The Morrison area as a floral biome is characterized by its
transitional nature, from the plains to the east and the mountains
to the west. Harrington (1954) has designated the environment as the
Mountain Shrub Subdivision of the Mountain and Plateau Area.
Especially characteristic of the zone are the following plants:
_Quercus Gambelli_—scrub oak
_Prunus Virginianus melanocarpa_—wild plum
_Crataegus_ spp. (Probably succulenta)—hawthorn
_Amelanchier_ spp.—service berry
_Crysothamus Lanceolata_—rabbit brush
_Rhus trilobata_—poison ivy
_Rosa Woodsi_—wood rose
From the Ponderosa Pine-Douglas Fir Subdivision the following
characteristic plants overlap:
_Pseudotsuga taxifolia_—douglas fir
_Pinus Ponderosa_—Ponderosa pine
_Mahonia Berberis aquifoliam_—Oregon grape
_Arctosaphylos uva-ursi_—kinnikinick
_Rubus occidentalis_—blackberry
_Rubus stigosus_—raspberry
_Populus tremuloides_—quaking aspen
These distinctive plants have invaded from the prairie fringe:
_Stipa cometa_—needle grass
_Agropyron smithii_—wheat grain
_Boutelorea grasilis_—grama grass
_Boutelorea curtipendula_—grama grass
_Poa fendleriana_—bluegrass
_Sphaeralcea ceccinea_—globe mallow
_Helianthus petiolaris_—sunflower
_Chrysopsis rillosa_—golden aster
_Muhlenbergia montana_—muhly
_Yucca glauca_—yucca
understory of sedges and broad-leaf herbs
The nature of the faunal belt characteristic of the Transition Zone
is varied. Both boreal and austral mammals are represented. Only six
species appear restricted to it, two squirrels of the _Sciurus aberti_
group, three pocket gophers of genus _Thomomys_ and a small brown bat.
The following mammals are not restricted to the Transition Zone but are
characteristic of it in the eastern foothills:
_Eutamias quadrivitratus_—Say chipmunk
_Peromyscus nastus_—Estes Park cliffmouse
_Neotoma fallax_—Gale wood rat
_Lepus campestris_—White-tailed jack rabbit
_Sylvilagus nuttalli pinetis_—Rocky Mountain cottontail
_Canis lestis_—Mountain coyote
_Lynx uinta_—Mountain wildcat
_Mephitis hudsonica_—Northern plains skunk
Mammals common to the Transition and Upper Sonoran Zones include:
_Antilocapra americana_—Antelope
_Odocoileus virginianus_—Macrourus white-tailed deer
_Onychomys brevicaudus_—Grasshopper mouse
_Castor canadensis frondator_—broad-tailed beaver
_Canis Occidentalis_—Grey wolf
_Spilogale tenuis_—Rocky Mountain spotted skunk
_Eptesicus fuscus_—Brown bat
The following are common to the Transition and Canadian (mountain)
Zones:
_Cervus canadensis_—Elk
_Callospermophilus lateralis_—Say ground squirrel
_Eutamias amvenus operarius_—Colorado chipmunk
_Erethiron epixanthum_—Yellow haired porcupine
_Eutamias mihumus consobrinus_—Least chipmunk
_Microtus nanas_—dwarf field mouse
_Microtus pennsylvanicus_—Saguache meadow mouse
_Zapus princeps_—Rocky Mountain jumping mouse
_Vulpus macrourus_—Western fox
_Ursus americanus_—Black bear
Common to the Transition, Canadian and Upper Sonoran Zones are:
_Odocoileus hemionus_—Mule deer
_Cynomys gunnisoni_—Gunnison prairie dog
_Cynomys leucurus_—White-tailed prairie dog
_Felis oregonensis hippolestes_—Mountain lion
_Lutreola vison energunenos_—Mink
_Putorius arizonensis_—Mountain weasel
_Taxidea taxus_—badger
The above lists were drawn mainly from Meritt Cary’s _Biological Survey
of Colorado_ (1911). Though this is the most complete work available,
it is somewhat out of date and contains certain species names that have
been superseded. An effort was made to check this with more modern
works, such as Warren’s _Mammals of Colorado_ (1942), but this was not
always possible.