United States

Department of

Agriculture

Forest Service

Response of Competing

Vegetation to Site Preparation

Southern Forest

Experiment Station on West Gulf Coastal Plain

New Orleans, Commercial Forest Land

Louisiana

General Technical Report

SO-116

September 1995

Gale L. Wolters, Henry A. Pearson, Ronald E. Thill,

V. Clark Baldwin, and Alton Martin, Jr.
SUMMARY

The response of woody and herbaceous vegetation to site preparation, subsoil texture, and fertilization was measured on the West

Gulf Coastal Plain. The influences of these treatments on competing vegetation were short-term. Drastic soil disturbance and

fertilization briefly increased herbage production. Shear-windrow

and shear-disk were generally the most effective methods to control early shrub density, height, and crown cover. Seven years after treatment, however, shrub and sapling densities were

unrelated to treatments.

ACKNOWLEDGMENTS

We gratefully acknowledge Boise Cascade; Cavenham Forest

Industries, Inc.; Georgia-Pacific Corporation; International Paper Company; Manville Forest Products Corporation; T.L. James

and Company, Inc.; Willamette Industries; and the USDA Forest

Service, Kisatchie National Forest, for providing suggestions, land,

equipment, and labor throughout the study. We also acknowledge

the USDA Natural Resource Conservation Service for suggestions

in soil classification and site selection; the Louisiana Department

of Agriculture and Forestry, Office of Forestry, for providing uniform loblolly pine seedlings; and numerous USDA Forest Service,

Southern Forest Experiment Station, employees who contributed

to this study. We also thank James D. Haywood, James H. Miller,

and Allan E. Tiarks of the Southern Station for their helpful review

comments and suggestions on earlier drafts of this document.
Response! of Competing Vegetation to Site Preparation

on West Gulf Coastal Plain Commercial Forest Land

Gale L. Wolters, Henry A. Pearson, Ronald E. Thill, V. Clark Baldwin, and Alton Martin, Jr.

INTRODUCTION

Land managers of the West Gulf Coastal Plain of

Louisiana and Arkansas routinely apply an array of

hardwood control techniques to improve the establishment and growth of planted loblolly pine (Pinus taedu

L.). Under proper environmental conditions, mechanical (e.g., shearing, chopping, and disking), chemical,

and fire treatments used singularly or in combination

provide the control necessary for pine regeneration

(Grano 1970, Slay and others 1987, Tiarks and

Haywood 1986, Trousdelll970, Trousdell and Langdon

1967). Cultural treatments are also frequently used

the first few years after planting to increase survival

and promote rapid growth of young pines (Schmidtling

1973, Tiarks and Haywood 1986). However, little information is available on the effects of site preparation and cultural treatments on associated understory

woody and herbaceous vegetation. This study was initiated to determine: (1) the response of saplings,

shrubs, and herbaceous vegetation to various mechanical, chemical, and burning treatments on soils common throughout the West Gulf Coastal Plain of

Louisiana, Arkansas, and Texas and (2) how fertilization affects understory vegetation response to site

preparation on these soils.

story consisted primarily of mixed loblolly and shortleaf pines, but proportions varied greatly (Walters and

Wilhite 1973). Hardwoods that commonly formed a

moderately dense midstory were blackgum, Nyssa

sylvatica Marsh.; flowering dogwood, Cornus florida

L.; mocker-nut hickory, Curya tomentosa (Pair.) Nutt.;

post oak, Quercus stellata Wangenh.; red maple, Acer

rubrum L.; southern red oak, Q. fulcata Michx.;

sweetgum, Liquidambar styraciflua L.; and white oak,

Q. alba L. Woody species common in the understory

included American beautyberry, CaZZicarpa americana

L.; blueberries, Vaccinium spp.; greenbriers, Smilux

spp.; hawthorns, Crataegus spp.; yaupon, IZex

uomitoria Ait.; and a mixture of small hardwood trees.

Little bluestem, Schizachyrium scoparium (Michx.)

Nash, was usually the main grass in forest openings.

Longleaf uniola, Chasmanthium sessiliflorium (Pair.)

Yates, and spike uniola, C. Zuxum (L.) Yates, were associated with little bluestem where the overstory was

moderately dense, and uniola species occurred in

nearly pure, although sparse, stands on heavily shaded

sites. Other grasses, legumes, and composites were

common but ordinarily produced little herbage.

Climate of the area is semihumid subtropical. The

frost-free season generally extends from mid-March

to mid-November, approximately 235 days. Annual

precipitation averages about 55 inches, more than ,3

Inches each month, and about 25 inches during the

April-September growing season. STUDY AREAAND METHODS

Study Area Soils

This study was conducted on commercial forest land

dispersed throughout the West Gulf Coastal Plain of

southern Arkansas and northwestern and west-central

Louisiana that had been managed for loblolly and

shortleaf pines (I? echinatu Mill.>. The dominant overThis study included five classes of soil ranging in

B-horizon texture from loam to clay. The series represented were primarily Boswell, Henry, Kirvin, Ruston,

and Sawyer. See Haywood and Burton (1990) for a

comprehensive description of these five soil series. The

Gale L. Wolters (retired) was a range scientist, U.S. Department OfAgriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station, Albuquerque, NM 87106; Henry A. Pearson (retired) was a range scientist, U.S. Department of Agriculture, Agricultural

Research Service, South Central Family Farm Research Center, Booneville, AR 72927; Ronald E. Thill is a research wildlife biologist, U.S.

Department of Agriculture, Forest Service, Southern Forest Experiment Station, Nacogdoches, TX 75962; V. Clark Baldwin and Alton

Martin, Jr., are forest biometrician and range technician, respectively, U.S. Department of Agriculture, Forest Service, Southern Forest

Experiment Station, Pineville, LA 71360.

1
A-horizon for all soils generally ranged from sandy to

silty loam.

Site-Preparation Treatments

Seven site-preparation treatments were tested on

each soil:

(1) Underplant-inject-plots were burned where

possible to reduce logging slash and residual live

plant material. Living hardwoods 21 inch in d.b.h.

were injected with 2,4-D [(2,4dichlorophenoxy) acetic acid] the spring after planting.

(2) Chop-burn-vegetation was chopped with a

crawler-tractor-drawn, rolling-drum chopper and

burned after fine fuels had dried.

(3) Chop-burn-disk-(hereafter referred to as

chop-disk) same as chop-burn except plots were

plowed with a crawler-tractor-drawn disk after

burning.

(4) Double-chop-vegetation was chopped with a

crawler-tractor-drawn, rolling-drum chopper and

then rechopped after several days to several weeks,

usually at a 90” angle to the initial chop.

(5) Shear-burn-a shearing blade mounted on a

crawler tractor was used to fell cull pine and hardwood trees; after all fine fuels had dried, the plots

were burned.

(6) Shear-windrow-cull pine and hardwood trees

were felled as with shear-burn, then piled into windrows with brush rakes.

(7) Shear-windrow-disk-(hereafter referred to as

shear-disk) same as shear-windrow except the

cleared area between windrows was cultivated with

a crawler-tractor-drawn disk.

Fertilization Treatments

Each site-preparation treatment was applied to rectangular 144- by 152-ft (0.51-acre) plots. Each treated

plot was then split into a 144-by 50-ft fertilized and a

144- by 102-ft control area. All fertilized split plots

received 150 lb/acre of P,O, triple superphosphate

(65.5 lb/acre phosphorus, P) surface broadcast before

pines were planted (Haywood and Burton 1990).

Site Description

Before site preparation, all merchantable timber

was harvested. Residual woody stems 21 inch in d.b.h.

averaged about 2,700 per acre with a total (nomnerchantable pine plus hardwood) basal area of 72 ft2/acre

(Wolters and others 1977). Due to extreme variation

in density and basal area of hardwoods on the upper

West Gulf Coastal Plain, study plots selected contained

at least 500 hardwood stems with 20 ft2/acre of basal

area before site preparation. Such stands generally

had been selectively cut for merchantable pines and

hardwoods and protected from fire.

Loblolly pines (l+O seedlings) were hand planted

on 6- by 8-ft spacings either the winter preceding herbicide injection of hardwoods or the winter after mechanical site preparation. One set of 35 plots planted

during the winter of 1970-71 was considered a replication; a second set (replication) was planted during

the winter of 1971-72, with a few of the second set

planted during the winter of 1972-73.

Vegetation Sampling

Ovendry weight of herbaceous plant material

(grasses, grasslikes, and forbs) was estimated in 20

quadrats 9.6 ft2 in size on each split plot using a

weight-estimate procedure (Pechanec and Pickford

1937). Density of shrubs (shrubs, vines, and hardwood

seedlings cl inch in d.b.h.) was ocularly estimated in

four O.Ol-acre circular quadrats on each split plot.

Height and crown cover of shrubs were also ocularly

estimated on these four quadrats. Production of herbaceous vegetation and density, height, and crown

cover of shrubs were sampled during fall of the first,

third, and seventh growing seasons after loblolly pine

seedlings were planted. Seven growing seasons after

planting loblolly pines, naturally regenerated sapling

(21 inch in d.b.h.) densities were sampled in four 0.025-

acre circular quadrats on each split plot. For ease of

discussion, saplings are separated into one of the following genera or groups: maples (Acer spp.), hickories (Curya spp.), oaks (Quercus spp.), conifers (Pinus

and Juniper-us spp.), gums (Liquidambar styraciflua

and Nyssa siZuaticu), other big-tree species (all other

species generally taller than 30 ft at maturity), and

small-tree species (all species generally less than 30

ft tall at maturity).

Experimental Design and Analysis

Data collected the first and third year after treatment were tested by analysis of variance for a completely randomized split-plot design with blocking by

year (P = 0.10). The data from replication two were

not available for analysis in year 7; thus, year 7 data

were tested only for main effects. Main effects were

separated using Scheffe’s Test (Steele and Torrie 1980)

at the O.lO-probability level.

RESULTS AND DISCUSSION

Site Preparation Effects

2
Herbaceous Plant Response.-Although herbage Haywood (1986) and Haywood and Tiarks (1990) reproduction varied greatly among treatments, differ- ported significantly greater survival of planted loblolly

ences were not significant within any year (table 1). pines with complete herb removal three times a year.

Herbage production remained high the third year af- Similar response to frequent cultivation was reported

ter treatment, but approached pretreatment levels in Mississippi (Schmidtling 1973) and Florida (Swindel

(Wolters and others 1977) by the seventh year. and others 1988).

Species composition changed greatly from the first

to the third year after treatment. Early sere forbs were

released by site-preparation disturbance and comprised about 75 percent of total herbage the first year

after treatment compared with less than 5 percent

before treatment (Wolters and others 1977). By year

3, perennial grasses and forbs comprised about 65

percent and 35 percent, respectively, of total herbage

production. Three years after treatment, forb production was significantly less on underplant-inject sites

than on the sites drastically disturbed by mechanical

treatment.

Abundance of herbaceous vegetation, particularly

forbs, apparently had little impact on survival and

early diameter growth of planted loblolly pines

(Haywood and Burton 1990). In fact, diameter and

density of 12-year-old loblolly pines were generally

greater on chop-disk and shear-burn, where forb production was greatest immediately following treatment,

than on underplant-inject. However, Tiarks and

Shrub Response.-Shear-disk provided the best

control of shrub density, height, and crown cover the

first 3 years after treatment, although differences

among other treatments were generally not significant (table 1). DeWit and Terry (1983) also reported

that shear and pile treatment reduced hardwood

sprouting more than treatments where hardwood

rootstocks were left intact. Shear-disk and chop-disk

also resulted in the best loblolly pine regeneration

(Haywood and Burton 1990). Shrub density, height,

and crown diameter were similar on all site-preparation treatments after seven growing seasons.

Sapling Response.-Total sapling density was not

influenced by site-preparation method seven growing

seasons after treatment (table 2). Large variation

among species within methods apparently masked

treatment responses. Even though differences were

not significant, sapling density ranged from a high of

847 per acre on underplant-inject to a low of 435 per

acre on double-chop sites. Pehl and Bailey (1983) also

Table l.- Herbage and shrub response to seven site-preparation methods 1, 3, and 7 years after

treatment

Site-preparation method

Plant variable

and year after Underplant Chop- Chop- Double- Shear- Shear- Shearsite preparation inject burn disk chop burn windrow disk

----__________~ ___---------________----------- Lb/acre _________--------_______________________---

Herbage production

First year 1,582* 2,376 2,502 2,125 1,945 1,733 1,882

Third year 1,485 1,833 1,961 2,102 1,869 1,924 2,145

Seventh year 8 4 109 8 7 381 250 102 9 9

Shrub density

First year

Third year

Seventh year

--------------___------------------- ----- Number/acre _______----------------------------------

10,347ab 12,321a 7,229ab 7,550ab 8,786ab 8,295ab 5,329b

7,347ab 8,042a 5,400ab 6,186ab 5,745ab 5,354ab 4,679b

5,733 5,401 5,516 6,128 5,330 6,690 5,431

Shrub height

First year

Third year

Seventh year

-_---___________-_______________________-------- Ft _____--__________________________ _ -_____________

7.22a 5.01bc 4.28bc 4.llbcd 5.47abc 3.57cd 2.54d

14.87a 14.16a 10.87ab 10.94ab 11.75ab 8.88b 6.76b

26.21 24.38 21.23 16.95 21.60 22.30 18.19

Shrub crown diameter

First year 2.60a 2.18ab 1.82bc 1.67bc 1.83bc 1.63bc 1.22c

Third year 4.42a 4.39a 3.01ab 3.04ab 3.30ab 2.8413 2.19b

Seventh year 5.86 5.77 5.20 4.57 4.73 5.78 4.32

*Values within rows lacking letters or followed by the same letter are not significantly different (P = 0.10).

3
Table 2.- Effect of seven site-preparation methods on sapling density and basal area 7 years

after treatment

Site-preparation method

Species Underplant Chop- Chop- Double- Shear- Shear- Shear

group inject bum disk chop bum windrow disk

Maples

Hickories

O&S

Conifers

Gums

Other big trees?

Small tree&

Total density

Basal area

--___--------______--..---________.

71* 134

6 6 2 3

242 217

1 0

182 185

110 2 9

173 190

847 781

.--------- Number/acre _____________-__________________________---

6 3 15 4 0 3 7 5 1

1 1 8 4 1 7 1 5 5

9 9 103 178 158 101

2 0 7 9 7 123

127 134 221 226 134

6 9 3 1 4 3 6 1 2 5

246 144 179 6 7 114

603 435 720 717 606

---- -----------___--------------------------- Fe/acre __-______________-______________________------

13.7 11.4 6.8 5.5 11.0 8.6 8.4

*Values within rows are not significantly different (P = 0.10).

tAl1 other species generally taller than 30 R at maturity.

*All species generally less than 30 R tall at maturity.

reported fewer hardwood stems 21 inch in d.b.h. on

intensively prepared sites (disk and chop) 10 years

after planting than on the control. Double-chop may

be preferred in stands dominated by maples, hickories, oaks, and other big-tree species. On the other

hand, shear-windrow and shear-disk may favor natural regeneration of loblolly pines.

Sapling basal area was nearly twice as great on

underplant-inject, chop-burn, and shear-burn as on

chop-disk and double-chop 7 years after treatment,

but as with sapling density, these differences were not

significant (table 2).

Soil Effects

Herbaceous Plant Response.-The effects of subsoil texture on herbage production varied with time

(table 3). The first year after treatment, herbage production ranged from nearly 1,600 lb/ acre on gravelly

clay subsoil to about 2,400 lb/acre on loam, although

these differences are not significant. Two years later,

however, herbage production was significantly greater

on loam than on gravelly clay and silt. By the seventh

year, total herbage production had declined 75 to 95

percent on all soils.

Graminoid (grass and grasslike plants) production

was significantly greater on loam the first and third

years after treatment than on silty clay and clay,

whereas the opposite was true for forbs. But, by the

end of the seventh growing season, production of

grasses, forbs, and total herbage was greater on silty

clay than on loam. Nevertheless, loblolly pines became

better established on the more mesic, medium-tex4

P- ‘ ”

tured, silty clay subsoils than on well-drained loam,

gravelly clay, and silt (Haywood and Burton 1990).

Shrub Response.-Subsoil texture significantly

influenced density of shrubs the first three growing

seasons after site preparation (table 3), although densities the first growing season after treatment did not

differ greatly from pretreatment densities (Wolters

and others 1977). The early differences were probably

due to the amount of residual rootstock associated with

the various subsoil textures. However, by the seventh

year, shrub densities were similar across soil textures

due to natural mortality, particularly on gravelly clay,

but to a lesser extent on clay and silty clay subsoils.

Subsoil texture effects on shrub height and crown diameter were minor and insignificant. Seven years after treatment, shrub density, height, and crown

diameter were not influenced by subsoil texture.

The high density of shrubs on gravelly clay subsoil

during the critical establishment period may explain

why loblolly pine survival at age 12 was lowest for

this subsoil class (Haywood and Burton 1990). Gravelly clay subsoils are typically found on dry upper

slopes and ridgetops where herbage production is low

and where low loblolly pine survival would be expected.

It is also possible that low woody plant density the

first year after treatment on silty-clay and clay subsoils allowed greater loblolly pine establishment there

than on other subsoils.

Sapling Response .-Density of all sapling groups

was influenced by subsoil texture seven growing seasons after treatment (table 4). Before treatment, only

red maple, elms, and common persimmon were significantly influenced by subsoil, with silt subsoils support-
Table 3.- Herbage and shrub responses to five subsoil textures 1,3, and 7 years after treatment

Plant variable

and year after

treatment Loam

Gravelly

clay

Soil texture

Silt

Silty

clay Clay

Herbage production

First year

Third year

Seventh year

________________________________________- Lb lucre________________________________________-

2,374* 1,582 1,874 2,070 2,303

2,584a 1,544bc 1,305c 1,940abc 2,237ab

75b 56b 103ab 343a 218ab

Shrub density

First year

Third year

Seventh year

______________________________________ Number/acm ______________________________________

6,243b 11,188a 8,862a 8,257ab 7,906ab

5,134b 7,512a 6,346ab 5,912ab 5,325ab

5,629 5,732 7,377 5,320 4,670

Shrub height

First year

Third year

Seventh year

____-----_________--____________________------- f?t -_ _ _ _ _ _ --- _ _ _ _ _ _ _ _ _ _- _ - _ _ _ _ _ _ _ _ _ _ -- _ _ _ _ _ _ _ _ _ _ _ _

3.9Ob 4.11ab 5.23a 4.2Oab 5.30a

10.75 10.50 12.26 11.19 10.59

22.75 20.61 22.01 19.70 22.44

Shrub crown diameter

First year

Third year

Seventh year

1.58 1.82

2.6513 3.39ab

5.74 4.78

1.90 1.83 2.10

3.88a 3.28ab 3.2Oab

5.56 4.92 4.86

*Values within rows lacking letters or followed by the same letter are not significantly different (P = 0.10).

Table 4.- Effect offive subsoil textures on o!ensity and basal area of saplings 7 years after treatment

Soil texture

Species group Loam

Gravelly

clay Silt

Silty

clay Clay

Maples

Hickories

Oaks

Conifers

Gums

Other big trees?

Small trees*

Total density

163a*

14bc

330a

Ob

345a

126a

152ab

1,130a

,----__---- Stem density /acre _____.

78ab 12b

66ab 84a

132b 105b

Ob 153a

206b 94b

84ab 9b

301a 122ab

867ab 583bc

llb

6c

121b

Ob

82b

34b

79b

334c

.____--___

44b

23ab

lllb

3 b

153b

17b

144ab

500bc

Basal area

________________________________________-- Fp/acre ___---__________________________________-

18.4 15.1 8.0 4.0 5.6

*Values within rows lacking letters or followed by the same letter are not significantly different (P = 0.10).

tAl1 other species generally taller than 30 ft at maturity.

*All species generally less than 30 ft tall at maturity

5
ing more saplings than other soils (Walters and others

1977). After treatment, density of maples, oaks, gums,

other big-tree species, and total saplings was greater on

loam subsoil than on silt, silty clay, or clay subsoil. Hickories and pines generally were denser on silt subsoil and

were scarce to absent on silty clay subsoil.

Data did not permit testing to determine if sitepreparation methods were less effective on loam subsoils or if deciduous trees typically regenerate better

there. However, pretreatment data (Walters and others 1977) suggest that density of some woody species

varied greatly with subsoil texture. Thus, viable rootstock may have been more extensive on loam subsoils;

therefore, site-preparation methods may or may not

have been as effective in controlling hardwood regeneration on these subsoils.

Sapling basal area was not influenced by subsoil

texture even though basal area ranged from 4 ft2/acre

on silty clay to over 18 ft2/acre on loam subsoils. Large

within-soil variation may have masked true subsoil

differences.

Loblolly pine survival at age 12 (Haywood and Burton 1990) appeared to be inversely related to sapling

and sapling-plus-shrub density 7 years ,after treatment. For example, sapling and shrub densities were

lowest on clay and silty clay where the best survival

of loblolly pines was reported; survival of loblolly pines

was lower on loam, gravelly clay, and silt subsoils

where density of saplings and shrubs was greater.

Fertilization Effects

Herbaceous Plant Response.-Phosphorus significantly increased herbage production the first 3

years after application (table 5). Early sere forbs responded rapidly to fertilization and produced approximately 24 percent more on fertilized plots than on the

control plots the first year after application. Three

years after application, forbs were still producing more

on fertilized plots (770 lb/acre) than on the controls

(580 lb/acre), but graminoids had increased in importance and were producing about twice as much as

forbs. Herbage production diminished on both fertilized and control plots with time but was greater on

the control plots 7 years after treatment than on fertilized plots.

Swindel and others (1988) reported that fertilization alone can quintuple volume of southern pines at

age 4, and fertilization plus complete control of competing vegetation can produce a short-term tenfold

increase in pine volume on some sites. Tiarks and

Haywood (1986) and Shiver and others (1990) reported

that control of herbaceous vegetation significantly increased pine growth. The greater volume per tree and

larger d.b.h. of planted pines on fertilized sites after

12 years of growth (Haywood and Burton 1990) suggest that, even though herbage production was greater

on fertilized plots during the early years of establishment, herbaceous vegetation did not significantly impair loblolly pine establishment or growth.

Shrub Response.-Shrub density was not influenced by phosphorus fertilization (table 5). Height and

crown diameter were significantly greater on fertilized plots than on the controls 3 years after treatment,

but by the seventh year that advantage had disappeared. Wolters and Schmidtling (1975) also found that

shrub density and crown cover were greater on fertilized plots 12 years after treatment than on the control. Haywood and Burton (1990) reported fertilization

did benefit growth of planted loblolly pines.

Sapling Response.-Fertilization alone did not

influence total sapling density, density of sapling

groups, or total sapling basal area 7 years after treatment (table 6).

Interactions

Herbaceous Plant Response.-A few significant

interactions were identified that could have important

management implications.

First- and third-year average forb production was

greatest on fertilized clay sites and somewhat less on

fertilized loam, gravelly clay, silt, and silty clay subsoils, and still less on all nonfertilized subsoils. Interestingly, Tiarks and Haywood (1986) and Haywood and

Burton (1990) reported rapid loblolly pine tree growth

when phosphorus was applied to loam, gravelly clay,

and silty clay subsoils. Apparently, young loblolly pines

use supplemental phosphorus more effectively than

do forbs on some subsoils.

Total herbage production was greatest on loam subsoil 3 years after treatment. However, greatest herbage response to fertilization (25 percent) occurred on

clay subsoils.

Fertilizer x subsoil texture effects were somewhat

blurred 7 years after treatment. For example, forb

production, representing about one-third of the total

herbage, averaged less than 15 lb/acre on loam, gravelly clay, and silt subsoils and about 85 lb/acre on silty

clay, whether fertilized or not. Fertilizer seemed to have

a negative effect on clay subsoil, reducing forb production from more than 100 lb/acre to less than 40 lb/acre.

Shrub Response.-Significant site-preparation x

subsoil texture interactions also influenced shrub

height. Underplant-inject was generally least effective in controlling first-year shrub heights on nearly

all soils, especially clay. Shear-burn was least effective on silt soils. Thus, underplant-inject and

shear-burn should probably not be applied across subsoil textures if first-year shrub height is a concern.

Three years after treatment, shear-disk was the

most effective method for control of shrub height.

6
Table 5.-Herbage and shrub response to fertilization 1,3, and 7

years after treatment

Plant variable

and year after

treatment

Not

fertilized Fertilized

Herbage production

First year

Third year

Seventh year

Shrub density

First year

Third year

Seventh year

Shrub height

First year

Third year

Seventh year

Shrub crown diameter

First year

Third year

Seventh year

___________________LbIacre__________________

l,809b* 2,255a

1,794b 2,031a

192a 125b

_______________NumberIacre _______________

8,588 8,436

6,128 6,011

5,863 5,635

_____ __________________Ft ____________________--_

4.42 4.64

10.54b 11.60a

21.52 21.45

_______________________Ft _ ______________________

1.82 1.85

3.14b 3.43a

5.26 5.08

*Values within rows lacking letters or followed by the same letter are not significantly different (P = 0.10).

CONCLUSIONS

The response of most competing vegetation to site

preparation, fertilization, and subsoil texture appeared to be short-term. Neither a single treatment

nor a combination of treatments controlled all competing woody and herbaceous vegetation 1, 3, and 7

years after treatment. In fact, all combinations of overstory removal and site preparation actually stimulated

herbage production for a few years.

All site-preparation methods except underplant-inject significantly increased production of early seral

forbs. Shear-disk was the most effective treatment for

controlling density of shrubs up to 3 years after application. Most site-preparation methods reduced shrub

density, height growth, and crown diameter slightly

the first 3 years after treatment. Shear-disk was one

of the most effective methods, whereas underplantinject and chop-burn were generally ineffective.

Herbage production was generally lower on silt subsoil than on other subsoil textures the first 7 years

after site preparation. Early shrub reestablishment

was greatest on gravelly clay subsoil and minimal on

loam. Seven years after treatment, shrub and sapling

densities were greatest on silt and loam subsoils, respectively. Herbage production was greatest on silty

clay subsoil where sapling density was lowest. Although no single attribute limited the success of

loblolly pine regeneration, Haywood and Burton (1990)

reported greatest survival at age 12 on silty clay where

7-year herbage production was high and sapling density, low.

Fertilization significantly increased forb and total

herbage production up to 3 years after treatment.

Shrub height and crown diameter were also greater

on fertilized plots 3 years after application.

Fertilizer produced the greatest herbage response

on clay subsoil; production on other subsoils was only

minimally influenced. Site-preparation methods were

equally effective in controlling shrub height the first

year after treatment, except that shear-burn was ineffective on silt subsoil.

Phosphorus fertilization alone did not appear to increase shrub density, crown cover, or height growth

enough to create pine regeneration problems. Shrubs

were significantly taller 3 years after fertilization of

underplant-inject and shear-burn plots than on the

controls, but fertilization did not influence shrub

height growth on other site-preparation treatments.

The density of gums 21 inch in d.b.h. 7 years after

site preparation was greater on fertilized than on conTable 6.- Effect of fertilization on sapling density and basal

area 7 years after treatment

Species group

Not

fertilized Fertilized

Maples

Hickories

Oaks

Conifers

Gums

Other big trees?

Small tree&

Total density

------- ---- &em&n&y/acre ____________

60* 5 9

3 4 4 5

165 149

2 4 3 9

176 171

6 3 4 2

135 185

659 693

Basal area

-----________--___ Fpjacre _________________

9.8 10.6

*Values within rows lacking letters or followed by the same letter are not significantly different (P= 0.10).

+All other species generally taller than 30 ft at maturity.

OAll species generally less than 30 R tall at maturity.

trol gravelly clay and silt subsoils but not on any other

subsoils. Site preparation did not influence density or

basal area of saplings 7 years after treatment, but

subsoil texture did influence sapling density. Sapling

density was minimal on silty clay subsoil, where

Haywood and Burton (1990) observed maximum density of 12-year-old loblolly pine trees.
LITERATURE CITED

DeWit, James N.; Terry, Thomas A. 1983. Site preparation effects on early loblolly pine growth, hardwood

competition, and soil physical properties. In: Jones,

Earle P., Jr., ed. Proceedings of the 2nd biennial southern silvicultural research conference; 1982 November

4-5; Atlanta, GA. Gen. Tech. Rep. SE-24. Asheville,

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

Southeastern Forest Experiment Station: 40-47.

Grano, Charles X. 1970. Small hardwoods reduce

growth of pine overstory. Res. Pap. SO-55. New Orleans, LA: U.S. Department of Agriculture, Forest

Service, Southern Forest Experiment Station. 8 p.

Haywood, James D.; Burton, James D. 1990. Phosphorus fertilizer, soils, and site preparation influence loblolly pine productivity. New Forests. 3:

275-287.

Haywood, James D.; Tiarks, Allan E. 1990. Elevenyear results of fertilization, herbaceous, and woody

plant control in a loblolly pine plantation. Southern

Journal of Applied Forestry. 14(4): 173-177.

Pechanec, Joseph F.; Pickford, G.D. 1937. A weight

estimate method for determination of range or pasture production. Journal of American Society of

Agronomy. 29: 894-904.

Pehl, C.E.; Bailey, Robert L. 1983. Performance to age

ten of a loblolly pine plantation on an intensively

prepared site in the Georgia Piedmont. Forest Science. 29(l): 96-102.

Schmidtling, Ronald C. 1973. Intensive culture increases growth without affecting wood quality of

young southern pines. Canadian Journal of Forest

Research. 3(4): 565-573.

Shiver, Barry D.; Rheney, John W.; Oppenheimer,

Michael J. 1990. Site-preparation method and early

cultural treatments affect growth of flatwoods slash

pine plantations. Southern Journal of Applied Forestry. 14(4): 183-188.

Slay, J. Melinda; Lockaby, B.G.; Adams, J.C.; Vidrine,

C.G. 1987. Effects of site preparation on soil physical properties, growth of loblolly pine, and competing vegetation. Southern Journal ofApplied Forestry.

ll(2): 83-86.

Steele, Robert G.D.; Torrie, James H. 1980. Principles

and procedures of statistics: a biometrical approach.

2d ed. New York: McGraw-Hill. 633 p.

Swindel, Benee F.; Neary, Daniel G.; Comer-ford, Nicholas B. [and others]. 1988. Fertilization and competition control accelerate early southern pine growth

on flatwoods. Southern Journal ofApplied Forestry.

12(2): 116-121.

Tiarks, Allan E.; Haywood, James D. 1986. Pinus tuedu

L. response to fertilization, herbaceous plant control, and woody plant control. Forest Ecology and

Management. 14: 103-112.

Trousdell, Kenneth B. 1970. Disking and prescribed

burning: sixth-year residual effects on loblolly pine,

and competing vegetation. Res. Note SE-133.

Asheville, NC: U.S. Department ofAgriculture, Forest Service, Southeastern Forest Experiment Station. 6 p.

Trousdell, Kenneth B.; Langdon, 0. Gordon. 1967.

Disking and prescribed burning for loblolly pine

regeneration. Journal of Forestry. 65: 548-551.

Wolters, Gale L.; Martin, Alton, Jr.; Clary, Warren P

1977. Timber, browse, and herbage on selected

loblolly-shortleaf pine-hardwood forest stands. Res.

Note SO-223. New Orleans, LA: U.S. Department

ofAgriculture, Forest Service, Southern Forest Experiment Station. 9 p.

Wolters, Gale L.; Schmidtling, Ronald C. 1975. Browse

and herbage in intensively managed pine plantations. Journal of Wildlife Management. 39: 557-562.

Wolters, Gale L.; Wilhite, A.T., Jr. 1973. Loblolly-shortleaf pine-hardwood range. Bull. N.S. 9. In: Range

resources of the South. Athens, GA: University of

Georgia: 20-23.

8
Wolters, Gale L.; Pearson, Henry A.; Thill, Ronald E.; Baldwin, V Clark;

Martin, Alton, Jr. 1995. Response of competing vegetation to site preparation on West Gulf Coastal Plain commercial forest land. Gen. Tech.

Rep. SO-116. New Orleans, LA: U.S. Department ofAgriculture, Forest Service, Southern Forest Experiment Station. 8 p.

The response of herbaceous and woody vegetation to site preparation

and fertilization of common loblolly pine forest soils was studied in

southern Arkansas and northwestern and west-central Louisiana. The

succession of competing vegetation is quantified the first, third, and

seventh years after site preparation and fertilization.

Keywords: Browse, ecology, herbage, loblolly pine, plant succession,

regeneration.

I I

The use of trade or firm names in this publication is for reader information

and does not imply endorsement by the U.S. Department ofAgriculture of any

product or service.

This publication reports research involving pesticides. It does not contain

recommendations for their use, nor does it imply that the uses discussed here

have been registered. All uses of pesticides must be registered by appropriate

State and/or Federal agencies before they can be recommended.

CAUTION: Pesticides can be injurious to humans, domestic animals, desirable plants, and fish or other wildlife-if they are not handled or applied properly. Use all herbicides selectively and carefully Follow recommended practices

for the disposal of surplus pesticides and their containers.

r- .