*;;.,* - .

,;@, United States

Department of

Agriculture

,#Y ‘..v,

f-nQ&&J

U S Forest Service Research Note -

Southern Forest so-330

Experiment Station December 1988

Understory Responses to Fertilization of Eroded

Kisatchie Soil in Louisiana

Ronald E. Thill and John C. Bellemore

SUMMARY

Responses of native vegetation growing on highly

eroded Kisatchie soil to a May 1982 application of 672

kg/ha of 16-30-l 3 fertilizer were monitored on two sites

through 1985. Herbage increased from 1,133 kg/ha on

control plots to 4,956 kg/ha on fertilized plots by August

of the first year. Litter accumulations on treated plots

provided excellent soil protection through the fourth year

but helped to reduce herbage production nearly to pretreatment levels by August 1985. Woody-plant cover had

nearly doubled on fertilized plots by May 1985.

INTRODUCTION

The Kisatchie soil series (a fine, montmorillonitic, thermic Typic Hapludalf) has the highest erosion potential of

any soil on the 241,900-ha Kisatchie National Forest.

This soil covers approximately 11,400 ha of National

Forest land in Louisiana, with about 12 percent on

slopes less than 5 percent, 65 percent on slopes of 5 to

40 percent, and 23 percent on sites classified as gullies.

This soil series is characterized by thin surface horizons,

high acidity, low natural fertility, and relatively sparse

vegetative cover. Monitoring of erosion on characteristic

sites on the Kisatchie District in 1980 revealed natural

sheet-erosion losses averaging 186 t/ha (1.3 cm) and

gully-erosion losses of 796 t/ha (5.3 cm). Soil losses of

twice these levels occurred within the first year after a

late-November control burn on a similar site.’

1Unpublished Forest Service report by soil scientist Lynn Schoelerman: “Soil Monitoring Plan for Prescribed Burning on Kisatchie National Forest, Kisatchie Ranger District, Bayou Lute Sub-Watershed”,

21 July 1980.

In May 1982 five sites totaling 89 ha were fertilized in

an attempt to reduce soil losses. This report summarizes

vegetative responses on two of these sites through the

fourth growing season following treatment.

STUDY AREAS AND METHODS

The two study areas are located on the Kisatchie

Ranger District in west-central Louisiana. Area I, consisting of 19 ha, was a 44-year-old sparsely stocked poletimber stand of primarily longleaf pine (Pinus palustris)

with some loblolly pines (f. taeda). Area II consisted of

20 ha of seedling loblolly pine planted in February 1982.

Longleaf pines dominated Area II prior to logging. The

50-year site index for longleaf pine for Areas I and II is

12.2 m and 18.3 m, respectively.

A 16-30-l 3 granular fertilizer formulation was applied

by helicopter at the rate of 672 kg/ha to both sites in May

1982. Area I was treated on May 18 and 19; Area II was

treated on May 21. Untreated 3.6-ha strips along the

edges of both treated areas served as controls.

Vegetation was measured on eight 30.5-m permanent

transects located in each treated and control unit. Transects within fertilized areas were randomly located;

those of the control strips were selected to match vegetative conditions along treated transects. Transects were

confined to slopes of less than 10 percent. Vegetation

within gullies was not measured, but some general observations were made.

The herbaceous standing crop (reported as oven-dry

weight) was estimated in late August 1982, 1983, and

1985 by clipping seven 0.14-m2 quadrats within 2 m of

Southern Forest Experiment Station/l-10210 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
each transect, for a total of 56 plots in each of the four

sampling areas. Other measurements were made in

May 1982 just before treatment and again in May 1983

and 1985. Woody-plant cover to a height of 1.52 m was

determined over the permanent transects using line intercept methods (Canfield 1941). Bare ground, rock, and

vegetative cover (defined as litter plus live vegetation)

were ocularly estimated within a 19-mm (3/4-in) diameter circular loop (Parker and Harris 1959) at 100 points

along a marked line stretched tightly between transect

stakes. These cover measurements were recorded to

the nearest 25percent increment, i.e., 0,25,50,75, and

100 percent. Plants rooted within the loop were tallied

and used to compute plant composition by absolute frequency. When more than one plant was rooted within the

loop, only the plant nearest th’e center of the loop was

recorded.

RESULTS

Ground Cover

Vegetative cover was comparable within areas before

treatment, averaging about 66 percent on Area I and 85

percent on Area II (fig. 1). Recent logging debris accounted for the higher cover on Area II.

Vegetative cover on control plots of Area I increased

from 68 to 84 percent from May 1982 to May 1985 but

remained nearly constant at about 87 percent on control

plots of Area II (fig. 1). Vegetative cover increased to

about 96 percent on both treated areas 1 year after

fertilizing and averaged 95 percent 3 years after treatment.

Woody Plants

Woody-plant cover was similar among all four sampling areas just before treatment in May 1982, averaging

5.8 percent on Area I and 4.8 percent on Area II (fig. 2).

Carolina jessamine (Gelsemium sempervirens), yaupon

(Ilex vomitoria), southern waxmyrtle (Myrica cerifera),

and blackjack oak (Quercus marilandica) were principal

species on Area I; yaupon, winter huckleberry (Vaccinium arborem), and blueberries (primarily Vaccinium

elliottii and some V. corymbosum) were most prevalent

on Area II (table 1).

By May 1983, cover on fertilized plots had increased

129 percent on Area I and 156 percent on Area II, compared to increases on control plots of 22 percent on Area

I and 6 percent on Area II (fig. 2). By May 1985, woodyplant cover on fertilized plots averaged twice that of controls on Area II and was nearly as great on Area I. These

BARE

GROUND

I p/Tiz1

--CONTROL-- --FERTILIZED-- --CONTROL-- --FERTILIZED--

AREA II

Figure l.-Percentages of bare ground, rock, and vegetative ground cover on control and

fertilized Kisarchie soils before (1982) and after treatment.

Ronald E. Thill is research wildlife biologist, Southern Forest Experiment Station, Forest Service-USDA, Nacogdoches, Texas. John C. Bellemore

is forest soil scientist, Kisatchie National Forest, Alexandria, Louisiana.

2
1982 1983 1985

m Fi2zaza

COVER, %

IR I

16 -

CONTROL FERTILIZED

AREA II

Figure 2.-Accumulative percentages of woody-plant cover on control and fertilized plots in May before

treatment (1982) and during 1983 and 1985.

increases were attributed mostly to yaupon and southern

waxmyrtle on Area I and to southern waxmyrtle, yaupon,

blueberries, and blackberries (Rubus, spp.) on Area II

(table 1).

Herbaceous Plants

The herbaceous standing crop on control plots varied

substantially among years. Production on Area I control

plots in 1985 (2,208 kg/ha) was more than double that of

1982 (863 kg/ha) and 1983 (952 kg/ha), and 1983 production on Area II (2,098 kg/ha) was nearly double the

average (1,200 kg/ha) for 1982 and 1985 (fig. 3).

Fertilized plots produced an average of 4,956 kg/ha of

herbage in August 1983 compared to 1 ,133 kg/ha on

control plots (fig. 3). Area I received an estimated 7-13

mm of rain immediately after treatment, but Area II received nu rain for 26 days after treatment. Consequently,

treated plots on Area I responded more rapidly to treatment, and by August 1983 the herbaceous standing crop

on Area I was 14.1 percent greater (5,281 vs. 4,630

kg/ha) than that on Area II.

Herbage composition values summarized in table 2

are based on absolute frequencies, i.e., the number of

rooted-plant occurrences/800 sampling points. Low

panicum grasses (Dicanfhelium spp.) and pinehill

bluestem (Schizachyrium scoparium var. divergens)

were the most abundant taxa on both sites, together with

beakrushes (Rhynchospora spp.) and rayless goldenrod

(Siglowia nuttallii) on Area I before treatment.

Following treatment, pinehill bluestem formed dense

stands l- to 1.5-m tall over much of both treated areas

and accounted for most of the increase in herbage during the first year. As this herbage died over winter, a thick

mat of litter accumulated that had a smothering effect on

subsequent herbage production. Compared to 1982, the

herbaceous standing crop on fertilized plots had decreased 52.5 percent on Area I and 26.7 percent on Area

II by 1983 (fig. 3). By August 1985, the standing crop on

fertilized plots had nearly declined to control plot pretreatment levels. However, despite decreases in standing live herbage, ground cover remained at 95 percent in

May 1985 (fig. 1).

Low panicum grasses showed initial increases in frequency following treatment but declined to below pretreatment level by 1985, presumably because of dense

litter accumulations. Rayless goldenrod and beakrushes

also decreased substantially on Area I following treatment. Twofold and threefold increases in pinehill

bluestem composition on fertilized plots of Areas II and

I, respectively, persisted throunh 1985 (table 2).

3
Table 1 .-Line-intercept coverage (%) of principal woody plants on control and fertilized plots before fertilization (1982)

and during 1983 and 1985

Area I Area II

Control Fertilized Control Fertilized

Taxa 1982 1983 1985 1982 1983 1985 1982 1983 1985 1982 1983 1985

Gelsemium sempervirens

Carolina jessamine

llex vomitoria

Yaupon

Myrica cerifera

Southern waxmyrtle

Pinus pa/us&is

Longleaf pine

P. taeda

Loblolly pine

Quercus marilandica

Blackjack oak

Rubus spp.

Blackberry

Vaccinium arboreum

Winter huckleberry

v. spp.’

Blueberries

Others*

Total

0.6 1.0 1.6 0.6 1.7 1.9 0.3

2.9 3.4 3.6 2.8 6.7 6.9 1.8

0.7 1.3 1.0 1.0 2.3 3.2 0.5

0.5 0.5 0.4 0.1 0.0 co.1 0.1

0.1 co.1 0.1 0.1 0.3 0.6 0.1

1.4 1.3 1.4 0.6 0.9 0.5 0.0

0.0 0.0 0.0 0.0 0.0 0.0 co.1

0.0 0.0 <O.l 0.1 0.3 0.2 0.8

co.1 0.0 0.0 0.1 0.2 0.4 1.1

co.1 0.2 0.1 0.2 0.2 0.5 0.4

0.4 1.3 0.1 0.2

1.8 2.4 0.6 1.8

0.2 0.9 0.4

0.0

0.1

0.0

0.1

0.9

1.2

0.4

2.0

0.0 0.0 0.1

0.1 1.0

0.0 0.0

0.1 co.1

0.5

0.0

0.7

0.8 1.1

1.6 1.4

2.6

0.3 0.2

3.3

1.1

0.3

2.1

3.5

0.2

1.2

0.0

0.9

2.9

4.4

1.9

6.3 7.7 8.2 5.6 12.8 14.4 5.2 5.3 8.3 3.8 12.3 17.4

’ Vaccinium elliottii and V. corymbosum.

*Consisted of trace amounts of Acer rubrum, Ascyrum hypericoides, Berchemia scandens, Callicarpa americana,

Chionanthus virginicus, Crataegus crus-galli, C. marshallii, Diospyros virginiana, Pinus echinata, Quercus nigra, Smilaw

glauca, and Vaccinium stamineum.

Figure 3.-Herbaceous standing crop on control and fertilized plots during August of the treatment

year (1982) and during August of 1983 and 1985.
Table 2.-Herbaceous botanical composition (%) on control and fertilized plots before fertilization (1982) and during

7983 and 1985

Areal Area II

Control Fertilized Control Fertilized

Taxa 1982 1983 1985 1982 1983 1985 1982 1983 1985 1982 1983 1985

Grasses

Aristida purpurascens 0.0 0.1 0.0 0.0 1.9 0.0 0.0 0.1 0.0 0.0 0.1 0.0

Arrowfeatherthreeawn

A . spp. 0.2 0.9 0.8 0.2 0.1 0.0 0.8 1.0 0.0 0.0 2.3 0.0

Threeawns

Dicanthelium spp. 6.4 5.4 6.1 3.1 4.3 1.1 11.0 10.2 6.1 9.6 11.1 3.0

Low panicum grasses

Muhlenbergia expansa 1.8 1.1 1.9 0.8 1.2 1.6 0.0 0.1 0.0 0.3 0.8 0.5

Cutover muhly

Schizachyrium scoparium 3.8 6.4 7.6 7.4 23.0 22.8 7.2 6.6 7.7 5.6 11.9 10.1

var. divergens

Pinehill bluestem

S. tenerum

Slender bluestem

Others

Subtotal

Grasslike Plants

Rhynchospora spp.

Beakrushes

Scleria ciliata

Fringe razorsedge

Others

Subtotal

Other Herbs

Aletris spp.

Stargrasses

Aster dumosa

Bushy aster

Bigfowia nuttallii

Rayless goldenrod

Helianthus angustifolius

Swamp sunflower

Liatris spp.

Gayfeathers

Lichens

Selaginella spp.

Spikemosses

Others

Subtotal

Total

0.0 0.3 0.6 0.0 0.1 0.5 0.4 0.4 1.6 0.1 0.6 0.4

0.2 0.1 0.0 0.0 0.5 0.6 0.0 0.0 0.0 0.0 0.1 0.1

12.4 14.3 17.0 11.5 31.1 26.6 19.4 18.4 15.4 15.6 26.9 14.1

5.5 6.8 5.8 3.8 2.3 1.3 1.3 0.8 1.5 1.8 4.4 3.0

1.0 1.6 1.6 1.4 2.1 1.2 1.4 1.4 0.5 2.3 3.2 1.5

0.4 0.2 0.0 1.0 0.2 0.0 0.2 0.6 0.0 0.2 0.0 0.1

6.9 8.6 7.4 6.2 4.6 2.5 2.9 2.8 2.0 4.3 7.6 4.6

0.4 0.4 0.2 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

0.8 0.4 0.1 0.2 0.0 0.8 0.0 0.1 0.1 0.1 0.4 0.0

9.0 10.3 10.9 12.6 7.3 4.0 4.0 4.2 4.5 0.2 0.0 0.1

0.9 1.1 0.4 0.5 0.9 0.9 0.9 1.8 3.1 0.9 3.2 3.5

0.1 1.4 1.8 0.1 0.5 0.1 1.4 0.8 2.6 0.8 0.9 1.0

1.9 2.8 3.6 2.8 0.4 0.1 1.8 2.1 1.6 0.0 0.0 0.0

0.9 0.4 1.2 0.8 0.6 1.8 0.8 1.9 2.9 0.8 0.8 2.1

1.7 1.4 1.6 1.3 1.3 1.4 1.4 1.7 1.7 2.7 1.7 1.4

15.7 18.2 19.8 18.2 11.0 9.1 10.3 12.6 16.5 5.1 7.0 8.1

35.0 41.1 44.2 35.9 46.7 38.2 32.6 33.8 33.9 25.0 41.5 28.8

DISCUSSION

The fertilizer used in this study was a custom formulation designed to meet pine nutrient deficiencies. As

such, this formulation was not necessarily optimum for

native herbage growing on these sites. Consequently, it

was probably not the most cost-effective formulation for

reducing soil erosion losses.

Pine responses to this treatment were not measured,

but Shoulders and Tiarks (1984) indicated that fertilization of young pines without subsequent control of competing vegetation may result in limited pine response. On

these erosion-prone sites, soil protection should initially

take precedence over timber production. Thus, additional research could yield a more cost-effective fertilizer

formulation for herbaceous vegetation growing on these

sites.

We did not monitor vegetation changes in gullies but

did observe substantial grass (primarily pinehill

bluestem) establishment on the more level, lower portions of several adjacent gullies. The excellent vegetation cover that developed on the adjoining uplands following treatment should reduce overland flow and

thereby reduce gully erosion substantially.

5
LITERATURE CITED

Canfield, R. H. Application of the line interception

method in sampling range vegetation. Journal of

Forestry. 39:388-394; 1941.

Parker, K. W.; Harris, Ft. W. The 3-step method for

measuring condition and trend of forest ranges: a resume of its history, development, and use. In: Techniques and methods of measuring understory vegetation: Proceedings of the symposium; October 1958;

U.S. Department of Agriculture, Forest Service,

Southern and Southeastern Forest Experiment Stations; 195955-89.

Shoulders, E.; Tiarks, A. E. Response of pines and native forage to fertilizer. In: Linnartz, N. E.; Johnson,

M. K., eds. Agroforestry in the southern United States.

33rd Annual Forestry Symposium; 1984 April 4-5;

Baton Rouge, LA: Louisiana State University Agriculture Center; 1984:105-l 26.

6