested.

This note provides growth data on planted hardwood

trees through 10 years where original planting spacing

was doubled after 5 years by selective thinning and

where some competition control was given yearly. Soil

properties before planting were also compared with

those after 5 and 10 years.

With

The study area was a flat site on the Delta Experimental Forest, a slackwater area near Stoneville, Mississippi.

The site had been forested before clearing and planting

in 1971. Soil is Sharkey clay.

Species planted were cottonwood (CW-Populus deltoides Bartr. ex Marsh.), sycamore (SY-flatanus occidentalis L.), green ash (GA-Fraxinus pennsylvanica

Marsh.), sweetgum (SG-Liquidambar styraciflua L.),

and Nuttall oak (NO-Quercus nuttalh Palmer). Estimated mid-range site index values for these species on

Sharkey clay are 9.5 feet for CW (30 years), 90 feet for SY,

SG, and NO, and 8.5 feet for GA (all 50 years) (Broadfoot

1976).

Trees were planted in a split-plot design with six blocks

(replications). Species subplots consisted of a 6- by 4-row

planting (24 trees) on a IO-foot spacing. Plots were

mowed (M5) or disked (D5) three to five times annually

the first 5 years.

After the 5th year, species subplots with 80 percent or

more survival for trees more than 4.5 feet tall were

thinned to six trees each, or an equivalent 20- by 20-foot

spacing. Sweetgum and Nuttall oak were not considered

in analysis of M5 plots as 5th-year survival was 50 percent or less. For thinning, subplots were subdivided into

squares of four trees each and one tree per square was

selected to maintain spacing over a subplot. Mowing

(MlO) or disking (DlO) treatments, one to three times

annually, for the next 5 years were randomly assigned to

whole blocks. Diagrammatically, treatment and species

for the first two blocks were as follows:

Southern Forest Experiment Station/T-10ZlO 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
Block 1: Ml0

D.5 SGjGAlCWlSY INO]

SY IX.IGAICWI

Block 2: DlO

~51s~ I?S.~GA~CW~?VQ

~SICWINO/GAISGISY

Thus, there were three replications of mowing or disking for years 6 through 10 for five species disked the first

5 years and for three species mowed the first 5 years.

Yearly height and dbh measurements were made. Soil

moisture readings were taken several times each growing season from 12 soil moisture tubes-two per block or

one per mowing/disking combination. A cornposited soil

sample was also taken across each mowing/disking’

combination before planting and after the 5th and 10th

years. Content of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), organic matter

(OM), and pH were determined.

Tree volumes were calculated from measurements of

samples of cut trees after the 5th year-30 to 37 trees per

species-and from standing trees with a Barr and Stroud

dendrometer’ after the 10th year-20 trees each for CW,

SY, and GA, and 10 trees each for SG and NO. Total

stem volume outside bark (V) equations, based on dbh

(D) and total height(H), were:

CW: V=O.1856+0.002074 D*H, r2=0.997,

S,,=O.203, v=2.91

SY: V=O.1046+0.002435 D*H, r2=0.989,

s,,=o.1oo,v=o.92

GA: V=0.1120+0.002180 D*H, r*=0.993,

s,,=o.o73, v=o.75

SG: V = 0.0791 + 0.002247 D*H, r2 = 0.993,

s, x = 0.037, v= 0.29

NO: V=O.O616+0.002452 D2H, r*=0.987,

S, X = 0.045, v = 0.28

Analyses of variance were tested at the 0.05 level.

Duncan’s multiple range test was used to compare

means.

RESULTS

Tree Growth

At age 5, disked CW was significantly larger in height,

dbh, and volume than all other species-treatment combinations Mowed CW and disked SY and GA were similar,

as were mowed SY and GA and disked SG and NO.

‘Mention of a trade name does not constitute a warranty of the product

by the U.S. Department of Agriculture or an endorsement by the

Department over other products not mentioned.

For the 6th- through 1 Oth-year period, height and dbh

growth was greatest with CW-M5, (table 1). Averaged

over all species, disking in years 6 through 10 provided

significant though very slight increases in height and

diameter growth but did not affect volume growth.

At age 10, CW did not differ in height, dbh, or volume

regardless of weed control treatment, and was greater

than all other species. Generally, SY was equal to GA and

SG to NO in height and dbh.

Overall height growth through 10 years was from 1.7

to 4.9 feet per year, depending on species-treatment

combination. The annual height growth values are comparable to or slightly greater than the mean annual height

increment obtained from the estimated site index values.

For volume production, CW is still far ahead of the

other species. After 5 years, whether mowed or disked,

CW produced two to three times the volume of the next

fastest growing species, and this difference increased to

three to four timesafter 10 years. ‘.x

Soil Moisture

Moisture tube readings nearest the middle of each

month from May to September of each year were used to

characterize growing season moisture conditions. Yearly

rainfall, as a factor in tree growth, was considered from

January through September.

Cultural treatments from the 6th through 10th years

had no effects on soil moisture; the same trend in years 1

through 4 was reported earlier (Kennedy 1981). Averaged over years, moisture was highest in May and

became progressively lower, with lowest measurements

usually recorded in September. From May to September,

average moisture values decreased from 41 to 32 percent on the surface, 51 to 41 percent at l- and 2-foot

depths, and 50 to 44 percent at 3- and 4-foot depths.

Yearly rainfall was above average 4 of the first 5 years

and 3 of the second 5 years.

Soil Properties

After 5 years there was no difference in N, K, and Ca

levels, compared to values before planting, whether plots

were mowed or disked (table 2). Both treatments significantly reduced Mg and lowered pH, whereas disking

increased P but lessened OM.

The only significant difference between 5- and 1 O-year

soil values was an increase in Mg, but there was no difference within 5-year values and no difference within loyear values by treatments.

Roger M. Krinard is Mensurationist and Harvey E. Kennedy, Jr., IS Prlnclpal Sllviculturist at the Southern Hardwoods Laboratory, maintained at Stoneville, Mlssisslppi, by the Southern Forest Experiment Statlon, Forest Service-USDA, in cooperation with the Mississippi Agricultural and Forestry

Experiment Station and the Southern Hardwood Forest Research Group.

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Table 1 .-Growth of five species in 6th through 10th year compared with 5th.year average, by cultural

treatment

Specres and

treatment1 Height

Frfth year

Dbh Volume

Sixth/tenth year growth

Height Dbh Volume

n

16.6

16.8

in

2.3

2.2

ft’

0.4

0.4

26.9a 4.3a 1.2a

20.6b 2.9b 0.5bc

179b 2.5b 0.4cd

10.4d 1.2d O.le

8.9d l.ld O.le

19.9b 2.9b 0.6b

13.lc

14.7c

1.4cd 0.2de

1.8~ 0.2de

ft in ftJ

All specres, avg.

D5 and M5, DlO

D5 and M5, Ml0

Cottonwood

D5

D5, DlO

D5, Ml0

Sycamore

D5

05, DlO

D5, Ml0

Green ash

D5

D5. DlO

D5, Ml0

Sweetgum

D5

D5, DlO

05, Ml0

Nuttall oak

05

D5, DlO

D5, Ml0

Cottonwood

M5

M5, DlO

M5, Ml0

Sycamore

M5

M5, DlO

M5. Ml0

Green ash

M5

M5, DlO

M5, Ml0

1 5.2az 3.4a

13.9b 2.8b

2.6 .,

2.1

22.1 b 4.2b 65a

21.5b 4.0bc 6.la

10.6cd 2.8efg 2.lb

9.Od 2.0gh

13.0cd 3.2cde

1.4b

2.lb

10.5Cb’ 2.2fgh

,”

1 1 .6cd ‘.:, 2.6efgh

l.lb

0.7b

ll.Oc! 2.2fgh

9.4cd 2.5efgh

8.4d 1.9h

27.8a 5.la

25.2ab 4.3b

13.0cd 3.3cde

13.0cd 2.8efg

13.8~ 3.6bcd

12.5cd 3.0def

0.5b

0.8b

0.3b

5.9a

5.la

1.4b

1 .Ob

1.6b

1.4b

‘Treatments were disk or mow in years 1 to 5 (D5 or M5) and years 6 to 10 (DlO or Ml 0).

‘Means in same part of same column (that is, above or below dashed line) followed by same letter are not

significantly drfferent from each other (P = 0.05) by Duncan’s multiple range test.

Table 2.-Prep/ant, 5th.year and 10th.year soil chemical levels, pH, and

oraanlc matter IOM) by cultural treatment

DISCUSSION AND CONCLUSIONS

Year and

Treatment’

Height and diameter growth differences between

mowing and disking for weed control in the 6th through

10th year were minimal. Growth of species in years 6 to

10, with disking or mowing, suggested that disking neither injured tree roots in a fashion to hinder growth nor

was especially beneficial in increasing growth. As mowing showed no advantage over no weed control for the

first 4 years (Kennedy 1981) and there was so little difference between mowing and disking the second 5 years,

weed control beyond the 5th year does not seem warranted on these soils.

If weed control is not needed beyond 5 years, how

N P K Ca Mg pH OM

wm %

1316 6.0 3.6

% pm wm wm

Preplant 0 172 46 439 5697

5th year

M5

D5

10th year

M5-Ml0

M5-DlO

D5-Ml0

D5-DlO

,188 53 412 5642 1079 5.6 3.2

,162 61 432 5692 1120 5.6 2.7

,179 43 404 5857 1213 5.4 3.4

,203 47 433 5920 1280 55 3.1

,153 46 420 5963 1322 5.5 3.0

,173 53 423 5949 1244 5.5 2.9

‘Treatments were disk or mow in years 1 to 5 (D5 or M5) and years 6 to

lO(DlOorMl0).

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long should it be maintained for individual species, and

what are the differences between disking and mowing?

Answers are not readily discernible in this study. Elsewhere, for CW plantations, intensive first-year cultivation

on good sites is recommended (McKnight 1970), while

on old-field clay soils disking gave better survival and

growth than mowing (Krinard 1964). Also for CW plantings, summer fallowing before planting on medium-textured, old-field sites-which reduced the johnsongrass

(Sorghum halepense (L.) Pers.) component-increased

1styear survival, but 2nd.year cultivation provided no

long-term benefits (Francis 1982). Sycamore plantations

with high survival have been established without weed

control measures, but clean cultivation gave most consistent high survival and best height growth (Briscoe 1969).

A cultural treatment guideline inferred from this study

for hardwood plantation establishment on clay sites

would be to expend the greatest effort in the 1 st year for

weed control by disking for greatest survival and to give

the plantation the best possible start. Second- and 3rd.

year disking would tend to optimize early growth, but,

practically, would obtain only another 1 to 1% feet a year

in height. Growing conditions and weed competition

would be influencing factors.

Considering costs of plantation establishment and the

growth obtained, hardwood planting on heavy clay soils

may be a disappointing investment if timber growth is the

only consideration. Expenditures on better sites are a

much better investment, as the lo-year-old CW and SY

are only about 55 to 60 percent as tall as plantings on

medium-textured sites (Krinard and Johnson 1975,

Schlaegel 1981). Even dominant trees in a nearby 1 lyear-old natural stand on clay soil (Krinard and Johnson

1981) were 70 percent (GA) to 90 percent (NO) as tall as

the planted trees.

The main benefit from planting on Sharkey clay soils

may well be in putting given species where they are

wanted. An alternative to planting other than natural regeneration would be direct seeding, but only NO of the five

species in this study is a likely candidate (Johnson 1981).

LITERATURE CITED

Briscoe, C. B. Establishment and early care of sycamore

plantations. Res. Pap. SO50,‘New Orleans, LA: US.

Department of Agriculture, Forest Service, Southern

Forest Experiment Station; 1969. 18 p.

Broadfoot, Walter M. 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;

1976.84 p.

Francis, John K. Fallowing of cottonwood plantations:

Benefits carry to rotation’s end. in: Zavitkovski, Jerry,

and Hansen, Edward A., eds. Proc., 19th annual

North American Poplar Council meeting; 1982 July

20 - 22; Rhinelander, WI. [Sponsored by Poplar Council of North America and North Central Forest Experiment Station.] Manhattan, KS: Kansas State University; 1982: 1 - 7.

Johnson, R. L. Oak seeding-it can work. South. J. Appl.

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

Kennedy, Harvey E., Jr. Foliar nutrient concentrations

and hardwood growth influenced by cultural treatments. Plant a$ Soil 63: 307 - 316; 1981.

Krinard, R. M. Weed control trials in cottonwood plantations. Inf. Sheet 854, Mississippi State, MS: Miss.

Agric. and For. Exp. Stn., Mississippi State University;

1964. 2 p.

Krinard, R. M.; Johnson, R. L. Description and yields of

an 1 l-year-old hardwood stand on Sharkey clay soil.

Res. Note SO-265, New Orleans, LA: U.S. Department

of Agriculture, Forest Service, Southern Forest Experiment Station; 1981. 2 p.

Krinard, R. M.; Johnson, R. L. Ten-year results in a cottonwood plantation spacing study. Res. Pap. SO-106,

New Orleans, LA: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station;

1975.10 p.

McKnight, J. S. Planting cottonwood cuttings for timber

production in the South. Res. Pap. SO-60, New

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

Service, Southern Forest Experiment Station; 1970. 17

P.

Schlaegel, Bryce E. Sycamore plantation growth: IO-year

results of spacing trials. In: Barnett, James P., ed.

Proc., first biennial southern silvicultural research conference; 1980 Nov. 6 - 7; Atlanta, GA. Gen. Tech.

Rep. SO-34. New Orleans, LA: US. Department of

Agriculture, Forest Service, Southern Forest Experiment Station; 1981. 149 - 155.

*u.s. GOVERNMENT PRINTING OFFICE: 1983-769-089:6

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