© U.S. Bureau of Land Management (Colorado Plateau Native Plant Program)

Factors Affecting the Plateau

What role did wildfire play on the Colorado Plateau?  How did fire shape the communities in the past and in the present?  These questions are important when considering the ability to restore ecosystems to resilient and functioning conditions.  Because of the variety of ecosystems and elevations at which they occur, there is not one answer to these questions.  Dry desert shrublands evolved differently than the ponderosa pine communities at mid elevations or the aspen communities and mixed conifer communities at the higher elevations.  Historically, the frequency and intensity of fires varied naturally because of fuels that accumulated and weather patterns that occurred.  Now, with the increase in non-native and invasive species, especially at lower elevations, significant changes have occurred in both fire frequency and severity, which has resulted in the inability of native ecosystems to re-establish.  Below is a list of some of the dominant communities that occur on the Colorado Plateau and their historically natural fire regimes.

Historically, ponderosa pine woodlands and some of the drier mixed conifer communities were characterized by frequent low and mixed severity fires (Fire Regime I).  These same mixed conifer communities can also have less frequent fires with the same low and mixed severity (Fire Regime III).  At the other extreme, some pinyon-juniper woodlands that occur scattered on rocky sites with little understory fuels have very infrequent, stand-replacing fires (Fire Regime V).  Mid-elevation sagebrush (mountain big sagebrush), low sagebrush, most salt desert and desert shrublands, and desert grasslands have frequent high-severity fires (Fire Regime II).  These communities typically have abundant fine fuels and are often some of the first to be replaced by invasive species, which results in an even high fire frequency.  Low-elevation sagebrush (Wyoming big sagebrush), Mat Saltbush Shrublands, and Blackbrush-Mormon tea communities with little herbaceous understory have mixed-severity fires with moderate to low frequency (Fire Regime III).  Aspen Forest and Woodlands and Gambel Oak-Mixed Montane Shrublands have similar fire regimes, but can include both low to mixed severity and stand replacement fire (Fire Regimes III and IV).

 

Fire Regime

Land Cover Type

FRCC Biophysical Setting[1]

I

Southern Rocky Mountain Ponderosa Pine Woodland

PPIN5

I & II

Intermountain Basins Montane Sagebrush Steppe

CSAG1

I & IV

Colorado Plateau Pinyon-Juniper Woodland

Intermountain Basins Juniper Savanna

JUPI1

II

Intermountain Basins Big Sagebrush Shrubland

BSAG1

II

Intermountain Basins Semi-Desert Grassland

DGRA1

II

Intermountain Basins Greasewood Flat

Intermountain Basins Mixed Salt Desert Scrub

Intermountain Basins Semi-Desert Shrub-Steppe

Southern Colorado Plateau Sand Shrubland

Colorado Plateau Blackbrush-Mormon-tea Shrubland (grasses well represented)

DSHB1

II

Colorado Plateau Mixed Low Sagebrush Shrubland

SAGE1

III

Colorado Plateau Blackbrush-Mormon-tea Shrubland (grasses not well represented)

DSHB2

III

Intermountain Basins Mat Saltbush Shrubland

DSHB4

III

Rocky Mountain Aspen Forest and Woodland

Rocky Mountain Gambel Oak-Mixed Montane Shrubland

DWOA

III & I

Rocky Mountain Dry-Mesic Montane Mixed Conifer Forest

SPDF

III & IV

Intermountain Basins Aspen-Mixed Conifer Forest and Woodland

SPIF7

V

Colorado Plateau Pinyon-Juniper Shrubland

JUPI2

[1] Source: Fire Regime Condition Class Guidebook

 

Fire Regime

Frequency

(years)

Severity

Severity Description

I

0-35

Low/Mixed

Generally low-severity fires replacing less than 25% of the dominant overstory vegetation; can include mixed-severity fires that replace up to 75% of the overstory

II

0-35

Replacement

High-severity fires replacing greater than 75% of the dominant overstory vegetation

III

35-200

Mixed/Low

Generally mixed-severity; can also include low severity fires

IV

35-200

Replacement

High-severity fires

V

>200

Replacement any severity

Generally replacement severity; can include any

severity type in this frequency range

 

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