Wildfire History on the Colorado 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.

Colorado Plateau Native Plant Program

Colorado Plateau Juniper burned area

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] Fire Regime Condition Class (FRCC) Biophysical Settings (BpS) Resources


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