No. 75 

1957 

@OREST RESEARCH NOTE

NORTHEASTERN FOREST EXPERIMENT STATION 

Upper Darby , Pennsylvania 

- 

GROWTH AND MORTALITY OF RESIDUAL LOBLOLLY 

PINES AFTER A SEED-TREE CUTTING 

Should loblolly pine seed trees be left to grow for 

many years, or should they be harvested as soon as adequate 

amounts of reproduction have started? What should be done 

with the trees too small for sawlogs: should they be cut for 

pulpwood, or will they develop into high-quality stems? From 

a study started in 1951 and previously described (4-1, we now 

e have indicative answers to these questions for old-field 

loblolly stands on Maryland's Eastern Shore. 

Seed Trees 

From studies elsewhere, some authors have indicated 

that loblolly pine seed trees suffer little mortality, have 

greatly accelerated growth, and may be left for 15 years or 

longer to produce high-quality products (2, 3, -, 5 7)o 

Trousdell (9) , however, reported sufficient mortality, 

chiefly from lightning and wind, so that removal of seed 

trees within 3 years was recommended, 

Results from our study, obtained following a 30-acre 

seed-tree cutting in the summer and fall of 1951, are similar to those reported by Trousdell. In our study three methods of seedbed preparation were used in experimental plots: 

(a) a small bulldozer dragging a stump before cutting, and 

then a late-summer fire after cutting; (b) a late-summer 

fire after cutting; and (c) plowing with a Ranger Pal plow 

and small bulldozer. In addition, there was a control plot, 

which was only logged. 

In all plots 10 seed trees per acre were left. Mortality averaged 14 percent greater in the summer-burned 

a plots (including those stump-dragged and those not dragged) 

than in the unburned plots during the first 19 months, 

# 1 

k 
Thereafter, windthrow and wind breakage caused practically 0 

all mortality. By April 1957, 35 percent of the seed trees 

in the control plot had died; nearly as many died as in the 

average burned plots (40 percent ) . The plowing and stumpdragging treatments apparently had little effect on seedtree mortality, Much of the variation in mortality between 

treatments was apparently due to spotty wind damage, 

Surviving seed trees have grown rapidly in diameter. 

The average tree in each plot gained 1.1 to 1.2 inches in 

diameter at breast height between 1953 and 1957. However, 

this growth has not been sufficient to offset the effects of 

mortality on net basal areas and board-foot volumes. Consequently, both basal area and volume tend to become progressively smaller (table l), 

Very different results may occur in pulpwood stands, 

particularly if the seed trees selected are dominants in 

understocked stands. From McClayls (6) - data, such trees 

would have very good survival and growth, 

Table 1.--Changes in number, basal area, and volume 

of seed trees following cutting in 1951 1 

1~~~~~~~~ IN APRIL 1953 AND APRIL 1957. PERCENTAGES ARE BASED ON 1951 RESIDUAL STAND OF SEED TREES. 

Seedbed treatment 

Percent Percent 

MORTALITY TO DATE 

Stump-dragged, summer-burned 24 51 

Summer-burned 19 29 

Plowed 6 23 

None 9 35 

All treatments 15 35 

BASAL-AREA LOSS SINCE 19 51 

Stump-dragged, summer-burned 18 3 6 

Summer-burned 15 13 

Plowed 2 5 

None 6 20 

All treatments 10 18 

BOARD-FOOT VOLUME LOSS SINCE 1951 

Stump-dragged, summer-burned 16 31 

Summer-burned 13 9 

Plowed 1 2 

None 5 18 

All treatments 8 14 

1953 1957 
However, for sawtimber stands of old-field origin 

such as the one studied, seed trees should be harvested as 

soon as adequate amounts of reproduction are established (or 

seedbeds are no longer favorable), Since all treated plots 

in this study had 6,160 or more pine seedlings per acre during the first summer after cutting (4), their seed trees 

could have been removed during the foilowing fall or winter 

(1952-53). Under such conditions, the loss in seed-tree 

volumes may be 5 percent or less in unburned areas and 15 

percent in summer-burned areas. Additional delay would 

usually result in increased volume losses, and thus increase 

the cost of reproducing the stand, 

Pulpwood Trees 

What about formerly intermediate and overtopped pines 

too small for sawlogs? Will they grow rapidly into highquality sawtimber trees as Reynolds (8) observed, or will 

many die as in a North Carolina stand studied by Chaiken (&)? 

Small overstory pines in mature old-field stands on 

the Eastern Shore will apparently behave like those studied 

by Chaiken. In our study, as in his, these trees usually 

had very short crowns. When released, many of them died, In 

April 1953, 125 of these trees that were still living were 

tagged: 64 in the stump-dragged and summer-burned plot and 

61 in the control plot, In the following 4 years, 31 percent 

of the tagged trees died (27 percent in the treated plot, 36 

percent in the control), In each plot the surviving trees, 

which had an average diameter of 7 inches in 1953, grew only 

0,6 inch in diameter during the 4 years, And the net change 

in the basal area of tagged trees was a loss of 19 percent, 

Evidently such pines should be removed for pulpwood 

when seed-tree cuttings are made, if their volume and that 

in the tops of sawtimber trees provide a commercially feasible operation. 

Conclusions 

When mature old-field stands of loblolly pine are 

harvested by seed-tree cuttings on the Eastern Shore, we 

recommend that : 

Seed trees be removed just as soon as they have served 

their purpose. Even then, there will be some loss in 

volume, 

Small non-sawtimber pines be cut for pulpwood, if feasible, when the seed-tree cutting is made. Leaving them 

is not advisable, because many die and surviving trees 

grow slowly. 
Literature Cited 

(1) Chaiken, L. E. 

1941. Growth and mortality during 10 years following 

partial cuttings in loblolly pine, Jour, 

Forestry 39: 324-329, 

(2) Chapman, Ho H, 

1942. Management of loblolly pine in the pine-hardwood region in Arkansas and in Louisiana 

west of the Mississippi River. Yale Univ, 

School Forestry Bul. 49. 150 pp. 

(3) Grano, C. X. 

1956. Growing loblolly and shortleaf pine in the 

Mid-South. U. S. Dept. Agr. Farmers' Bulo 

2102. 25 pp, 

(4) Little, So, and Mohr, Jo J. 

1954, Reproducing pine stands on the Eastern Shore 

of Maryland. Northeasto Forest Expt. Sta., 

Sta. Paper 67. 11 pp, 

(5) Lotti, To 

1956. Growing loblolly pine in the South Atlantic 

States. UoS. Dqpt. Agr. Farmers' Bul, 2097, 

33 PP. 

(6) McClay, To Ao 

1953. Growth, mortality, and regeneration after cutting in loblolly pine pulpwood stands, 

Southeast. Forest Expt. Sta., Sta. Paper 28. 

14 PP. 

(7) Pomeroy, KO Bo 

1949. Loblolly pine seed trees: selection, fruitfulness, and mortality. Southeast. Forest 

Expt. Sta., Sta. Paper 5. 17 pp~ 

(8) Reynolds, Re Re 

1952. Suppressed pines not always inferior. Southern 

Forest Expt. Sta., Southern Forestry Note 82: 

2-3 0 

(9) Trousdell, KO B. 

1955. Loblolly pine seed tree mortality. Southeast. 

Forest Expt. Sta., Sta. Paper 61. 11 pp. 

--S. LITTLE 

Northeastern Forest Experiment Station 

Forest Service, UoS. Dept. Agriculture 

and Jo Jm MOHR 

Maryland Department of Forests and Parks 

AGRICULTURE-FOREST SERVICE-UPPER DARBY