Forest Service 

Northeastern Forest 

Experiment Station 

FIBER - -- -- HANDBOOK: 

A Growth Model for Spruce-Fir 

and Northern Hardwood 

Forest Types 

Dale S. Solomon 

Richard A. Hosmer 

Homer T. Hayslett, Jr. 
Abstract 

A matrix model, FIBER, has been developed to provide the forest manager with a 

means of simulating the management and growth of forest stands in the Northeast. Instructional material is presented for the management of even-aged and 

multi-aged spruce-fir, mixedwood, and northern hardwood stands. FIBER allows 

the user to simulate a range of silvicultural treatments for a variety of species - 

compositions growing on different sites. The internal structure of the model is 

defined and explanations on the use of FIBER are offered. Examples of input, 

interim procedures, and final output are shown. 

The Authors 

DALE S. SOLOMON joined the Northeastern Forest Experiment Station in 1962. 

He has been engaged in mensuratiollal research on the growth and yield of 

northern species in the Northeast at the Station's laboratories at Durham, New 

Hampshire, and Orono, Maine. 

RICHARD A. HOSMER joined the Northeastern Station in 1980. He is employed 

as a computer prograinmer at the Station's laboratory at,Orono, Maine. 

HOMER T. HAYSLETT, JR. has been a member of the mathematics faculty at 

Colby College, Waterville, Maine, since 1962. He has been working on cooperative'research studies at the Northeastern Station at Orono, Maine. 

Manuscript received for publication October 16, 1986. 

1 I . . 

Northeastern Forest Experiment Station 

370 Reed Road, Broomall, PA 19008 

June 1987 
Introduction 

A stand projection growth model, FIBER, was developed to 

predict the growth interactions among species within 

spruce-fir, northern hardwood, and mixedwood forest types 

(Solomon et al. 1986). This prototype model has been 

modifed by further testing of independent variables for the 

regression equations and by the inclusion of data sets from 

a broader geographical area, which allowed for additional 

species (Solomon and Hosmer 1986). The model allows the 

forest manager to simulate the growth of trees for management practices and silvicultural treatments over a range of 

stand densities, harvest intervals, species compositions, 

and sites. These options allow the user to predict the 

growth and yield, over a specified time interval, of either 

individual forest stands or large forested areas receiving 

similar management practices. 

The species composition of the forest stands used in the 

construction of the model ranged from complete softwood 

stands to complete northern hardwood stands. Softwood 

stands were defined as those having at least 65 percent of 

their basal area in softwood species; hardwood stands had 

at most 25 percent of their basal area in softwood species; 

and mixedwood stands had 25 to 65 percent of their basal 

area in softwood species. 

The species groups available in the model are: 

Balsam fir 

Spruce 

Black 

Red 

White 

Eastern hemlock 

Northern white-cedar 

Sugar maple 

Red maple 

Yellow birch 

Paper birch 

American beech 

White ash 

Aspen 

Other hardwoods 

Gray birch 

Striped mapfe 

Pin cherry 

Black ash 

Other softwoods 

Tamarack 

White pine 

Abies balsamea (L.) Mill 

Picea mariana (Mill.) B.S.P. 

Picea rubens Sarg. 

Picea glauca (Moench) Voss 

Tsuga canadensis (L.) Carr. 

Thuja occidentalis L. 

Acer saccharum Marsh. 

Acer rubrum L. 

Betula alleghaniensis Britton 

Betula papyrifera Marsh. 

Fagus grandifolia E hrh . Fraxinus americana L. 

Populus tremuloides Michx. 

Betula populifolia Marsh. 

Acer pennsylvanicum L. 

Prunus pensylvanica L.F. 

Fraxinus nigra Marsh. 

Larix laricinia (Du Roi) K. Koch 

Pinus strobus L. 

The data used to develop this model came from a wide 

range of site conditions across the Northeast. The model 

was constructed to cover a range in the site indices of 30 

to 70 for softwood, 35 to 75 for mixedwood, and 40 to 80 

for hardwood at base age 50 years. 

Some of the stands used for the model development were 

the result of harvesting practices that resembled different 

forms of forest management. Other stands, primarily the 

softwoods, were natural stands that had developed with 

only occasional management. As a result of the range in 

management practices, FIBER can be applied within both 

even-age and multi-age types of managem'ent. 

Softwood, mixedwood, and hardwood stands can be managed or controlled within the model by allowing the stand 

to grow to a specified stocking level, as measured by 

square feet of basal area or cubic volume, or by allowing 

the stand to grow for a specified time (years). The forest 

manager can control the level of residual basal area and 

cubic volume through thinning, by specifying a desired 

level or by using B lines as presented in the stocking 

charts (Figs.1-3). The quality line for hardwoods may be 

used to maintain a higher density and better quality in 

younger and smaller diameter stands (Solomon and Leak 

1986). 

Thinning practices that can be used in the program 

include: thinning from above, thinning from below, thinning 

to a q-line (de Liocourt 1898), removal of trees from any 

diameter class, or thinning uniformly across all diameter 

classes. 

Sources of Data 

Beginning in 1953, a series of 359 permanent plots was 

established within a softwood forest on the Penobscot 

Experimerrtal Forest, Bradley, Maine. The 115-acre 

(0.08-ha) plots were both randomly and systematically 

located within forest stands (compartments) to be used for 

various silvicultural practices. Harvests were conducted in 

each compartment at 5-, lo-, or 20-year intervals (Frank 

and Blum 1978). Each plot was remeasured at 5-year intervals regardless of harvest cycle; if there was a harvest, the 

plot was remeasured both before and after the harvest. 

A study of multi-aged northern hardwoods was begun in 

1964 using forty-eight 113-acre (0.14-ha) plots (Solomon 

1977) located on the Bartlett Experimental Forest, Bartlett, 

New Hampshire. Each plot was measured, thinned uniformly across size classes to a predetermined residual 

basal area and size structure, and remeasured at 5-year 

intervals, as in the softwood study. 

Independent data sets of more than 2,500 growth plots 

from northern Maine, New Hampshire, northern New York, 

and Vermont also were included to increase the flexibility 

and reliability of the prototype model (Solomon et al. 1986). 

Each plot was measured from 1959 to 1974 at 5-year intervals; the data sets covered a wide range of species compositions, sites, management options, and densities (Fig. 4). 
YEAN STAND DIAMETER lmchesl 

% 7 

HARDWOOD 

150 450 750 1050 

. - TREES . - PER -. ACRE 

Figure 1.-Stocking chart for northern hardwoods is based on trees in the main crown 

canopy. The A line is average maximum stocking. The I3 line is recommended 

minimum stocking for adequate growth response per acre. The C line defines the 

minimum amount of acceptable growing stock for a manageable stand. The quality 

line defines the stocking measure in young stands for maintaining quality development. 

240- 

,200 - N 

w 

s 

W 

a 

3 150 - 

6 

0 

a 

g 100- 

4 

-1 

4 

tn 

3 50- 

150 450 750 1050 1350 

TREES PER ACRE 

Figure 2.-Stocking chart for spruce-fir stands is based on trees in the main crown 

canopy. The A line is average maximum stocking. The B line is recommended 

minimum stocking for adequate growth response per acre. The C line defines the 

minimum amount of acceptable growing stock for a manageable stand. 
2i0 4b 6b 920 ll'50 

TREES PER ACRE 

Figure 3.-Stocking chart for mixedwood stands is based on trees in the main crown 

canopy. The A line is average maximum stocking. The B line is recommended 

minimum stocking for adequate growth response per acre. The C line defines the 

minimum amount of acceptable growing stock for a manageable stand. 

In the Northeast, softwood stands often are found on 

poorer sites, and northern hardwood stands on better sites, 

with a mixture of both species on intermediate sites. The 

soils on sites used for study locations ranged from poorly 

drained to well drained.' Site index was not calculated for 

each plot within the data sets. However, some softwood 

stands had site indices of 40 to 50 for red spruce at base 

age 50 years, and hardwood stands had site indices of 50 

to 60 for sugar maple at base age 50 years. The data 

ranged from the poorer spruce-cedar stands to the better, 

pure northern hardwood stands. An expression of site 

index was not included as a variable in the development of 

FIBER since site measurements were not recorded on all 

plots used in model construction. 

Model Pefinitions 

FIBER is a two-stage matrix model. One stage of the model 

is a set of linear regression equations that predict transition 

probabilities of tree growth and mortality as a function of 

stand density, tree size, and proportion of hardwoods. 

' For definitions of poorly drained and well drained see the 

county soil surveys published by the USDA Soil Conservation Service. 

Figure 4.-Dotted area is geogra~hic region of growthplot data used for model construction and testing. 
These predicted probabilities are the elements of stand 

projection matrices that are used to project the distribution 

of stand diameters over a 5-year period (Solomon et al. 

1986). This two-stage matrix model is a modification and 

extension of an earlier matrix model (Buongiorno and 

Michie 1980). 

For each species, a matrix Gt of transition probabilities was 

applied to a stand table vector yt, which displays the number of trees of that species in each d.b.h. class. By adding 

the ingrowth, these two operations generate the stand table 

vector after 5 years of growth for each species: 

where G, = 

with 

ai, = the probability that a tree survives and is in the ith 

diameter class during the time interval from t to 

t+5; 

bi, = the probability that a tree survives'and is in diameter 

class i at time t and in diameter class i + 1 at time 

t+5: 

c,,, = the probability that a tree survives and is in diameter 

class i at time t and in diameter class i+2 at time 

t + 5; and 

k = ingrowth into the 5-inch class during the time 

interval from t to t + 5. 

The data sets described earlier were combined. Tree diameters were measured at 4.5 feet (1.3 m) and placed in 

1-inch classes, which ranged from 5 to 30 inches (12.7 to 

76.2 cm). In subsequent inventories, each tree on the plot 

was categorized as ingrowth, survivor, or mortality (m). For 

a given plot, the diameter distribution for any one species 

was sparse; therefore, the pqoling of plots was required to 

obtain more reliable estimates of a, b, c, and m. Because 

the growth response of forest stands may vary by magnitude of change in density (Solomon 1977; Solomon and 

Frank 1983), the plots were categorized by both the initial 

basal area (IBA,) prior to harvest and the residual basal 

area (RBA,) after a harvest. If there was no harvest at time 

t, the IBA, and RBA, were the same. The plot data were 

grouped by basal area in 20 ftzlacre intervals: The range 

from 20 to.260 ft2/acre (4.6 to 59.6 m21ha) of basal-area 

categories for these data sets was sufficient to provide 

growth response information for the general management 

alternatives. The plots grouped in any specific IBA-RBA 

category were considered to have the same growth rate. 

For each species, linear equations were developed to 

predict: ingrowth into the smallest class (k); the probability 

of a tree remaining in its present diameter class (ast); the 

probability of a tree growing into the next diameter class 

(b,,); the probability of a tiee growing two diameter classes 

larger (clt); and the probability of a tree dying (md. Note 

that the mortality rate is not included in the Gt matrix but is 

inherent in the model since mIt = 1.0 - a,t - b,, - c,,. 

The set of probabilities associated with diameter class i is 

assumed to have a multinomial distribution, and is modeled 

by linear functions of the form: 

where 

IBA, = initial stand basal area prior to harvest at time t 

(ft2/acre), 

RBAt = residual stand basal area after harvest at time t 

(ft2/acre), , ,, 

Dl = midpoint of the diameter class i (inches), I 

Pt = proportion of hardwoods in the stand at time t, and 

Pjk = regression coefficients to be estimated. 

The entries of Gt can be found from these equations using 

the coefficients in Table 1 of the Appendix that were developed from the combined data sets of softwood, mixedwood, 

and hardwood. 

Not all of the species in the data sets r,anged to the same 

maximum-size diameter and did not have a sufficient number of trees in the larger diameter classes. Thus, the a, b, 

c, and m equations did not accurately describe the movement of trees in these larger classes. To decrease the 

growth rate and increase the mortality of the larger trees 
over time in mature stands (RBA > 125 ft21acre), the a-, b-, 

and c- values were linearly reduced from the predicted 

equation value to zero within the, range of the maximumsize diameter classes of each species (Table 2). The 

amount removed from these transition probabilities was 

added to mortality (m) as the stand matures, ensuring that 

partial trees will not accumulate in the 30-inch class. 

To model differences in growth rate due to species composition on different sites, the b- and ,c-values were modified 

if the site index value differed from the average value of 

that forest type: 

b* = b Sllx and c* = c Sllx 

where 

SI = site index, 

for softwood stands 

for mixedwood stands 

for hardwood stands. 

Then 

a* = a (1.0 - m)l(a + b* + c*) 

b** = b* (1.0 - m)/(a + b* + c*) 

c** = c* (1.0 - m)/(a + b* + c*). 

This procedure assures that a*, b**, and c** are all less 

than 1 andthata* + b** + c** + m = 1.0. ltalso 

leaves mortality unaffected by site index. 

When the stand re,aches age 80 or the'number of iterations 

equals 80 years, the "shorter lived" species of paper birch, 

aspen, and other hardwoods are forced out of the stand. 

The c-value is forced to zero by 100 years, the b-value by 

110 years, and the a-value by 130 years. All of the amounts 

removed are added to mortality (m). If the RBA falls below 

60 ft2/acre, ingrowth trees of these species are allowed to 

enter and grow in the stand for another 80 to 130 years. 

For ingrowth, a threshold diameter of 5.5 inches (14.0 cm) 

was used for one large data set and 4.5 inches (1 1.4 cm) 

for the other smaller data sets. After testing several variables and combinations of variables, separate linear equations were developed for each species: 

k = a, + a, RBA, + a2 P, + a, PS,, 

where PS, is the proportion of that species in the stand at 

time t (Table 1). 

Model Reliability 

To validate the predictions of the model, the data set was 

stratified by species and forest type. The actual growth on 

each plot was compared to the predicted growth over a 

15-year period (Table 3). The predicted final volume differed from the actual volume by 0.8 to 14.1 percent. The 

poorest predictions were in the lowest basal-area categories. This was primarily due to large amounts of ingrowth, 

but predictions are expected to improve as more data sets 

are iricluded. 

Overall, the model predicted the growth of softwood and 

hardwood stands more accurately than the growth of 

mixedwood stands. This, too, is to be expected since 

detailed studies have not been conducted in mixedwood 

stands. As the results of thinning studies in smaller size 

stands become available, the predictabilty of the lower 

basal-area categories should improve. 

The largest differences between the actual and predicted 

values are for balsam fir and spruce in hardwood and 

mixedwood stands. Since the harvesting practices and true 

site were not known for every plot, some softwood plots 

could have been considered as hardwood stands after 

thinning. The softwood species may have been removed, 

leaving the residual hardwood in the remaining stand. 

Thus, more spruce and fir ingrowth resulted in the actual 

stand than in the predicted stand. 

Model Application 

The model projects forest stands through time in 5-year 

intervals (Fig. 5). The user can input an inventory of one or 

several stands and grow these stands for the entire rotation 

period or for any specified number of years. FIBER will 

prompt the user with a menu that will determine the scope 

of each run. A control file that stores all of the information 

pertaining to each run is written to disk. The user is asked 

to provide the file name of this control file and whether it is 

a new or existing file. On subsequent runs, the user can 

use this file to duplicate an earlier run, modify the file to 

meet new criteria, or create a new Set of control information. There also is the opportunity to select either the 

printer or a disk file as the primary output device. 

The user is asked to choose from one of the options from 

the following mequ: 

(1) HELP (7) SITE INDEX 

(2) NEW CONTROL (8) PERCENT CULL 

(3) TITLE- (9) THINNING 

(4) STOCKING (7 0) DISPLAY CONTROL 

(5) GROWTH PERIOD (11) DISPLAY STAND 

(6) STAND 'AGE c 12> EXECUTE 
Option 12 is the default value and will be in effect if a 

carriage return is entered. There are default values to a 

variety of questions in this section and they are all designated on the console by being enclosed in < >. Entering a 

minus sign in -response to any question will terminate the 

program.. . . 

Option (1): 

Help A summary of instructions for 

creating a control file will be 

printed on the console. After 

every 15 to 20 lines, the program 

waits for a carriage return to be 

entered before continuing. 

Option (2): 

New An entire control file containing 

the information requested in 

options 3 through 9 will be created. If a file of this name 

already exists, the user will be 

given the choice of renaming the 

file, returning to the menu, or 

continuing, which will cause the 

existing file to be destroyed. 

A first-time user should only use options 1 or 2 to start. 

Options 3 through 9 allow you to modify the control file 

without creating a new file. 

Option (3): 

Title A title for this run that will appear 

at thetop of each page of output. 

Option (4): 

Stocking choice A list of the species that will be 

allowed in this stand projection 

must be supplied. This is accomplished by entering a one (1) for 

the species to be included and a 

zero (0) for species not included. 

There are three choices for 

inputting the initial stand diaineter distribution. 

(1) User inputs diameter lists for 

each species. The program 

prompts the user by giving the 

species and asking for the number of trees in each diameter 

class of 5 through 17 inches on 

the first line, and then asking for 

the entries for the 18- through 

30-inch diameter class on a 

second line. A carriage return 

will enter zeros for the remainder 

of the line. The model uses real 

numbers so fractional parts of a 

tree may be entered. However, 

any entry less than 0.1 is 

changed to a zero. 

(2) The user is prompted to input 

the total number of stems for a 

given species and the percent- 

. age of these trees in diameter 

classes 5, 6, 7, 8, 9, 10, 11, 12, 

13 to 15, 16 to 19, and 20+. 

These percentages are checked 

to see if they total 190; if they do 

not, the user is asked to re-enter 

them. 

Figure 5:-~eneral logic for main program of FIBER. 
<3> The user can input several 

plots of various sizes and obtain 

an average plot to represent the 

initial stand. These plots can be 

a mixture of fixed plots or prism 

plots. If they are fixed plots, the 

user must supply the inverse of 

the plot size. For prism plots, the 

basal-area factor must be given. 

This option also allows the user 

to enter the tree list in 1- or 

2-inch diameter classes. The 

stand entered in 2-inch classes 

will be adjusted into 1-inch 

classes programmatically. 

The diameter classes by species are displayed on the 

terminal and the user may modify the stand, if desired. The 

modification process redisplays the stand information just 

entered, species by species. The user can change the 

entries for each species or preserve the values by entering 

a carriage return. After checking each species group, the 

stand is again displayed and the user is given the choice of 

further modification or continuing with entering other projection information. 

Option (5): 

Report 

interval The number of years of growth 

between the stand table reports 

sent to the printer. This must be 

a multiple of 5 years. The default 

value is 10 years. 

Projection length The total number of years that 

the model is to grow the stand. 

This, too, must be a multiple of 5 

years. 

Harvest 

diameter 

Managed1 

unmanaged 

Option (6): 

Even-aged1 

multi-aged 

Stand age 

The quadratic mean stand diameter of the stand when it is harvested. The model will continue 

to grow the stand until it reaches 

this diameter or reaches the 

projected age. 

Will thinning operations be conducted? (Y), < N >. 

Is the stand managed as an 

even-aged or multi-aged stand. 

For even-aged stands, enter the 

age. For multi-aged stands, enter 

the approximate number of years 

since the last major harvest, or a 

Option (7): 

Forest type 

Site index 

Option (8): 

Percent cull 

Option (9): 

Thinning 

specification 

When to thin 

Interactive1 

batch 

thin control 

carriage return < cr > will continue the program if this information is not available. 

If the forest type and site are 

known as spruce-fir or northern 

hardwoods, the model will operate within the range of the specified type regardless of the species present. If the forest type is 

unknown, the model will determine the forest type based on 

the initial stand composition. 

Enter the site index for the stand 

within the following ranges for 

each forest type: 

softwood 30 to 70, < 50 > 

hardwood 40 to 80, <60> 

mixedwood 35 to 75, < 55>. 

The percentage of sawtimber for 

each species that can be considered as cull and be moved to the 

pulpwood category upon harvesting. The default value, <cr>, 

will enter zero values for cull. 

The user can choose to control 

the thinning by square feet of 

basal area or cubic feet of volume. 

There are two ways to control 

when to thin the stand. One 

choice is to specify the number 

of years to run prior to thinning 

(0, 5, 10, 15. . .). The other 

choice is to specify a basal area 

or volume level for the stand to 

attain before thinning. 

If the user desires, the model will 

stop before each thinning, display the stand and ask for any 

silvicultural treatment desired. 

This process is referred to as the 

"interactive" control and, if 

chosen, the input phase is ended 

and control is returned lo 'the 

menu. 
Silvicultural 

treatment 

If the user chooses to specify a 

treatment for the entire projection 

period, the model will not display 

the thinning information to the 

terminal but will send it to the 

printer. This version is the 

"batch" option. 

No thinning-this is the default 

value; it causes the model to 

grow the stand until the next 

thinning (if in the interactive 

mode) or continue until the end 

of the projection (if in the batch 

mode). 

Thin from above-the amount of 

basal area or cubic feet to 

remove from each species is 

specified. The model begins 

removing trees from a userspecified diameter class and 

continues to smaller classes until 

the specified residual level is 

reached or until a species has 

been completely harvested. If a 

species is removed, the remaining amount to be thinned is 

distributed over the species with 

the highest priority. 

Thin from below-similar to thinning from above except that the 

process begins at the userspecified diameter class and 

works to larger classes. 

Maximum 

Diameter class removal-if the diameter 

user is controlling the thinning class 

interactively, this option allows 

the user to specify the number of 

trees to remove from a given 

species and diameter class. 

Uniform thinning-the amount to 

thin for each species is divided 

evenly among all diameter 

classes with at least 0.1 of a 

tree. If a given diameter class 

does not have enough trees in it 

to satisfy the thin, the remaining 

amount to be thinned is distributed evenly over the remaining 

diameter classes. Once a species is completely removed by 

thinning, the remaining amount 

is divided among the species 

with the highest thinning priority. 

q-line thinning-refers to a value 

that gives the slope of a negative 

exponential curve using the 

diameter distribution of your 

stand. This term was first used 

by de Liocourt (1898) and a 

method of calculating q is given 

by Leak (1963). This method can 

only be used for multi-aged 

stands. A theoretical tree distribution is developecj with the 

same q-value as the current 

stand. This stand will have the 

desired basal area after thinning 

and will have no entries larger 

than a user-specified maximum 

diameter class for the stand. The 

number of trees to remove is 

then calculated for each diameter class by calculating the difference between the actual tree list 

and the theoretical tree list. The 

trees are removed from the stand 

according to a priority list. After 

this first pass, the user has the 

option to lower the 2-inch q-value 

by 0.1 if the stand structure has 

not met the management objective. The residual basal area and 

stand structure are given and the 

user can lower the 2-inch q-value 

by 0.1 for a second time. The 

stand values are presented and 

no further thinning is allowed 

without a growth period. 

Users who specify thinning to the 

q-line are asked to enter a maximum diameter class to retain in 

the stand. If this is less than the 

largest class in the current stand, 

all trees above the specified 

class will be removed. If the 

specified value is larger than any 

tree in the stand, the stand may 

be at a lower stocking level than 

specified after thinning. For 

thinning from above, the user 

gives a diameter class for the 

thinning to start and then smaller 

diameter classes are thinned. 

Thinning from below is similar 

except the thinning starts in the 

specified size class and then 

moves to larger classes. 
Thinning level If q-line thinning was specified, 

to retain the user is asked to input the 

desired level of basal area to 

retain. For the other thinning 

modes, the user has two choices 

depending on the type of management. One choice is to specify the residual stand in either 

basal area or volume, depending 

on the response to the thinning 

specification question earlier. 

The second choice, for evenaged stands, is to thin to the B 

line, based on stocking charts for 

softwood, mixedwood and hardwood stands (Figs. 1-3). 

Percentage For thinning from above, from 

to thin below, or uniformly, a percentage 

of the total amount to remove 

must be specified and is then 

taken from the species. These 

values range from 0 to 100 percent with the sum of all species 

groups totaling 100 percent. By 

changing these percentages the 

user can fully control removals 

from the stand. If the percentage 

to be removed from any species 

category is greater than the 

amount contained in it, the 

remainder is divided among the 

species with the highest priority 

of removal. 

The user is asked to specify a 

priority of removal for each of the 

species groups in a range of I 

(low) to 9 (high). The same priority may be specified for more 

than one species group. If q-line 

thinning was chosen, these 

priorities are used to determine 

which species to remove first to 

obtain the desired diameter 

distribution. For thinning from 

above, below, or uniformly, this 

priority list is used only when, for 

a particular species, the percentage to thin times the amount to 

remove gives a value that is 

more than is present in that 

species. The excess amount to 

remove is then reassigned to 

other species by first considering 

species that had been targeted 

for thinning (by giving a nonzero 

Priority 

thinning list 

percent-to-thin value) and that 

have the highest priority. If these 

species have not been totally 

removed, the extra amount to 

remove will be divided evenly 

among those with the highest 

priority; otherwise the next lower 

priority species on the "to be 

thinned" list are considered. If all 

of the species that are on the 

thin list have been removed, the 

extra amount is taken from species not previously targeted for 

thinning, according to priority. 

If the thinnings are being controlled interactively, after each 

thinning the use[ is given the option of returning to the 

prethinning conditions to attempt an alternative method. 

At this point, the control file on disk is complete and control 

is returned to the menu. The remaining options are: 

Option (10): 

Display control Displays the contents of the 

control file named at the beginning of this run. 

Option (1 1): 

Display stand Prints the initial stand table on 

the console and a chance to 

modify is given. 

Option <12>: 

Execute Starts the growth projection 

according to the criteria contained in the control file. 

An example of creating a control file for a hardwood stand 

and sample terminal output are shown in Table 4 (items in 

italics are entered by the user). The yield tables for intermediate thinnings and standing and total yields are given. 

The volume and board-foot values are obtained from local 

tables for the Penobscot Experimental Forest (softwood 

species) and the Bartlett Experimental Forest (hardwood 

species).* The cubic foot sawlog volume includes the whole 

tree, whereas the board-foot volume represents only 

sawlog material and not the volume of the tops. In order to 

estimate the top volume, the board-foot volume should be 

converted to cubic feet and subtracted from the total cubic 

feet in sawlog volume. At the end of a projection the user 

is asked if he or she desires another run on this control 

*Volume and board-foot values were determined using the 

International IICinch rule. 
file. A Y response will return the menu, allowing the user to 

make the necessary changes for the next run. If an N or a 

<cr> response is given, the user is asked if a new control 

file is desired. A Y response will return the user to entering 

the file name of the control file and the destination of the 

printed output; an N or a <cr> response terminates the 

run. 

For every execution of FIBER, a file designed for a printer 

is created. This file consists of 132 characters per line plus 

a carriage control character and can be sent directly to a 

printer or stored in a disk file to be printed later. A summary of the control information is printed first, then the 

initial stand table, stand tables at the specified intervals, 

final stand tables, and the yields. For every thinning that 

occurs, a prethin stand table, the thinning criteria, a 

postthin stand table, and the yield from this thinning are 

written. The stand tables in this printer file are more 

detailed than the ones shown in Table 4. These stand 

tables show basal area, volume, and board-foot values by 

species and diameter class. 

Beginning users may find it helpful to complete the sample 

worksheet before running the program (Table 5). This form 

contains the questions in the order that they will be 

prompted by the program for the answers. Values do not 

have to be given for species categories that are not 

selected at the beginning of projection. 

Model Limits 

The model predicts well within the range of the data sets 

for managed stands. However, for some combinations of 

IBA, RBA, and proportion of hardwoods the equations 

predict unlikely values of a, b, or c when required to predict 

growth outside the development data sets at very high 

'densities. Since q,, bit, cit, and mit are probabilities, their 

true values are non-negative. At high densities, the predicted a-, b-, c-, or m- values might be negative, in which 

case, the value is set equal to zero and the values were 

standardized to sum to 1. 

Due to insufficient data for mature unmanaged stands over 

a long time period, constraints were placed on the. model to 

prevent the predictions from becoming unreasonable values. After the stand basal area reaches 15 square feet over 

the A line on the stocking charts, (Figs. 1-3), the c-value is 

linearly reduced from the predicted equation value to zero 

before the stand grows to 20 square feet over the A line. 

This reduction in the c-value is added to m. Similarly, if the 

stand should grow to more than 20 square feet over the A 

line, then the b-value also is linearly reduced to zero before 

the stand grows to 40 square feet over the A line. Half of 

the amount removed from the b-value also is added to m 

with the other half added to the a-value. These two procedures force the projected stand to return below the A line 

in the stocking charts. 

Since the ingrowth equations were developed in managed 

stands, the ingrowth equations for unmanaged stands had 

to be modified as the RBA increased beyond the range of 

the original data (Table 6). When the residual basal area 

was more than the first number of the range, the predicted 

ingrowth value was linearly reduced to zero by the second 

value in the range given. For most species groups, the 

predicted value went to zero before reaching these constraints. However, these constraints are still in the model 

should different ingrowth equations be implemented. 

These limitations are governed by forest type, which can 

change over time depending on composition and site index 

unless the user specified a forest type. The rules for changing the forest type are presented in Table 7. If the conditions stated are not met, the forest type remains the same. 

Since all of the development data plots were greater than 

20 ft2/acre (4.6 m2/ha), the model is programmed to terminate if a stand goes below this density level during a projection. This limitation prevents the acquisition of possible 

erroneous information and does not appear to impose a 

restriction on the usefulness of the model. 

Conclusion 

A two-stage stand projection model, FIBER, has been 

developed to predict the growth and yields for spruce-fir, 

northern hardwood, and mixtures of these forest types in 

the Northeast. It is a matrix model-using linear equations to 

predict ingrowth, the probability of survivor growth, and the 

probability of mortality by species. The model incorporates 

transition probabilities, that change over time, to project 

future diameter distributions and to predict volumes. The 

model can be applied to managed and unmanaged stands, 

both even-aged and multi-aged, over a range of densities, 

site indices, species mixtures, and treatment intervals. A 

variety of thinning options are possible, including thinning 

by diameter class. Both thinning and harvest yields are 

presented. Volume tables are in separate files and can be 

modified easily for local conditions. The model has been 

designed for use by researchers, educational institutions, 

and forest managers of both small woodlots and large 

forested land areas. 

An attempt has been made to make FIBER as "user 

friendly" as possible. The model is written in Fortran 77, 

requires 256K, and has been tested on the following computers: 

Mainframe: IBM 4341 

Operating System: VMlCMS 

Availability: Magnetic Tape; EBCDIC, 9-track Electronic 

Transfer via BITNET 
Micros: 

IBM PC and compatables 

Operating system: MS-DOS 2.0 

Availability: 5 114 floppy disk 

Contact: Dale S. Solomon or Richard A. Hosmer 

Northeastern Forest Experiment Station 

USDA Building, University of Maine 

Orono, Maine 04469 

207-581-3666 

Literature Cited 

Buongiorno, Joseph; Michie, Bruce R. 1980. A matrix 

model of uneven-aged forest management. Forest 

Science. 26:609-625. 

de Liocourt, F. 1898. De I' amenagement des sapinieres. 

Bulletin de la Sociefe' Forestieke de Franche-Comte et 

Belfort, Besancon. 

Frank, Robert M.; Blum, Barton M. 1978. The selection 

system of silviculture in spruce-fir stands-procedures, early results, and comparisons with unmanaged stands. Res. Pap. NE-425. Broomall, PA: U.S. 

Department of Agriculture, Forest Service, Northeastern 

Forest Experiment Station. 15 p. 

Leak, William B. 1963. Calculations of "q" by the least 

squares method. Journal of Forestry. 61 :227-228. 

Solomon, Dale S. 1977. The influence of stand density 

and structure on growth of northern hardwoods in 

New England. Res. Pap. NE-362. Upper Darby, 

PA: US. Department of Agriculture, Forest Service, 

Northeastern Forest Experiment Station. 13 p. 

Solomon, Dale S.; Frank, Robert M. 1983. Growth 

response of managed uneven-aged northern conifer 

stands. Res. Pap. NE-517. Broomall, PA: US. Department of Agriculture, Forest Service, Northeastern Forest 

Experiment Station, 17 p. 

Solomon, Dale S.; Hosmer, Richard A. 1986. FIBER: a 

growth model for forest types in the Northeast. 

In: Proceedings, forestry microcomputer software symposium; 1986, June 30-July 2; Morgantown, WV. 

Morgantown, WV: West Virginia University. p. 131-145. 

Solomon, ale S.; Hosmer, Richard A.; Hayslett, Homer T., 

Jr. 1986. A two-stage matrix model for predicting 

growth of forest stands in the Northeast. Canadian 

Journal of Forest Research. 16(3):521-528. 

Solomon, Dale S.; Leak, William B. 1986. Simulated yields 

for managed northern hardwood stands. Res. Pap. 

NE-578. Broomall, PA: US. Department of Agriculture, 

Forest Service, Northeastern Forest Experiment Station. 

24 p. 
Table 1.-Regression coefficients for equations used to predict the a-, b-, c-values and ingrowth in the 

stand projection matrices 

Dependent Independent variablea 

Species variable Intercept IBA RBA D P D2 R BA2 PS 

Fir 

Spruce 

Hemlock 

Cedar 

Other 

softwood 

Sugar 

maple 

Red maple 

Yellow 

birch 

Paper 

birch 

Beech 
Table 1 .-Cont. 

Independent variablea Dependent 

Species variable Intercept IBA RBA D P D2 RBA~ PS 

White ash a 

b 

C 

k 

Aspen a 

b 

C 

k 

Other a 

hardwoods b 

C 

k 

alBA = initial basal area; RBA = residual basal area; D = diameter class; P = proportion hardwood composition; 

PS = proportion of species in the composition. 

Table 2.-Linear reductions of transition probabilities a, b, and c within the range of 

maximum diameter classes for trees in 

stands with more than 125 ft2/acre 

Transition D.b.h. 

probability class Species 

Inches 

c 15-20 All species 

b 15-25 Balsam fir, paper birch, aspen, 

other hardwoods 

20-30 All other species 

a 20-30 All species 
Table 3.-Actual and predicted average stand volume (ft3/acre) after 15 years, by species, residual 

basal-area class, and forest type 

Residual Speciesa basal area Percent 

(ft2/acre) Yield BF SP HE CE OS SM RM YE PB BE WA AS OH Total error 

SOFTWOOD 

40(n = 94) Initial 286 270 9 152 10 2 19 22 19 1 0 4 1 796 

Actual 667 596 24 179 16 7 31 34 35 2 0 8 4 1605 8.7 

Predicted 605 529 19 182 14 6 36 31 30 2 0 9 2 1465 

80(n = 191) Initial 545 662 21 218 38 9 38 51 34 4 1 17 9 1648 

Actual 8991069 31 251 51 12 60 57 47 6 1 16 11 2511 3.2 

Predicted 833 1051 33 252 46 13 60 61 45 5 1 20 11 2430 

120(n = 135) Initial 864 866 59 377 44 31 70 103 88 5 0 20 5 2532 

Actual 1128 1193 70 405 49 29 100 98 94 4 1 22 2 3195 1.3 

Predicted 10921186 73 417 25 35 94 106 97 6 0 17 6 3155 

160(n = 29) Initial 727 1035 40 1148 69 1 72 63 75 6 0 57 2 3295 

Actual 759 1245 54 1232 67 2 95 39 71 0 0 52 3 3618 -3.0 

Predicted 853 1288 54 1234 26 2 85 62 71 5 0 45 3 3727 

MIXEDWOOD 

40(n = 54) Initial 184 139 10 40 2 88 89 159 69 66 4 26 19 896 

Actual 486 338 21 59 4 167 143 203 113 88 9 28 29 1689 14.1 

Predicted 363 259 22 52 3 148 151 193 102 96 5 37 20 1452 

80(n = 74) Initial 390 289 32 77 1 249 163 317 60 114 4 27 24 1748 

Actual 751 457 59 88 1 348 227 363 82 132 5 34 27 2574 8.8 

Predicted 586 428 53 89 1 333 231 350 75 138 5 30 30 2348 

120@ =45), lntial 670 489 45 46 32 243 228 352 129 143 7 256 34 2674 

Actual 757 676 53 65 38 273 250 347 140 139 11 229 24 3004 - 5.4 

Predicted 839 641 61 57 29 263 294 349 157 156 12 269 39 3167 

160(n = 6) Initial 454 618 320 289 0 561 107 266 143 194 28 439 50 3469 

Actual 718 827 343 327 0 423 133 255 169 82 34 434 37 3787 12.9 

Predicted 569 769 238 235 0 402 129 219 132 188 34 331 53 3299 

HARDWOOD 

40(n = 59) Initial 42 27 3 0 0 215 92 ,227 75 184 9 31 4 909 

Actual 146 78 5 0 0 400 192 339 126 261 16 52 6 1620 12.9 

i. , Predicted 96 51 10 0 0 358 159 296 118 249 14 49 11 1411 

80(n = 69) Initial 62 51 7 4 0 541 177 383 39 535 23 29 6 1858 

Actual 113 82 12 3 0 774 230 417 58 561 34 34 10 2326 - 0.8 

Predicted 96 73 11 4 0 736 252 438 52 607 33 34 10 2346 

120(n = 20) Initial 104 39 21 1 0 1077 72 406 14 942 77 0 16 2769 

Actual 128 68 23 2 0 1004 99 430 10 984 90 0 7 2846 - 6.7 

, . Predicted 147 55 32 2 0 1136 97 434 16 1006 95 0 16 3036 

aBF = balsam fir; SP = spruce; HE = eastern hemlock; CE = northern white-cedar; OS = other softwoods; 

SM = sugar maple; RM = red maple; YB = yellow birch; PB = paper birch; BE = American beech; WA = white ash; 

AS = aspen; OH = other hardwoods 
Table 4.-lnputloutput for a hardwood stand 

thinned to 40 ft21acre and then projected for 50 years (Items in italics are 

entered by the user) 

FIBER 

Version 2.0 

Please choose the output device < 1 > printer (2) diskfile 

2 

Please enter the disk file name: 

FIBER. PRT 

Please enter control file name: 

SAMPLE.CTL 

Is control file < 1 > old (2) new? 

2 

Choose one of the following: 

HELP (7) 

NEW FILE (8) 

TITLE (9) 

GROWTH PERIOD (10) 

STOCKING (1 1) 

STAND AGE <12> 

SITE INDEX 

PERCENT CULL 

THINNING 

DISPLAY CONTROL 

DISPLAY STAND 

EXECUTE 

Enter title: 

HARDWOOD STAND THINNED THEN ALLOWED TO GROW 

FOR 50 YEARS 

Choose one stocking choice: 

(1) lnput a tree list. 

(2) lnput 010 stocking by dbh class. 

<3> lnput several plots to be averaged. 

1 

Please specify which species are to be included in the 

treelist 

Enter a 1 for those to be included, a 0 for those not to be 

included. 

BF SP HE CE OS SM RM YB PB BE WA AS OH 

01 10001111000 

entering a <cr> will make whole line 0 

First line is diameter classes 5-17, second is 18-30 

Please enter the number of trees in each of the 5-17 inch 

classes for SPRUCE (1 3 values) 

0003000030000 

Please enter the number of trees in the 

remaining classes 18-30 for SPRUCE (13 values) 

<cr> 

Please enter the number of trees in each of the 5-17 inch 

classes for HEMLOCK (13 VALUES) 

6603000000000 

Please enter the number of trees in the remaining classes 

18-30 for HEMLOCK (1 3 values) - 

<cr> 

Please enter the number of trees in each of the 5-17 inch 

classes for RED MAPLE (13 values) 

3360030030000 

Please enter the number of trees in the 

remaining classes 18-30 for RED MAPLE (13 values) 

<cr> 

Please enter the number of trees in each of the 5-17 inch 

classes for YELLOW BIRCH (1 3 values) 

6033690000000 

Please enter the number of trees in the 

remaining classes 18-30 for YELLOW BIRCH (1 3 

values) 

<cr> 

Please enter the number of trees in each of the 5-17 inch 

classes for PAPER BIRCH (13 values) 

0066367536 

Please enter the number of trees in the remaining classes 

18-30 for PAPER BIRCH (13 values) 

<cr> 

Please enter the number of trees in each of the 5-17 inch 

classes for BEECH (13 values) 

1821 15 1260300003 

Please enter the number of trees in the remaining classes 

18-30 for BEECH (13 values) 

<cr> 

HARDWOOD STAND THINNED THEN ALLOWED TO GROW FOR FIFTY YEARS. 

INITIAL STAND CONDITIONS Stand age: 0 

DIAMETER CLASSES 

5 6 7 8 9 10 11 12 13-15 16-19 20+ TOTAL SQ. FT. CU.FT. 

................................................ 

TOT 33 30 30 27 15 18 18 3 12 3 0 189 73.76 1627.2 

Mean stand diameter = 8.46 
Table 4.-Cont. 

< cr > to continue 

<cr> 

Do you want to change initial stand? 

N 

Please enter the report interval in years < 10 >: 

20 

Projection length (years)? 

50 

Harvest diameter < 30 > ? 

<cr> 

Will you be growing this stand: 

(1) under management? 

t 2 > unmanaged? 

1 

Is stand (1) even-aged or <2> multi-aged? 

<cr> 

Enter the approximate age of the stand or 

the number of years since major harvest. 

(If unknown then enter <a>) 

<cr> 

Is the stand on a (1) softwood site (2) hardwood site 

or <3> unknown? 

2 

Enter in the site index for your hardwood stand 

(40-80, < 60 >) . 

Executing. . . 

<cr> 

Enter the percent cull for each species 

SP HE RM YB PB BE 

5 5 5 1010 5 

Will you specify thinning levels in (1) basal area, 

or in < 2> cubic feet? 

1 

Do you wish to thin on a (1) time interval or 

at a <2> stocking level? 

7 

Enter in the time interval 

0 

Do you want to control each thinning interactively? 

(1) INTERACTIVE 

<2> BATCH 

1 

Choose one of the following: 

(1) HELP (7) SITE INDEX 

(2) NEW CONTROL (8) PERCENT CULL 

(3) TITLE (9) THINNING 

(4) GROWTH PERIOD (10) DISPLAY CONTROL 

(5) STOCKING (11) DISPLAY STAND 

(6) STAND AGE < 12 > 'EXEC-UTE 

<cr> 

HARDWOOD STAND THINNED THEN ALLOWED TO GROW FOR FIFTY YEARS. 

PRE-THINNING STAND CONDITIONS 0th YEAR Stand age: 0 

DIAMETER CLASSES 

5 6 7 8 9 10 11 12 13-15 16-19 20+ TOTAL SQ. FT. CU.FT. 

............................................. 

SP00030000 3 0 0 6 3.81 91.5 

HE66030000 0 0 0, 15 3.04 37.8 

RM336003OO 3 0 0 18 7.00 148.8 

YB60336900 0 0 0 27 10.23 203.4 

PB 006636153 6 0 0 45 26.08 677.4 

BE 18 21 15 12 6 0 3 0 0 3 0 78 23.59 468.3 ................................................ 

TOT 33 30 30 27 15 18 18 3 12 3 0 189 73.76 1627.2 

Mean stand diameter = 8.46 q-value = 1.4 (2-inch q-value = 1.8) 

< cr > to continue 

<cr> 

Please choose a type of thinning: 

(1) Thin from above (4) Thin along q-line 

(2) Thin from below (5) Thin by diameter class 

(3) Thin uniformly <6> No thinning 

1, 

Enter the diameter class to start thinning <30> 

20 
Table 4.-Cont. 

Enter the total amount to retain: 

40 

Please enter the percentage to thin for each species 

SP HE RM YB PB BE 

10 10 10 20 20 30 

Enter thinning priority for each species (1 to 9) 

SP HE RM YB PB BE 

997553 

Thinning. . . 

HARDWOOD STAND THINNED THEN ALLOWED TO GROW FOR FIFTY YEARS. 

POST-THINNING STAND CONDITIONS 0th YEAR Stand age: 0 

DIAMETER CLASSES 

5 6 7 8 9 10 11 12 13-15 16-19 201- TOTAL SQ. FT. CU.FT. ............................................. SP 0 0 0 0 0 0 0.0 0 0 0 0 .oo .o 

HEOOOOOOOO 0 0 0 0 . 00 .O 

RM336OOlOO 0 0 0 13 3.15 56.7 

YB60331000 0 0 0 13 3.11 52.6 

PB 006636151 0 0 0 37 18.98 486.6 

BE182115 8 0 0 00 0 0 0 62 13.38 225.9 ............................................. TOT 27 24 30 17 4 7 15 1 0 0 0 125 38.61 821.8 

Mean stand diameter = 7.53 q-value = 1.5 (2-inch q-value = 2.1) 

<cr> to continue 

<cr> 

Do you wish to: 

(1) thin on a time interval <2> at a stocking level 

(3) return to pre-thin (4) no more thinning 

4 

Growing. . . 

HARDWOOD STAND THINNED THEN ALLOWED TO GROW FOR FIFTY YEARS. 

FINAL STAND CONDITIONS 50th YEAR Stand age: 50 

DIAMETER CLASSES 

5 6 7 8 9 10 11 12 13-15 16-19 20-1- TOTAL SQ.FT. CU.FT. -------------------------.-------------------- 

SP00000000 0 0 0 0 .oo .o 

HE33222222 2 0 0 21 9.41 158.6 

RM55433322 4 1 0 32 15.49 344.5 

YB22222222 4 1 0 21 11.41 240.3 

PB 11 11 10 8 6 4 4 4 15 5 0 77 42.49 1044.8 

BE99988888 14 1 0 82 43.26 1006.9 

TOT30 30 27 24 21 19 19 18 38 '7 0 233 122.06 2795.1 

Mean stand diameter = 9.80 q-value = 1.4 (%-inch q-value = 1.6) 
Table 4.-Cont. 

< cr > to continue 

<cr> 

Do you wnat to see the yields for this run? 

Y 

Standing yield 

PULPWOOD 

------ 

B. A. 

--- 

SPRUCE .O 

HEMLOCK 2.0 

RED MAPLE 5.7 

YELLOW BIRCH 3.9 

PAPER BIRCH 14.6 

BEECH 13.2 

TOTAL 39.4 792.9 

<cr> to continue 

<cr> 

Total yield from thinnings 

PULPWOOD 

------ 

B.A. CU.FT. 

------- 

SPRUCE .2 4.6 

HEMLOCK 2.0 23.5 

RED MAPLE .2 4.6 

YELLOW BIRCH 2.7 56.0 

PAPER BIRCH .7 19.1 

BEECH 4.4 97.1 

TOTAL 10.2 204.9 

<cr> to continue 

<cr> 

SAWTIMBER 

------- 

BOARD : 

B.A. CU.FT. FEET 

------------ 

.o .O .o 

7.4 132.2 851.3 

9.8 238.8 1142.3 

7.5 167.3 890.6 

27.9 721.8 4039.6 

30.0 744.2 3561.3 

SAWTIMBER 

------- 

BOARD 

B.A. CU.FT. FEET --aq-------- 

3.6 86.9 432.0 

1.0 14.3 .O 

3.7 87.5 357.0 

4.4 94.8 .O 

6.4 171.7 954.0 

5.9 145.3 852.0 

Total yield 

PULPWOOD 

SPRUCE 

HEMLOCK 

REP MAPLE 

Y ELLQW BIRCH 

PAPER BIRCH 

@ECH 

B.A. 

--- 

.2 

4.0 

5.9 

6.6 

15.3 

17.6 

TOTAL 49.6 997.8 

SAWTIMBER 

------- 

BOARD 

B:A. CU.FT. FEET 

------------ 

3.6 86.9 432.'0 

8.4 146.4 851.3 

13.5 324.3 1499.3 

11.9 262.0 890.6 

34.3 893.5 4993.6 

35.9 889.6 4413.3 

Do you want another run on this control file? 

N 

Do you want to use another control file? 

<cr> 

Stop - Program terminated 
Table 5.-FIBER worksheet 

OUTPUT: < 1 > PRINTER (2) DISKFILE: 

CONTROL FILE: < 1 > OLD (2) NEW 

TITLE: 

SPECIES 

CHOICE: BF SP HE CE OS SM RM YB PB BE WA AS OH 

---------+--A 

INPUT CHOICE: a) DIAMETER LlST BY SPECIES 

b) # STEMS BY SPECIES AND % IN 

DIAMETER CLASS 

c) PRISM PLOTS OR FIXED PLOTS 

(1) BAF OR INVERSE OF PLOT SIZE 

(2) 1- or 2-INCH CLASSES 

REPORT INTERVAL (5,10,15. . . .): 

PROJECTION LENGTH: 

HARVEST DIAMETER: 

MANAGED OR UNMANAGED: 

STAND STRUCTURE: (1) EVEN-AGED 

< 2 > MULTI-AGED 

STAND AGE: 

FOREST TYPE: (1) SPRUCE-FIR (2) NORTHERN 

HARDWOODS <3> UNKNOWN 

SITE INDEX: 

BF SP HE CE OS SM RM YB PB BE WA AS OH 

PERCENT 

CULL: - - - - - - , , , -- - - THINNING SPECIFICATIONS: (1) SQUARE FEET 

< 2 > CUBIC FEET 

WHEN TO THIN: (1) YEARS TO RUN PRIOR 

TO THIN - 

< 2 > STAND DENSlTY LEVEL - 

INTERACTIVE , BATCH 

SILVICULTURAL TREATMENT: 

ABOVE - q-LINE - 

BELOW - DIAMETER CLASS - UNIFORM- ' NONE - 

MAXIMUM DIAMETER CLASS FOR q-LINE 

STARTING DIAMETER CLASS FOR ABOVE, BELOW 

THINNING LEVEL TO RETAIN: (1) BA VOL - 

(2) B-LINE FOR EVENAGED STANDS 

BF SP HE CE OS SM RM YB PB BE WA AS OH 

PERCENT 

THINNED: ------ - ----- PRIORITY 

LlST (1-9): - - - - - - - - , -- - - 

Table 6.-Basal-area range, by forest type and 

species, at which ingrowth is forced to I 

I 

zero I 

Species Softwood Mixedwood Hardwood 

- - - - - - - - - ft2/acre - - - - - - - - - 

Fir 190-220 1 60-1 90 110-140 

Spruce 190-220 130-1 60 110-140 

Cedar 190-220 130-1 60 110-140 

Aspen 80-1 10 80-1 10 80-1 10 

All other 1 50-1 80 130-1 60 110-140 

Table 7.-Criteria for allowing a change in forest 

type 

Current New I 

forest type Condition forest type 

Softwood Site index for softwood 

- > 50 for hardwood Mixedwood 

composition 2 50% 

Mixedwood Site index for softwood 

<50 and hardwood Softwood 

&mposition 135% 

Site index for hardwood 

160 for hardwood Hardwood 

composition 2 75% 

Hardwood Site index for hardwood 

5 60 and hardwood Mixedwood 

composition < 50% 
Solomon, Dale S.; Hosmer, Richard A.; Hayslett, Homer T., Jr. 1987 FIBER 

handbook: a growth model for spruce-fir and northern hardwood 

types. NE-RP-602. Broomall, PA: U.S. Department of Agriculture, 

Forest Service, Northeastern Forest Experiment Station. 19 p. 

A matrix model, FIBER, has been developed to provide the forest manager 

with a means of simulating the management and growth of forest stands in 

the Northeast. Instructional material is presented for the management of 

even-aged and multi-aged spruce-fir, mixedwood, and northern hardwood 

stands. FIBER allows the user to simulate a range of silvicultural treatments for a variety of species compositions growing on different sites. The 

internal structure of the model is defined and explanations on the use of 

FIBER are offered. Examples of input, interim procedures, and final output 

are shown. 

ODC: 562.2:564:228.3 

Keywords: Growth; model; mixed species; spruce; northern hardwoods 
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. 

e Parsons, West Virginia. 

Princeton, West Virginia. 

Syracuse, New York, in cooperatiin with the State University of New York 

College of Environmental Sciences and Forestry at Syracuse University, 

Syracuse. 

e University Park, Pennsylvania, in cooperation with the Pennsylvania State . University. 

e Warren, Pennsylvania. 

Persons of any race, color, national origin, sex, age, religion, or with any handicapping condition are welcome to use and enjoy all facilities, programs, and services 

of the USDA. Discrimination in any form is strictly against agency policy, and 

should be reported to the Secretary of Agriculture, Washington, DC 20250. 

*U. S.GOVERNAENT PRINTING OFF ICE:1987-748-076140026 ;