USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 1

UNITED STATES

DEPARTMENT OF

AGRICULTURE

Field Guide to Old 

Ponderosa Pines in the 

Colorado Front Range

By 

Laurie Stroh Huckaby

Merrill R. Kaufmann

Paula J. Fornwalt

Jason M. Stoker

Chuck Dennis

FOREST SERVICE

ROCKY MOUNTAIN

RESEARCH STATION

GENERAL TECHNICAL

REPORT RMRS-GTR-109

SEPTEMBER 2003

Field Guide to Old 

Ponderosa Pines in the 

Colorado Front Range

By 

Laurie Stroh Huckaby

Merrill R. Kaufmann

Paula J. Fornwalt

Jason M. Stoker

Chuck Dennis
All photos and illustrations by Laurie S. Huckaby, unless otherwise noted.

Huckaby, Laurie Stroh; Kaufmann, Merrill R.; Fornwalt, Paula J.; Stoker, Jason 

M.; and Dennis, Chuck. 2003. Field guide to old ponderosa pines in the 

Colorado Front Range. Gen. Tech. Rep. RMRS-GTR-109. Fort Collins, 

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain 

Research Station. 43 p. 

We describe the distinguishing physical characteristics of old ponderosa 

pine trees in the Front Range of Colorado and the ecological processes 

that tend to preserve them. Photographs illustrate identifying features of old 

ponderosa pines and show how to differentiate them from mature and young 

trees. The publication includes a photographic gallery of old ponderosa pine 

trees growing on poor, moderate, and good sites. We illustrate trees growing 

under various forest conditions and with different injuries and histories. The 

companion general technical report includes a more detailed description of 

ponderosa pine ecology and the role of old trees in the historical and modern 

landscapes.

Keywords: ponderosa pine, old growth, Colorado Front Range, fire ecology, 

montane zone

You may order additional copies of this publication by sending your mailing information in label form through one of the following media. Please 

send the publication title and number.

Telephone (970) 498-1392

Email rschneider@fs.fed.us

Fax (970) 498-1396

Mailing address Publications Distribution

Rocky Mountain Research Station

240 W. Prospect Rd.

Fort Collins, CO 80526

Rocky Mountain Research Station

Natural Resources Research Center

2150 Centre Avenue, Building A

Fort Collins, CO 80526

On the cover: An old ponderosa pine growing on an open, south-facing slope 

in the Arapaho-Roosevelt National Forest. It is more than 350 years old.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 1

Field Guide to Old Ponderosa Pines in the 

Colorado Front Range

by

Laurie Stroh Huckaby, Merrill R. Kaufmann,

Paula J. Fornwalt, Jason M. Stoker, and Chuck Dennis

Introduction

Old trees were historically a major component of montane forests in the Colorado 

Front Range. They were an integral part of the spatial and temporal heterogeneity 

inherent in the ecosystem. Now they are relatively scarce. Many were harvested 

during the Euro-American settlement period in the late 19th and early 20th centuries. 

Century-old stumps of trees that were 400 to 500 years old when cut remain like 

ghosts amid stands of trees that have established during the last 100 years. Other old 

trees were destroyed in extensive human-caused fires during the same period and 

later. Surviving old trees are now stressed by competition from dense ingrowth of 

younger trees and are in danger from insect outbreaks and stand-replacing fires.

Land managers are now aware that modern forest structure differs from that of 

the pre-settlement landscape, and that change in structure is precipitating a change 

in disturbance processes such as fire and insect outbreaks. Urban encroachment 

into the montane zone puts pressure on land managers to mitigate the danger of 

wildfire. The best way to handle this danger is to restore an ecologically sustainable 

landscape that resembles the patterns that existed before Euro-American settlement—patterns that encouraged the survival of old trees. Old ponderosa pines are 

resistant to surface fire, provide food and habitat for wildlife, and are a source of 

genetic continuity for the forest. They are aesthetically attractive, and they are an 

intrinsic part of the beautiful, dynamic landscape that draws thousands of people to 

the Front Range every year. They record the history of climate and fire in their rings. 

This guide is written to help the reader identify old trees and understand their past 

and present role as components of forests in the montane zone.

Ecological Zones of the Colorado Front Range

For this publication, we define the Front Range as the area south of the Wyoming 

border, east of the Continental Divide, west of the Great Plains, and north of Pikes 

Peak (near Colorado Springs; fig. 1). Two related environmental factors drive ecological processes and the distribution of species of the Front Range: elevation and 

moisture availability. Going up in elevation has effects similar to going up in latitude. At higher elevations, the growing season becomes shorter, temperatures are 

cooler, and precipitation is greater. Fire and other disturbances become less frequent 

at higher elevations. Vegetation changes along this gradient reflect these environmental changes. Our focus is the montane zone, between 6000 and 9000 ft (1850-

2770 m) elevation, below the level of persistent winter snowpack. Most of this 

elevational zone is dominated by forests of ponderosa pine mixed with Douglas-fir, 

interspersed with shrublands, grasslands or aspen stands.
2 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Figure 1—Overhead view of the Front Range showing the elevational gradient. 

Light green designates the plains at around 5000 ft (1540 m). The montane 

zone is shown as dark green. The subalpine zone is shown as a gradient of 

tan to redish brown; white areas are above 14,000 ft (4300 m). Sampling sites 

are denoted by yellow stars. (Map by J. Stoker.)
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 3

Ponderosa Pine and the Montane Zone of the 

Front Range

Ponderosa pine (Pinus ponderosa Dougl. ex Laws.) is one of the most widespread tree species in the western United States, ranging from northern Mexico into 

southern Canada, and from California to Nebraska. The Rocky Mountain variety is 

called scopulorum, to distinguish it from the variety found in the Pacific Northwest 

and from the subspecies arizonica, found in the Southwest near the Mexican border. 

In the Colorado Front Range, ponderosa pine grows from the border of the prairie 

and the foothills, up to around 9000 ft (2770 m) elevation, depending on topography. It may be found up to 10,000 ft (3070 m) on warm south-facing slopes. It is 

the dominant tree in the montane zone (6000 and 9000 ft [1850-2770 m]), where 

it often occurs with Douglas-fir (Pseudotsuga menziesii), especially on north-facing slopes. Ponderosa pines can grow to be very large in other parts of the country, 

but rarely exceed 100 ft (30 m) in height in the Front Range. It is tolerant of heat, 

drought, and fire.

Ponderosa pines have needles in fascicles of three, or sometimes two. Each tree 

produces both male and female reproductive structures; the female strobili mature 

into woody cones. Seeds are moderate in weight for tree seeds, and may be widely 

dispersed by wind. Ponderosa pine is susceptible to infestation by dwarf mistletoe (Arceuthobium vaginatum) and to attack by several insects, most notably the 

mountain pine beetle (Dendroctonus ponderosae). Ponderosa pine has long been an 

important tree for timber, though logging has not been a major industry in the Front 

Range in recent decades.

Ponderosa pine is a long-lived species. The oldest known ponderosa pines are 

more than 700 years old (843 years, Central Utah; 780 years, Mt. Rosa, CO; 742 

years, NW Arizona; OLDLIST database http://www.rmtrr.org/oldlist.htm). The 

oldest known ponderosa pines in the Front Range are a little over 600 years old. 

However, ponderosa pines that old are uncommon in the Front Range. Trees between 300 and 500 years old are frequent, and trees more than 200 years old are 

common throughout the Front Range above about 6500 ft (2000 m) elevation. 

Stands of old-growth ponderosa pine are now relatively rare in the Front Range because of past logging and wildfire (fig. 2). However, individual trees older than 200 

years are not uncommon, and in many locations trees that were too small to be cut 

during the Euro-American settlement period are now around 200 years old.

Historically, fire was the primary regulator of forests in the Front Range. Fire history reconstructions have shown that before Euro-American settlement of the Front 

Range (beginning with the influx of settlers in the gold rush of 1859), a fire occurred 

in any given location in the montane zone on average every 10-20 years. Larger 

fires with variable effects occurred at longer intervals, on the order of 30-60 years. 

Most pre-settlement fires in the montane zone were of low or mixed severity. By the 

early 1900s, fire frequency in the montane zone dropped dramatically. In some locations, heavy livestock grazing over the preceding decades had reduced surface fuels 

and retarded fire spread. Many areas had been recently logged or burned or both, 

which had also reduced fuels. Most significantly, organized fire suppression became 

effective during the early 20th century and has continued to the present.
4 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Douglas-fir trees are now more numerous in the Front Range than they were 

historically. While Douglas-fir has always shared the montane zone with ponderosa 

pine (fig. 3a), many more young Douglas-fir survive now than when fire was more 

frequent. Young Douglas-fir trees have thin bark and a long proportion of live 

crown to the height of the tree (live crown ratio) that make them susceptible to fire 

(fig. 3b). Old Douglas-fir are quite resistant to fire. They self-prune as ponderosa 

pines do, and they have very thick bark. Many of the older trees also have fire scars. 

The species composition of montane forests is now shifting toward dominance by 

Douglas-fir.

Identification of Old Ponderosa Pines in the Front Range

Appearance of Old Trees (>200 Years)

At around 200 years of age, ponderosa pines begin to take on distinctive physical 

characteristics as the result of physiological changes (fig. 4). Trees growing in poor 

sites or those that are otherwise stressed, as by dwarf mistletoe infestation, may 

look old earlier. Trees acquire these characteristics gradually as they interact with 

their environment (fig. 5).

Figure 2—Old trees in the modern landscape. This group of old trees (designated 

by yellow arrows) lives on a bench at the base of a west-facing slope along the 

Mt. McConnell trail off the Pingree Park road at 7592 ft (2336 m) elevation. This 

is a better site than the sparse, disturbed slopes above. Young ponderosa pines, 

Douglas-fir, and juniper are filling in the understory in the absence of surface fire. 

The old trees have smooth orange bark, small live crown ratios, open crowns with 

large branches and flattened tops, lightning scars, and fire scars. We cored the 

tree designated by the orange arrow. Its DBH was 24.9 inches (63 cm). Its pith 

date is 1642. It had a fire scar in 1707.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 5

Figure 3a—An old Douglas-fir dominates 

a west-facing slope at Cheesman Lake 

where the young ponderosa pines are 

infested with dwarf mistletoe.

3b—A young Douglas-fir grows amid 

a post-Euro-American settlement 

ponderosa pine forest in Rist Canyon. 

Young Douglas-fir trees have thin bark 

and branches that extend all the way to 

the ground, making them susceptible to 

burning. Trees like these are common 

in the understory of ponderosa pine forests in the absence of surface fire.

Crown shape is determined in part by the site where the tree lives and by its history, but in general, as a tree ages and stops growing taller, the crown appears to 

flatten out on the top and to acquire a “bonsai” look (fig. 6). Older trees often have 

sparse or very open crowns, as fine branches on the interior of the crown have died 

over the years, leaving a few large branches. Also, the growing tips of the branches 

are farther from the trunk, and the interior of the crown often has little foliage. The 

ratio of live crown to the height of the tree becomes less, both through self-pruning 

and fire pruning. This has the added benefit of removing ladder fuels from the lower 

part of the trunk, making it less likely that a surface fire will get into the crown.

Old tree trunks become columnar over time due to differential growth in the upper crown. Old trees allocate wood in the upper crown first, and if there is any carbohydrate left, they grow wood in the lower part of the trunk. The tops of old trees 

are often killed by lightning, fungi, or insects, giving them a spiked appearance. 

Trees with dead tops are often hollow because the injury allows the entry of fungi.
6 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Figure 4—Idealized silhouettes of ponderosa pines of various ages and on various 

site conditions in the Front Range of Colorado (in the style of the Keen [1955] tree 

vigor classification for ponderosa pine in Oregon). The horizontal rows represent 

three age classes: top, the youngest, less than 150 years; middle, transitional 

trees 150 to 250 years old; and bottom, the oldest, trees more than 250 years old. 

The three site classes are represented by the vertical columns: left, good sites 

such as meadow edges and riparian areas; middle, moderate sites such as eastfacing slopes or gentle slopes; and right, poor sites such as steep south-facing 

slopes or ridgetops (drawing by Joyce VanDeWater).
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 7

Figure 5—Typical characteristics of old ponderosa pines. This classic old tree lived 

on a south-facing slope at Cheesman Lake. The inside date on a cross-dated core 

from this tree was 1455, and that was an inch or so short of the pith, which was 

rotten. Most of the other trees on this slope were around 300 years old. They all 

burned in the Hayman fire in 2002.

Spiky dead 

top

Small live 

crown ratio; 

branches 

pruned up 

higher on 

uphill side

Roots 

exposed by 

centuries of 

erosion

Sparse; 

flattened 

crown

Smooth, 

orange 

bark

Fire scar
8 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Figure 6—Old trees growing on steep, rocky south- and west-facing slopes. These 

two old trees live on a rocky west-facing slope along the Crosier Mountain trail at 

7500 ft (2300 m) elevation. Both have smooth, gray-orange bark, gnarled branches, live crowns pruned up above the ground, and fire scars. The tree on the left 

also has a lightning scar, and its top is dead, probably killed by lightning.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 9

As ponderosa pines age, their bark becomes pale in color and appears smoother, 

with finer flakes. The exact color of the bark varies from location to location, perhaps because of genetics. The old trees we found in the northern Front Range were 

more gray, while those in the southern Front Range were more orange. Sun exposure may also bleach the bark color. Old tree bark lacks the deep fissures and black 

color of young tree bark (fig. 7a, b).

The longer a tree lives, the more likely it is to be damaged (fig. 8a, b, c, d). Dead 

tops, broken branches, lightning scars, fire scars, rot pockets, and burls are all signs 

of past injury. A ponderosa pine with an exposed fire scar face is probably at least 

150-200 years old, since spreading surface fires of the kind that cause such scars 

ceased in most of the Front Range around 1900. Mature ponderosa pines have thick 

bark that insulates the cambium from heat. Fire scars are caused when heat kills 

the cambium on a portion of the tree’s circumference. In subsequent years, the tree 

heals by growing wood around the wound. Fire scars create distinctive patterns in 

the tree’s annual rings, which allow dating fires to a precise year.

7b—Typical bark on an old tree near 

Cheesman Lake; it is mostly pale orange, 

smooth, with small flakes.

Figure 7a—Typical bark on a young tree 

near Cheesman Lake; it is dark in color, 

with deep fissures and big flakes.
10 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

8b—Dwarf mistletoe causes charac- teristic swellings on the branches and may create tangled “witches’ brooms” in the crown. This para- site deforms tree crowns and may cause a younger tree to take on old tree crown characteristics pre- maturely. Figure 8a—A lightning scar on an old tree near Cheesman Lake. Lightning scars can sometimes look like fire scars, but they are usually long and narrow, extending down from the crown but sometimes not to the ground, and often spi- raling around the trunk.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 11 8d—Porcupine damage on a ponderosa pine. The aspen behind it was dam- aged by elk. Porcupine scars can look like fire scars, but they are usually more irregular in shape, and usually do not extend to the ground. 8c—Fire scar on an old tree above Trumbull on the South Platte River.
12 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

The Transition From Young to Old 

(Canopy Trees 150 to 250 Years Old)

At around 200 years of age, the form of ponderosa pine trees begins to change 

(fig. 9). They are still vigorous, but their upward growth is slowing rapidly, so their 

tops start to flatten out as apical dominance weakens. Lower branches have begun to 

die and self-prune. The crown begins to open up as dense, small branches die near 

the trunk. The remaining branches become longer and larger in diameter, and the 

needles are distributed toward the outside of the crown. The general shape of the 

crown becomes round or oval rather than teardrop-shaped with a pointed top. The 

deep fissures in the bark begin to smooth out, and the bark color becomes lighter, 

more orange or gray than black. Middle-aged trees are old enough to have a fire scar 

or two, but it has been long enough in most locations since the last surface fire that 

such scars may have nearly healed and are not readily visible. A healed scar might 

appear as a deep fissure low on the trunk, rather than the easily recognized “catface.” Trees of this age are often the dominants in present Front Range stands. See 

table 1 for a summary of characteristics of ponderosa pines at different life stages.

Table 1—Identifying characteristics of ponderosa pine trees at different life stages.

 

Live crown Trunk

Crown shape ratio Branches shape Bark Likely injuries

Old trees flattened, “bonsai” small; often few but large columnar smooth, small fire scars, dead

(>200 years) shape, sparse and fire-pruned flakes, pale tops, broken 

open, may be orange or gray branches, 

lopsided lightning scars, 

 rot, burls, 

 exposed roots

Transitional ovoid, flattening moderate; fine branches beginning orange or gray relatively few; 

trees on the top, full perhaps half in the interior to lose flakes with dark possibly healed 

(150-250 and rounded the trunk, of the crown taper edges, shallow or mostly 

years) beginning to dying, longer fissures, healed fire 

self-prune branches becoming scars, lightning 

 thickening smoother scars, mistletoe

Young canopy pointed top, large many fine tapered large, coarse very few; 

trees “teardrop” or branches, flakes, deep possible 

(<150 years) “Christmas tree” dense foliage fissures, dark mistletoe or

shape, dense near the trunk gray or black lightning scars

foliage with dark

 orange 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 13

Figure 9—A middle-aged tree showing the transition in appearance to old tree 

characteristics. This tree, growing on a gentle south-facing slope above Lily Lake 

in Rocky Mountain National Park, is around 200 years old. It is beginning to take 

on old tree characteristics: its crown is still full but beginning to open up as fine 

branches die, and its top is ovoid and beginning to flatten. Its branches are beginning to self-prune. Its bark is becoming smooth and orange, losing its deep fissures.

Moderate 

live crown 

ratio; some 

pruning

Ovoid crown 

shape, 

rounded and 

flattening on 

top

Fine branches 

in the interior 

of the crown 

dying, longer 

branches 

thickening, but 

crown is still 

moderately full

Bark 

becoming 

smooth, lighter 

in color
14 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Appearance of Young Trees (Canopy Trees <150 Years Old)

Ponderosa pines less than 150-200 years old usually have pointed tops, because 

they are still growing taller (fig. 10). Strong apical dominance allows young trees 

to grow fast and to compete for light. Seedlings less than 3 or 4 years old must 

compete with grasses and forbs, and their survival is always in question. Once 

seedlings are about six inches tall, they are considered established, and are likely to 

survive. However, such small trees are more susceptible to factors in their immediate environment than to larger-scale climatic factors. When they are 3 to 6 ft. (1 to 

2 m.) tall, they begin to interact with the other trees around them, and are likely to 

reach the canopy. How long it takes a tree to reach this size varies tremendously. It 

may take only 20 years or so on a good site, but even tiny trees may be older than 

they look, especially on poor sites. We have sampled trees that were only three feet 

(1 m.) tall but were more than 90 years old.

The trunks of young trees are usually tapered toward the top. Branches grow 

relatively low on the trunk and have usually not begun to self-prune. The bark of 

young ponderosa pines is dark gray or dark orange and black, with deep fissures 

and thick, flaky layers. On some small trees the bark appears almost all black; these 

slender youngsters are called “blackjacks.” Most young trees do not have fire scars. 

They may have mistletoe, but if trees are infected while young, the mistletoe will be 

distributed throughout the crown and may distort the shape of the branches. Young 

trees on good sites may be very large, but they usually have a distinctive pointed 

top and a full crown that extends most of the length of the trunk. Crowns of healthy 

young trees have many dense, small-diameter branches, most of which bear live 

needles, so the crown looks full and thick with few dead branches. Dense forests are 

more likely to be composed of young trees.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 15

Figure 10—Typical characteristics of young ponderosa pines. This vigorous young 

tree grows along the Crown Point road. Its pith date is 1887. There are many other 

young trees in this stand.

Pointed, 

live top

Lots of 

small, living 

branches; 

full, 

vigorous 

crown

Fissured 

brown bark, 

beginning 

to turn 

orange

Long live 

crown 

relative to 

total tree 

height; 

this tree is 

beginning 

to selfprune
16 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Tree Size

Not all old trees are large, and not all large trees are old. However, if a tree is 

by far the largest or tallest tree in the stand, it is probably older than its neighbors 

(fig. 11). Ponderosa pines in the Colorado Front Range are usually limited by the 

availability of water. Trees grow larger and more quickly on sites where water is 

readily available. Such sites include those along streams, even intermittent streams 

where water may not flow on the surface year around; flat, grassy areas where water 

soaks into the soil; and at the base of rock outcroppings, where water collects off the 

rocks. A 150-year-old tree on a good site may be 30 in. (80 cm.) in diameter.

Where water is less readily available, trees grow more slowly and have a smaller 

maximum size. Steep slopes, slopes that face south and west and are exposed to 

sun and wind, ridgetops, rocks, and places where the soil is very shallow or welldrained do not hold water. Trees on these sites must depend on brief pulses of water 

from rain or snow events. Small, old trees are likely on such sites. A 400-year-old 

tree might be as little as 12 in. (30 cm.) in diameter. On such sites, trees are usually 

less subject to competition and to the spread of parasites and diseases. The lack of 

water means that understory spe-cies like grasses and shrubs are sparse, providing 

little fuel for fires. Fires burning there are not likely to be intense, so old tree survival is enhanced.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 17

Figure 11—A case in which size does indicate an older tree: this old tree towers 

above more recent in-growth at the base of a slope along the Pingree Park Road. 

Its pith date is 1672 and it has a fire scar in 1846. The old tree has the sparse, 

pruned crown and smooth orange bark typical of old trees. Its smaller neighbors 

have full, pointed crowns and dark, fissured bark.
18 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Open-Grown Versus Forest-Grown

Trees that have grown in the open tend to have a different appearance from those 

that have grown in a forest. Open-grown trees tend to have fuller, more rounded 

crowns and a few long, large-diameter branches (fig. 12a). Trees that have grown in 

a more closed environment will be relatively slimmer, with shorter, thinner branches (fig. 12b). Old trees can be found in closed forest environments, but the oldest 

trees are usually open-grown, possibly because they lack competition, or because 

they are less likely to be destroyed in a fire.

 Ponderosa pines require 

full sunlight to grow well, 

and when stands are dense 

and trees shade one another, 

the shaded trees grow slowly, often develop poor form, 

and may ultimately die. 

However, such suppressed 

trees may be relatively old 

despite their small size (fig. 

12c). They can persist for 

hundreds of years under the 

shade of other trees. If the 

other trees are eliminated (by 

fire or logging, for example), 

suppressed trees may be 

released and start growing 

faster. Douglas-fir does not 

suffer as much from shading 

as ponderosa pine. Young 

Douglas-fir trees actually 

benefit from shaded conditions where the soil surface 

is not as hot as in the open.

Figure 12a—Open-grown tree. This tree lives in a 

sage meadow near a south-facing ridgetop along 

the Redfeather-Rustic road at 8453 ft (2601 m) 

elevation. Note the full, rounded crown and long 

heavy branches. Its top is beginning to flatten out, 

but the lack of surface fire during the 20th century 

has allowed it to keep its lower branches. Its pith 

date is 1811; its DBH is 21 inches (53.3 cm). The 

core revealed a healed fire scar near the pith and 

relatively rapid growth.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 19

12c—Suppressed tree. This tree lives on 

a small, rocky ridge in a relatively dense 

forest along Highway 7 near Olive Park 

at 8349 ft (2569 m). It is rotten at the 

center, but the inside date on the core 

was 1671, and narrow rings indicated 

very slow growth. Its DBH is only 

10.2 inches (25.9 cm). Note its small 

size, twisted branches, sparse crown 

and flattened, deformed top.

12b—Forest-grown tree. This tree grows 

in a relatively dense ponderosa pine 

forest on an east-facing slope along 

Highway 7 at 8670 ft (2668 m) elevation. It is a dominant forest-grown tree. 

Note its straight trunk and narrow crown 

with short lower branches. Its bark is 

beginning to look smooth and pale. Its 

pith date is 1762; its DBH is 22.2 inches 

(56.4 cm).
20 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Common Locations of Old Trees

Despite the disruptions to the montane ecosystem in the last 150 years, trees 

older than 200 years are widespread in the Front Range. Trees in inaccessible locations and on poor sites often were not cut when logging was easier elsewhere. Rock 

outcroppings, steep slopes, ridgetops (fig. 13), and higher elevations (fig. 14) that 

were historically less accessible by road, less populated, and less susceptible to fire 

provided havens for old trees. Rock outcrops in meadows and the edges of meadows also protect old trees from fires.

We found relatively few old ponderosa pines below about 6500 ft (2000 m) elevation. It is unclear whether this is because trees at lower elevations were more accessible from settlements and were cut, or because there were just fewer trees there 

naturally. Warm south-facing slopes as high as 10,000 ft (2770 m) elevation support 

old ponderosa pines, and older ponderosas are common in the mixed conifer zone, 

where they occur with lodgepole pine, limber pine, Douglas-fir, and aspen.

Old trees are often found on south- and west-facing slopes (fig. 15), on and 

around rock outcrops, at the edges of high meadows (fig. 16), and on the upper third 

of slopes. Even in areas that were logged and now support young forest, individuals with twisted or scarred trunks, rot, large limbs, and dead tops were passed over 

by loggers. Old trees often occur in small groups, but it is unusual to find a stand 

in which all the trees are old. Old-growth stands are usually multi-aged. Of course, 

none of these suggestions is a rule. We found old ponderosa pines alone, on northfacing slopes, near rivers, in fairly dense stands, and right beside houses and campgrounds. When viewed across a vista, groups of old trees are apparent as taller, roughlooking, browner areas amid the smoother, greener, more uniform-looking young 

forest.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 21

Figure 13—This old tree inhabits a dry, rocky ridge along Highway 7. It is small, deformed, and rotten at the center, but it is more than 350 years old. It has a healed 

fire scar and a lightning scar, smooth gray bark, a flattened top, and a sparse open 

crown. Many of its neighbors are of similar age and are stunted by the harshness 

of the site.
22 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Figure 14—Though ponderosa pine forests are most common at lower elevations, older ponderosas can be found on sunny, south-facing slopes 

above their usual range. They may be relicts from a past climate or fire regime. This lone, old ponderosa pine lives on a south-facing slope at 10,000 ft 

(3077 m) elevation along the Old Flowers Road trail. Note the clone of young 

aspen around the old pine.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 23

Figure 15—Old trees on open, grassy south and west-facing slopes. This old 

tree lived on a barren, grassy-shrubby, south-facing slope at Cheesman Lake at 

7066 ft (2174 m) elevation; its center was rotten, but its inside date was 1720, and 

its estimated pith date was 1550. It was typically open-grown, with a flattened top, 

large, gnarled branches, and pale orange smooth bark. It had a visible fire scar 

face with several scars.
24 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Figure 16—A classic old tree along the Redfeather-Rustic road at 8320 ft 

(2560 m) elevation; its pith date is 1569, its DBH is 24.4 inches (62.1 cm). It lives 

on the west edge of a ridge-rock outcrop in the midst of a meadow, and has the 

typical flattened top, smooth orange-gray bark, and a fire scar.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 25

Gallery of Old Tree Photos

How We Found Trees for This Publication

We searched for old trees along a north-south transect of the Front Range to 

capture changes in soils and weather conditions that vary along this latitudinal gradient. We took four excursions: one along the dirt road from Rustic in the Poudre 

Canyon to Redfeather Lakes; one along the Pingree Park and Crown Point roads 

above the Poudre Canyon; one along the Glen Haven road from Drake to Estes 

Park (where many old trees occur on private land), and then south along Highway 

7 from Estes Park to Allenspark; and one in the Cheesman Lake property in the 

South Platte basin, which is owned by Denver Water. Based on other research on 

the Cheesman Lake property, we knew old trees were common there because that 

area was never logged. Except for Cheesman Lake, we did all our sampling on 

U.S. Forest Service land. We deliberately avoided canyons that were and are travel 

corridors, and where fire probably behaved differently. Our sampling locations are 

marked by yellow stars in figure 1.

We selected trees from which we could get a good picture and age. We photographed them and cored them with an increment borer to determine their ages. 

Coring does not usually damage the tree. We selected trees in a variety of growing 

conditions, from harsh to moderate to good sites. We have included a few portraits 

of young and middle-aged trees under different site conditions for comparison. 

With each tree portrait, we report the tree’s diameter at breast height (DBH; standardized to 1.4 meters above the ground) as a general measure of a tree’s size. We 

also report the tree’s age, which we derived by cross-dating cores taken low on the 

trunk. When trees were rotten, we estimated their ages by estimating the number of 

rings that would fill out the remaining length of the tree radius and using a negative 

exponential curve to take into account age-related growth trends. Most of the trees 

pictured are between 400 and 500 years old. The trees pictured from Cheesman 

Lake all burned in the Hayman fire in June 2002.
26 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Figure 17—Old ponderosa pines on poor sites

17a—DBH=18.4 inches (46.7 cm), pith date 1545. This was a typically scraggly-looking old tree on a poor, rocky site. Its flattened, very sparse crown, small 

live crown ratio, and smooth orange bark were exaggerated by the harshness 

of the site. At 7319 ft. (2252 m.) elevation, this mostly east-facing ridge on the 

Cheesman Lake property is relatively low and dry, but young Douglas-firs were 

moving into the understory.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 27

17b—DBH=20.8 inches. (52.9 cm), pith date 1574. This tree lived in a common 

location for old pines: an open, south-facing slope just below a ridgetop at 7000 ft 

(2154 m) elevation on the Cheesman Lake property. It had a scar face with several 

fire scars, small live crown ratio, a sparse, slightly flattened, open-grown crown, 

and smooth orange bark.
28 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

17c—DBH=18.8 inches (47.7 cm), pith date 1605. This small old tree grows on a poor, 

rocky site at 8778 ft (2701 m) elevation. It has been encroached by aspen and lodgepole pine. It has a somewhat flattened top, a very sparse crown and tiny live crown 

ratio, smooth orange-gray bark, and four fire scars. It lives along Highway 7 at Meeker 

Park.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 29

17d—DBH=21.4 inches (54.3 cm) inside date 1663, est. pith date 1521. This tree 

lives near seven other old trees on a steep, rocky, west-facing slope at 7592 ft 

(2336 m) elevation along the Mt. McConnell trail. Evidence of local disturbance 

includes many fallen trees. It and its neighbors are infested with dwarf mistletoe. 

Nearby trees have fire scars from 1851, 1707, and 1700. This tree has typical 

smooth orange-gray bark, a flattened top, twisted and pruned branches, and a 

big burl (caused by an injury) beside a fire scar. It is rotten in the center.
30 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

17e—DBH=15.2 inches (38.5 cm), pith date 1560. This group of old trees lives on 

a rock outcrop in the middle of a meadow along the Redfeather-Rustic road at 

8307 ft. (2556 m.) elevation. We cored the tree on the left. The flattened tops, 

deformed crowns, small live crown ratios and smooth orange-gray bark identify 

them as both old and stressed.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 31

17f—DBH=12.5 inches (31.7 cm), pith date 1889. This younger tree lives on 

a south-facing slope near ridgetop at 8453 ft (2601 m) elevation along the 

Redfeather-Rustic road. Its pointed crown, long live crown ratio, and darker bark 

indicate that it is younger than some of its neighbors, though its small size attests 

to the harshness of the site.
32 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Figure 18—Old trees on moderate sites

18a—DBH=19 inches (48.4 cm), pith date 1589. This tree lives on the edge of a 

north-facing ridge at 8307 ft (2557 m) elevation along Highway 7 at Olive Park. It 

is open-grown but not very tall. It has a flattened top, smooth orange bark, large 

branches, and fire scars on the north side.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 33

18b—DBH=20.6 inches (52.3 cm), inside date 1744, est. pith date 1626. This tree 

lived on an open east-facing slope just below a ridge on the Cheesman Lake 

property at 7319 ft (2252 m) elevation. The entire stand was old; there were many 

fallen trees, perhaps killed by a past fire. The tree was rotten in center, possibly 

because of its dead top. It had very smooth, pale bark and a sparse, open-grown 

crown.
34 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

18c—DBH=25.3 inches (64.2 cm), pith date 1595. This open-grown tree grows 

in an east-facing meadow at 8710 ft (2680 m) elevation along Highway 7. It has 

classic old-tree characteristics: the flattened, “bonsai” open crown, and smooth 

orange bark. Though it lacks visible fire scars on the trunk, its lower branches are 

charred from past surface fires.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 35

18d—DBH= 23.4 inches (59.5 cm), pith date 1769. This middle-aged tree lives on a 

flat, rocky ridgetop along the Pingree Park Road at 7293 ft (2244 m) elevation, in 

a location that sees heavy recreation use and has much ingrowth of juniper. It has 

a full, open-grown crown that is beginning to flatten at the top, fire scars, wounds 

from bear scratches, and bark beginning to shift from dark gray to orange.
36 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

18e—DBH=24.4 inches (62 cm), pith date 1527. This tree lives on a gentle, 

open, south-facing slope near the hilltop along the Redfeather-Rustic road at 

8453 ft (2601 m) elevation. It has a typical flattened top and smooth orange bark. 

Because it is on a moderate site, it has a fuller crown than trees of similar age on 

poor sites. A core revealed a rot pocket from a healed fire scar—perhaps from the 

same fire that killed the short snag beside it?

Please note: The printed version of this publication duplicated

 Figure 18d in Figure 18e. The correct image is below

 but only the smaller version was available when

 this PDF was corrected.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 37

18f—DBH=15.7 inches (40 cm), pith date 1887. This tree grows on a gentle eastfacing slope at the edge of a meadow along the Crown Point road at 8425 ft 

(2500 m) elevation. It has the typical pointed top of a rapidly growing tree, no visible scars, and a long, full crown. Its bark is fissured, beginning to turn orange, and 

lower branches are starting to self-prune.
38 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

Figure 19—Old trees on good sites

19a—DBH=27 inches (68.5 cm), inside date 1718; est. pith date 1581. This 

large tree lives on a grassy, shrubby, gentle north-facing slope at 6409 ft 

(1972 m) elevation above a river valley along the Glen Haven road. Its center is 

rotten. It is open-grown, with large heavy branches, a dead top, smooth orange 

bark, a sparse crown, and a large burl near the base.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 39

19b—DBH=40.8 inches (103.8 cm), inside date 1729; est. pith date 1486. This 

ancient tree grows on a flat bench above a southeast-facing slope, just below 

the ridge at 8453 ft (2601 m) elevation, along the Redfeather-Rustic road. It is 

the oldest and largest tree in the vicinity. It has a dead top, smooth red-orange 

bark, small live crown ratio, and large, heavy branches. No fire scars showed on 

the trunk, but it had an axe scar from long ago. It has been marked by the Forest 

Service for preservation as a wildlife habitat tree. It was rotten in the center. This 

was the second-largest and second-oldest tree we found.
40 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

19c—DBH=31 inches (79.1 cm), inside date=1586; est. pith date 1539. This tree 

lives in a flat sage meadow at the abandoned townsite of Manhattan, 300 ft 

(100 m) above a stream at 8460 ft (2603 m) elevation along the Redfeather-Rustic 

road. The center is rotten. It is typically open-grown, and has smooth orange bark, 

but because it is on a good site, its old tree crown characters are subtle; the crown 

is more rounded and full than a tree of similar age on a poor site.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 41

19d—DBH=42.5 inches (108 cm) inside date=1710, est. pith date 1614. This tree 

also lives in a flat sage meadow at the abandoned townsite of Manhattan, 300 ft 

(100 m) above a stream at 8460 ft (2603 m) elevation along the Redfeather-Rustic 

road. The tree was so large our borer could not reach the center, so we estimated 

its pith date. It is the largest tree we sampled. It is typically open-grown, and has 

smooth orange bark, but because it is on a good site, its old tree crown characters 

are subtle.
42 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003 

19e—DBH=25.4 inches (64.6 cm), inside date 1600, est. pith date 1462. This old 

tree, surrounded by a cluster of younger ones, lives at 8125 ft (2500 m) elevation 

along the Crown Point Road at the base of a gentle, east-facing slope near the 

edge of a meadow. It was rotten in the center. It has a deformed, dying top, lopsided crown with lower branches scorched on the underside, and a scar on the uphill 

side. If the estimate of age is correct, this is the oldest tree that we sampled.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-109. 2003. 43

19f—DBH=31.9 inches (81.2 cm), pith date 1879. This large, open-grown young 

tree was being encroached by younger ingrowth of ponderosa pine and Douglasfir. Its growth rate was tremendous. It lived on the Cheesman Lake property on a 

gentle west-facing slope not far from a perennial stream at 7157 ft (2202 m) elevation. It had dark, fissured bark, a long live crown, pointed top, and no scars. It was 

one of the largest trees we sampled.
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