I have no idea how many secluded ravines there are in Colorado with Ponderosas, Doug Firs, Colorado Blues, and Englemanns reaching the big numbers. Finding out is a mission that I'd like to undertake. We would be breaking new ground. Here is a sample of what is out there on the Internet relative to the maximum dimensions achieved by several species.
USDA Natural Conservation Service
Heights to 60 meters
Utah State Extension Service
Growth Characteristics: Engelmann spruce is a large tree, averaging 30 inches in diameter and 90 feet in height.
Picea engelmannii is a medium-sized to large evergreen tree growing to 25–40 m (82-131 ft) tall, exceptionally to 65 m (213 ft) tall, and with a trunk diameter of up to 1.5 m (4 ft, 9 in).
Montana Plant-Life Association
General: straight, spire-like evergreen tree up to 50 m. tall, the trunk seldom over 1 m. thick.
North American Silvics
Growth and Yield- Engelmann spruce is one of the largest of the high-mountain species. Under favorable conditions, average stand diameter will vary from 38.1 to 76.2 cm (15 to 30 in), and average dominant height from 14 to 40 m (45 to 130 ft), depending upon site quality and density (20). Individual trees may exceed 101.6 cm (40 in) in diameter and 49 m (160 ft) in height (60). Engelmann spruce is a long-lived tree, maturing in about 300 years. Dominant spruces are often 250 to 450 years old, and trees 500 to 600 years old are not uncommon (13).
Some Other species in North American Silvics
Colorado Blue Spruce
Growth and Yield- Blue spruce is apparently a long-lived tree, surviving up to 600 years or more. Diameter growth is slow; trees 10 to 13 cm (4 to 5 in) in d.b.h. may be 125 to 135 years old; at 46 to 56 cm (18 to 22 in), they may be 275 to 350 years of age (84). The "1982 National Register of Big Trees" lists the largest blue spruce as 154.4 cm (60.8 in) in d.b.h. and 38.4 m (126 ft) tall, on the Gunnison National Forest, CO.
Growth and Yield- Ponderosa pine grows to impressive size. Stems 263 cm (103.5 in) in d.b.h. and 70.7 m (232 ft) in height have been recorded (13). Diameters at breast height of 76 to 127 cm (30 to 50 in) and heights of 27.4 to 39.6 m (90 to 130 ft) are common throughout most of its range. Trees often reach ages of 300 to 600 years.
The interior variety of Douglas-fir does not attain the growth rates, dimensions, or age of the coastal variety. Site class for Rocky Mountain Douglas-fir is usually IV or V (site index 24 to 37 m or 80 to 120 ft at age 100) when compared with the growth of this species in the Pacific Northwest (1,43). On low sites, growth is sometimes so slow that trees do not reach saw-log size before old age and decadence overtake them. Interior Douglas-fir reaches an average height of 30 to 37 m (100 to 120 ft) with a d.b.h. between 38 and 102 cm (15 and 40 in) in 200 to 300 years. On the best sites, dominant trees may attain a height of 49 m (160 ft) and a d.b.h. of 152 cm (60 in) (23). Diameter growth becomes extremely slow and height growth practically ceases after age 200. Interior Douglas-fir, however, appears capable of response to release by accelerated diameter growth at any size or age (35). The interior variety is not as long lived as the coastal variety and rarely lives more than 400 years, although more than 700 annual rings have been counted on stumps (23).
Growth and Yield- Red spruce is a medium-size tree at maturity, reaching 30 to 61 cm (12 to 24 in) in d.b.h. and 18 to 23 m (60 to 75 ft) in height in the Northeast, and up to 35 m (115 ft) in the Appalachian Mountains. Its maximum age is about 400 years (22). The American Forestry Association lists a tree 133 cm (52.5 in) in d.b.h. and 33.5 m (110 ft) Eall in Great Smoky National Park in North Carolina as the largest living red spruce.
Need I comment? Ball's in our court.
Robert T. Leverett
Co-founder and Executive Director
Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest