Comparison of Historical and Contemporary Forest Structure and Composition on Permanent Plots in Southwestern Ponderosa Pine Forests
Abstract:We compared historical (1909–1913) and contemporary (1997–1999) forest structure and composition on 15 permanent plots in ponderosa pine (Pinus ponderosa Dougl. ex Laws.) forests of Arizona and New Mexico. We used the same sampling methods as in the early 1900s and compared stand density, diameter distributions, species composition, and broad age classes from the two periods. Stand density (trees ≥9.14 cm dbh) significantly (P < 0.001) increased on plots from an average of 77.4 trees per plot (s = 49.9) at plot establishment in 1909–1913 to 519.1 trees per plot (s = 252.3) at remeasurement in 1997–1999. Basal area significantly (P < 0.001) increased from 8.0 m2 per plot (s = 3.5) to 28.5 m2 per plot (s = 10.1). Contemporary tree diameter distribution shifted toward smaller size classes as demonstrated by a significant (P = 0.001) decrease in quadratic mean diameter from 38.5 cm (s = 7.5) in 1909–1913 to 28.6 cm (s = 7.1) in 1997–1999. Broad age classes yielded an average of 61.5 (s = 49.5) residual live trees classified as “blackjack” ponderosa pine (P. ponderosa <150 years) and 13.3 (s = 11.9) “yellow pine” (P. ponderosa ≥150 years) in 1909–1913. In 1997–1999, 416 live trees (s = 229.6) were “blackjack” and 57.2 (s = 28.5) trees on average were “yellow pine.” Twelve of the 15 plots were not invaded by other tree species (remained pure ponderosa pine type), while composition shifted slightly on three plots toward more shade-tolerant and fire-intolerant species. Ninety-one percent of the historically (1909–1913 or older) mapped tree structures (live trees, snags, logs, stumps, etc.) were relocated, which suggested that the forest reconstruction field techniques are reliable within 10%. Dramatic increases in tree densities may represent an increased potential for bark beetle epidemics and stand replacing wildfire over large areas in the Southwest. FOR. SCI. 50(2):162–176.
Keywords: Arizona; G.A. Pearson; New Mexico; Pinus ponderosa; T.S. Woolsey, Jr; early 1900s; environmental management; forest; forest management; forest resources; forest structural changes; forestry; forestry research; forestry science; natural resource management; natural resources; reference conditions; residual stands
Document Type: Regular Article
Affiliations: 1: Professor School of Forestry Northern Arizona University Box 15018 Flagstaff AZ 86011 Phone: (928) 523-7457;, Fax: (928) 523-1080, Email: email@example.com 2: Research Associate Ecological Restoration Institute Northern Arizona University Box 15018Flagstaff AZ 86011 3: Associate Professor School of Forestry and Ecological Restoration Institute Northern Arizona University Box 15018 Flagstaff AZ 86011 4: Regents' Professor School of Forestry and Ecological Restoration Institute Northern Arizona University Box 15018 Flagstaff AZ 86011 5: Applications Systems Analyst Ecological Restoration Institute Northern Arizona University Box 15018 Flagstaff AZ 86011
Publication date: 2004-04-01
- Forest Science is a peer-reviewed journal publishing fundamental and applied research that explores all aspects of natural and social sciences as they apply to the function and management of the forested ecosystems of the world. Topics include silviculture, forest management, biometrics, economics, entomology & pathology, fire & fuels management, forest ecology, genetics & tree improvement, geospatial technologies, harvesting & utilization, landscape ecology, operations research, forest policy, physiology, recreation, social sciences, soils & hydrology, and wildlife management.
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