Merchantable Timber Value

This behavior calculates the value of merchantable timber.

Parameters for this behavior

Parameter name	Description
Merchantable Timber Value Form Class	The form class of the species. Valid values are 78, 79, 80, 81, 84, and 85.
Merchantable Timber Value Price / 1000 Board Feet	The price per thousand board feet for each species. The currency used doesn't matter.

How it works

The value for each tree is calculated by finding out its volume in board feet, and multiplying that by the price for its species. The price is held in the Merchantable Timber Value Price / 1000 Board Feet parameter. The currency used doesn't matter. The tree's final value is placed in a tree data member called "Merchantable Value". The total value for each species is saved in a grid called Merchantable Timber Value. You can save these values in a detailed output file for analysis.

The volume of merchantable timber in a tree depends on its size and form class. These control how many 16-foot logs there are in a tree, and how many board feet of timber (assuming 0.25-inch thickness) those logs can create. The form class is entered in the Merchantable Timber Value Form Class parameter.

The behavior begins by finding out how many 16-foot logs the tree can provide in its bole. 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. 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 tree's form class. 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.

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 contain no merchantable timber and have a value of zero. Trees greater than 40 inches of DBH are treated like 40-inch trees.

Once the behavior figures out how many 16-foot logs a tree contains, it uses another set of tables, based on form class, to determine how many board-feet of timber the tree contains. These tables are also from Messavage and Girard, 1956, and are shown below.

Average upper-log taper (inches) in 16-foot logs

DBH (in)	2-log tree	3-log tree		4-log tree			5-log tree				6-log tree
DBH (in)	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

Volume (board feet) by number of usable 16 foot logs
Form Class 78:

DBH (inches)	1 log	2 logs	3 logs	4 logs	5 logs	6 logs
10	36	59	73	---	---	---
11	46	76	96	---	---	---
12	56	92	120	137	---	---
13	67	112	147	168	---	---
14	78	132	174	200	---	---
15	92	156	208	242	---	---
16	106	180	241	285	---	---
17	121	206	278	330	---	---
18	136	233	314	374	---	---
19	154	264	358	427	---	---
20	171	296	401	480	542	---
21	191	332	450	542	616	---
22	211	368	500	603	691	---
23	231	404	552	663	714	---
24	251	441	605	723	782	---
25	275	484	665	800	865	---
26	299	528	725	877	1,021	---
27	323	572	788	952	1,111	---
28	347	616	850	1,027	1,201	1,358
29	375	667	920	1,112	1,308	1,488
30	403	718	991	1,198	1,415	1,619
31	432	772	1,070	1,299	1,526	1,754
32	462	826	1,149	1,400	1,637	1,888
33	492	880	1,226	1,495	1,750	2,026
34	521	934	1,304	1,590	1,864	2,163
35	555	998	1,394	1,702	2,000	2,312
36	589	1,063	1,485	1,814	2,135	2,461
37	622	1,124	1,578	1,926	2,272	2,616
38	656	1,186	1,670	2,038	2,410	2,771
39	694	1,258	1,769	2,166	2,552	2,937
40	731	1,329	1,868	2,294	2,693	3,103

Form Class 79:

DBH (inches)	1 log	2 logs	3 logs	4 logs	5 logs	6 logs
10	38	61	77	---	---	---
11	48	78	100	---	---	---
12	58	96	124	141	---	---
13	70	117	153	176	---	---
14	82	138	182	211	---	---
15	95	160	214	252	---	---
16	108	183	246	292	---	---
17	124	212	286	340	---	---
18	140	240	325	388	---	---
19	158	272	370	442	---	---
20	176	305	414	496	561	---
21	196	342	464	558	636	---
22	216	378	514	621	710	---
23	238	418	571	687	792	---
24	260	458	628	753	875	---
25	282	499	685	826	960	---
26	305	540	742	899	1,046	---
27	331	588	810	980	1,144	---
28	357	635	877	1,061	1,242	1,404
29	385	686	948	1,148	1,350	1,537
30	413	737	1,020	1,235	1,458	1,670
31	444	792	1,100	1,338	1,572	1,808
32	474	848	1,181	1,440	1,685	1,945
33	506	907	1,265	1,544	1,808	2,094
34	538	966	1,349	1,647	1,932	2,244
35	570	1,026	1,435	1,754	2,000	2,384
36	602	1,087	1,521	1,860	2,189	2,525
37	638	1,154	1,620	1,980	2,338	2,694
38	674	1,220	1,720	2,101	2,488	2,862
39	712	1,292	1,822	2,232	2,632	3,031
40	750	1,365	1,923	2,362	2,775	3,200

Form Class 80:

DBH (inches)	1 log	2 logs	3 logs	4 logs	5 logs	6 logs
10	39	63	80	---	---	---
11	49	80	104	---	---	---
12	59	98	127	146	---	---
13	71	120	156	181	---	---
14	83	141	186	216	---	---
15	98	166	221	260	---	---
16	112	190	256	305	---	---
17	128	219	296	354	---	---
18	144	248	336	402	---	---
19	162	281	382	457	---	---
20	181	314	427	512	580	---
21	201	350	478	575	656	---
22	221	387	528	638	732	---
23	244	428	586	706	816	---
24	266	469	644	773	899	---
25	290	514	706	852	992	---
26	315	558	767	931	1,086	---
27	341	606	836	1,014	1,185	---
28	367	654	904	1,096	1,284	1,453
29	396	706	977	1,184	1,394	1,588
30	424	758	1,050	1,272	1,503	1,723
31	454	814	1,132	1,376	1,618	1,862
32	485	870	1,213	1,480	1,733	2,001
33	518	930	1,298	1,586	1,858	2,152
34	550	989	1,383	1,691	1,984	2,304
35	585	1,055	1,477	1,806	2,124	2,458
36	620	1,121	1,571	1,922	2,264	2,612
37	656	1,188	1,672	2,044	2,416	2,783
38	693	1,256	1,772	2,167	2,568	2,954
39	732	1,330	1,874	2,300	2,714	3,127
40	770	1,403	1,977	2,432	2,860	3,300

Form Class 81:

DBH (inches)	1 log	2 logs	3 logs	4 logs	5 logs	6 logs
10	40	65	82	---	---	---
11	50	82	106	---	---	---
12	60	100	130	150	---	---
13	72	122	160	186	---	---
14	85	144	190	221	---	---
15	100	170	228	268	---	---
16	115	197	265	316	---	---
17	132	226	306	366	---	---
18	148	256	346	415	---	---
19	166	290	392	471	---	---
20	185	323	439	527	598	---
21	206	360	492	592	676	---
22	227	398	544	656	754	---
23	250	439	602	724	838	---
24	272	480	659	791	923	---
25	298	528	726	877	1,024	---
26	324	575	793	963	1,124	---
27	351	624	863	1,047	1,226	---
28	378	674	933	1,131	1,327	1,502
29	406	726	1,006	1,220	1,438	1,640
30	435	779	1,080	1,310	1,549	1,777
31	466	836	1,162	1,416	1,666	1,918
32	497	892	1,245	1,522	1,784	2,059
33	530	953	1,332	1,628	1,910	2,214
34	563	1,014	1,419	1,734	2,037	2,368
35	600	1,084	1,518	1,859	2,188	2,534
36	637	1,154	1,618	1,984	2,338	2,700
37	674	1,223	1,721	2,109	2,494	2,874
38	712	1,292	1,824	2,234	2,649	3,049
39	751	1,366	1,928	2,368	2,796	3,224
40	790	1,441	2,032	2,502	2,944	3,399

Form Class 84:

DBH (inches)	1 log	2 logs	3 logs	4 logs	5 logs	6 logs
10	43	71	91	---	---	---
11	54	91	118	---	---	---
12	66	111	145	168	---	---
13	80	135	178	208	---	---
14	93	159	212	248	---	---
15	108	185	249	295	---	---
16	123	211	286	342	---	---
17	142	244	332	398	---	---
18	160	277	377	453	---	---
19	180	314	428	524	---	---
20	200	351	479	576	657	---
21	223	392	537	649	744	---
22	246	434	595	722	830	---
23	271	480	660	798	925	---
24	296	525	724	873	1,020	---
25	322	572	790	958	1,118	---
26	347	619	855	1,042	1,217	---
27	376	673	932	1,136	1,331	---
28	406	727	1,010	1,230	1,445	1,636
29	438	786	1,092	1,330	1,569	1,790
30	470	844	1,173	1,429	1,693	1,943
31	504	907	1,265	1,546	1,823	2,101
32	538	970	1,357	1,664	1,953	2,259
33	574	1,037	1,453	1,782	2,096	2,431
34	611	1,104	1,549	1,901	2,240	2,603
35	647	1,173	1,648	2,023	2,387	2,766
36	683	1,242	1,746	2,145	2,534	2,929
37	724	1,318	1,859	2,284	2,706	3,123
38	765	1,393	1,972	2,422	2,877	3,317
39	808	1,476	2,088	2,570	3,042	3,512
40	851	1,558	2,203	2,719	3,208	3,706

Form Class 85:

DBH (inches)	1 log	2 logs	3 logs	4 logs	5 logs	6 logs
10	45	74	94	---	---	---
11	56	94	122	---	---	---
12	68	114	150	173	---	---
13	82	138	184	214	---	---
14	95	163	217	254	---	---
15	111	191	257	304	---	---
16	127	219	297	355	---	---
17	146	252	342	412	---	---
18	164	285	388	468	---	---
19	184	322	440	531	---	---
20	205	360	492	594	678	---
21	228	402	550	667	765	---
22	251	444	609	740	852	---
23	276	490	675	818	950	---
24	302	537	741	895	1,047	---
25	330	588	812	986	1,153	---
26	357	638	882	1,076	1,259	---
27	387	693	961	1,172	1,374	---
28	417	745	1,040	1,267	1,490	1,689
29	448	807	1,122	1,368	1,616	1,844
30	481	866	1,205	1,469	1,741	1,999
31	516	930	1,298	1,588	1,874	2,160
32	550	993	1,391	1,706	2,006	2,321
33	587	1,061	1,488	1,827	2,150	2,495
34	624	1,129	1,586	1,948	2,294	2,669
35	663	1,204	1,692	2,080	2,454	2,846
36	702	1,278	1,797	2,212	2,614	3,022
37	744	1,355	1,912	2,352	2,788	3,219
38	785	1,432	2,027	2,493	2,962	3,416
39	828	1,515	2,144	2,644	3,130	3,614
40	872	1,598	2,260	2,795	3,298	3,813

How to apply it

Apply this behavior to saplings, adults, or snags of any species. 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 "Merchantable Value". Add this to your detailed output file to output volume in cubic feet. You can also use the Detailed output grid setup window to save the data members in the Merchantable Timber Value grid, which contains the total value for each species. You can then view the contents of this grid as a table using SORTIE's data visualization system.