Difference between revisions of "Growth Results"
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==Gross vs. net growth== | ==Gross vs. net growth== | ||
Gross growth includes mortality while net growth only includes survived trees. | Gross growth includes mortality while net growth only includes survived trees. | ||
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==MAI and CAI== | ==MAI and CAI== | ||
Reported for all species and per species. | Reported for all species and per species. | ||
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| align="left" style="background:#f0f0f0;width: 50%;"|'''Description''' | | align="left" style="background:#f0f0f0;width: 50%;"|'''Description''' | ||
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| − | | CAI ... || [[Dictionary:m3sk|m<sup>3</sup>sk/ha,yr|| Current annual increment (from the beginning or midpoint of the previous period) | + | | CAI ... || [[Dictionary:m3sk|m<sup>3</sup>sk]]/ha,yr|| Current annual increment (from the beginning or midpoint of the previous period) |
|- | |- | ||
| − | | MAI ... || [[Dictionary:m3sk|m<sup>3</sup>sk/ha,yr|| Mean annual increment since year 0 or from the time for final felling of the previous rotation. '''Reset after final felling'''. | + | | MAI ... || [[Dictionary:m3sk|m<sup>3</sup>sk]]/ha,yr|| Mean annual increment since year 0 or from the time for final felling of the previous rotation. '''Reset after final felling'''. |
|- | |- | ||
| | | | ||
|} | |} | ||
| + | ==How growth is calculated== | ||
| + | [[File:Growth.png|450px]] | ||
| + | |||
| + | ====CAI net==== | ||
| + | The current annual '''net''' volume growth is the same as the volume change from one time (before harvest) to the next (before harvest). Mortilty is not included. CAI net is calculated as:<br> | ||
| + | |||
| + | <math>G_{t+a} = \displaystyle \frac{V_{t+a}- V_t + H_t}{a} </math> | ||
| + | |||
| + | where <br> | ||
| + | ''G<sub>t+a</sub>'' = Annual volume net increment from time ''t'' to time ''t + a'', and<br> | ||
| + | ''H<sub>t</sub>'' = Volume harvested at time t, and <br> | ||
| + | ''a'' = number of years | ||
| + | |||
| + | ====CAI gross==== | ||
| + | The current annual '''gross''' volume growth includes mortality and is calculated as CAI net but with mortality added:<br> | ||
| + | |||
| + | <math>G_{t+a} = \displaystyle \frac{V_{t+a}- V_a + H_t + M_t}{a} </math> | ||
| + | |||
| + | where <br> | ||
| + | ''G<sub>t+a</sub>'' = Annual volume net increment from time t to time t + a, and<br> | ||
| + | ''H<sub>t</sub>'' = Volume harvested at time t, and <br> | ||
| + | ''M<sub>t</sub>'' = Mortality volume from time ''t'' to ''t+a'', and <br> | ||
| + | ''a'' = number of years | ||
| + | |||
| + | This is the same as the volume change from one time (after harvest) to the next (before harvest), plus mortality. | ||
| + | ====MAI==== | ||
| + | MAI is calculated similarly to CAI but the first time is set to year 0 or, if a final felling has been simulated, the year for the last final felling. The harvest and mortality variables in the equations are replaced with sums over the harvesting and mortality that occurs between the time points. The result is the same as taking the average of CAI. | ||
[[Category:Result Variables]] | [[Category:Result Variables]] | ||
Latest revision as of 13:31, 31 May 2024
This result group contains: Volume growth results.
Gross vs. net growth
Gross growth includes mortality while net growth only includes survived trees.
MAI and CAI
Reported for all species and per species.
| Variable name | Unit | Description |
| CAI ... | m3sk/ha,yr | Current annual increment (from the beginning or midpoint of the previous period) |
| MAI ... | m3sk/ha,yr | Mean annual increment since year 0 or from the time for final felling of the previous rotation. Reset after final felling. |
How growth is calculated
CAI net
The current annual net volume growth is the same as the volume change from one time (before harvest) to the next (before harvest). Mortilty is not included. CAI net is calculated as:
where
Gt+a = Annual volume net increment from time t to time t + a, and
Ht = Volume harvested at time t, and
a = number of years
CAI gross
The current annual gross volume growth includes mortality and is calculated as CAI net but with mortality added:
where
Gt+a = Annual volume net increment from time t to time t + a, and
Ht = Volume harvested at time t, and
Mt = Mortality volume from time t to t+a, and
a = number of years
This is the same as the volume change from one time (after harvest) to the next (before harvest), plus mortality.
MAI
MAI is calculated similarly to CAI but the first time is set to year 0 or, if a final felling has been simulated, the year for the last final felling. The harvest and mortality variables in the equations are replaced with sums over the harvesting and mortality that occurs between the time points. The result is the same as taking the average of CAI.