Appendix 6 

APPENDIX 6—CHARACTERISTICS OF OLD-GROWTH 

FORESTS—BLM PINEDALE FIELD OFFICE 

There are multiple (and varying) definitions of old growth forests because of differing fire influences and 

environmental conditions in the Intermountain West. Most of the current definitions are based on stand 

level structure, composition, and function. The two primary types of forests reflect the role of fire within 

them–those forests shaped by natural change and plant succession and forests where succession processes 

are greatly influenced by major biological disturbances such as fire, insects, wind or drought. Kaufmann 

et al. (2007) use the following table to determine old growth: 

Table A6-1. Essential Structural Features of Old Growth in Fire-Adapted Forests 

(Note: Whether a feature is essential may depend on scale, e.g., patch, stand, or landscape. For example, age 

variability is likely at a landscape scale, and snags and large dead and downed fuels may not exist in some patches.) 

Structural Feature Essential Structural 

Feature? Comment 

Large trees No 

Tree size depends on individual site characteristics (species, 

precipitation, soils, etc.) and competition. Young trees may be 

large, and old trees may be small. 

Old trees Yes 

Trees develop structural characteristics that are relatively unique 

when old. Examples are dead tree tops, flattened crowns, different 

branch characteristics, diversity in crown form, and altered bark 

color and texture. 

Age variability No 

This is an additional feature in some old-growth forest types. Some 

forests regenerate episodically (even aged) with most trees 

establishing in a few years to a decade, probably in conjunction 

with wet years and large seed crops, and in concurrence with 

relatively long intervals between fires. Others may regenerate over 

decades (uneven aged). 

Snags and large dead 

and downed fuels Yes 

Snags and large downed wood are essential elements of old 

forests although frequent historical fires may have limited the 

accumulation of dead wood. The density and sizes of these 

features vary depending on forest type, precipitation, and other 

factors. Snags and large dead and downed fuels may be unevenly 

distributed across the landscape. 

Between-patch 

structural variability 

Yes 

High variability is a critical feature of these forests. Within-patch 

variability may be low, but variation among patches is large. 

Proportions of patches with different developmental stages varies 

depending on forest type, climate, etc. 

This table along with the Biophysical Settings (BpS) of the Landfire system, which show the approximate 

age class distribution on a landscape scale, will be the primary tools used to determine old growth within 

the Pinedale planning area. By combining these two tools, the forest land of the planning area can be 

analyzed to ensure that the appropriate seral stages, from early seral post disturbance to late seral old 

growth, can be maintained on the landscape. 

The following are the standardized Society of American Foresters definitions and descriptions. These 

descriptions are based on Clementsian theories of succession and do not include disturbance as a change 

element in the forest. They are included here as a reference material and can be used on a stand-by-stand 

basis if it is determined to be applicable. 

Record of Decision and Approved Pinedale Resource Management Plan A6-1 
Appendix 6 

Old growth forests are ecosystems distinguished by old trees and related structural features. Old growth 

encompasses the later stages of stand development that typically differs from earlier stages in several 

ways, including tree size; accumulation of large, dead woody material; number of canopy layers; species 

composition; and ecosystem function. 

Old growth is typically distinguished by the following: 

• Large trees of specific species 

• Wide variation in age classes and stocking levels 

• Accumulations of large, dead, standing and fallen trees 

• Decadence in the form of broken or deformed tops and boles 

• Multiple canopy layers 

• Canopy interspaces and understory patchiness. 

ENGELMANN SPRUCE—SUBALPINE FIR; SOCIETY OF AMERICAN 

FORESTERS (SAF) COVER TYPE 206 

Live Trees (Cold/Dry Environment) 

DBH: > or equal 15” 

Trees/Acre: > or equal 15 

Age: > or equal 150 to 180 

Variation in Tree Diameter: Yes 

Tree Decadence: > or equal 2; DBH 14; Evident dead, broken, or deformed tops and/or bole or root rot 

Multiple Tree Canopy Layers: Yes 

Dead Trees (Cold/Dry Environment) 

Standing DBH/ht ft: > or equal 10/15 

Standing Trees/Acre: 2 to 4 

Down Diameter (in): > or equal 8 or > 6 

Down Pieces/Acre—length in ft: > or equal 16 – 8 ft or 100 pieces > 8 feet 

DOUGLAS-FIR; SAF COVER TYPE 210 

Live Trees (Higher Productivity Site) 

DBH: 24” 

Trees/Acre: > or equal 15 

Age: > or equal 200 

Variation in Tree Diameter: Yes 

Tree Decadence: Evident dead, broken, or deformed tops and/or bole or root rot 

Multiple Tree Canopy Layers: Yes 

Dead Trees (Higher Productivity Site) 

Standing DBH/ht ft: > or equal 20/20 

Standing Trees/Acre: > or equal 1 

Down Diameter (in): > or equal 12 

A6-2 Record of Decision and Approved Pinedale Resource Management Plan 
Appendix 6 

Down Pieces/Acre—length in ft: > or equal 0 - 16 

Live Trees (Lower Productivity Site) 

DBH: 18” 

Trees/Acre: 10 

Age: > or equal 200 

Variation in Tree Diameter: Yes 

Tree Decadence: > or equal 2; DBH 15; Evident dead, broken, or deformed tops and/or bole or root rot 

Multiple Tree Canopy Layers: Yes 

Dead Trees (Lower Productivity Site) 

Standing DBH/ht ft: 16/10 

Standing Trees/Acre: 0 to 3 

Down Diameter (in): > or equal 15 

Down Pieces/Acre—length in ft: Infrequent 4 - > or equal 8 

LODGEPOLE PINE; SAF COVER TYPE 218 

Live Trees 

DBH: > or equal 11” 

Trees/Acre: > or equal 25 

Age: > or equal 140 

Variation in Tree Diameter: Yes 

Tree Decadence (trees per acre [TPA]-DBH): > or equal 2–11; evident dead, broken, or deformed tops 

and/or bole or root rot 

Multiple Tree Canopy Layers: Yes 

Dead Trees 

Standing DBH/ht ft: > or equal 11 

Standing Trees/Acre: 5 

Down Diameter (in): > or equal 11 

Down Pieces/Acre—length in ft: > or equal 50 - > or equal 8 

LIMBER PINE; SAF COVER TYPE 219 

Live Trees (Lower Timberline) 

DBH: > or equal 16 

Trees/Acre: > or equal 10 

Age: > or equal 250 

Variation in Tree Diameter: Yes 

Tree Decadence: Evident dead, broken, or deformed tops and/or bole or root rot 

Multiple Tree Canopy Layers: Yes 

Record of Decision and Approved Pinedale Resource Management Plan A6-3 
Appendix 6 

Dead Trees (Lower Timberline) 

Standing DBH/ht ft: N/A 

Standing Trees/Acre: Few 

Down Diameter (in): N/A 

Down Pieces/Acre—length in ft: Rare 

Live Trees (Montaine Woodlands) 

DBH: > or equal 1 

Trees/Acre: 10 

Age: > or equal 500 

Variation in Tree Diameter: Yes 

Tree Decadence: Evident dead, broken, or deformed tops and/or bole or root rot 

Multiple Tree Canopy Layers: No 

Dead Trees (Lower Productivity Site) 

Standing DBH/ht ft: N/A 

Standing Trees/Acre: Few 

Down Diameter (in): N/A 

Down Pieces/Acre—length in ft: Rare 

ASPEN; SAF COVER TYPE 217 

Live Trees 

DBH: > or equal 12” 

Trees/Acre: > or equal 10 dry—20 mesic 

Age: 100 

Variation in Tree Diameter: Yes 

Tree Decadence (TPA-DBH): N/A 

Multiple Tree Canopy Layers: Yes 

Dead Trees 

Standing DBH/ht ft: > or equal 10/15 

Standing Trees/Acre: 2 

Down Diameter (in): > or equal 8 

Down Pieces/Acre—length in ft: > or equal 10–10 

ROCKY MOUNTAIN JUNIPER; SAF COVER TYPE 220 

Note: Extrapolated old growth characteristics from Pinyon-Juniper old growth characteristics. 

Live Trees 

DBH: 12” 

Trees/Acre: 12 

Age: 200 

A6-4 Record of Decision and Approved Pinedale Resource Management Plan 
Appendix 6 

Variation in Tree Diameter: Yes 

Tree Decadence (TPA-DBH): N/A 

Multiple Tree Canopy Layers: N/A 

Dead Trees 

Standing DBH/ht ft: 12/5 

Standing Trees/Acre: > or equal .05 

Down Diameter (in): > or equal 10 

Down Pieces/Acre—Length in ft: > or equal 2–5 

Record of Decision and Approved Pinedale Resource Management Plan A6-5