United States

Department

of Agriculture

Growth - m- -I \/: - I -I t-- *1-s -I r, I dllU Y lela In iuatural xanas

of Slash Pine and Suggested

Southeastern Forest

Experiment Station Management Alternatives

Forest Service

Research Paper

SE-211 by Frank A. Bennett
August 1980

Southeastern Forest Experiment Station

Asheville, North Carolina
Growth and Yield in Natural Stands of Slash Pine

and Suggested Management Alternatives

Frank A. Bennett, Silviculturist’

Naval Stores and Timber Production Laboratory

Olustee, Florida

ABSTRACT.-Yields are presented by stand age, site index, and stand basal area at the beginning of

a growth period. Differences between these yields and those projected 20 and SO years ago are

explained partly by changing definitions of normal or full stocking and partly by changes in forest

management. If only pulpwood harvesting is envisioned, fairly high stocking is needed to get full

production from the site. To produce sawtimber and veneer in a 3S-year rotation, however, stocking

must be considerably lower. For longer sawtimber-veneer rotations, heavier stocking is required to

maximize yield.

Keywords: Pinus elliortii, stand density, stocking, growth projections, yield tables.

In 1929 the U.S. Department of Agriculture

issued Miscellaneous Publication 50 (MP-50),

which contained yields for unthinned natural

stands of slash pine (Pinus elliottii Engelm. var.

elliottii), and other southern pines, with “normal” or full stocking. In 1960, Schumacher and

Coile published yields for unthinned, “wellstocked” stands of slash and other southern

pines. In 1970, I published variable-density yield

tables and projected yields for thinned stands of

natural slash pine (Bennett 1970). I also published

yields for unthinned old-field slash pine plantations (Bennett and Clutter 1968).

This array of information might seem to preclude any need for additional reports on yields for

this species, especially for natural stands. However, there are no published estimates of the effects of density on yields in unthinned natural

stands, or of the effects of thinning on growth in

natural stands. And the published effect of density on board-foot yield is contradictory-positive

in natural stands and negative in plantations.

Furthermore, the yield estimates in MP-50 and in

Schumacher and Coile differ greatly. In this

Paper, I-

* Describe and attempt to reconcile some of

the differences between the earlier natural-stand

data sets.

l Present yield tables by density classes for

unthinned natural slash pine stands.

‘Retired.

l Present data on periodic annual growth in

thinned natural slash stands.

l Present modern slash pine yields for maximum stocking levels (normal yields).

l Explain the apparent contradictory effects

of density on board-foot yields.

l Suggest some management alternatives

based on growth and yield patterns observed in

both natural stands and plantations.

CONFLICTING ESTIMATES

Differences between yields reported in MP50 for “normal” stands and those in Schumacher

and Coile for unthinned, well-stocked stands are

quite large (table 1). MP-50 shows 13 to 133 percent more surviving trees per acre, 1 to 49 percent

greater basal-area stocking, and 1 to 46 percent

greater cubic-volume yield. Differences of this

magnitude are of considerable practical significance.

Some of the differences can be explained by

utilization standards. Schumacher and Coile include inside-bark volumes from stump to tip, but

the appropriate MP-50 table for this comparison

also includes stump volumes. Most of the differences in yield, however, arise from variations

in the observed number of surviving trees per

acre. The “normal” stands in MP-50 clearly are

more heavily stocked than the “well-stocked”

stands in Schumacher and Coile. For example,

MP-50 shows 380 trees per acre as normal stock-
Table I.--Slash pine stocking and cubic-yield inside bark from Miscellaneous

Publication 50 (USDA 1929) and Schumacher and Coile (1960)

Age Data

(years) source’ 60 70

Site index

80 90 100

. . . . . . . . . . . . . . . . . . . Number of treeslaw . . . . . . . . . . . . . . . . . . . .

20

30

40

50

20

30

40

50

20

30

40

50

MP-50 2,035

S&C 875

MP-50 1,140

S&C 499

MP-50 710

S&C 379

MP-50 550

S&C 318

MP-50

S&C

MP-50

S&C

MP-50

S&C

MP-50

S&C

. . . . . . . . .

143

96

152

104

155

109

157

113

. . . . . . . .

MP-50 1,800

S&C 1,360

MP-50 2,500

S&C 1,870

MP-50 3,050

S&C 2,200

MP-50 3,500

S&C 2,390

).....

1,445 1,090 835 625

628 474 373 303

820 610 470 365

377 298 244 206

500 380 295 225

294 238 199 172

390 295 220 175

254 209 177 155

. Basal area in squure feetlucre . . . . . . . . . . . .

146 148 149 150

102 108 116 126

156 158 159 160

111 120 130 143

159 161 163 164

117 128 140 155

161 163 165 166

122 134 147 164

. Perled cubic ,feetluc‘re . . . . . . . . . . . . . . . . . . . . .

2,250 2,700 3,100 3,500

1,770 2,240 2,810 3,480

3,150 3,750 4,300 4,800

2,390 3,000 3,720 4,580

3 ,xso 4,600 5,300 5,950

2,800 3,500 4,320 5,350

4,400 5,300 6,050 6,750

3,100 3,880 4,780 5,920

‘Data from Miscellaneous Publication SO (MP-50) include tree\ 2 inches t1.h.h. and above; total

volumes inside bark are measured from groundtine to treetop. Data from Schumacher znd Coile IS&C)

include all trees; total volumes inside bark are measured from stump height to tree top.

ing for site 80 at age 40. Schumacher and Coile

show 238 trees per acre under comparable conditions. But I have measured stands a

site quality containing more than 7

acre. In fact, in my study on natural stands of

slash pine (Bennett 1970), the three stands I

measured in the O-year-age class contained an

average of 445 stems per acre. These data illustrate that “normal stocking” and “well-stocked”

are subjective terms impossible to calibrate in the

forest. Today’s intensive management practices

require more precise information. Therefore, in

this and other papers, I have reported yields for a

wide range of ages, sites, and densities identified

and accurately measured in the field.

The data used here came from 176 permanent, %-acre plots established in pure, natural

slash pine stands in 1955-56. The sample area

extended from Dooly County, Georgia, in the

north to Hemando County, Florida, in the south

and from the east coast of Florida and Georgia to

2
Santa Rosa County, Florida, in the west. Stands

selected for sampling showed no evidence of

thinning, severe burning, insect or disease

damage, or collection of naval stores. Stocking

ranged from 88 to 1,800 trees per acre, site index

from 40 to 100, and age from 17 to 68 years.

Average age was 3 I .4 years.

CUBIC YIELDS IN

UNTHINNED STANDS

The diameters of all trees on each plot were

measured to the nearest 0.1 inch. From a heightdiameter curve constructed for each plot, a mean

volume for each diameter class 5 inches and

above was calculated from an equation from

Cooper and Olson (1958):

cubic-foot volume (outside bark)

= 0.002853D’H - 0.976

where:

(1)

D = diameter at breast height in inches

H = total height in feet.

Plot volumes were established by applying

diameter-class volumes to the observed diameter

distributions and summing the results.

After expanding plot volumes to an acre

basis, multivariate regression analysis was used

to develop the following predictor:

Log CFY = 2.7058 - =$

+ 0.87266 (log basal area)

51.051

site index (2)

where log = common logarithm and CFY =

cubic-foot yield (outside bark) per acre.

This simple model removed 94 percent of the

variation in the logarithm of yield. The density

variable accounted for 53 percent of the variation

removed. The strong influence of density is refiected in yields as predicted by Equation (2)

(table 2). For example, 100 square feet of basalarea stocking produce 83 percent more cubic yield

than 50 square feet, and 125 square feet produce

56 percent more yield than 75 square feet. Since

the average basal-area stocking in the slashlongleaf pine type is about 50 square feet, these

figures demonstrate the urgent need to increase

stocking on much of the acreage occupied by

these species.

Note that, for a given basal-area density, 73

percent of the 50-year yield is produced by age 30

(table 2). The corresponding percentages for the

data in MP-50 and Schumacher and Coile are 72

and 74, respectively. Yields estimated by Equation (2) for the basal-area stockings in MP-50 at

age 30 range from 78 to 98 percent of the yields

(outside bark) listed for normal stands. Estimates

for Schumacher and Coile’s densities at the same

age range from 93 to 109 percent of the yields they

list for well-stocked stands:

Site index

Estimated yield at age 30 as

a percent of yield in-

(MP-50) (Schumacher and Coile)’

60 78 93

70 86 106

80 88 107

90 94 109

100 98 103

IOutside-bark yields were estimated by applying ratios of

inside-bark yields in MP-50 and Schumacher and Coile to the

outside-bark yields in MP-50.

The differences between my estimates and

those in MP-50 can be explained largely by differences in merchantability limits. MP-50 includes volumes in the entire stem from groundline

to tip as well as those in trees 2 to 5 inches d.b.h. 1

report volumes from stump to a 4-inch top

diameter outside bark, and I exclude yields in

trees smaller than 5 inches d.b.h.

There is no easy explanation for my yields

being larger than those of Schumacher and Coile.

The difference would be even greater if they had

not included upper-stem volumes and those in

trees 1 to 5 inches d.b.h. No doubt, differences in

the methods of construction of volume tables contribute to the discrepancies in yield. Schumacher

and Coile’s yields for slash pine are based on an

adaptation of a loblolly pine volume table by

MacKinney and Chaiken (1949).

The yields in table 2 cannot be directly compared on a maximum stocking basis with the

yields in MP-50 or Schumacher and Coile. In

order to produce such a comparison, the observed

maximum numbers of surviving trees per acre in

the study plots were smoothed by regression. The

following equation was then entered with the predicted maximum number of trees, by age-site categories, to produce estimates of basal-area stocking:

3
Table 2.-Estimated per acre yields outside bark for unthinned, natural stands of

slash pine’

Age

(years)

50-year

site

index 50

Basal area (square feet)

75 100 125 150

. . . . . . . . . . . . . . . . . . . . . . . . . Cubic feet . . . . . . . . . . . . . . . . . . . . . . . . . . . .

672 957

889 1,267

1,097 1,562

1,291 1,840

1,477 2,087

994 1,416

1,315 1,874

1,623 2,311

1,910 2,721

2,177 3,101

1,209 1,723

l,@o 2,279

1,974 2,811

2,323 3,310

2,647 3,771

1,360 1,937

1,799 2,563

2,220 3,162

2,613 3,722

2,977 4,241

1,230 1,495 1,753

1,628 1,978 2,3 19

2,008 2,440 2,861

2,364 2,873 3,368

2,694 3,274 3,838

1,820 2,212 2,593

2,408 2,926 3,431

2,97 1 3,610 4,232

3,498 4,250 4,983

3,986 4,842 5,677

2,214 2,690 3,154

2,929 3,559 4,173

3,614 4,390 5,148

4,254 5,169 6,061

4,847 5,890 6,905

2,490 3,026 3,548

3,295 4,003 4,693

4,064 4,938 5,789

4,785 5,813 6,816

5,45 1 6,624 7,766

20

30

40

50

60

70

80

90

100

60

70

80

90

100

60

70

80

90

100

60

70

80

90

100

‘Includes all trees 4.6 inches d.b.h. and larger to a 4-inch top d.o.b.

Log basal area = 1.524 17 -z

32.227

site + 0.45395 LogN

(3)

R2 = 0.70

where log = common logarithm and N = number

of trees per acre. Basal-area estimates from Equation (3) were then used in Equation (2) to estimate

maximum cubic yields (table 3).

Except for site 60, the predicted maximum

numbers of surviving trees per acre through age

40 are somewhat greater than the corresponding

numbers in MP-50 and are, of course, well above

those in Schumacher and Coile. For example,

through age 40 the data on surviving trees in table

3 for sites 80 and above are from 25 to 100 percent

greater than the corresponding data in MP-50. If

volumes were computed with the same threshold

diameter and utilization standards, it is evident

that the yields in table 3 would be well above the

MP-50 estimates, at least through age 40. This

difference indicates that so-called normal stocking of one era will not necessarily apply in

another.

The spread in basal-area yield within each

site index class is much greater in table 3 than in

MP-50 because of a much smaller spread in number of trees per acre in MP-50. Consequently, the

effect of site on cubic yield as shown in table 3 is

much greater than that shown in MP-50. For

example, yields in MP-50 for site 70 are about 70

percent of the yields for site 100, whereas yields in

table 3 for site 70 range from 49 to 56 percent of the

yields for site 100. The effect of site on yield in

table 3 would be reduced, of course, if volume for

all trees 2 inches and above were included.

PERIODIC ANNUAL GROWTH

IN THINNED STANDS

The 176 quarter-acre plots were established

to evaluate growth and total yield for given

residual densities in thinned stands. Accordingly,

each plot was assigned a stocking density and, if

4
Table 3.-Per acre cubic-volume and basal-area yields outside bark for maximum stocking levels in

unthinned, natural stands of slash pine

Site index

Age

Wears) 60 7 0 8 0 90 100

Basal Basal Basal Basal

Trees Yield’ area Trees Yield’ area Trees Yield’ area Trees Yield’ area Trees Yield’ Basal

area

20

30

40

50

Cubic Square Cubic Square Cubic Square Cubic Square Cubic Square

NO. feet feet No. feet feet No. feet feet No. feet feet No. feet feet

1,652 1,537 129 1,520 2,292 148 I.421 2,507 164 1,344 3,305 177 1,282 4,695 189

1,020 2,608 134 888 3,450 151 789 4,550 163 712 5,614 172 651 6,656 180

704 2,765 129 572 3,929 140 474 5,057 147 394 6,060 I50 335 6,945 151

515 2,941 121 383 4,030 126 284 4,792 I26

*Includes all trees 4.6 inches d.b.h. and larger to a 4-inch top d.o.b.

required, was thinned to that level initially, and at

5-year intervals thereafter. Unfortunately, 94

plots were destroyed or inadvertently thinned

during the first 5-year growth period. Our study

design held basal area constant within site and

forced a negative correlation between site index

and number of trees per acre. Also, mortality in

number of trees per acre was essentially the same

on all sites. These results masked the effect of site

on basal area and cubic-volume growth since tree

sizes increased as site increased. However, remeasurement of 12 1 plots at the end of the second

5-year growth period permitted development of

the following equations for predicted and projected yield and growth:

Lny = 5.98812 - !.$I!? - !2$!

+ 0.89683 LnB (4)

Lny,

‘5

= 5.98812 - -!?J$!? _ F

2

+ 4.632

(

+ 0.89683 (3

LnB2=LnBl( 2

2

> +S.l,Y(I-2)

2 (6)

CFG=Y[=$ - 0.89683 -LnB A + -4.632A 1

(7)”

“Equation (7) was not published at the time the others in

this group were. but it was developed at the time the others

were.

BFY = 1236.12 - 186.1601 I(B)

+ 7.3 1406 (cubic-foot stocking) (8V

where:

Ln = natural logarithm

Y = cubic-foot yield

y2 = projected cubic-foot yield

S = 50-year site index

A = any given age

Al and A2 = initial and terminal age

B = any given basal area

BI andB2 = initial and terminal basal-area

stocking

CFG = periodic annual cubic-foot

growth rate

BFY = board-foot yield

Theoretically, Equation (7) does not estimate

the volume that accrues over a year; rather, it

gives an instantaneous growth rate applicable

only at a specific age (table 4). Practically, however, estimates derived from this equation are

good indicators of current annual increment, because the amount of change in cubic volume and

basal-area stocking (independent variables in this

equation) over the span of a year does not greatly

alter the growth rate.

Slightly more accurate estimates of current

annual growth can be obtained by using Equations (5) and (6) to project cubic volume and basalarea stockings at yearly intervals. From these

stocking data, growth rate can be estimated at

5
Table 4.-Instantaneous rates of cubic-foot growth per acre at specific ages in

thinned, natural stands of slash pine, by site index and basal-area stocking

Age

(years)

50-year

site

index

60

70

20 80

90

100

60

70

30 80

90

100

. . . . . . . . . . . . . . . . . . . . . . . Cubic feet . . . . . . . . . . . . . . . . . . . . . . . . . .

69 8 2 90 96 98

92 109 121 128 131

114 136 150 159 163

135 161 178 188 193

155 184 204 215 221

54 62 6 5 66 64

72 82 8 7 88 86

89 102 108 I10 107

106 121 128 130 127

121 139 147 149 145

60 43 48 49 48 45

70 58 64 66 65 60

40 80 72 80 8 2 80 7 5

90 8 5 95 97 95 89

100 97 108 111 109 102

60 36 39 39 37 34

70 48 5 2 5 3 50 45

50 80 59 6 5 6 5 62 56

90 70 77 7 7 7 3 66

100 8 1 88 89 84 76

Basal area (square feet)

50 7 5 100 125 150

yearly intervals and average growth rates can be

computed. For example, the average of the

growth rates at ages 20 and 21 would represent

current annual growth for the 20th year.

Current annual increment of merchantable

volume is greatest at age 20 and declines thereafter. As in unthinned stands, this increment is

maximum in thinned stands at an early age (sometime prior to age 20) because it is a function of

number of trees per acre. Consequently, ingrowth, diameter growth, and good height growth

at young ages, produce early culmination of current and periodic annual increment of merchantable volume.

As with all growth patterns, added units of

stocking contribute successively lower volumes

of increment. Otherwise, culmination would

never occur. The point of primary interest on

managed stands IS the amount or’ volume Increase

per increased unit of stocking. At the point of

culmination of periodic annual growth, a large

portion of the stocking contributes only a minor

amount to the total production (table 5). On the

basis of the data in table 5, attainment of the

biological growth potential is financially unattracti;le. to say the least.

Although no equation for board-foot growth

was developed in the analysis of the study data, an

estimate of sawtimber growth can be derived from

Table 5.-Contributions of various stocking

levels to total growth at the point ofculmination in thinned. natural stands of slash pine

Age Basal-area stocking (square feet)

(years) 75-_ 50 7 5 100 125 I.50 175

. . . . Pcrc~erlt o/’ tottrl grolc~tll~ .

6
Table 6.-Periodic annual board-foot growth as

developed from projected board-foot yields

for thinned, natural stands of slash pine

50-year Age .

Basal area (square feet)

(years) i,“~~x 5. 75 loo 12s

. . . . . . . . . . . Board feet . . . . . . . . . . . .

70 0 0 0 0

20 ;; 0 0 0 0

434 609 726 275

100 576 783 912 1,138

70 43 208 0 0

30 80 67 348 44s 577

90 290 489 585 680

100 400 612 719 818

70 130 178 224 274

40 80 236 284 339 388

90 332 393 446 488

100 418 489 551 591

70 113 146 173 209

50 80 204 239 265 295

90 279 326 355 380

loo 353 406 433 461

projected board-foot yields (table 6). Projected

board-foot yields were obtained by applying

Equation (8) to projected cubic volume and basalarea yields (Bennett 1970). Like cubic-volume

growth, periodic annual board-foot growth is

greatest at age 20. The very high growth rate on

the best site at age 20 no doubt reflects heavy

i~growth. Site 60 is excluded from table 6 because

ows no sawtimber potential. Sites 70 and 80

oduction at age 20, even for

on these sites averaged 714

at age 20, and thinnin~s did

not occur until this age or later. Board-foot

lmination in relation to densicontrast, board-foot

in relation to

on any site in relation to

of coiirs~ produce early and large

ever, as age increases in

sawtimber size, and board-foot yield then tends to

increase as density increases. Once all trees reach

sawtimber size, to use the perfect example, every

time we add a cubic foot of growth we increase

board-foot yield, and we know that cubic-foot

growth and yield increase as density increases.

CHANGING CONDITIONS

Comparison of the new cubic yields for maximum stocking in table 3 with those from MP-50

and Schumacher and Coile in table I illustrates

that “normal stocking” and “well stocked” are

concepts that are strongly influenced by personal

judgment. Although based on a sound biological

principle, the concept of normal stocking is not

useful in applied management because it is not

definable in measureable parameters. Furthermore, it is not economically viable in a freely

competitive market of diversified primary

products, nor will it be as long as the free market

dictates management. Even if defined in terms of

products, the concept is not economically viable

because there is a point beyond which the cost of

carrying additional stocking exceeds the return

from the added stocking.

If we grant that the yields published in 1929

for normal stocking represented the maximum for

that era, then the data in table 3, especially for

ages 20 and 30, demonstrate that optimum stocking of one period may not apply to subsequent

stands produced under different conditions. A

stand or forest type is a product of its history. The

lack of management-indeed, the mismanagement and destructive practices of the late 1800’s

and early 1900’s-must have been reflected, to

some extent, in the normal yields of the 1920’s. It

is not surprising, therefore, that (optimum stocking and yield patterns developed under a better

level of management and fire protection are different from those presented in

GE

m the growth and yield patterns reported

here natural stands and those previously ob-

~antations, we can determine

stocking levels and rotation lengths that appear

best for growing various products. Yield tables

for both plantations and natural stands demonstrate that cubic yield is a function of number of

trees per acre-as trees per acre increase, cubic

yield increases. Tables of board-foot yields for

natural stands also show that both these yields
and periodic growth increase as density in-

&eases. Tables of board-foot yields for plantations, on the other hand, show that board-foot

yields at age 35 and under are greatest in stands of

200 to 300 trees per acre. These growth and yield

patterns suggest the following alternative management regimes for the two types of stands:

1. For pulpwood production on a 25- or 30-

year rotation, a fairly heavily stocked stand is

needed. Since the yield increase per unit of stocking will decline as stocking increases, the optimum stocking level will depend on overall management costs, including harvesting costs as influenced by tree size. For this reason, specific

stand stockings are not suggested. The owner or

manager can be guided by the fact that cubic

production and harvesting costs increase with

density and that densities beyond 600 trees per

acre significantly reduce height growth.

2. For sawtimber and veneer production in a

relatively short rotation (35 years), no more than

200 to 3OOsurviving trees per acre are needed to

maximize yields. In plantations, the equivalent of

a IO- by IO-foot or greater spacing should be used

if total product yield is the primary concern. This

assumes a survival percentage of 75 to 80. In

natural stands, a precommercial thinning to this

level of stocking at an early age (before age 5)

would be required. Lightly stocked stands on

good sites can be commercially thinned around

age 20 to stimulate diameter growth without reducing sawtimber ingrowth in a short rotation.

3. For sawtimber and veneer production in

rotations over 40 years, especially those 45 years

and above, the stand should be started with several hundred surviving trees per acre, if near maximum volume production is desired. Such a level

will permit two or more thinnings, with an accompanying increase in average tree quality and

the heavier basal-area stocking necessary for optimum, or near optimum, board-foot and veneer

yields in these long rotations.

As we have seen, board-foot yields in natural

stands increase as basal-area density increases.

This pattern develops when a majority of the trees

reach sawtimber-size and it will continue until

density causes mortality among sawtimber-size

trees. It is easy to rationalize a positive correlation between board-food growth and density. As

noted earlier, once all trees are of sawtimber size

and quality, every cubic foot ofgrowth, at least in

the saw-log portion of the tree, is board-foot

growth. Hence, heavier stocking is needed to

maximize board-foot growth and yield in long

rotations.

We should note again, however, that the

density which maximizes product yield is not

likely to optimize net return. The stocking level

that will produce the greatest net return is influenced greatly by management costs, interest

rates, taxes, etc., and these are not stable variables. When we consider further that the law of

diminishing returns applies to stocking, it becomes difficult to specify an optimum density that

will hold for a majority of owners. As with cubic

production, the owner or manager must be guided

by the fact that board-foot and veneer-stock production is positively correlated with density in

long rotations, and that harvesting and manufacturing costs are markedly influenced by tree size.

LITERATURE CITED

Bennett, Frank A.

1970. Variable-density yield tables for managed stands

of natural slash pine. USDA For. Serv., Res. Note

SE-141,7 p. Southeast. For. Exp. Stn.. Asheville,

N.C.

Bennett, Frank A., and G.L. Clutter

1968. Multiple-product yield estimates for unthinned

slash pine plantations-pulpwood, sawtimber,

gum. USDA For. Serv., Res. Pap. SE-35, 21 p.

Southeast. For. Exp. Stn., Asheville, N.C.

Cooper, Robert W., and David F. Olson, Jr.

19%. Volume determinations for second-growth slash

and longleaf pine in northeast Florida. USDA For.

Serv., Southeast. For. Exp. Stn. Pap. 92, I I p.?

Asheville, N.C.

MacKinney, A.L., and L.E. Chaiken

1949. Volume, yield, and growth of loblolly pine in the

Mid-Atlantic coastal region. USDA For. Serv.,

Appalachian For. Exp. Stn. Tech. Note 33, 58 p.

Asheville, N.C. [Originally issued 1939 by Appalachian For. Exp. Stn., revised in 1946, reprinted

by Southeast. For. Exp. Stn. in 1949 and 19Sh.l

Schumacher, F.X.. andT.S. Coile

1960. Growth and yield of natural stands ofthe southern

pines. I I5 p. T. S. Coiie, Inc., Durham, N.C.

U.S. Department of Agriculture

1929. Volume, yield, and stand tables for secondgrowth southern pines. USDA Misc. Publ. SO,

202 p. Washington, D.C.
r

-~--___--____-__

Bennett, Frank A

I

1980. Growth and yield in natural stands of slash pine and suggested management

i

alternatives. USDA For. Serv., Res. Pap. SE-21 1 . 8 p. Southeast. For. Exp.

Stn., Asheville, N.C.

Yields are presented by stand age. site index, and stand basal area at the beginning ofagrowth

period. Differences between these yields and those projected 20 and 50 years ago are

explained partly by changing definitions of normal or full stocking and partly by changes in

forest management. If only pulpwood harvesting is envisioned. fairly high stocking is needed

to get full production from the site. To produce sawtimber and veneer in a 35-year rotation,

however. stocking must be considerably lower. For longer sawtimber-veneer rotations,

heavier stocking is required to maximize yield.

KEYWORDS: Pinus elliotrii, stand density, stocking. growth projections, yield tables.

I

I Bennett, Frank A

I

1980. Growth and yield in natural stands of slash pine and suggested management

I

alternatives. USDA For. Serv., Res. Pap. SE-21 I, 8 p. Southeast. For. Exp.

Stn., Asheville, N.C.

I

Yields are presented by stand age. site index, and stand basal area at the beginning ofa growth

period. Differences between these yields and those projected 20 and 50 years ago are

explained partly by changing definitions of normal or full stocking and partly by changes in

forest management. If only pulpwood harvesting is envisioned, fairly high stocking is needed

I

to get full production from the site. To produce sawtimber and veneer in a 35-year rotation,

however. stocking must be considerably lower. For longer sawtimber-veneer rotations,

heavier stocking is required to maximize yield.

KEYWORDS: Pinus ellinffii, stand density, stocking, growth projections, yield tables.
The Forest Service, U.S. Department of Agriculture, is dedicated to the principle of multiple

use management of the Nation’s

forest resources for sustained

yields of wood, water, forage,

wildlife, and recreation. Through

forestry research, cooperation

with the States and private forest

owners, and management of the

National Forests and National

Grasslands, it strives-as directed by Congress-to provide

increasingly greater service to a

growing Nation.

USDA policy does not permit discrimination because of

race, color, national origin, sex or religion. Any person

who believes he or she has been discriminated against in

any USDA-related activity should write immediately to

the Secretary of Agriculture, Washington, D.C. 20250.