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c& Forest Service Research Note

II. Southern Forest

Experiment Station so-309

December 1984

Long-Term Artificial Annual Flooding

Reduces Nuttall Oak Bole Growth

Bryce E. Schlaegel

SUMMARY

Nuttall oak (Quercus nuttallii Palmer) bole

volume growth is significantly reduced by longterm artificial annual flooding of thinned stands,

Regardless of size, trees growing in a green-tree

reservoir grew significantly less in cubic-foot

volume than trees in a nearby nonflooded area

during the 6-year study period. Trees subject to

heavy thinning grew significantly faster than those

lightly thinned in the nonflooded area, but thinning intensity was not significant in the greentree reservoir. This indicates a general decline in

tree vigor caused by artificial annual flooding for

the prior 17 years. Mortality for 6 years in the

flooded and nonflooded areas has been 17 and 0

percent, respectively.

Additional keywords: Quercus nuttallii, thinning,

green-tree reservoir.

INTRODUCTION

Green-tree reservoirs are artificial water impoundments created in living bottomland hardwood stands to enhance winter feeding areas for

migrating waterfowl. The impoundments are flooded in the late fall after the growing season and

drained in the early spring before growth commences.

Benefits to tree growth from annual water impoundments have been cited. A 50-percent increase in radial dbh growth was reported by Broadfoot (1967) .after timber stands were flooded from

February to July over a 4-year period. Raised

water tables through artificial flooding also increased tree radius growth by 50 percent over a

5-year period after impoundment (Broadfoot 1973).

A correctly managed green-tree reservoir should

increase the quantity of mast (acorns) produced

and improve tree growth (Rudolph and Hunter

1964). Pin oak (Quercus palustris Muenchh.)

acorn production was increased after 4 years in

Missouri (Minckler and McDermott 1960). But,

after an additional 10 years of study in the same

area, based on averages over the 14 years, flooding had reduced the production of mature acorns

about 25 percent (from 97,000 to 73,00O/ac).

Because the percent that was insect infested was

less in the flooded areas (16 percent) than on the

normal areas (33 percent), the number of sound

acorns was approximately the same between the

two areas (65,000 on the normal vs. 61,15O/ac. on

the flooded area) (McQuilkin and Musbach 1977).

Nuttall oak (Q. nuttallii Palmer) acorn production

for 5 years in a 15year-old green-tree reservoir

was about half that of an unflooded control area

(Francis 1983). Based on a small sample, Newling

(1981) reported no significant difference in rate of

growth for Nuttall oak in a green-tree reservoir

and unflooded reference areas, and variable

results for other species.

This paper reports the effects on Nuttall oak

volume growth of long-term flooding in a greentree reservoir.

METHODS

The study areas are on the Delta National Forest, near Rolling Fork, MS, in mostly pure, evenaged Nuttall oak stands that averaged 50 to 60

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
years old. Two locations were selected, one in the

green-tree reservoir (GTR) of the Sunflower Waterfowl Project, and one in a nearby area not subject

to artificial flooding (nonflooded area-NA).

The GTR, flooded annually since 1958, is flooded during the first 2 weeks of October with drainage beginning about February 15. However, due

to poor drainage and frequent overflows from the

adjacent Sunflower River, drainage is often not

complete until mid-June.

Except for annual water impoundment in the

GTR, both areas are similar in site and stand

conditions. Soils at both locations are associations of Sharkey and Alligator, which are level to

nearly level, poorly drained, slackwater clays.

At each location, three dominant/codominant

Nuttall oak trees were selected from each of four

dbh classes in each of three blocks. This provided

36 test trees per location, a total of 72 trees. The

four dbh classes were small (8.5 to 11.5 in dbh),

medium (14.5 to 17.5 in dbh), large (20.5 to 23.5

in dbh), and extra large (26.5 to 29.5 in dbh).

Thinning treatments imposed in each block were

control (no thinning), moderate (all trees adjacent

to the test tree were removed to allow a 15foot

minimum clearance around the crown), and heavy

(all adjacent trees removed to allow a 30-foot

minimum clearance around the crown). Thinning

treatments were randomly assigned to trees of

each size class in each block. The study area was

thinned in the late summer of 1974 and the study

was installed 1 year later in the 1975-76 dormant

season.

The test trees were measured prior to the 1976

growing season and at the end of the 1981 growing season, thus recording 6 years’ growth. Bole

circumference was measured at heights of 4.5, 9,

17, and 25 feet. Upper bole measurements were

obtained using Swedish tree climbing ladders.

Cubic-foot bole volumes were estimated by Smalian’s formula (Husch et al. 1972) for the 20.5-

foot interval between 4.5 and 25 feet. Periodic

volume growth is the difference between the final

and initial measurements.

RESULTS

Volume Growth

During the 6-year growth period, 6 trees died

in the GTR while one in the NA was severely

Table l.-Mean B-year bole volume growth by free size c/asses

on flooded and unflooded areas

Treatment area

Size class Flooded Nonflooded

. . . . .._........_ cubjc feet per tree

Small 3.2al 4.2a

Medium 5.4a 6.1 b

Large 6.6b 6.9b

Extra-large 7.8b 9.3c

‘Means within columns followed by the same letter are not

significantly different (a = 0.05).

Table 2.-Mean g-year bole volume growth by thinning treatment on flooded and unflooded areas

Thinning

Treatment

Control

15foot radius

30-foot radius

Treatment area

Flooded Nonflooded

________________._.. c,,,,jc feet per tree

4.la’ 4.2a

6.0a 7.2b

6.4a 8.6c

‘Means within columns followed by the same letter are not

significantly different ((Y = 0.05).

wind damaged. Average bole volume growth in

the GTR of 5.6 cubic feet was significantly (LY =

0.05) less than the 6.6 cubic feet in the NA.

Volume growth increased significantly with tree

size in both flooded and nonflooded areas (table

1). In the GTR large and extra-large trees added

significantly more volume than the small and

medium trees. In the NA each successively larger

tree size produced significantly more wood except

in the large tree category.

Both thinning treatments significantly increased

bole growth in the nonflooded area (table 2).

Trees in the heavier thinned plots (30-foot) grew

significantly more volume than those subject to

light (15-foot) thinning, -with respective growth

means of 8.6 and 7.2 cubic feet. The trees that

were thinned had approximately doubled the

volume growth of the control trees. Thinned but

unflooded volume growth averaged 7.9 cubic feet

for the two treatments compared to 4.2 for the

control. Although thinning in the GTR also increased growth, the increase was not statistically

significant.

Bryce E. Schlaegel is Principal Mensurationist at the Southern Hardwoods Laboratory, maintained at Stoneville, Mississippi, by the

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

2
DISCUSSION

The continuous annual flooding has had a

small, though statistically significant, negative

effect on bole volume growth over the 6-year

growth period. Trees in the GTR averaged 5.6

cubic feet of growth for the period compared to

6.6 cubic feet in the NA.

Trees in the GTR did not significantly respond

to thinning treatment as expected, but the trees

in the NA did. This indicates an overall deterioration in tree vigor in the GTR, resulting in the

inability to respond to thinning regardless of tree

size.

As expected, small trees had less volume growth

than big trees but had the highest percent growth.

Trees in the NA responded to the thinning treatments for all size trees. The heavier thinned trees

grew faster than those receiving a moderate thinning.

Although significant growth differences exist between the two areas, the growth magnitudes are

small. But the death of six trees in the GTR in 6

years and the lack of thinning response indicate

the GTR trees are deteriorating due to the annual

artificial flooding.

LITERATURE CITED

Broadfoot, W. M. Shallow-water impoundment increases soil moisture and growth of hardwoods.

Soil Sci. Sot. Am. J. 31: 562-564; 1967.

Broadfoot, W. M. Raised water tables affect southern hardwood growth. Res. Note SO-168, New

Orleans, LA; U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment

Station; 1973. 4 p.

Francis, John K. Acorn production and tree growth

of Nuttall oak in a green-tree reservoir. Res.

Note SO-289, New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern

Forest Experiment Station; 1983. 3 p.

Husch, Bertrom; Miller, Charles I.; Beers, Thomas

W. Forest mensuration. 2d ed. New York: Ronald Press; 1972. 410 p.

McQuilkin, R. A.; Musbach, R. A. Pin oak acorn

production on green tree reservoirs in southeastern Missouri. J. Wildl. Manage. 41: 218-225;

1977.

Minckler, L. S.; McDermott, R. E. Pin oak acorn

production and regeneration as affected by

stand density, structure, and flooding. Missouri

Agricultural Experiment Station Res. Bull. 750.

Columbia, MO: University of Missouri, 1960. 21

P.

Newling, Charles J. Ecological investigation of a

green tree reservoir in the Delta National Forest, Mississippi. Waterways Experiment Station

Misc. Pap. EL-81-5. Vicksburg, MS: U.S. Army

Engineers Waterways Experiment Station, 1981.

67 p.

Rudolph, R. R.; Hunter, C. G. Green trees and

greenheads. In: Linduska, J. P., ed. Waterfowl

tomorrow. Washington, DC: U.S. Dep. Interior;

1964: 611-618.