unitedStates

Departmentof

Agriculture

ForestService-

- North_,entral Growth and Yield of Noncommercially

ForestExperiment

station - Thinned Black Spruce in Northern

ResearchNote NC.-364 Minnesota

1994

Glen W. Erickson

ABSTRACT.--Presents yields in number of trees, Slopes are 0 to 1 percent. The study area was

basal area, diameter distribution, and total eleareut in 1921 and had reseeded naturally to

commercial volumes 38 years after thinning a black spruce. The ages of the trees ranged from

black spruce sapling stand. 27 to 33 years in 1954, so we can assume the

stand originated in 1924. In the spring of 1954,

Key Words: Pic_a mar/ana, spacing/thinning, the stand was thinned to 800 trees/acre,

volumes: thinned to 1,300 trees/acre, or leit unthinned.

Spacing guides were used (8x8 for the 800

trees/acre, and 6x6 for the 1,300 trees/acre),

Blaekspruee (Ptc_amaflana(Mill)B.S.P.) is one but good crop trees at closer spacing were leit.

of the most abundant conifers in northern North Each treatment is unreplieated and subsampled

America. It rages in a broad band from the with four permanent, circular measurement

northeastern U.S. to Labrador, and west across plots. Measurements were taken on 1/lO-aere

Canada to westem Alaska. Its southem limits plots for the thinned, and on 1/20-acre plots for

• include the northern portions of the Imke the checks. Trees were thinned using hand

States. In Minnesota, black spruce is the domi- tools. Helnselman (1954) estimated that 2 to 3

nant timber species on organic soils, occupying workforce days per acre were needed to thin the

1.3 million acres in the northeastem third of stands, although no actual times were docuthe State (johnston 1977). mented.

Black spruce commonly regenerates dense Diameters and heights were measured alter the

stands. A study of the effects of _ on a 1953, 1967, 1973, and 1992 growing seasons,

black spruce sapling stand in northern Minne- using diameter tapes, a clinometer, and height

sota was established in spring 1954. The poles.

objectives of this study were to (1) determine the

stocking level that produces the maximum RESULTS AND DISCUSSION

commercial yield, and (2) determine the effect of

Stocking density on length of rotation. In this Growth and yield summaries are presented for

note, we present information obtained from measurements taken in 1953, 1967, 1973, and

stand measurements after the 1953, 1967, 1992; also included are basal area (ft2/acre)

1973, and 1992 growing seasons, projections using equation 7 developed by

Perala (1971). Site index from the 1973 data

MEI_IODS was determined to be 38 feet at 50 years.

This black spruce stand was located on State As expected, stand growth in the thinned and

land near Littlefork in Koochiching County. The check plots responded proportionately to re0rgardc softs there are in the Wildwood series, sidual density. Thirty-eight years after thinning,

which consists of deep, very poorly drained, trees in the most heavily thinned plots (800

slowly permeable softs on glacial lake plains, trees/acre) averaged 1.45 inches more at d.b.h.

(table 1) and trees >3.5 inches d.b.h, averaged

Glen W° Erlckson is a Forestry Technician for 0.83 inches more at d.b.h, than trees in the

the North Central Forest Experiment Station at check plots (table 2).

the Forestry Sciences Laboratory in Grand

Rapids, Minnesota.

...................... [ .............
Table l.---Black sprta_ stand data by tream_nt for all trees

Number of trees per acre Mean d.b.h. Basal area per acre

(inches) (feet2)

Treatment Pre-thinI 19532 1967 1973 1992 1953 " 1967 1973 1992 1953 1967 1973 1992

800 3,673 801 800 798 713 2.35 4.21 4.82 6.29 29 83 107 160

1,300 5,187 1,305 1,322 1,320 1,048 2.02 3.57 4.07 5.54 35 101 130 187

Checks 5,240 1,145s 1,980 2,075 1,285 2.32 3.02 3.30 4.84 37 111 140 182

Data based on:

1Four 150-acre plots per treatment (all trees counted).

2Four 1/10-acre plots for each treatment of 800 and 1,300 treesacre.

aT_ees >1.5 in. d.b.h, only on 120-acre permanent plots in 1953.

o

J

Table 2.--B!ack spntc_ stand data by treammnt (trees >3.5 in. d.b.h.)

Number of trees per acre Mean d.b.h. Basal area per acre

(inches) " (feet2)

Treatment Pre-thin_ 1953= 1967 1973 1992 1953 1967 1973 1992 1953 1967 1973 1992

800 30. 95 558 683 698 4.24 4.77 5.12 6.36 10 71 102 159

1,300 25 53 580 790 953 4.54 4.59 4.85 5.75 6 69 105 177

•Checks 85 85 440 765 955 4.26 4.60 4.58 5.53 9 52 91 166

Data based on:

1Four 150-acre plots per treatment (all trees counted).

2Four 1/ 10-acre plots for each treatment of 800 and 1,300 trees acre.

The 800 trees/acre plots (with 257 fewer trees/ Actual basal area vs. age shows a near linear

acre) had a lower basal area per acre (7 ft2 less) relationship, but the predicted basal area is

than the check plots (table 2), but produced 3.8 curvilinear (fig. 3). Clearly, Perala's (1971)

cords/acre more (table 3). growth model, developed almost entirely from

older natural stands, does not estimate growth

All these volumes exceed the 27 cords/acre well for younger stands.

estimated by Heinselman (1957) for a medium

site at age 70. CONCLUSIONS

Both the cordwood rotation chart (Johnston Black spruce growing on an average site re1977) and the mean and current annual incre- sponded to thinning, achieving greater diameter

ment data (tables 4 and 5) show that the stand, growth and about 10-percent greater yield than

regardless of treatment, is past the recom- unthinned black spruce over a 40-year period.

mended rotation and could be harvested (fig. 1). Additional analyses would be required to deterThe 800 trees/acre treatment has only 15 trees/ mine if putting in 2 to 3 workforce days/acre to

acre that are <3.5 in. d.b.h.; the check plots gain 3.8 cords on 257 fewer crop trees is ecohave 330 unmerchantable trees/acre, nomically efficient.

Cumulative diameter distribution (fig. 2) com- LITERATURE CITED

pares by treatment how the trees grew from the

initial study installation in 1954 to 1992. The Heinselman, M.L. 1954. Work plan for a non800 trees/acre plots had no ingrowth trees; the commercial thinning in swamp black

check plots from 1953 to 1973 had 930. During spruce. Unpublished report on file at North

.the next 19 years (1974-1992), 790 of those Central Forest Experiment Station, Grand

trees died. Rapids, MN.

2
Table 3. Merchantable volume of black spruce treatment (trees >3.5 in. cLb.l_)

Treatment Cubic feet/acreI Cords/acre2

1953 1967 1973 1992 1953 1967 1973 1992

800 190 1,377 2,009 3,251 2.1 14.9 21.6 34.8

1,300 116 1,339 2,066 3,585 1.0 11.9 18.7 33.6

Checks 171 1,018 1,799 3,369 1.8 9.8 17.0 31.0

..

i Using equation 3 (Perala 1971).

2Using equation 4 (Perala 1971).

Table 4..---Black spruce mean and current annual increment (trees >3.5 in. d.b.h.)

J

Cords/acre/year

MAI CAI

Treatment 291 43 49 68 37 46 59

800 trees/acre 0.07 0.35 0.44 0.51 0.91 1.12 0.69

1,300 trees/acre .03 .28 .38 .49 .78 1.13 .78

•Checks .06 .23 .35 .46 .57 1.20 .74

IAge (years)

Table 5.mBlack spruce mean d.b.lz and current annual volume growth 1954-1967, 1968-1973, and

1974-1992

Mean current annual volume

Mean d.b.h, growth/year (inches) growth (d.b.h. > 3.5 in.)

Treatment All trees Trees > 3.5 in. d.b.h. Cubic feet/acre Cords/acre

54-67 68-73 74-92 54-67 68-73 74-92 54-67 68-73 74-92 54-67 68-73 74-92

800 trees/acre 0.133 0.102 0.077 0.038 0.058 0.065 84.8 105.3 65.4 0.91 1.12 0.69

1,300 trees/acre .111 .083 .077 .004 .043 .047 87.4 121.2 79.9 .78 1.13 .78

• . Checks .050 .047 .081 .024 -.003 .050 60.5 130.2 89.5 .57 1.20 .74

1 .25_

I 4-

I .oo1

m

0.75

z

O. 50.

0

o o. 2_

o. oo I _ Figure l.--Black spruce mean and current

='0 3o .;,:, so s'0 70 annual increment by cords for trees

AGE(yea=) >3.5 inches d.b.lz
.r_nJ,,..,. • 8" • •

• • • o

. _ o

8 o •

80 1953 " . . o

• • •

• o

• 1992+ IZ 80 . •

_J • • • •

0

ILLJ

• • • •

an

20_ • . . o o 80O

• . . . • 1300

° • • • - • Chock

O: 8 • s S • o

I , i o , , I i i i i l

0 O0 (_ _" _I 0 O0 (0 _" _I 0 @ (0 _"

.4

D.B.H. (incites)

J

Flgure 2 --B!ack spruce cumulative d bh distribution 1953 and 1992

:il jj Olc_I

i ; , , , 1 i i

25 3S 45 SS 6S 75 8S

AGE (years)

Figure 3--Black spnu_ observed and predicted

(Equatfon 7, Perala 1971) basal area over ame

Heinselman, M.L. 1957. Silvical characteristics

Of black spruce. Stn. Pap. 45. St. Paul, MN:

U.S. Department of Agriculture, Forest Service,

•Lake States Forest Experiment Station. 30 p.

Johnston, William F. 1977. Managers handbook

for black spruce in the north central

States. Gen. Tech. Rep. NC-34. St. Paul, MN:

U.S. Department of Agriculture, Forest Service,

North Central Forest Experiment Station. 18 p.

Perala, Donald,a, 1971. Growth and yield of

black spruce on organic soils in l__!nnesota.

Res. Pap. NC-56. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North

Central Forest Experiment Station. 16 p.

4

"_'U.S.GOVERNMENTPRINTINGOFFICE 1994 559--174/00058

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