Table 2. Minimum stand structural requirements for old-growth ponderosa pine

Parameter Minimum Value
Live tree density 20–25 trees per ha (tph)
Diameter at breast height (dbh) 38–50 cm (dry sites); >50 cm (moister sites)
Age at breast height 125–150 years
Number of canopy layers 1 story, 2 stories, or multi-storied
Tree decadence Not required, but expected if some very old trees are present
Snag density 5 per ha >25 cm diameter (desired)
Downed logs Not required, but numbers increase in the absence of fire