Characteristics of dry site old-growth ponderosa pine in the bull mountains of Montana, USA

Todd A. Morgan, Carl E. Fiedler, Chris Woodall

Research output: Contribution to journalArticlepeer-review

Abstract

Increasing public interest in old-growth forests has spurred new research and legislation aimed at managing this resource. The old-growth ponderosa pine (Pinus ponderosa var. scopulorum Engelm.) forests of central and eastern Montana, USA, are one such resource that requires management information in the face of threats from catastrophic fire and diameter-limit cutting (removal of trees greater than a specified diameter). This study examined five randomly selected old-growth ponderosa pine stands on state-owned land in central Montana for a variety of site-, stand-, and tree-level attributes. For trees ≥ 12.7 cm in diameter (dbh), stand densities ranged from 245 to 410 trees ha-1 and basal area ranged from 16.3 to 22.7 m2 ha-1. Regeneration ranged from 10 to 5078 seedlings (trees > 0.15 m but < 1.4 m tall) per hectare and 133 to 1620 saplings (trees ≥ 1.37 m tall with dbh < 12.7 cm) per hectare. Each site retained four to eight snags per hectare with dbh ≥ 38.1 cm. Across all sites, 94% of sampled live trees ≥ 38.1 cm dbh were ≥ 120 years, while 17% were ≥ 300 years. By site, 56% to 88% of trees ≥ 38.1 cm dbh displayed crown deformities, and 14% to 43% exhibited external fire scars. Areas of old-growth ponderosa pine typically occur along drainage features as a component of uneven-aged forests maintained by low-intensity fires. This study was the first of its kind in central Montana and should aid managers and researchers in identifying and maintaining old growth in the region.

Original languageEnglish
Pages (from-to)11-19
Number of pages9
JournalNatural Areas Journal
Volume22
Issue number1
StatePublished - 2002

Keywords

  • Fire
  • Montana
  • Old-growth forest
  • Pinus ponderosa var. scopulorum
  • Uneven-aged forest

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