Understory vegetation in young Douglas-fir forests: does thinning help restore old-growth composition?

2004 ◽  
Vol 192 (2-3) ◽  
pp. 285-296 ◽  
Author(s):  
Briana C Lindh ◽  
Patricia S Muir
Keyword(s):  
Douglas Fir ◽  
Understory Vegetation ◽  
Old Growth

Leaf area index of an old-growth Douglas-fir forest estimated from direct structural measurements in the canopy

2000 ◽  
Vol 30 (12) ◽  
pp. 1922-1930 ◽  
Author(s):  
Sean C Thomas ◽  
William E Winner
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Understory Vegetation ◽  
Western Hemlock ◽  
Old Growth ◽  
Area Index ◽  
Contact Frequency ◽  
Canopy Access

Leaf area index (LAI) in old-growth Douglas-fir (Pseudotsuga menziesii var menziesii (Mirb.) Franco) forests exceeds that of any other forest ecosystem by some estimates; however, LAI determinations in coniferous forests have generally been indirect, involving extrapolations of patterns observed in younger stands. Aided by a 75-m construction crane for canopy access, we used a vertical line-intercept method to estimate LAI for a [Formula: see text]450-year-old Douglas-fir - western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest in southwestern Washington state. LAI was calculated as the product of foliage contact frequency and an "extinction coefficient" accounting for foliage angular distribution, geometry, and the ratio of "interceptable" to total leaf area. LAI estimates were 9.3 ± 2.1 (estimate ± 95% confidence interval), 8.5 ± 2.2, and 8.2 ± 1.8 in 1997, 1998, and 1999, respectively, or 8.6 ± 1.1 pooled across years. Understory vegetation, including foliage of woody stems <5 cm diameter, represented 20% of this total. Sample points in which Douglas-fir was dominant had a higher total LAI than points dominated by western hemlock, including a higher LAI of understory vegetation. Our results do not support the contention that old-growth Douglas-fir - western hemlock forests maintain an appreciably higher LAI than do other forest ecosystems. Moreover, LAI in very old stands may decline as western hemlock replaces Douglas-fir through the course of succession.

Comparison of Methods of Estimating Leaf-Area Index In Old-Growth Douglas-Fir

Ecology ◽  
1986 ◽  
Vol 67 (4) ◽  
pp. 975-979 ◽  
Author(s):  
J. D. Marshall ◽  
R. H. Waring
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Douglas Fir ◽  
Comparison Of Methods ◽  
Old Growth ◽  
Area Index

Canopy disturbances over the five-century lifetime of an old-growth Douglas-fir stand in the Pacific Northwest

2002 ◽  
Vol 32 (6) ◽  
pp. 1057-1070 ◽  
Author(s):  
Linda E Winter ◽  
Linda B Brubaker ◽  
Jerry F Franklin ◽  
Eric A Miller ◽  
Donald Q DeWitt
Keyword(s):  
Pacific Northwest ◽  
Variable Density ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Old Growth ◽  
The Pacific ◽  
History Of ◽  
Horizontal Heterogeneity ◽  
Restoration Strategies

The history of canopy disturbances over the lifetime of an old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stand in the western Cascade Range of southern Washington was reconstructed using tree-ring records of cross-dated samples from a 3.3-ha mapped plot. The reconstruction detected pulses in which many western hemlock (Tsuga heterophylla (Raf.) Sarg.) synchronously experienced abrupt and sustained increases in ringwidth, i.e., "growth-increases", and focused on medium-sized or larger ([Formula: see text]0.8 ha) events. The results show that the stand experienced at least three canopy disturbances that each thinned, but did not clear, the canopy over areas [Formula: see text]0.8 ha, occurring approximately in the late 1500s, the 1760s, and the 1930s. None of these promoted regeneration of the shade-intolerant Douglas-fir, all of which established 1500–1521. The disturbances may have promoted regeneration of western hemlock, but their strongest effect on tree dynamics was to elicit western hemlock growth-increases. Canopy disturbances are known to create patchiness, or horizontal heterogeneity, an important characteristic of old-growth forests. This reconstructed history provides one model for restoration strategies to create horizontal heterogeneity in young Douglas-fir stands, for example, by suggesting sizes of areas to thin in variable-density thinnings.

Long-term patterns of diameter and basal area growth of old-growth Douglas-fir trees in western Oregon

2002 ◽  
Vol 32 (7) ◽  
pp. 1232-1243 ◽  
Author(s):  
Nathan J Poage ◽  
John C Tappeiner, II
Keyword(s):  
Large Diameter ◽  
Basal Area ◽  
Douglas Fir ◽  
Slope Aspect ◽  
Site Factors ◽  
Old Growth ◽  
Site Class ◽  
Basal Area Growth ◽  
Area Growth ◽  
Age Range

Diameter growth and age data collected from stumps of 505 recently cut old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees at 28 sample locations in western Oregon (U.S.A.) indicated that rapid early and sustained growth of old Douglas-fir trees were extremely important in terms of attaining large diameters at ages 100–300 years. The diameters of the trees at ages 100–300 years (D100–D300) were strongly, positively, and linearly related to their diameters and basal area growth rates at age 50 years. Average periodic basal area increments (PAIBA) of all trees increased for the first 30–40 years and then plateaued, remaining relatively high and constant from age 50 to 300 years. Average PAIBA of the largest trees at ages 100–300 years were significantly greater by age 20 years than were those of smaller trees at ages 100–300 years. The site factors province, site class, slope, aspect, elevation, and establishment year accounted for little of the variation observed in basal area growth at age 50 years and D100–D300. The mean age range for old-growth Douglas-fir at the sample locations was wide (174 years). The hypothesis that large-diameter old-growth Douglas-fir developed at low stand densities was supported by these observations.

Relationship of Pacific Madrone Sprout Growth to Productivity of Douglas-Fir Seedlings and Understory Vegetation

1990 ◽  
Vol 5 (1) ◽  
pp. 20-24 ◽  
Author(s):  
Thomas F. Hughes ◽  
John C. Tappeiner ◽  
Michael Newton
Keyword(s):  
Pseudotsuga Menziesii ◽  
Secondary Succession ◽  
Douglas Fir ◽  
Understory Vegetation ◽  
Diameter Growth ◽  
Area Index ◽  
Old West ◽  
Pacific Madrone ◽  
Relationship Of ◽  
Sprout Growth

Abstract We studied the development of Pacific madrone (Arbutus menziesii) sprout clumps of various initial densities and their effect on Douglas-fir (Pseudotsuga menziesii) seedling growth and understory vegetation. Five years after density treatments, average leaf area index (LAI) of 9-year-oldmadrone sprouts ranged from 3.6-1.0 m²/m² and total aboveground biomass from 25,630-8,390 kg/ha on the high- and low-density plots, respectively. Diameter of 9-year-old Douglas-fir was inversely related to madrone LAI and ranged from about 27 mm on the high-density plots to 54 mmin the absence of madrone. Analyses of diameter growth trends also indicated that, in the absence of madrone, Douglas-fir grew significantly (P = 0.001 to 0.023) faster than in other treatments. An index of shrub, forb, and grass density was inversely related to madrone LAI, suggesting thatunderstory species are quickly excluded from young madrone stands during secondary succession. We provide equations relating the 5-year growth of 9-year-old Douglas-fir to measures of madrone density and seedling size made when the plantation was 5 years old. West. J. Appl. For. 5(1):20-24.

A Sustained-Yield Scheme for Old-Growth Douglas-fir

1987 ◽  
Vol 2 (1) ◽  
pp. 22-25 ◽  
Author(s):  
Michael Newton ◽  
Elizebeth C. Cole
Keyword(s):  
High Risk ◽  
Pseudotsuga Menziesii ◽  
Volume Growth ◽  
Douglas Fir ◽  
Management Approach ◽  
Old Growth ◽  
Minimal Impact ◽  
Rotation Culture ◽  
Annual Volume ◽  
Sustained Yield

Abstract From analysis of two Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) stands, 120 and 140 years old, we conclude that managed stands can meet established criteria for old-growth Douglas-fir and simultaneously produce near-maximum yields of good-quality timber. With the management approach outlined here, average annual volume growth may approach that of shorter-rotation culture, but in logs of a size and quality normally found only in older stands, and with minimal impact on high-risk watersheds or old-growth habitat. This possibility encourages development of silvicultural systems that can achieve such goals in a variety of timber types. West. J. Appl. For. 2:22-25, Jan. 1987.

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