Crown structure of old-growth Douglas-fir in the western Cascade Range, Washington

2001 ◽  
Vol 31 (7) ◽  
pp. 1250-1261 ◽  
Author(s):  
Hiroaki Ishii ◽  
Megan E Wilson
Keyword(s):  
Structural Complexity ◽  
Douglas Fir ◽  
Cascade Range ◽  
Old Growth ◽  
Crown Structure ◽  
Branch Biomass ◽  
Size Variability ◽  
Branch Density ◽  
Branch Size ◽  
Epicormic Branches

Crown structure of old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) is characterized by low live-branch density, numerous dead branches and epicormic branches, high branch-size variability, and large gaps in the crown. These features define structural complexity of the crown and create variable crown microenvironments. For the 60 m tall, 400-year-old Douglas-fir trees measured in this study, number of live branches decreased and dead branches increased from the upper to lower crown. Dead branches were found below the lowest live branch indicating that crown recession had occurred. Live-branch biomass culminated at 45 m and decreased markedly below 35 m. Numerous vertical gaps between branches occurred below 40 m. Epicormic branches accounted for 14.6–47.5% of the total number of live branches per tree and contributed to increased crown depth. Epicormic branches filled inner regions of the crown, and contributed to increased branch-size variability. A model of crown structure developed for young trees could be fit to the upper crown of the study trees but could not be applied to the middle to lower crown because of increased branch-size variability. Relative levels of photosynthetically active radiation in the crown decreased with decreasing height, but a local peak occurred around 35–40 m, coinciding with the height of marked decrease in live-branch biomass.

Fire-related landform associations of remnant old-growth trees in the southern Washington Cascade Range

2004 ◽  
Vol 34 (11) ◽  
pp. 2371-2381 ◽  
Author(s):  
William S Keeton ◽  
Jerry F Franklin
Keyword(s):  
Forest Cover ◽  
Fire Behavior ◽  
Douglas Fir ◽  
Cascade Range ◽  
Fire Intensity ◽  
Old Growth ◽  
Biological Legacies ◽  
Digital Elevation ◽  
Biological Legacy ◽  
Topographic Heterogeneity

The spatial distribution of biological legacies left by natural disturbances is an important source of variability in forest development. We investigated one type of biological legacy: remnant old-growth trees persisting in mature Douglas-fir forests. We hypothesized that persistence varies with topographic heterogeneity influencing fire behavior. Our two study areas are located in the southern Washington Cascade Range, USA. They have an unfragmented, mature forest cover that regenerated following wildfire. We mapped all remnant old-growth trees (live and dead) within 4.2–6.4 km long belt transects. Digital elevation models were used to generate convergent and divergent landform classes. Frequency analysis was used to test for landform associations. Live remnant western hemlock and western redcedar were strongly associated with convergent landforms and aspects that had greater availability of soil moisture. Live remnant Douglas-fir were most abundant, but were not correlated with convergence or divergence, although certain landforms had higher concentrations. Remnant snags were abundant across convergent and divergent landforms. We conclude that species with low fire resistance survive most frequently on landforms that have a dampening effect on fire intensity. Topographic variability may indirectly influence ecological functions associated with biological legacies by affecting the spatial distributions of remnant old-growth trees.

Distribution of epicormic branches and foliage on Douglas-fir as influenced by adjacent canopy gaps

2018 ◽  
Vol 48 (11) ◽  
pp. 1320-1330
Author(s):  
John W. Punches ◽  
Klaus J. Puettmann
Keyword(s):  
Branch Length ◽  
Canopy Gaps ◽  
Douglas Fir ◽  
Canopy Gap ◽  
Tree Age ◽  
Gap Size ◽  
Terminal Bud ◽  
Total Branch Length ◽  
A Minor ◽  
Epicormic Branches

The influence of adjacent canopy gaps on spatial distribution of epicormic branches and delayed foliage (originating from dormant buds) was investigated in 65-year-old coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco). Sample trees were selected across a broad range of local densities (adjacent canopy gap sizes) from a repeatedly thinned stand in which gaps had been created 12 years prior to our study. Lengths and stem locations of original and epicormic branches were measured within the south-facing crown quadrant, along with extents to which branches were occupied by sequential (produced in association with terminal bud elongation) and (or) delayed foliage. Epicormic branches, while prevalent throughout crowns, contributed only 10% of total branch length and 2% of total foliage mass. In contrast, delayed foliage occupied over 75% of total branch length, accounted for nearly 39% of total foliage mass, and often overlapped with sequential foliage. Canopy gap size did not influence original or epicormic branch length or location. On original branches, larger gaps may have modestly negatively influenced the relative extent of sequential foliage on branches and (or) slightly positively influenced delayed foliage mass. Delayed foliage appears to contribute substantially to Douglas-fir crown maintenance at this tree age, but canopy gap size had a minor influence, at least in the short term.

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

Crown structure of a codominant Douglas-fir

1983 ◽  
Vol 13 (2) ◽  
pp. 264-269 ◽  
Author(s):  
Edward C. Jensen ◽  
James N. Long
Keyword(s):  
Photosynthetic Efficiency ◽  
Photosynthetic Capacity ◽  
Basic Structure ◽  
Douglas Fir ◽  
Intensive Study ◽  
Crown Structure

Results are presented from an intensive study of crown structure in a 39-year-old codominant Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco). The patterns of crown development observed may represent a species adaptation for maximizing photosynthetic efficiency. While branches originating at nodes provide the basic structure of the crown, short-lived nonnodal branches provide much of the photosynthetic capacity. In addition, nonnodal branches support nearly half of the young needles near the top and outside edges of the crown.

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.

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