Clasificación de peligros para cada puesto de trabajo 73

A Stand Policy Label set is a list of policies that apply to the stand and it is entered using the SPLABEL keyword. An activity group will not be scheduled if its label set and the stand’s label set do not contain a common member. The stand policy label(s) are entered on a supplemental record(s), just as with the activity group policy label. Each label must be separated by one comma and the total number of characters for all labels may not exceed 100 including commas.

For example, expanding on examples shown previously, assume the Central Rockies variant is being used and the stand management policy is as follows:

For stands with at least 200 square feet of basal area in spruce, commercially thin them using group selection; clearcut 25 percent of the stand, and leave 75 percent of existing basal area in the remaining 75 percent of the stand; establish 360 trees/acre in the clearcut patches, and assume no regeneration in the remaining stand; there will be no re-entry and thinning will be from below to the target basal area; label this management policy

“GROUPSELECT”. Furthermore, for stands with more than 100 but less than 200 square feet of basal area in spruce, commercially thin them using a uniform shelterwood cut from below, leaving 70 percent of existing basal area; no re-entry; and establish 220 Engelmann spruce per acre; label this management policy “SHELTERWOOD”. To simulate this stand management policy, the following keyword set is developed: INVYEAR 2001. STDINFO 204. 138. MODTYPE 4. DESIGN 0. 1.0 999. 4. 0. SITECODE ES 85. NUMCYCLE 10. COMPUTE 0. ESBA = SPMCDBH(2,ES,0) CUTTYPE = 0 END *

* shelterwood thinning specification *

IF 999.

THEN THINBBA 0. PARMS(BBA*0.7,1.,0.,999.,0.,999.) COMPUTE 0. CUTTYPE = 1 END AGPLABEL SHELTERWOOD ENDIF *

*shelterwood establishment specification *

IF

CUT EQ 1.0 AND CUTTYPE EQ 1 THEN ESTAB PLANT 0.0 ES 220. END AGPLABEL SHELTERWOOD ENDIF *

* group selection thinning specification * IF 999. ESBA GE 200 THEN THINBBA 0. PARMS(BBA*0.525,1.,0.,999.,0.,999.) COMPUTE 0. CUTTYPE = 2 END AGPLABEL GROUPSELECT ENDIF *

* group selection establishment specification *

IF

CUT EQ 1.0 AND CUTTYPE EQ 2 THEN ESTAB PLANT 0.0 ES 90. END AGPLABEL GROUPSELECT ENDIF

*

* stand policy label specification * SPLABEL GROUPSELECT * PROCESS STOP

This keyword set is similar to ones presented previously in this section, but there are a few differences. The user-defined variable ESBA is defined using a compute statement and subsequently used in the condition statements. The pre-defined event monitor variable BBA is used in the PARMS statements. The variable CUTTYPE will have a value of 1 if a shelterwood thinning was done, a value of 2 if a group selection thinning was done, and a value of 0 otherwise. The keyword set is annotated and separated into logical blocks using comment records beginning with the “*” character.

The important thing to notice, however, is the inclusion of the SPLABEL keyword and the stand policy label “GROUPSELECT”. When this simulation is run, only the two activity groups labeled with the “GROUPSELECT” activity group policy labels will be considered by FVS. The two activity groups labeled with the “SHELTERWOOD” activity group policy labels will not be considered in this simulation. By simply changing the supplemental record for the stand policy label from “GROUPSELECT” to

“SHELTERWOOD”, the opposite would be true. The activity groups labeled with “SHELTERWOOD” would be considered, and the two labeled with “GROUPSELECT” would not. This gives users an easy way to evaluate different management alternatives for a stand, using a single keyword set. In addition, if the supplemental record is changed to include both policy labels,

SPLABEL

GROUPSELECT, SHELTERWOOD

then all four activity groups are considered in the simulation. In this case, the appropriate treatment gets applied depending on the basal area of Engelmann spruce in the stand. It is under this scenario that the variable CUTTYPE comes into play to determine how much regeneration to bring into the stand. Consider what would happen if the condition on the two establishment activity groups were simply “CUT EQ 1” instead of “CUT EQ 1 AND CUTTYPE EQ x”. The first regeneration activity group is labeled with the activity group label “SHELTERWOOD”, and the second with “GROUPSELECT”. Because the stand policy label set contains both activity group policy labels, both regeneration activity groups would be triggered because the value of the variable CUT would be 1 regardless of which type of thinning occurred. This would result in too much regeneration being simulated (e.g. 220 + 90 = 310 trees/acre).

1. If more than one SPLABEL set is specified for a stand, or if more than one AGPLABEL set is specified for a single activity group, the sets specified last will be used and the others will be ignored.

2. If no SPLABEL set is specified, the default stand policy label set is the union over all of the activity group policy label sets.

3. The SPLABEL set is assigned to activity groups where no AGPLABEL is defined.

4. If no SPLABEL and no AGPLABEL keywords are used in the run, then the model uses none of the logic associated with the labeling scheme.

Policy labeling is most useful when including several stands in a simulation. Management policies can be developed for any number of different situations, and descriptive activity group policy labels can be included. Any particular management policy is considered only for those stands that have a stand policy label in common with the specified activity group policy label(s).

Policy labeling is particularly useful when using the Parallel Processing Extension (Crookston and Stage 1991). However, it can also be very useful in evaluating different management alternatives for a single stand using a single keyword set (as shown in the example keyword set in this section), or for running groups of stands such as all stands in a watershed.