A redwood tree whose crown is a forest canopy.
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Sillett and VanPelt A redwood tree whose crown is a forest canopy. Northwest Science. 2000; 74(1): 34-43Keywords:
Tree canopy
Tree (set theory)
Sequoia
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The effect of the spatial distribution of trees and foliage on understory conditions was examined in six tall old-growth forests along the Pacific Coast: two sites each in Washington, Oregon, and California. Detailed field measurements of crown parameters were collected on over 9000 trees encompassing over 14.5 ha in the stands. Crown parameters were used to construct a spatially explicit model useful in analyzing the variability of crown distributions in both vertical and horizontal dimensions. Sapwood measurements of over 400 trees in combination with published equations and 240 hemispherical photos were used to assess leaf area and understory light levels, respectively. Shrub and herb cover was used as a biological indicator of growing conditions in the understory. Although leaf area is often assumed to be correlated with the amount of light penetrating the canopy, this is not the case in tall, old-growth forests. The semivariance of the horizontal distribution of canopy volume was strongly correlated with shrub cover and understory light levels and was an overall predictor of canopy structure. This variability gives rise to potentially higher understory light levels and shrub cover values when compared with a forest lacking this vertical heterogeneity and may allow the stand to support a higher volume of foliage.
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Tree canopy
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Understory
Tree canopy
Forest dynamics
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Within the canopy of old‐growth redwood ( Sequoia sempervirens [D. Don] Endl.) forests, accumulations of plant debris in crotches and on massive limbs serve as parent materials for “arboreal soils” up to 1 m thick and over 50 m above the forest floor. These soils are important habitats and water sources for desiccation‐sensitive organisms in the forest canopy ecosystem. We investigated two of these arboreal soils to better understand how they form and function. The primary vascular epiphyte growing in these soils is leather‐leaf fern ( Polypodium scouleri ). Fern biomass and redwood leaves and bark are the main parent materials of the soils, which are entirely organic. The soils have distinct horizons and soil structure, and have been changed from their initial parent materials as a result of additions, losses, and transformations of organic matter. They are classified as Typic Udifolists. The soils become more decomposed with depth as fibrous components transition to sapric materials. They have low bulk densities (0.07–0.16 g cm −3 ) and lose most of their water at relatively high matric potentials. Field water contents and potentials of the arboreal soil materials taken near the end of the dry season indicate that water remains available for uptake by ferns. High base saturation values (>55%) suggest that nutrients are available for plant uptake. The soils are extremely acidic, with pH values around 3.0 in 0.01 M CaCl 2 Decomposition may be hindered by the low soil pH and by relatively low soil moisture contents in surface horizons during the dry season.
Sequoia
Histosol
Forest floor
Old-growth forest
Coarse Woody Debris
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Epiphyte functional groups (alectorioid lichens, cyanolichens, other lichens, and bryophytes) were sampled in nine old-growth, canopy-emergent, Pseudotsuga menziesii trees along a riparian corridor in the Wind River Experimental Forest, Washington State, U.S.A., with the objective of determining epiphyte abundance and its relationship to crown structure. An additional objective was to develop a sampling design that reasonably captured the variation in epiphyte distribution so that total biomass could be estimated for an individual large tree, a design efficient enough to make description economically and logistically possible. Trees ranged in height from 51 to 66 meters and averaged 83 live and 79 dead limbs in a crown length of 40 meters. Diameter at breast height was a useful estimator of tree crown structural complexity. Epiphytes averaged 27.1 kg/tree, with alectorioid lichens (19.3 kg/tree) dominating the assemblages, followed by other lichens (3.3 kg/tree), bryophytes (2.6 kg/tree) and cyanolichens (1.9 kg/tree). The foliage region had the highest biomass of lichens (16.4 kg/tree), followed by the branches (8 kg/tree) and trunk (2.6 kg/tree). Alectorioid lichens predominated in the upper, middle and outer portions of the tree crown, whereas the lower and inner portion of the tree crowns had more equal distributions of all four functional groups. Relative height and limb size were the most significant structural attributes influencing epiphyte distribution. Limb size had a particularly strong effect on the distribution of bryophytes regardless of height. In old, canopy-emergent P. menziesii, the crown structural variables which determine epiphyte distribution and abundance are height, crown length, trunk surface area and exposure, distribution and abundance of small, medium and large branches, and distribution and exposure of foliated branches.
Epiphyte
Tree canopy
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Silviculture
Stand development
Coarse Woody Debris
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The presented paper is oriented on the analysis of interspecific crown competition within the middle and upper layer of the selection forest. The research was conducted in the Norway spruce and silver fir dominated selection forest (demonstration object Donovaly-Mistríky) and in the common beech dominated selection forest in the territory of School Forestry Enterprise of the Technical University in Zvolen, Slovakia. We intended to evaluate the species specific crown-stem relation through the tightness of correlation between the crown volume and the stem volume. Our research confirmed the obvious effect of crown capacity on the production of stem biomass in the selection forest. The analysis revealed significant differences between coniferous and broadleaved species. However the low correlation for both middle and upper layers did not exceed r 2 = 0.46 for common beech, the high significant correlations were for spruce and fir (r 2 = 0.82 and 0.78, respectively). There were also significant differences between separated canopy layers. In the middle layer, the crown-stem correlations were lower than in the upper layer, what points out the obvious spatial competitiveness in the middle canopy layer, despite the relatively autonomous position of tree crowns within the canopy.
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Scots pine
Tree canopy
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Methods have been developed to yield total tree estimates of biomass for various components of a tree (trunk, axes, twigs, and needles) and its community of epiphytes (microorganisms, lichens, and bryophytes). Trees were sampled with the help of climbing techniques modified from mountain climbing. Two stages of sampling were involved. First, all units of the population were described so that their weights could be predicted. Second, several units were chosen with probability of selection dependent upon predicted weight and sampled in detail. Biomass estimates from the sampled units were expanded to tree totals with information gathered during the first sampling stage. Internal structure of the crown (tree components and epiphytes) is illustrated by maps of trunk and branch systems and by diagrams of horizontal and vertical distributions. This internal structure was also derived from the first sampling stage.These methods have been applied to nine old-growth Douglas fir trees (Pseudotsugamenziesii (Mirb.) Franco). Data from a single 400-year-old tree (1.46 m dbh, 77 m in height) in the H. J. Andrews Experimental Forest in the western Cascade Mountains of Oregon are presented. Biomass and surface area estimates are as follows: trunk, 26 870 kg, 223 m 2 ; axes (>4 cm), 1530 kg, 81 m 2 ; living twigs (<4 cm), 480 kg, 373 m 2 ; dead twigs, 78 kg, 104 m 2 ; needles, 198 kg, 2860 m 2 ; lichens, 13.1 kg; and bryophytes, 4.7 kg. Total cell volume of microepiphytes on twigs was estimated to have been 300 cm 3 and total cover by microepiphytes on needles was estimated to have been 191 m 2 .
Epiphyte
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