Analysis behaviors are those whose only purpose is to prepare data for output. They do not change model state, such as growing trees or updating grid values. They assemble, calculate, or analyze data for the user.
This behavior calculates the volume of tree trunks. It can be used to find both merchantable volume and total volume. Make sure to distinguish between this behavior and the other tree volume behavior.
Tree volume is estimated by dividing the trunk into segments, and calculating the volume of each segment. You control where the trunk starts and stops, and the length of segments used.
Trunks start at the value in the Height to Begin Calculating Trunk Volume, in cm parameter. To calculate merchantable volume, set this to the average stump height. To calculate total volume, set this to zero. Trunks end when their diameter inside the tree bark becomes smaller than the volume in the Minimum Trunk Diameter for Volume Calculations, in cm parameter. For merchantable volume, set this to the minimum usable diameter. For total volume, set this to zero.
Trunks are divided into segments for volume calculations. The length of these segments is set in the Trunk Segment Length for Volume Calculations, in m parameter. Setting this to a smaller value increases the accuracy of the calculations. Setting this to a larger value increases the speed at which the calculations are made. The total tree's volume is the sum of the volumes of each of the segments. Any segments whose beginning or ending diameter is less than the value in the Minimum Trunk Diameter for Volume Calculations, in cm parameter are not included in the volume total.
The volume of a tree trunk segment is found as follows:
The cross-sectional area of a tree trunk at a particular point above the ground (such as at the beginning or end of a trunk segment) is calculated as:
To find the diameter of the tree trunk inside the bark at a particular height above the ground, the taper equation is used. (This equation comes from Kozak (2004) Forest Chronicle 80: 507 - 515; it's the "2002 model"). The equation is:
SORTIE considers its DBH parameter to be diameter without bark. To find the diameter outside the bark, the equation is:
Important note. The math in this behavior is particularly susceptible to producing extreme numbers if the parameters are not chosen very carefully. These extreme numbers (incredibly large or small numbers) will crash SORTIE if they happen, and cannot be guarded against ahead of time. Be very careful when selecting parameters, and test your parameters to ensure they produce sensible results for a wide range of tree sizes. If you have problems with SORTIE crashing, try verifying that this behavior is the problem by removing it from the run and trying again. If you can verify that this behavior is the problem, carefully re-examine your parameters.
Apply this behavior to saplings, adults, or snags of any species, and enter parameters in the Parameter edit window. This behavior does not automatically create output. Once you have added this behavior to your run, the Detailed output setup window for trees will have a tree data member called "Tree Volume". Add this to your detailed output file to output volume in cubic meters. You can then view charts and graphs with the resulting volume data using data visualization on your detailed output file.
This behavior calculates the biomass of trees based on DBH. This approach comes from Jenkins et all, 2004.
The paper above outlines 9 different biomass equations in Table 6, as follows:
ID | Equation |
---|---|
1 | log10 biomass = a + b * (log10(dia c)) |
2 | ln biomass = a + b * dia + c * (ln(dia d)) |
3 | ln biomass = a + b * ln(dia) + c * (d + (e * ln(dia))) |
4 | biomass = a + b * dia + c * (dia d) |
5 | biomass = a + (b * dia) + c * (dia 2) + d * (dia 3) |
6 | biomass = a * (exp(b + (c * ln(dia)) + (d * dia))) |
7 | biomass = a + ((b * (dia c)) / ((dia c) + d)) |
8 | log100 biomass = a + (b * log10(dia)) |
9 | ln biomass = ln(a) + (b * ln(dia)) |
In all equations, dia is DBH. You choose the equation ID that you wish to use for each species.
There are many different published parameters using the equation forms above, which use a range of different units. Thus, you specify what units dia (that is, DBH) is in, and what units of biomass the equation is expected to produce. The possible DBH units are millimeters (mm), centimeters (cm), and inches (in); the possible biomass units are grams (g), kilograms (kg), and pounds (lb). This behavior handles all unit conversions so that biomass is appropriately calculated. The final biomass values are reported in metric tons (Mg).
For those equations that calculate log10, log100, or ln biomass, some papers specify a correction factor to remove bias that may be introduced when biomass is calculated. If you wish, you may use such a correction factor. Set the value of the Dimension Analysis: Use Correction Factor? parameter to "true", then specify the appropriate correction factor in the Dimension Analysis Correction Factor parameter. This value is multiplied by the final biomass value.
Apply this behavior to saplings, adults, or snags of any species, and enter parameters in the Parameter edit window. This behavior does not automatically create output. Once you have added this behavior to your run, the Detailed output setup window for trees will have a tree data member called "Tree Biomass". Add this to your detailed output file to output biomass in metric tons (Mg). You can then view charts and graphs with the resulting volume data using data visualization on your detailed output file.
This behavior calculates merchantable tree volume. Make sure to distinguish between this behavior and the other tree volume behavior.
Tree volume is calculated as follows:
The bole length is the number of 16-foot logs the tree can provide, in feet (i.e. 3 logs = bole length of 48 feet). The base of the bole is the top of the cut stump; the top of the bole is the merchantable height. This behavior defines the merchantable height as the height at which the trunk diameter inside the bark tapers to 60% of DBH.
To determine at what bole length the merchantable height occurs, the behavior tries fitting in as many 16-foot logs as possible before the 60% taper occurs. The amount of taper at the top of the first 16-foot log is established by the form classes. A species's form class is the percentage of DBH to which the bole has tapered at the top of the first 16-foot log. This value is entered as the Bole Volume Form Class, 60% - 100% parameter.
Then the behavior determines how many more logs the tree contains. The amount of taper at the top of the first 16-foot log is subtracted from the DBH, to see how much taper is left before the 60% merchantable-height diameter is reached. There is no formula that establishes clearly how many logs will fit; the behavior uses a trial-and-error approach taken from Messavage and Girard, 1956. This paper includes the table below for upper-log taper for trees of various DBH and bole heights. The behavior uses this table to determine the maximum number of logs it can fit into the taper available.
Trees below 10 inches of DBH have no volume. Trees greater than 40 inches of DBH are treated like 40-inch trees.
DBH (in) | 2-log tree | 3-log tree | 4-log tree | 5-log tree | 6-log tree | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2d log | 2d log | 3d log | 2d log | 3d log | 4th log | 2d log | 3d log | 4th log | 5th log | 2d log | 3d log | 4th log | 5th log | 6th log | |
10 | 1.4 | 1.2 | 1.4 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
12 | 1.6 | 1.3 | 1.5 | 1.1 | 1.4 | 1.9 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
14 | 1.7 | 1.4 | 1.6 | 1.2 | 1.5 | 2 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
16 | 1.9 | 1.5 | 1.7 | 1.2 | 1.6 | 2.1 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
18 | 2 | 1.6 | 1.8 | 1.3 | 1.7 | 2.2 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
20 | 2.1 | 1.7 | 1.9 | 1.4 | 1.8 | 2.4 | 1.1 | 1.6 | 2.2 | 2.9 | --- | --- | --- | --- | --- |
22 | 2.2 | 1.8 | 2 | 1.4 | 2 | 2.5 | 1.1 | 1.7 | 2.3 | 2.9 | --- | --- | --- | --- | --- |
24 | 2.3 | 1.8 | 2.2 | 1.5 | 2.2 | 2.6 | 1.1 | 1.8 | 2.4 | 3.1 | --- | --- | --- | --- | --- |
26 | 2.4 | 1.9 | 2.3 | 1.5 | 2.3 | 2.7 | 1.1 | 1.9 | 2.5 | 3.2 | --- | --- | --- | --- | --- |
28 | 2.5 | 1.9 | 2.5 | 1.6 | 2.4 | 2.8 | 1.2 | 1.9 | 2.6 | 3.3 | 0.9 | 1.4 | 2.1 | 3.2 | 4.4 |
30 | 2.6 | 2 | 2.6 | 1.7 | 2.5 | 3 | 1.2 | 2 | 2.7 | 3.5 | 0.9 | 1.4 | 2.1 | 3.2 | 4.5 |
32 | 2.7 | 2 | 2.7 | 1.7 | 2.5 | 3.1 | 1.2 | 2.1 | 2.9 | 3.7 | 1 | 1.4 | 2.1 | 3.2 | 4.6 |
34 | 2.8 | 2.1 | 2.7 | 1.8 | 2.5 | 3.3 | 1.3 | 2.1 | 3 | 3.8 | 1 | 1.4 | 2.2 | 3.3 | 4.7 |
36 | 2.8 | 2.1 | 2.8 | 1.8 | 2.6 | 3.4 | 1.3 | 2.2 | 3 | 3.9 | 1.1 | 1.5 | 2.2 | 3.3 | 4.9 |
38 | 2.9 | 2.1 | 2.8 | 1.9 | 2.6 | 3.4 | 1.3 | 2.2 | 3.1 | 3.9 | 1.1 | 1.5 | 2.3 | 3.4 | 5.1 |
40 | 2.9 | 2.2 | 2.8 | 1.9 | 2.7 | 3.4 | 1.4 | 2.3 | 3.2 | 4 | 1.2 | 1.5 | 2.4 | 3.5 | 5.3 |
Apply this behavior to saplings, adults, or snags of any species, and enter parameters in the Parameter edit window. This behavior does not automatically create output. Once you have added this behavior to your run, the Detailed output setup window for trees will have a tree data member called "Tree Bole Volume". Add this to your detailed output file to output volume in cubic feet. You can then view charts and graphs with the resulting volume data using data visualization on your detailed output file.