ity Response o 

Forest Service 

Northeastern Forest 

Experiment Station 29=Year=Old, Even-Aged 

Research 

Paper P=l E-546 Central Hardwoods 

After Thinning 

- 

David L. Sonderman 
The Author 

David L. Sonderman, research forest product technologist, received a 

B.S. degree in forestry from West Virginia University in 1962. He joined the 

Northeastern Forest Experiment Station in June 1962, and was on the staff of 

the Eastern Softwood Timber Quality project until June 1972. He is currently 

with the Northeastern Station's project on Management and Utilization Alternatives for Nonindustrial Private Forests located at Delaware, Ohio. 

Manuscript received for 

publication 13 February 1984 

Abstract 

Describes the quality response of a 29-year-old upland hardwood stand 

grown for 6 years under different levels of residual stand density. Both the 

number of defects per square foot of surface area and the number of epicormic 

branches changed under different stocking levels. The results suggest that the 

effect of stocking on potential stem quality of certain species may be substantial even after a few years of treatment. 
introduction The Stand 

In the last decade, much research 

has been done on diameter and height 

growth responses associated with 

various silvicultural treatments designed to regulate density of evenaged upland hardwood stands (Hilt 

1979). But there has been little research on comparing the response of 

quality-related tree characteristics to 

those treatments. Stem quality of 

trees can be changed, sometimes 

adversely, by regulating the stand 

density. Recent studies (Dale and 

Sonderman 1983) have shown that 

live and dead branches on young 

white oak trees grown under different 

density levels increased the most on 

the lowest density plots. Sonderman 

(1983) found that the number of defects per square foot of surface area 

for 80-year-old white oaks increased 

significantly at the heaviest thinning 

level. Godman (1968) showed that 

after 16 years, heavy stem release of 

sugar maple shortened the average 

clear bole length. Godman and Books 

(1971) also showed that stem quality 

improvement in northern hardwoods 

was related to residual stand density. 

In this study, 6-year changes in 

individual limb-related characteristics 

for several species have been summarized in relation to different levels 

of residual stand density. Limb-related 

defects are the greatest deterrent to 

stem quality and the most important 

consideration in managing a stand 

for maximum quality development. 

Hardwood quality research has shown 

that potential stem quality also is affected by species, age, crown class, 

and crown ratio. However, limb-related 

defects and epicormic branches still 

are the bole characteristics that are 

affected most by thinning treatments, 

and they should be considered simultaneously when interpreting results. 

The trees selected for this study 

are located on the Vinton Furnace 

Experimental Forest in southern Ohio. 

The stand originated on an &acre demonstration plot after a clearcut in 1954. 

The area was originally a mature, 

even-aged, fully stocked, mixed oak 

stand with an average site index of 

64. The stand was divided into twentytwo 1/10 acre-plots with M-chain isolation strips around each treatment 

area. In 1976, the basal area of the 

young stand was 93 square feet before thinning. Thinning treatments of 

30, 50, and 70 percent stocking were 

applied to groups of plots. Five plots 

were used as a control. After treatment, the stand was composed of 

aspen, red maple, mixed oaks, yellowpoplar, black cherry, and hickory. A 

totai of 338 trees are included in the 

study. Four species groups were used 

in the analyses (Table 1). A miscellaneous group, which included black 

cherry and hickory, accounted for 

only a few trees and was not included 

in the analyses. 

Table 1.-Number of trees used in study, 

by species group and stocking level 

Stocking level (%) 

Species group 

30 50 70 Control 

Oak 19 22 24 16 

Vellow-poplar 15 3 19 8 

Red maple 29 9 21 46 

Aspen 7 34 42 24 
Methods Results and Discussion 

A quality classification system 

(Sonderman and Brisbin 1978) was 

used to systematically measure the 

external characteristics of all trees 

3.6 inches or larger in diameter at 

breast height (d.b.h.). All measurements, including limb-related measurements taken on the first and 

second 8-foot section of each tree, 

were made before thinning in the 

spring of 1976 and in 1982. Limb size 

had to be at least 0.3 inch in diameter 

to be measured. 

Tree quality characteristics 

(Sonderman 1979) recorded were: 

d.b.h. 

total height 

crown ratio 

0 number of live limbs on the 1st and 

2nd 8-foot section 

number of dead limbs on the 1st 

and 2nd 8-foot section 

diameter of the largest live limb on 

the I st and 2nd 8-foot section 

diameter of the largest dead limb 

on the 1st and 2nd 8-foot section 

number of epicormic branches on 

the 1st and 2nd 8-foot section 

These characteristics were summarized by species, plot, and treatments; limb-related variables were 

analyzed by covariance analysis. The 

value of the variable at initial time 

was used as the covariate. 

Diameter Growth 

The effect of stocking on diameter growth over the 6-year period is 

evident. Mean diameter growth of 

sample trees in the 30 percent stocking plots was almost twice as much 

as on the controls (Table 2). Hilt (1979) 

reported similar trends in diameter 

growth in relation to stocking from a 

much larger data base representing 

the largest trees. Aspen and yellowpoplar had the highest diameter 

growth in all treatments. Red maple 

was next and the oaks had the slowest growth. In the control, the oaks 

had the least diameter growth of all 

species compared. 

Height Growth 

The effect of stocking on height 

growth (Table 2) follows a different 

pattern than diameter growth. Trees 

grown at levels of stocking where 

crowding of stems occurs tend to 

have greater height growth than diameter growth (Toumey and Korstian 

1947). Maximum height growth of all 

species combined occurred between 

50 and 70 percent stocking and averaged slightly more than 2 feet a year 

from 1976 to 1982. The trend was 

similar for individual species. The 

30 percent plots and the control plots 

had the least overall change except 

for aspen. in the control, aspen grew 

3 times faster than other species. 

Crown Ratio 

Crown ratio is the ratio of live 

crown length to total tree height. 

Changes in crown ratio after 6 years 

of thinning treatments are shown in 

Table 2. For all species combined 

there was a reduction of crown ratio 

in all treatments except for the 30 

percent treatment. The increase in 

crown ratio was caused by the open 

conditions created by heavy thinning. 

Opening a stand provides additional 

growing space and light needed to 

develop epicormic branches and promote the development of live branches. 

This contributes to a downward extension of the crown and results in 

an increase in crown ratio. 

Looking at the species individually, crown ratios for yellow-poplar 

increased nearly twice as much as 

other species in the 30 percent plots. 

Most species increased in crown 

ratio in the 30 percent plots and decreased in the control. In the control 

after 6 years, aspen changed in crown 

ratio only by 0.3 percent. Red maple, 

which had the most uniform change 

in crown ratios, was affected the 

least by treatment. 

The 30 percent treatment, regardless of species, showed significantly 

greater crown ratio than the other 

treatments (P < .005). However, within 

the same treatment there was no significant difference in crown ratio between oaks and all species combined. 
Table 2.-Summary of average tree characteristics in 1976 and 1982, 

by species group and stocking level 

Stocking level (%) 

Species group 30 50 70 Control 

1976 1982 1976 1982 1976 1982 1976 1982 

D.b. h. (Inches) 

Oak 

Yellow-poplar 

Red maple 

Aspen 

Height (Feet) 

Oak 

Yellow-poplar 

Red maple 

Aspen 

Crown Ratio (Percent) 

Oak 

Yellow-poplar 

Red maple 

Aspen 

Defectslft2 Surface Area (N~mber)~ 

Oak 

Yellow-poplar 

Red maple 

Aspen 

aLive and dead limbs, butt 16-foot section. 

Live and Dead Limb Defects 

Per Square Foot of Surface Area 

Aspen showed by far the greatest 

reduction in number of live and dead 

limb defects per square foot of surface area over all treatments. Yellowpoplar and red maple showed the 

least change of live and dead limbs in 

the 30 percent plots. The oaks displayed a low but uniform reduction in 

live and dead limb defects per square 

foot of surface area throughout all 

treatments. 

both the 70 percent and control plots 

each decreased by about 61 percent 

from 1976 to 1982. However, there 

was no significant difference among 

treatments and species. 

Both volume and total surface 

area of the bole increase as the tree 

grows. Expansion of the surface area 

expressed in square feet may show 

an increasing or decreasing number 

of defects per square foot of surface 

area, depending on how many existing and new defects come and go. 

This is apparent in Table 2, which 

shows an overall reduction in the 

number of live and dead limb defects 

per square foot of surface area in the 

butt 16-foot section after 6 years. 

Comparing limb defects per 

square foot of surface area for oaks 

after 6 years, the 30 percent treatment was significantly greater than 

the other treatments (P < .13). 

When combining all species, the Epicormic Branches 

number of live and dead limb defects 

per square foot of surface area in 

When a tree stem changes, as in 

sudden full exposure to sunlight, 
dormant buds on the stem begin to 

grow and develop into epicormic 

branches. These epicormic branches 

can develop into small live limbs if 

allowed to grow in sunlight under 

conditions of open stocking. 

Tablte 3.-Percentage of trees with epicormic branches in butt 8=foot 

and second 8=foot sections 1976-82, by species 

Stocking level (%) Number of 

epicormic 30 50 70 Control 

branches 

1976 1982 1976 1982 1976 1982 1976 1982 In this study, epicormic branches 

were grouped to facilitate counting 

on each tree section. The groups are: OAK 

Butt &Foot Section 

70.0 15.8 86.4 4.5 96.0 20.8 73.7 

20.0 42.1 9.1 27.3 4.0 41.7 21.0 

10.0 42.1 4.5 68.2 - 37.5 5.3 

0 = No epicormic branches 

1 = 1 to 6 epicormic branches 

2 = 7+ epicormic branches 

Silviculturists attempt to regulate the development of epicormic 

branches by maintaining different levels of stocking and favoring species 

that are not prolific epicormic sprouters. Some of the species included 

(Table 3) are considered prolific epicormic sprouters. For example, red 

maple showed an increase in the 

number of epicormic branches in both 

the butt and the second 8-foot section 

as the stocking level decreased. Both 

sections increased the most at the 

50 percent level. 

Second &Foot Section 

YELLOW-POPLAR 

Butt &Foot Section 

75.0 53.3 100.0 - 90.0 52.6 100.0 

25.0 46.7 100.0 10.0 42.1 - - - - - - 5.3 - 

Second 8-Foot Section At all stocking levels, the oaks 

increased in the percentage of trees 

with epicormic branches; the largest 

increases were in the 50 and 70 percent plots. The oak trees had a somewhat uniform distribution of epicormic 

branches in both the butt 8-foot section and the second &foot section. 

This was not the case for many of the 

other species groups. 

RED MAPLE 

Butt 8-Foot Section 

90.0 10.4 100.0 11.1 100.0 38.1 82.6 

10.0 44.8 - 44.4 - 47.6 15.2 - 44.8 - 44.5 - 14.3 2.2 In the second 8-foot section, the 

percentage of yellow-poplar trees with 

epicormic branches increased at all 

treatment levels. Percentages were 

3 times greater than the original figure for the 30, 50, and 70 percent 

levels. Percentages in the control 

increased only by one-third. 

Second 8-Foot Section 

ASPEN 

Butt &Foot Section 

100.0 71.4 76.5 50.0 97.7 69.0 100.0 - 28.6 20.6 50.0 2.3 31.0 - - 2.9 - - - - 

Second 8-Foot Section 

100.0 85.7 88.2 73.5 100.0 69.0 100.0 - 14.3 11.8 26.5 - 31 .O - - - - - - - - 
Aspen showed little change in 

the percentage of trees with epicormic 

branches in the butt 8-foot section. 

In the second 8-foot section, the proportion of aspen trees with epicormic 

branches increased the most in the 

control plots. On all plots, the number 

of epicormic branches on the second 

8-foot section never exceeded six 

branches. 

Table 4.-Percentage of trees with live limbs in butt 8-foot and 

second 8=foot sections 19'76-82, by species 

Stocking level (%) 

Number of 

live limbs 30 50 70 Control 

OAK 

Live Limbs Butt 8-Foot Section 

100.0 57.9 100.0 86.4 100.0 95.8 100.0 - 42.1 - 13.6 - 4.2 - Limbs were classified by number, size, and condition (live or dead). 

Limb size had to be at least 0.3 inch 

in diameter to be considered; anything 

smaller was classified as an epicormic 

branch. Red maple showed the greatest reaction to treatment (Table 4). In 

1982, the percentage of red maple 

trees with live limbs in the butt 8-foot 

section was 45 at 30 percent stocking 

level and 22 at 50 percent stocking. 

The 70 percent and control plots 

showed no live iimb development in 

the butt 8-foot section. 

Second 8-Foot Section 

YELLOW-POPLAR 

Butt 8-Foot Section 

In the second 8-foot section, the 

percentage of red maple trees with 

live limbs at 30 percent stocking was 

10 in 1976 and 86 in 1982. At 50 percent stocking, the percentages were 

11 in 1976 and 56 in 1982, the percentage of trees with live limbs decreasing as stocking increased. The 

number of live limbs ranged from 1 to 

16 limbs on the 30 percent plots to 

only 1 to 2 limbs on the control plots. 

Second 8-Foot Section 

100.0 40.0 33.3 100.0 85.0 84.2 100.0 - 40.0 33.3 - 10.0 10.6 - - 20.0 33.4 - - 5.2 - 

RED MAPLE 

Butt 8-Foot Section 

100.0 55.2 100.0 77.8 100.0 100.0 100.0 - 31 .O - 11.1 - - - - 10.4 - - - - - - 3.4 - 11 .I - - - 

In comparing the butt and second 

8-foot sections of the tree, the percentage of yellow-poplar trees with 

live limbs in 1982 was 13 for the butt 

8-foot section and 60 for the second 

8-foot section. The second 8-foot 

section usually contains more live 

limbs. 

Second &Foot Section 

90.0 13.8 88.9 44.5 76.2 42.9 89.1 

6.7 51.7 - 33.3 14.3 47.6 10.9 

3.3 20.6 - - 9.5 9.5 - - 10.5 11.1 11.1 - - - - 3.4 - 11.1 - - - The oaks responded to the lowest stocking treatment-52 percent 

of the trees had live limbs in the 

second 8-foot section in 1982. In 1976, 

the oaks were free of live limbs in the 

30 percent plots. In the 50 and 70 

percent plots, the oaks accounted for 

32 and 17 percent of the trees with 

live limbs. The control plots showed 

little change. 

ASPEN 

Butt 8-Foot Section 

100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Second 8-Foot Section 

100.0 100.0 97.1 100.0 100.0 100.0 100.0 - - 2.9 - - - - 
One reason for the increase in 

the percentage and number of trees 

with live limbs is that many of the 

small shoots and twigs that were less 

than 0.3 inch in diameter in 1976 and 

classified as epicormics grew larger 

in diameter by 1982 and, therefore 

were classified as measurable live 

limbs. Under heavy thinning, most 

trees with epicormic branches will 

feather out and develop more epicormic branches. Some of these 

epicormic branches will become live 

limbs in a short time. 

When comparing all species, 

treatment differences for live limbs 

were significant (P < .001). In the 

30 percent treatment alone, there was 

an increase of 1.8 live limbs over the 

control. When separating out only the 

oak species, treatment differences for 

live limbs were significant (P < ,089). 

Diameter of Live Limbs 

The average diameter of the 

largest live limbs in 1976 and 1982 is 

shown in Table 5. The diameter of live 

limbs was larger on the second 8-foot 

section than the butt 8-foot section. 

On the butt 8-foot section, the oaks, 

yellow-poplars, and red maples increased in live limb size at both the 

30 and 50 percent stocking. The 70 

percent and control plots showed 

little change. 

In the second 8-foot section, the 

average size of the largest live limbs 

appeared somewhat uniform for the 

6-year period. Red maple had the 

greatest change, with limb size decreasing in all treatments except the 

control. Because the second 8-foot 

section usually encompasses part of 

the living crown in the younger trees, 

it receives more light than the lower 

bole section. Consequently, the development of live limbs on the second 

8-foot section is not at the same rate 

as on the butt 8-foot section. 

Table 5.-Average diameter of the largest live limbs in butt 89foot and 

second 8=foot sections 1976-82, by species 

Stocking level (%) 

Species 30 50 70 Control 

1976 1982 1976 1982 1976 1982 1976 1982 

Oak 

Yellow-poplar 

Red maple 

Aspen 

Oak 

Yellow-poplar 

Red maple 

Aspen 

............................................... inches -------- --------- --------------- --------------- 

Second 8-Foot Section 

- .94 - 1.03 - 1.12 - - - 1.16 1.20 - .91 1.08 - - 

1.08 .84 2.00 .84 1.75 1.41 1.15 1.95 - - 1.25 - - 4.00 - - 
Table 6.-Percentage of trees with dead limbs in butt 8-foot and 

second 8=foot sections 1976-82, by species 

Stocking level (%) 

Number of 

dead limbs 30 50 70 Control 

Dead Limbs 

Two important factors that affect 

the presence of dead limbs in trees 

are species and stand density. Species is important because of inherent 

differences caused by growth, vigor, 

shade tolerance, and natural pruning. 

Stand density is important because 

of its effect on the factors just cited. 

OAK 

Butt 8-Foot Section 

57.9 59.1 81.8 60.0 

36.8 40.9 13.6 24.0 

5.3 - 4.6 4.0 - - - 12.0 

Aspen had the largest percentage 

of trees with dead limbs and the 

largest number of dead limbs in the 

butt 8-foot section (Table 6). In all 

treatments, aspen showed a reduction 

in the percentage of trees with dead 

limbs in the butt 8-foot section over 

the 6-year period. The 70 percent plots 

had the greatest reduction in the 

percentage of trees with dead limbs, 

and the 30 percent plots had the least 

reduction. Other species showed similar trends for dead limbs in the butt 

8-foot section. 

Second 8-Foot Section 

YELLOW-POPLAR 

Butt 8-Foot Section 

Second 8-Foot Section 

80.0 33.3 66.7 65.0 

13.3 - - 25.0 

6.7 66.7 33.3 10.0 

Analysis of the data for the upper 

8-foot section shows aspen with both 

the largest percentage of trees with 

dead limbs and the largest number of 

dead limbs. For red maple, the percentage of trees with dead limbs in 

the second &foot sect ion decreased 

from 83 percent in 1976 to 38 percent 

in 1982 in the 30 percent plots, and 

from 96 to 44 percent in the control 

plots. Trends were similar for many 

other species. 

RED MAPLE 

Butt 8-Foot Section 

89.7 44.4 88.9 47.6 

10.3 44.4 11 .I 47.6 - 11.2 - 4.8 

Second 8-Foot Section 

ASPEN 

Butt 8-Foot Section 

42.8 5.9 38.2 14.0 

42.9 32.3 41.2 44.2 

14.3 38.3 17.7 20.9 

- 20.6 2.9 16.3 - 2.9 - 4.6 

Second 8-Foot Section 
Summary and Conclusions 

The response of the oaks to 

treatment showed a reduction in the 

percentage of trees with dead limbs 

as the stocking increased. However, 

there was no significant difference 

among treatments in the number of 

dead limbs for the oak group. 

Diameter of Dead Limbs 

The average diameter of the 

largest dead limbs on the butt &foot 

section (Table 7) was smaller than the 

average diameter of the dead limbs 

on the second 8-foot section. Analyzing all species for both 8-foot sections, the size of dead limbs in 1982 

decreased in all treatments except 

for the control. One reason for the 

larger dead limbs in the dense control 

plots is that the smaller dead limbs 

naturally pruned off over the 6-year 

period, leaving only the larger remaining limbs to be counted during the 

second measurement period. 

Results of this research are not 

intended as guidelines for applying 

cultural treatments to forest stands. 

Instead, they allow the woodland 

manager to look at what might happen to a forest stand in a short time 

at different levels of stocking. The 

results have limited application because only one site class and one age 

group was used. The comparisons 

and quantifications in this paper are 

the beginning of a long-term research 

study to determine the effects of 

different cultural practices on tree 

quality. 

In 6 years, there have been numerous changes due to treatment in 

both the rate of growth and the bole 

quality of certain species groups. The 

defect characteristics covered in this 

study are not independent of each 

other. There is a sequence of events 

that occurs simultaneously. For exTable 7.-Average diameter of the largest dead limbs in butt 8-foot and 

second 8-foot sections 1976-82, by species 

ample, epicormic branches that develop will grow into live limbs, live 

limbs die and become dead limbs, 

and dead limbs fall off and become 

overgrowths. It is equally important 

to note that growth and quality sometimes develop naturally even when 

nothing is done to the forest stand. 

As evidence of this, some of the control plots had better quality than 

some of the treated plots. Drastic 

cutting schemes sometimes are applied to stimulate the growth rate; 

this adversely affects bole quality. 

Therefore, there is a trade-off between 

growth and quality when both are 

objectives. 

Stocking level (O/O) 

Species 30 50 70 Control 

1976 1982 1976 1982 1976 1982 1976 1982 

Oak 

Yellow-poplar 

Red maple 

Aspen 

Oak 

Yellow-poplar 

Red maple 

Aspen 

........................................................ inches -------------------------------. 

Butt 8-Foot Section 

1.06 0.56 0.77 0.81 1.32 1.30 

1.49 .50 .75 - .80 .75 

1.42 1.10 .55 .50 1.06 .75 

.60 .56 .58 .55 .56 .54 

Second 8-Foot Section 
Literature Cited 

Some of the findings in this study 

indicate that: 

* Diameter (d.b.h.) growth increased 

with an increase in growing space. 

Average crown ratio of all trees 

combined increased only at the 

lowest stocking level. 

Live and dead limb defects per 

square foot of surface area decreased as stocking increased. 

The number of live limbs and the 

percentage of trees with live limbs 

decreased as stocking increased. 

There were more dead branches 

than live branches on the butt 

16-foot log regardless of stocking 

level. 

The second 8-foot section of the 

butt 16-foot log of the tree had 

more and larger live and dead limbs 

than the bottom 8-foot section. 

8 The number of epicormic branches 

and the percentages of trees with 

epicormic branches increased as 

the stocking level declined for all 

species combined. 

Aspen and yellow-poplar increased 

the most in diameter growth after 

6 years. 

Red maple outperformed all other 

species in height growth in the 30 

percent plots. 

Aspen had fewer limb defects per 

square foot of surface area than 

any other species. 

Dale, Martin E.; Sonderman, David L. 

Effect of thinning on growth and 

potential quality of young white 

oak crop trees. Res. Pap. NE-539. 

Broomall, PA: U.S. Department of 

Agriculture, Forest Service, Northeastern Forest Experiment Station; 

1983. 12 p. 

Godman, R. M. Culture of young 

stands. In: Proceedings, sugar 

maple conference. 1968 August 

20-22; Houghton, MI: Michigan 

Technological University and U.S. 

Department of Agriculture, Forest 

Service; 1968: 82-87. 

Godman, Richard M.; Books, David J. 

Influence of stand density on stem 

quality in pole-size northern hardwoods. Res. Pap. NC-54. St. Paul, 

MN: U.S. Department of Agriculture, Forest Service, North Central 

Forest Experiment Station; 1971. 

7 P. 

Hilt, Donald E. Diameter growth of 

upland oaks after thinning. Res. 

Pap. NE-437. Broomall, PA: U.S. 

Department of Agriculture, Forest 

Service, Northeastern Forest Experiment Station; 1979. 11 p. 

Sonderman, David L. The quality response of evenoaged 80-year-old 

white oak trees after thinning. Res. 

Pap. NE-543. Broomall, PA: U.S. 

Department of Agriculture, Forest 

Service, Northeastern Forest Experiment Station; 1984. 6 p. 

Sonderman, David L. Guide to the 

measurement of tree characteristics important to the quality classification system for young hardwood trees. Gen. Tech. Rep. NE-54. 

Broomall, PA: U.S. Department of 

Agriculture, Forest Service, Northeastern Forest Experiment Station; 

1979. 12 p. 

Sonderman, David L.; Brisbin, Robert L. 

A quality classification system for 

young hardwood trees-the first 

step in predicting future products. 

Res. Pap. NE-419. Broomall, PA: 

U.S. Department of Agriculture, 

Forest Service, Northeastern Forest Experiment Station; 1978. 7 p. 

Toumey, James W.; Korstian, Clarence 

F. Foundations of silviculture. New 

York: John Wiley and Sons; 1947. 

468 p. 

At 30 percent stocking, yellowpoplar was the only species to 

show an increase in limb defects 

per square foot of surface area. 
Sonderman, David L. Quality response of 29-year-old, even-aged 

central hardwoods after thinning. Res. Pap. NE-546. Broomall, 

PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1984. 9 p. 

Describes the quality response of a 29-year-old upland hardwood 

stand grown for 6 years under different levels of residual stand 

density. Both the number of defects per square foot of surface 

area and the number of epicormic branches changed under 

different stocking levels. The results suggest that the effect of 

stocking on potential stem quality of certain species may be 

substantial even after a few years of treatment. 

ODC 228.1:242:851:852.11 

Keywords: silviculture; thinning; bole quality 

a U.S. GOVERNMENT PRINTING OFFICE: 1984-705-0291520 
Headquarters of the Northeastern Forest Experiment Station are in 

Broomall, Pa. Field laboratories are maintained at: 

* Amherst, Massachusetts, in cooperation with the University of 

Massachusetts. 

@ Berea, Kentucky, in cooperation with Berea College. 

@ Burlington, Vermont, in cooperation with the University of 

Vermont. * Delaware, Ohio. * Durham, New Hampshire, in cooperation with the University of 

New Hampshire. * Hamden, Connecticut, in cooperation with Yale University. 

* Morgantown, West Virginia, in cooperation with West Virginia 

University, Morgantown. * Orono, Maine, in cooperation with the University of Maine, 

Orono. * Parsons, West Virginia. * Princeton, West Virginia. * Syracuse, New York, in cooperation with the State University of 

New York College of Environmental Sciences and Forestry at 

Syracuse University, Syracuse. * University Park, Pennsylvania, in cooperation with the 

Pennsylvania State University. 

Warren, Pennsylvania.