The Input Summary Table

The Input Summary Table displays information about the keyword and data records read from the input files. Users should review this information closely to verify that the projection is based on their intended silvicultural and ecological assumptions, and that their data records were read correctly. This table is comprised of three sections as discussed below, and facilitates record keeping and problem determination. It is one of the most important tables in the FVS main output file.

4.3.1.1.1 Program Options Section

The Program Options Section is comprised of two parts. The Options Selected by Input part was designed to provide information about the keyword records that were included by the user. The Options Selected by Default part was designed to provide information about some of the default values that were used in the projection.

The keyword records are printed, as they are processed, along with descriptions of parameters and supplemental data associated with the keywords. Within this section of the output, messages may appear, such as:

FVSO3 WARNING: FOREST CODE INDICATES THAT THE GEOGRAPHIC LOCATION IS OUTSIDE THE RANGE OF THE MODEL. These messages are intended to bring attention to potential problems with keyword parameters. Even though the messages may indicate doubt, FVS usually assumes that users know what they are doing and the projection is continued unless program capacities have been exceeded. The possible warning messages, along with explanatory details and suggested user responses are shown in section 9.

Users may turn off and back on the printing of the keyword records to the main output file using the NOECHO and ECHO keywords, respectively, as discussed in section 4.2.4. However, this is only suggested when using keywords which are stored in auxiliary files and have been shown to be error free.

Several keyword records will be specifically printed if they are omitted from the input file. These records contain data that are particularly useful for resolving problems but may not be easily remembered. They include:

1. the tree record format (TREEFMT),

2. the sampling design parameters (DESIGN), and 3. the stand description data (STDINFO).

These data are printed immediately following the input keyword records, beneath the heading “OPTIONS SELECTED BY DEFAULT”. TREEFMT and DESIGN are examples of keyword records that appear in this section of the example output file. This section also includes values of site index and stand density index maximums, by species, for variants that used these variables. Frequently, values are not entered for these

variables for all species. By looking at this table, users can see how the model translated provided values, or the default values, for each species in the model. For most variants, a species cross-reference chart is also provided which shows the numeric code, the alpha code, and the corresponding FIA code, such as shown in table 4-1. In addition, a table is printed showing which volume equations from the National Volume Estimator Library were used for each species in the run.

The input keyword records are always displayed in the order that they are processed. Usually this order is unimportant, but there are exceptions. If a TREEDATA record is used and the species codes or the tree record format differ from the default specifications, the SPCODES and/or TREEFMT records must precede the TREEDATA record in the input file. Failure to meet this requirement will result in a variety of errors. Also,

keyword order can be important when simulating thinning activities and using minimum harvest constraints or adjusting the cutting priority formula. These considerations will be discussed in section 5.2. Keyword order is also important when defining species groups as discussed in section 4.2.5.

4.3.1.1.2 Activity Schedule Section

The Activity Schedule section follows the Program Options section. The management activities specified by keyword input are arranged in the order that they will be simulated. Parameters associated with the keyword are also displayed, along with the part of the FVS model that the keyword pertains to (e.g. “BASE” in the example output file indicating the base FVS model).

The dates on the activity schedule are calculated from the inventory year, as entered on the INVYEAR record, and the intervals specified on the TIMEINT record. These dates represent projection cycle endpoints. In the example output file, cycle 1 is the period 1990-2000; cycle 2 is the period 2000-2010, and so on. For ease in understanding cycles, consider cycle 1 ending and cycle 2 beginning January 1, 2000. So in this example the first cycle contains the 10 growing seasons from 1990 through 1999.

Activities that are conditionally scheduled (see section 5.5) are not displayed in this table. These types of activities may, or may not, be scheduled depending on conditions

occurring in the simulation. Check the Activity Summary section of the output file (see section 4.3.1.4.2) to see if conditionally scheduled activities were, in fact, scheduled.

4.3.1.1.3 Calibration Statistics Section

After the keyword input is interpreted, and the tree input data records have been read, the tree records are scanned for missing height and crown ratio observations and missing values are estimated. Then, factors that scale growth predictions to match the input growth data are computed. These activities are reported in the Calibration Statistics sec- tion of the Input Summary Table.

This table is arranged by species encountered in the tree input data records. The first line of this section reports the total number of tree records read by species. The total number

of tree records excludes records that were rejected because DBH was not recorded. It also excludes records of those trees that died before the start of the mortality observation period (tree history codes 8 and 9). The count includes the trees that died during the mortality observation period (tree history codes 6 or 7). These recent mortality records are used to compute the stand density estimates that are used in scaling models and they may be used by some extensions. The number of recent mortality records is given immediately below the total tree record count. These records will be removed from the tree record file before the stand is projected. If either of these counts appears to be inaccurate, the tree history codes, species codes, and tree record format should be checked.

The Forest Vegetation Simulator will accept records with omitted height or crown ratio observations. However, these data must be estimated before the stand can be projected. Heights are usually predicted from DBH and species. Users should consult their variant overview document to see which specific equations and parameters are being used to estimate missing heights.

If three or more records for a species have measured heights, and the height-diameter calibration suppression flag is not set (see NOHTDREG keyword discussion, section 7.1.3.1) and the parameters of the equation used for that species will be calibrated to the input data. However, records with measured heights but dead or broken tops are not used. The total number of records less the number of records with missing heights and broken or dead tops gives the number of records available for calibrating the height-diameter relationship for a species.

The omitted crown ratio observations are estimated using a variety of stand and tree characteristics. Users should consult their variant overview document to see which equations are used. However, it’s strongly recommended that crown ratios for all sample trees be measured and recorded. If crown ratios and/or heights were recorded, and the output indicates they are missing, the tree record format is probably in error (see section 4.2.2).

Of the remaining entries in the calibration statistics table, all but the last one refer to the process of computing growth model scale factors. If increment data are provided with the tree records, the large-tree diameter increment model and the small-tree height increment model will be scaled to reflect local deviations from the regional growth trends

represented in the models. In order to compute scale factors for either increment model, for any species, there must be at least a minimum number of increment observations. By default this minimum is five, but it can be changed using the CALBSTAT keyword. Diameter increment observations are accepted only from trees that were larger than some threshold diameter at the start of the growth measurement period. This threshold differs by variant, but is generally 3 inches DBH. Users should consult their variant overview document and look for definitions of what size of tree is considered a “large tree”. Height increment observations are accepted only from trees that were less than 5 inches DBH at the end of the period. The number of records that is reported as available for scaling a

model includes only those records that have measured increments and meet the above size restrictions.

The height increment scale factor is used as a direct multiplier of predicted height incre- ment. However, the diameter increment scale factor is used as a multiplier of change in squared diameter (DDS) and is, in effect, a multiplier of basal area increment. The rate of conversion of DDS to diameter increment is dependent on the magnitude of tree DBH. The scale factors for both models should normally fall between 0.5 and 2.0. The model estimate of basal area increment derived from the extensive database used to fit the model is the best available predictor of long-term growth performance. As a stand is projected through time, the basal area increment scale factors move toward a value that is one-half the difference between the initial scale factor and 1.0. The effect of this transition is to gradually replace sample-based estimates of increment with the model-based estimates. The other entries in the calibration statistics table that relate to growth model scale factors are by-products of the diameter increment scaling process. They indicate how the

distribution of the growth sample compares to the distribution of the database used to fit the model. The distribution variances are compared using the ratio of the standard

deviation of the residuals for the growth sample to the model standard error. If the values of this ratio consistently exceed 1.0, the user should carefully examine the growth

measurement techniques used, including the methods used to delineate stands. It is assumed that stands are uniform with regard to slope, aspect, elevation, and habitat type. If this assumption is stretched too far, the variance in the growth sample residuals will be exaggerated.

One table entry is the weight given to the diameter increment sample during scaling. This weight is part of an empirical Bayes estimation process (Krutchkoff 1972) that is com- plex and will not be explained here. The interpretation of the weight, however, is quite simple. Values in the vicinity of zero imply the models were not adjusted, while values close to 1.0 imply the models were adjusted. The weight is an expression of confidence that the growth sample represents a different population than does the database used to fit the model. In other words, a value of .90 would indicate a 90% certainty that the growth sample represents a different population than the database used to fit the model.

The final entry in the Calibration Statistic section shows the number of records on which dwarf mistletoe was recorded as a damaging agent. All western variants of FVS include the dwarf mistletoe extension as part of the base model code (see section 8.3).