Bristlecone Pine Growth-Forms Tree Index

Under the SilGro home page for Alan Silverstein and Cathie Grow
Email me at ajs@frii.com
Last update: January 19, 2026

This is a cross reference by tree number to the August 28, 2006 booklet: Growth-Form Characteristics of Ancient Rocky Mountain Bristlecone Pines (Pinus aristata), Colorado by F. Craig Brunstein of the USGS in Denver, Colorado.

Unfortunately this lovely study makes many references to specific trees such as "90-11" without any master index, nor any correlation to metal tags like "CB-18" found on many of the trees on the south slopes of Black Mountain in Park County west of Guffey, Colorado. I was unable to find other notes or papers Craig Brunstein (1952-2008? obituary 1-11-2008) might have left behind with friends or at the USGS, although clearly he was abstracting from an extensive data record.

Note: In other Brunstein papers the tree numbers are preceded by a prefix like "CB-90-11". Also this Black Mountain is not to be confused with several other peaks of the same name in Colorado or even in the same county!

The book mentions 134 dated trees (see page 1) that are 20-2500 years old, including 125 from core samples (see page 5) taken 1968-70 and 1988-96.

See also below the tables for more notes about what's missing from this booklet.

Sorted by tree numbers (47 entries):

Number	Pages	Min/Est Age (2005)
68-1	88,90	788/800 (ponderosa pine)
68-3	18-19,33,56,63,88	1992/2050
69-2	48,88	1188/1200
69-4	42,82	960
69-R4	18-19,63,67	1550
69-7	42-43,82	1080
88-4	88	1250/1300
88-5	30-31,33,56	1100
88-7	18-19	1160
88-8	18-19,34-38,56,88	1191/1210
88-9	88	1247/1260
88-17	82,88	1134/1170
88-10	18-19,39,63	1410
88-20	18-19	1180
89-2	66-67,88	1907/1980
90-1	18-19,32-33,56,88	2198/2220
90-3	18-19,20	300
90-4	18-19,48,88	1854/1870
90-5	18-19,81	500
90-8	22	510
90-10	18-19,56	2370-2500
90-11	18-19,88	2449/2500 (sampled at 12')
90-15	56,63,82	>1870
91-2	18-19,81	1850
91-7	18-19,81	760
91-8	18-19	720
91-12	88	1251/1270
91-14	18-19,56,63,82	1180
91-15	88	1131/1160
91-28	18-19	2350
91-38	63	?
91-41AL	18-19,81	140
91-65	40,56,82	1660
91-67	88,90	1669/1680 (limber pine)
93-10	18-19	340
93-17	18-19,81	200
93-38	18-19,81	830
93-39	18-19,56,82,88	1834/1870
93-40	82,88	1792/1880
93-45	18-19,88	1044/1180
93-55	18-19,88	1497/1520
93-R18	18-19	1400
93-61	88	1611/1630
94-1	88,90	688/710 (ponderosa pine)
95-11	18-19,81	580
95-13	18-19,81	760
Krebs34	18-19,88	1603/nc

Sorted by estimated age:

Number	Pages	Min/Est Age (2005)
91-38	63	?
91-41AL	18-19,81	140
93-17	18-19,81	200
90-3	18-19,20	300
93-10	18-19	340
90-5	18-19,81	500
90-8	22	510
95-11	18-19,81	580
94-1	88,90	688/710 (ponderosa pine)
91-8	18-19	720
91-7	18-19,81	760
95-13	18-19,81	760
68-1	88,90	788/800 (ponderosa pine)
93-38	18-19,81	830
69-4	42,82	960
69-7	42-43,82	1080
88-5	30-31,33,56	1100
88-7	18-19	1160
91-15	88	1131/1160
88-17	82,88	1134/1170
88-20	18-19	1180
91-14	18-19,56,63,82	1180
93-45	18-19,88	1044/1180
69-2	48,88	1188/1200
88-8	18-19,34-38,56,88	1191/1210
88-9	88	1247/1260
91-12	88	1251/1270
88-4	88	1250/1300
93-R18	18-19	1400
88-10	18-19,39,63	1410
93-55	18-19,88	1497/1520
69-R4	18-19,63,67	1550
Krebs34	18-19,88	1603/nc
93-61	88	1611/1630
91-65	40,56,82	1660
91-67	88,90	1669/1680 (limber pine)
91-2	18-19,81	1850
90-4	18-19,48,88	1854/1870
93-39	18-19,56,82,88	1834/1870
90-15	56,63,82	>1870
93-40	82,88	1792/1880
89-2	66-67,88	1907/1980
68-3	18-19,33,56,63,88	1992/2050
90-1	18-19,32-33,56,88	2198/2220
91-28	18-19	2350
90-10	18-19,56	2370-2500
90-11	18-19,88	2449/2500 (sampled at 12')

When I opened the (physical) booklet in late 2025 I found a handwritten note I'd forgotten some years ago. I decided to type it in:

The book is silent on:

• Author's reasons and history of tree study, including his gap between 1968 and 1990.
• Mapping from metal tags (like "CB-18") on trees to IDs used here (like "CB-90-11"); apparently lost, I asked USGS and others to look for it.
• Rate of wood growth, is it really widely quoted 100 years per inch? Plus density compared with other species.
• Relationship and distance to Pinus longaeva, eg 140 miles apart in Utah, per a different source.
• Apparent fragility and poor competition of P. aristata versus other evergreens EXCEPT in poor conditions, plus ability to form living bark strips and stay "alive" after the main trunk dies at ~500 years and weathers to a pith spike.
• Why did he never date other krummholz trees? (Well he did mention a few ponderosa and limber pines.)
• Unable to tell barely-living from fully dead bristlecones in forest at any distance.