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FOREST RESEARCH NOTES 

NORTHEASTERN FOREST EXPERIMENT STATION 

Upper Darby , Pennsylvania 

NO. 76 

1957 

SEEDBED TREATMENT INCREASES DOMINANCE 

OF NATURAL LOBLOLLY PINE REPRODUCTION 

a 

In 1951 a 30-acre mature stand of loblolly pine on 

Maryland's Eastern Shore was cut, leaving 10 pine seed trees 

per acre; and three different methods of seedbed preparation 

were tried on experimental plots within the stand. Besides 

a control plot, which was only logged, the plot treatments 

included: (a) pulling a stump with a small bulldozer before 

cutting, followed by a late-summer fire after cutting; (b) 

pulling a Ranger Pal plow with the same bulldozer before 

cutting; and (c) using a late-summer fire after cutting, 

Since tractor treatments (a and b above) were restricted to 

creating paths 6 to 10 feet apart, and since the fire was 

intense, the latter produced a better seedbed and greater 

redrtction in competing vegetation (1). 

Results 

@ Five years after treatment, all plots contained large 

amounts of pine reproduction. Treated plots had 5,500 to 

10,160 seedlings per acre, and 94 to 98 percent of their 

sampled milacre quadrats were stocked with at least one pine 

seedling. The control plot had 6,960 small pines per acre, 

stocking 82 percent of the quadrats. 

In the fall of 1956 the average height of the tallest 

pines on stocked quadrats was 6.7 feet where stump dragging 

and summer burning had been used, 5.5 feet in the summerburned area, 4.2 feet in the plot plowed before cutting, and 

3.0 feet in the control. However, the largest individuals 

in the study area were 8 to 11 feet tall. Reproduction of 

this size occurred on 40 percent of the sample quadrats in 

the stump-dragged and summer-burned plot, 18 percent in the 

surnmer-burned plot, 10 percent in the plowed plot, and only 

2 percent in the check, 

1 

1 
The number of hardwood seedlings and sprout clwnps 

increased in all plots between 1952 and 1956. The increase 

was greater in the burned plots (1,370 per acre) than in the 

unburned plots (630 per acre), However, in 1952, a year 

after cutting, the burned plots had contained 2,580 fewer 

hardwoods per acre than the unburned plots. In 1956 hardwoods were found on 86 to 100 percent of the sample quadrats 

in all plots. 

The tallest hardwoods were 2,6 feet shorter (average) 

in the burned plots than in the unburned plots--5.8 feet 

compared to 8.4 feet. However, their average height growth 

between 1952 and 1956 was 4 feet in all treated plots, in 

contrast to 3 feet in the control. 

The most important effect of the seedbed treatments 

will be on future stand composition. To estimate this effect, the tallest pine on each sample quadrat was classified 

in one of the following categories: (a) dominant; (b) equal 

in height to competing hardwoods and shrubs; (c) shorter 

than competing hardwoods and shrubs, but in a small hole SO 

that it might become a part of the overstory; and (dl overtopped. The results (table 1) indicate that pines will form 

a relatively pure stand, probably 90 percent of the next 

overstory, in the stump-dragged and summer-burned plot. In 

the summer-burned plot they may form 75 percent of the next 

overstory; in unburned plots (whether plowed or not), about 

50 percent. Plowing as used in this study created so little 

disturbance that its effect on the next stand will apparently be negligible. 

A seed-tree cutting alone cannot usually be expected 

to give so good results as in this study. Here, seed trees 

were selected from the most prolific producers of cones in 

Table 1.-Position of pine reproduction.in relation to competing vegetation 1 

I Quadrats with pines- I 

Seedbed treatment Equal to In Dominant competitors small hole Overtopped 

1 I I 

Percent Percent Percent Percent 

Stump-dragged, summer burned 54 32 4 8 

Summer-burned 28 30 20 16 

Plowed 2 12 40 40 

None 2 22 2 6 32 

'percentage figures are based on all quadrats sampled, including those not 

stocked. 
the stand, and the cutting was made just before an exceptionally heavy crop of pine seed matured, Usually there 

would be much less seed, because of less fruitful trees or a 

poorer crop. Then seedbed treatments would be far more important, both in establishing an adequate amount of pine reproduction and in providing for its dominance over competing 

vegetation. 

Costs of Seed-tree Cutting and Summer Burning 

What would be the cost of natural reproduction established by seed-tree cutting and a summer fire? If living 

seed trees could have been salvaged with no decrease in 

stumpage value, and if volume loss were limited to 15 percent (21, - the seed-tree cost would have been about $10 per 

acre. The average cost of summer burns used on the Eastern 

Shore has been about $8 per acre, relatively high because 

most of the areas have been small (10 to 40 acres) and have 

adjoined other woodlands that had to be protected. Thus, 

the two treatments combined may cost about $18 an acre. However, their possible use is limited to years when a good 

crop of pine seed is produced and to times when summer burning is feasible (I), - 

Conclusions 

The 5-year results from testing seedbed-preparation 

methods in combination with seed-tree cutting in mature loblolly pine on Maryland's Eastern Shore show that: 

' 

The more effective seedbed treatments tested increased 

the amount of pine reproduction, its stocking, and its 

early height growth. 

Although reductions in the number of hardwood seedlings 

and sprout clumps tended to be temporary, their height 

in the most effective treatments was appreciably less 

after 5 years than in areas that were only logged, 

Effective treatments that blanket areas, such as the 

summer-burning method tested here, can be expected to 

materially increase the proportion of pine in the succeeding stand. 

Literature Cited 

(1) Little, S., and Mohr, J. J. 

1954, Reproducing pine stands on the Eastern Shore 

of Maryland. Northeast, Forest Expt, Sta,, 

Sta, Paper 67. 11 pp, 
(2) Little, S., and Mohr, J. J. 

1957. Growth and mortality of residual loblolly 

pines after a seed-tree cutting. Northeast. 

Forest Expt. Sta., Forest Res. Note 75. 4pp. 

--S. LITTLE 

Northeastern Forest Experiment Station 

Forest Service, U.S. Dept. Agriculture 

and J. J. MOHR 

Maryland Department of Forests and Parks 

AGRICULTURE-FOREST SERVICE-UPPER DARBY