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A general form for expressing gross volume increment in terms of stand density is derived and tested with data from spacing trials in red alder ( Alnus rubra Bong.), eastern white pine ( Pinus strobus L.), longleaf pine ( Pinus palustris Mill.), and loblolly pine ( Pinus taeda L.). The equation relates the stand sum of individual-tree volume increment per metre height increment to a power function of quadratic mean diameter times tree density. The proposed equation fit the data best when the model included an intercept. Within each species, the fits were unbiased with respect to the independent variables, plantation age, and site height, and with the exception of the youngest ages for red alder and loblolly pine, they were unbiased with respect to the plot sums of individual-tree volume increment divided by individual height increment. Exponents estimated for quadratic mean diameter for each species ranged from 1.58 to 1.80. The resulting equations indicate a linear relationship between the stand sum of individual-tree volume increment per metre height increment and stand density. Scattergrams of gross-volume increment per hectare per year and stand density can be recovered by multiplying the predicted values of the regressions by Lorey's height. The regressions support the hypothesis that each metre of height growth produces consistent changes in stem size, regardless of initial tree size, age, or site quality, and implies that the change in stem size is a predictable power function of stem diameter for an individual tree or quadratic mean diameter for a stand. [ABSTRACT FROM AUTHOR]

In recent decades, red alder (Alnus rubra Bong.) has become an important Pacific Northwest hardwood in appearance-grade lumber markets, such as exports, furniture, and cabinets. However, red alder generally is a short-lived pioneer species, and small logs can result in proportionally large volumes of lower grade lumber containing numerous visual defects, such as knots, often referred to as character marks. Given that markets for character-marked wood could provide an income stream for management of red alder, it becomes important to understand consumer and retailer response to character-marked red alder products. In the current study, we used a policy capturing approach (the lens model) to assess the cues used by furniture consumers and retailers to evaluate several furniture pieces constructed from character-marked red alder lumber. The cues used by consumers and retailers to form willingness-to-pay judgments were found to be different. Character marks, design, and naturalness were important to consumers. None of the investigated cues were significant to retailers, suggesting they were using an entirely different model. Such divergence creates challenges in the forestry supply chain for development of new forest products. [ABSTRACT FROM AUTHOR]

Studies on red alder (Alnus rubra Bong.) and sycamore (Acer pseudoplatanus L.) were carried out to assess their timber and wood-fuel properties when grown at wide spacing as in a silvopastoral system. Initial tree-planting density had significant effects on the modulus of elasticity (MOE) in red alder and compression strength in sycamore. Wood samples taken from red alder in high-density plots of 2500 stems·ha–1 had a significantly higher MOE than those from trees in low-density plots of 400 stems·ha–1 (silvopastoral system). Sycamore wood from the high-density plots had significantly higher compression strength than that from the low-density plots. However, there was no significant effect of planting density on the modulus of rupture in either species. On average, red alder had lower wood density, modulus of rupture, and compression strength than sycamore, but there was no significant difference in MOE between the two species. Planting density did not have any effect on the wood-fuel higher heating value of either red alder or sycamore, nor was there a significant difference in wood-fuel higher heating value between the two species. However, red alder wood had a significantly higher fuel-value index than sycamore, owing to its lower ash content. [ABSTRACT FROM AUTHOR]

Factors (riparian stand condition, management regimes, and channel properties) affecting distributions of wood, detritus (leaves and branches), and sediment were examined in headwater streams draining young-growth red alder (Alnus rubra Bong.) – conifer riparian forests (< 40 years old) in southeast Alaska. More riparian red alder were found along streams affected by both timber harvesting and mass movement than in streams affected by timber harvesting alone. Young-growth stands produced little large wood material (diameter ≥10 cm) and had little effect on altering the size distribution of functional large wood in channels, although more alder wood pieces were found in streams with greater numbers of riparian alder trees. Legacy wood pieces (>40 years old) remained in channels and provided sites for sediment and organic matter storage. Despite various alder–conifer mixtures and past harvesting effects, the abundance of large wood, fine wood, and detritus accumulations significantly decreased with increasing channel bank-full width ( 0.5–3.5 m) along relatively short channel distances (up to 700 m). Changes in wood, detritus, and sediment accumulations together with changes in riparian stand characteristics create spatial and temporal variability of in-channel conditions in headwater systems. A component of alder within young-growth riparian forests may benefit both wood production and biological recovery in disturbed headwater stream channels. [ABSTRACT FROM AUTHOR]

Interest in mixed red alder (Alnus rubra Bong.) – conifer young-growth stands has grown in southeast Alaska, USA, because they appear to provide much more productive understory vegetation and wildlife habitat than do similar-aged pure conifer stands. We studied understory vegetation in nine even-aged young-growth stands (38–42 years old) comprising a gradient of red alder – conifer overstory composition, with red alder ranging from 0% to 86% of stand basal area. Conifers were Sitka spruce (Picea sitchensis (Bong.) Carr.), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and western redcedar (Thuja plicata Donn ex D. Don). We measured understory biomass and net production (current annual growth) in each stand by species and plant part and estimated carrying capacity for black-tailed deer (Odocoileus hemionus sitkensis Cowan) with a food-based habitat model. Highly significant positive relations (P < 0.002) were found between red alder basal area and all of the following: total understory biomass (r2 = 0.743), net production of shrubs (r2 = 0.758) and herbs (r2 = 0.855), and summer carrying capacity for deer (r2 = 0.846). The high correlation between red alder and herbaceous production is especially important, because herbs are least abundant and most difficult to maintain in young-growth conifer forests of this region. Red alder offers prospects for increasing understory vegetation biomass and its food value for deer and other wildlife when included as a hardwood overstory species in mixed hardwood–conifer young-growth forests. [ABSTRACT FROM AUTHOR]

In the Pacific Northwest, a mixture of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and red alder (Alnus rubra Bong.) often results when red alder regenerates naturally in planted conifer stands. The relationships among stand structure, tree mortality, tree size, and understory development in the two species mixtures were explored at two sites for the first 16 years after planting. Treatments included a range of species proportions, and red alder was either planted simultaneously with Douglas-fir or planting was delayed for 5 years. Red alder was also removed from some simultaneously planted proportions. Both replacement effects (total stand density held constant) and additive effects (stand density doubled) of the interaction were considered. Red alder grew relatively better at Cascade Head Experimental Forest in the Coast Range, while Douglas-fir grew better at H.J. Andrews Experimental Forest in the less temperate Cascade Mountains. Possible production benefits from mixed plantings were examined using two methods of calculation. Potential production benefits from certain planted proportions of the two species occurred at H.J. Andrews Experimental Forest. No planting time or species proportion resulted in yield improvements over monoculture stands at Cascade Head Experimental Forest. Understory species also varied because of differences in site and stand characteristics that resulted from the differences in planting times and species proportions. [ABSTRACT FROM AUTHOR]

The relationships among stand structure, Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) branch characteristics, and red alder (Alnus rubra (Bong.)) stem form attributes were explored for 10- to 15-year-old trees growing in mixed Douglas-fir – red alder plantations. Treatments included a range of species proportions, and red alder was either planted simultaneously with Douglas-fir or after 5 years. Both replacement effects (total stand density held constant) and additive effects (stand density doubled) of competition were considered. When the two species were planted simultaneously and red alder proportion was low, red alder trees had low crown bases and much stem defect (lean, sweep, and multiple stems). Douglas-fir grew slowly when the two species were planted simultaneously. When red alder planting was delayed, species proportion did not affect red alder stem form, and height to the base of the Douglas-fir live crown decreased with increasing red alder proportion. Doubling Douglas-fir density increased the height to the base of the Douglas-fir live crown; however, doubling stand density by adding red alder did not affect Douglas-fir crown height. Douglas-fir lumber coming from mixed stands may be inferior because of the changes in knot characteristics associated with these different patterns of crown recession. In stands with a low proportion of red alder, red alder product recovery may be compromised because of the stem defects described above. [ABSTRACT FROM AUTHOR]

Stand structure and dynamics were evaluated in mixed red alder (Alnus rubra Bong.) – conifer forests of southeast Alaska. We assessed stand development, tree density, total basal area, diameter distribution of live and dead trees, height distribution of live trees, and mean diameter of all and largest conifers in 40-year-old red alder – conifer stands that developed following logging. Forty-five plots were established in nine stands sampled across a com po si tional range of 0%–86% alder. Alder height growth was initially rapid then slowed considerably, whereas conifer height growth was initially slow then rapidly increased with conifers now being 4–9 m taller than associated alders. Most alder diameters were 20–30 cm and conifer diameters were more variable with numerous small (3–10 cm) and a few large (>25 cm) trees. Total stand basal area significantly decreased (p = 0.013) with increasing proportions of alder, but density of live and dead trees was not closely associated with alder composition. More than 60% of all dead trees died standing regardless of size or species. Overall, these mixed red alder – conifer stands provided more heterogeneous structures than pure conifer stands, with more even diameter distributions, multiple canopy layers, and similar numbers of large diameter conifers. [ABSTRACT FROM AUTHOR]

To evaluate the distance over which red alder patches influence adjacent conifer stands, we measured light transmission and nutrient contents of soil and litterfall along transects crossing the boundary between alder and conifer stands at three sites (10–15, 20–25, and >= 40 years old) in coastal British Columbia. Light levels were higher in the understory of alder stands than in adjacent conifer stands. In simulated openings, light levels rapidly increased with distance from the alder edge, reaching 60% of full sunlight at south-facing edges, 5 m from north-facing edges, and 2–3 m from east- and west-facing edges. Soil N, NH4-N, NO3-N, and mineralizable N remained elevated for about 10 m from the alder boundary. Nitrogen contents of Douglas-fir seedlings grown in soil from the alder stand were elevated and correlated to soil N concentrations. Nutrient inputs in alder litterfall were positively related to concentrations of total C; total, extractable, and mineralizable N in soils; and the N, P, and B concentrations of seedlings. Alder litterfall drift extended 8–18 m into adjacent conifer stands. The optimal arrangement for alder–conifer mixtures would be alder patches or strips at least 10 m wide and about 20 m apart oriented north to south. [ABSTRACT FROM AUTHOR]

In southern coastal British Columbia, red alder (Alnus rubra Bong.) is recommended for reforestation on some low-elevation, fertile, and moist sites (e.g., alluvial sites). Correlative data indicate that P deficiencies limit the growth of alder in low-pH soils; deficiencies of P and other elements may also develop in the presence of an alder stand. Because alder may be grown in repeated rotations on alluvial sites, we sought to determine whether elemental deficiencies were likely in soils from mature stands. We examined the effects of P additions (as triple super phosphate) and liming (as dolomitic limestone) on potted red alder seedlings grown in soils from mature alluvial alder stands. Four soils were "low-pH" (mean = 4.5) and two were "high-pH" (mean = 5.5); all were classified as very rich. Growth of unfertilized seedlings was greatest in the soil with the highest soil Bray-P levels. Growth rates increased with P supply, but the response decreased with increasing Bray-P and was less in the high-pH soils. Liming increased soil pH and uptake of Mg, but did not increase growth. Phosphorus additions increased growth mainly by increasing P uptake, leaf size, and biomass allocation to branches. Photosynthetic rates were highest in the intermediate P treatment, but instantaneous water use efficiency increased with P rate. Phosphorus deficiencies may limit the growth of alder seedlings in alluvial soils previously containing mature alder stands. [ABSTRACT FROM AUTHOR]

Examines growth and biomass allocation of individual Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and red alder (Alnus rubra Bong.) seedlings grown under contrasting combinations of light and water. Alder growth that was always greater than Douglas-fir; Full sunlight and soil moisture at field capacity that caused large differences in size between the two species; Differences that were smaller with limited light and water; Douglas-fir that allocated a high portion of its biomass to roots under full light and limited water; Red alder that allocated a high percentage to aboveground biomass components under full light and limited water; Red alder growth that responded negatively to water limitation; Red alder that exhibited greater foliage plasticity to light; Species differences in size and allocation in response to resource availability that may determine pathways by which Douglas-fir and red alder interact in a mixed community; Findings that support the hypothesis that the potential of species to use growth-limiting resources is an indicator of competitive ability; Suggestion that red alder and Douglas-fir can co-exist under conditions of full light and limiting soil moisture availability; Douglas-fir's relatively greater tolerances to low light that allow it to better persist in the understory; Red alder's rapid early growth and competitive ability that will be superior under full light and nonlimiting soil moisture conditions.

Examines the influence of the density and rectangularity of plantation on the growth and development of red alder in Oregon. Patterns of tree growth and stand development; Comparisons of the growth of trees with other plantations; Analysis of the diameter-density relationships in spacing.