MAPPING UNIT ATTRIBUTE CODE: 42001

MAPPING UNIT NAME: Spruce - fir type.

DOMINANT SPECIES: Engelmann Spruce (Picea engelmannii) and Subalpine
fir (Abies lasiocarpa).

DESCRIPTION: Spruce fir forest not significantly affected by logging.
Engelmann spruce and/or subalpine fir must be dominant or co-dominant in
the canopy. This type will also include spruce fir krummholz communities.
Total canopy coverage by all tree species must be greater than 25%.

DISTRIBUTION: Abies lasiocarpa and Picea engelmannii are found in the
subalpine zone throughout the state of Colorado. The subspecies A.l.
arizonica begins to replace the subspecies A.l. lasiocarpa in the southern
part of the state. Abies is absent from the relatively dry subalpine zone of
Pike's Peak.

ELEVATION RANGE: 2590-3659m (8500 - 12000')

DIAGNOSTIC SPECIES: Picea engelmannii, Abies lasiocarpa

NOTES: Spruce fir forest characterizes the subalpine portion of the Rocky
Mountains. This type is usually the highest forested zone on the mountain,
the next lower zones being lodgepole pine and/or Douglas fir types. The
spruce fir zone extends to lower elevations in wet valley bottoms, cool
ravines and sheltered northern slopes (Peet, 1988). Picea usually dominates
the upper slopes of the subalpine zone and especially in the southern part of
Colorado and appears to be more tolerant of extreme conditions. In Front
Range forests, Picea is dominant on very wet or boggy sites, and Abies is
more numerically dominant on more mesic sites (Peet, 1988).

Abies is absent from timberline forests in northern New Mexico, shares
dominance with Picea in the lower portion of the subalpine zone in the
Sangre de Cristos and is co-dominant with Picea at timberline in Rocky
Mountain National Park (Allen and Peet, 1989).

Krummholz forms are infrequent in northern New Mexico, but become more
common as latitude increases. Treeline decreases from 3800m in northern
New Mexico to 3400m in the Medicine Bow (Allen and Peet, 1989).

There are several habitat and community types for the Picea engelmannii
series recognized by the Forest Service (Alexander, 1987). It is associated
with Salix pseudolapponum, Heracleum sphondyllum (a riparian type) and
Trifolium dasyphyllum. On drier sites associates are Vaccinium myrtillus,
Polemonium pulcherrimum, and Saxifraga bronchialis. Common tree associates
are A. lasiocarpa, P. contorta, P. flexilis, P. tremuloides, and P. aristata.

Habitat and community types identified for the Abies lasiocarpa series
include, on warmer sites, Pachystima myrsinites, Pedicularis racemosa and
Rubus parviflorus. On cooler sites, associates include Juniperus communis,
Vaccinium scoparium, Carex geyeri, Arnica cordifolia, Polemonium
pulcherrimum, Saxifraga bronchialis (associated with scree environments),
various mosses, Vaccinium myrtillus, Erigeron eximus, Salix glauca,
Calamagrostis canadensis, Mertensia ciliata, and Senecio triangularis.
Common tree associates are P. engelmannii, P. menziesii, P. tremuloides, P.
contorta, P. aristata, and A. concolor.