bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in organic components for fallen logs in old-growth Douglas-fir forests monitored by 13C nuclear magnetic resonance spectroscopy
Authors: Preston Caroline M. , Sollins Phillip , Sayer Brian G.
Published: February 2008

13C cross-polarization magic-angle spinning nuclear magnetic resonance (CPMAS NMR) spectroscopy was used to characterize heartwood from decaying fallen boles of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), western hemlock (Tsugaheterophylla (Raf.) Sarg.), and western red cedar (Thujaplicata Donn). The sample decay classes I to V had been previously assigned based on field observations. Solid-state 13C CPMAS NMR spectra were analyzed to determine the proportion of C of the following chemical types: carbohydrate, lignin, aliphatic, and the sum of carboxyl plus carbonyl. For both Douglas-fir and western hemlock, the proportion of carbohydrate C increased slightly in the early stages of decay. This was followed by a substantial increase in lignin C, while carbohydrate C declined to about 10% of total C. By contrast, the spectra for western red cedar generally showed little change with increasing decay class. One exceptional sample of western red cedar class IV was highly decomposed, indicating complete loss of carbohydrate C, and some loss of lignin side-chain C. For all three species, signals from alkyl and carbonyl C were weak, but tended to increase slightly with decomposition, most likely because of the selective preservation of waxes and resins (alkyl C), and oxidation. Accumulation of chitin was not observed, and there was little evidence for lignin decomposition or for formation of humic polymers. 13C CPMAS NMR offers a simple and information-rich alternative to wet chemical analyses to monitor changes in organic components during decomposition of woody litter.
Atmospheric CO2 enrichment and the development of frost hardiness in containerized black spruce seedlings
Authors: Margolis Hank A. , Vézina Louis-P.
Published: February 2008

The hypothesis that a relatively brief exposure to elevated atmospheric CO2 could increase the frost resistance of shoots was tested on containerized black spruce seedlings (Piceamariana (Mill.) B.S.P.). Seedlings were exposed to 1000 ppm CO2 toward the end of their second growing season in an unheated production tunnel and in a heated greenhouse. In 1987, continuous 10-week CO2 exposures were applied in conjunction with mineral nutrient fertilization, and freezing tests were conducted each week. In 1988, a series of shorter 2-week CO2 exposures was applied to different groups of seedlings and no mineral nutrients were added. Controlled freezing tests were conducted at −10 °C and were followed by electrolytic conductivity measurements to assess frost injury. Under all experimental conditions, freezing tests on seedlings from both the production tunnel and the greenhouse indicated significantly greater frost damage for the CO2-enriched seedlings than for the controls. Late-growing season CO2 enrichment negatively affected the bud initiation – bud development stage of frost-hardiness development.
Relationships between breast-height and whole-stem growth indices for red spruce on Whiteface Mountain, New York
Authors: LeBlanc David C.
Published: February 2008

This paper describes relationships between tree growth indices based on ring width measurements at 1.4 m aboveground and indices derived from whole-stem analysis for red spruce (Picearubens Sarg.) in a high-elevation spruce-fir forest on Whiteface Mountain, New York. Coefficients of determination for linear regressions between mean, standardized chronologies for breast-height ring width versus whole-stem ring width and basal area increment versus annual volume increment are 0.89 and 0.93, respectively. However, substantial variability is apparent in breast-height versus whole-stem relationships for individual trees, particularly for unstandardized growth indices. Also, relationships between unstandardized growth indices exhibit temporal instability associated with individual tree maturation and stand dynamics. Nonetheless, strong relationships between mean standardized chronologies of breast-height and whole-stem growth indices validate the use of breast-height growth indices to represent year-to-year variation in mean growth performance of red spruce. A volume-equation-based procedure is described that provides better dendrochronological estimates of annual volume increment than estimates based on basal area increment alone.
Red spruce decline on Whiteface Mountain, New York. I. Relationships with elevation, tree age, and competition
Authors: LeBlanc David C.
Published: February 2008

Detailed stem analysis and stand structure and history analyses are used to evaluate relationships between growth decline in populations of red spruce (Picearubens Sarg.) on Whiteface Mountain and elevation, tree age and size, and stand dynamics. The study sites are virgin, uneven-aged spruce-fir forests at 900 and 1100 m elevation. Most red spruce sampled exhibited substantial decreases in annual stem wood volume increment from 1964 to 1984, particularly large trees and trees from higher elevation. While larger trees exhibited more severe growth decline, there is no evidence of a direct causal link between tree age and decline. Inverse relationships between growth and competition indices are evident for periods prior to the onset of decline, but these relationships degrade during the period of growth decline; competition is not causally linked to decline. There is some indication that the decline-inciting stress was particularly severe for canopy-emergent and exposed red spruce, suggesting the action of an atmospheric stress.
Red spruce decline on Whiteface Mountain, New York. II. Relationships between apical and radial growth decline
Authors: LeBlanc David C. , Raynal Dudley J.
Published: February 2008

Understanding the relationship between apical and radial growth decline can contribute toward the evaluation of hypotheses regarding causal mechanisms of red spruce decline. The etiology of red spruce decline in montane spruce-fir forests of the northeastern United States includes loss of foliage at branch apices, crown dieback, and unreversed radial growth decline since the 1960s. Demographic analyses of crown damage and radial growth decline for red spruce on Whiteface Mountain, New York, indicate that large, canopy-emergent trees with exposed crowns exhibit greater decline than codominant trees within an intact canopy. In this paper, radial growth decline is shown to have been coincident with decreased apical growth and increased incidence of injury to terminal leaders. Incidence of leader mortality is greatest for canopy-emergent red spruce or trees with exposed crowns, similar to patterns described for radial growth. This relationship suggests that the post-1960 decline of red spruce on Whiteface Mountain is caused, at least in part, by stresses that act directly on the crown.
Dynamic standardization of tree-ring series
Authors: Warren William G. , LeBlanc David C.
Published: February 2008

The compound growth function of Warren (W.G. Warren. 1980. Tree-Ring Bull. 40: 35–44) represented an attempt at developing a model-based approach that standardized tree ring width sequences and was more flexible than the monotonic functions that were then commonly used. While the idea was conceptually attractive, operational difficulties of fitting hindered its use as a practical tool. This paper describes the modifications, and what are believed to be improvements, that have recently been made to the method, and which have led to an interactive computer program by which the fitting of the model to any sequence of ring widths may be readily accomplished. The approach also permits the location of both positive and negative departures from a trend (releases and suppressions, respectively) and estimation of the rate of ring-width increase or decrease. For illustration it has been applied to a sample of red spruce (Picearubens Sarg.) cores from Whiteface Mountain, New York. Some synchrony in releases and suppressions was detected, with suppressions being very conspicuous since the late 1950s. Also, the recent reductions in growth rates are as great, or greater, than those previously exhibited by the trees of this sample.
Cone and seed development in a wind-pollinated, western hemlock (Tsugaheterophylla) clone bank
Authors: Colangeli Anna M. , Owens John N.
Published: February 2008

Seed and seed-cone development were observed in a wind-pollinated western hemlock (Tsugaheterophylla (Raf.) Sarg.) clone bank in 1983 and 1986. Seed efficiency, the number of filled seed per cone divided by the seed potential, averaged 64% for 58 wind-pollinated clones in 1983 and 20% for 38 clones in 1986. Based on anatomical observations and cone dissections, seed losses resulted from pre- and post-pollination ovule abortion, insufficient pollen, no fertilization, and embryo degeneration. Prepollination ovule abortion, identified by small, flat seed in mature cones, contributed to 11 and 14% reduction in filled-seed yield in 1983 and 1986, respectively. Full-sized but empty seed (lacking an embryo) accounted for 25 and 66% reduction in potential seed yield in the 2 years, respectively. In 1983, 98% of the clones bore a pollen-cone crop compared with 53% in 1986. Lack of fertilization resulting from a limited pollen supply was believed to be the main cause for the lower filled-seed yield in 1986. The effect of wind and controlled (cross-) pollination on filled-seed production was determined for 16 clones in 1983. Seed efficiency after wind and cross-pollination averaged 65 and 69%, respectively. Seed potential averaged 34 and 31 ovules per cone for the wind- and cross-pollinated cones, respectively. Prepollination ovule abortion averaged 12 and 14%, respectively. From anatomical observations, the full-sized but empty seed resulted from lack of fertilization and embryo degeneration. The different factors affecting final filled-seed yield are discussed in terms of their effect on seed production.
An operational, spatially constrained harvest scheduling model
Authors: Clements Stephen E. , Dallain Patrick L. , Jamnick Mark S.
Published: February 2008

A Monte Carlo integer programming algorithm was developed to generate short-term (25-year), spatially feasible timber harvest plans for a New Brunswick Crown license. Solutions for the short-term plan are considered feasible if they meet spatial and temporal harvest-flow and adjacency constraints. The solution search procedure integrates a randomly generated harvesting sequence and checks of harvest-flow and adjacency constraints. The model was used to determine the annual allowable cut under three constraint formulations. The three formulations represented increasing levels of adjacency constraints, from no constraints to levels similar to current provincial requirements. The annual allowable cut under the most strict constraint formulation was reduced by 9% from the unconstrained formulation, for a given mapping strategy of a long-term harvest schedule. These applications of the model indicate that it is suitable for spatially constrained harvest scheduling on Crown licenses in New Brunswick.
Promotion of flowering in young Larixlaricina grafts by gibberellin A4/7 and root pruning
Authors: Eysteinsson Throstur , Greenwood Michael S.
Published: February 2008

Flowering was promoted on potted, indoor, and field-grown 3-year-old juvenile and mature Larixlaricina (Du Roi) K. Koch grafts by foliar sprays of the plant-growth regulator gibberellin A4/7 and root pruning. Biweekly gibberellin A4/7 applications of three different durations, commencing at the start of long-shoot elongation, yielded similar increases in female flowering in the greenhouse; this effect was synergistically enhanced by root pruning. Male flowering was promoted by gibberellin A4/7 + root pruning in mature but not juvenile grafts. In the field, female flowering was also promoted by the gibberellin A4/7 treatment commencing at the start of shoot extension, but gibberellin A4/7 applications starting later were not effective. Grafted scions from mature trees responded significantly better to gibberellin A4/7 + root pruning than did seedling scions.
Seed production and dispersal patterns in populations of Liriodendrontulipifera at the northern edge of its range in southern Ontario, Canada
Authors: Kavanagh Kevin , Carleton T. J.
Published: February 2008

Seed production, viability, and dispersal patterns were examined for populations of Liriodendrontulipifera L. (tuliptree) at the northern edge of its range in Ontario, Canada, to determine whether these factors could account for its locally limited distribution. Seed production was measured by estimating the number of samara cones present in the canopy, and samaras collected in traps were dissected to determine potential seed viability under different stand conditions. Seed-trap collections were used to delineate seedfall patterns around individual tree stems and within high-density stands. Results indicate that seed production in Ontario begins when trees reach approximately 25 cm diameter at breast height and increases with maturity. Large trees often produce more than 2000 cones in good years, a level similar to more southern populations. The proportion of samaras containing filled seed increases with stand density, ranging from approximately 8–10% for isolated trees to over 20% for old-growth, high-density stands. Although low, these values are comparable to those reported elsewhere in the species' range. Seedfall patterns followed a leptokurtic distribution about individual stems. Life-history attributes other than seed viability may therefore be the cause of the restricted distribution and low population levels of L. tulipifera in Ontario.
Tarifs de cubage paramétrés: application à l'épinette noire de Lebel-sur-Quévillon
Authors: Ung Chhun-Huor
Published: February 2008

The mean ratio of height to diameter at breast height of dominant trees in a stand resulted in more accurate one-entry volume tables than general two-entry volume tables. These parametrical one-entry volume tables were established with the allometric model and Hummel's line. The values of their coefficients were estimated from stem analysis data of felled trees in black spruce stands at Lebel-sur-Quévillon. In the search for simple and effective methods to increase the reliability of standing stock estimation for managing a relatively homogeneous forest region, parametrical one-entry volume tables reduce the cost of estimating standing volume and increase the accuracy of volume estimation compared with general two-entry volume tables.
Growth responses of seven major co-occurring tree species of the northeastern United States to elevated CO2
Authors: Bazzaz F. A. , Coleman J. S. , Morse S. R.
Published: February 2008

We examined how elevated CO2 affected the growth of seven co-occurring tree species: American beech (Fagusgrandifolia Ehrh.), paper birch (Betulapapyrifera Marsh.), black cherry (Prunusserotina Ehrh.), white pine (Pinusstrobus L.), red maple (Acerrubrum L.), sugar maple (Acersaccharum Marsh.), and eastern hemlock (Tsugacanadensis (L.) Carr). We also tested whether the degree of shade tolerance of species and the age of seedlings affected plant responses to enhanced CO2 levels. Seedlings that were at least 1 year old, for all species except beech, were removed while dormant from Harvard Forest, Petersham, Massachusetts. Seeds of red maple and paper birch were obtained from parent trees at Harvard Forest, and seeds of American beech were obtained from a population of beeches in Nova Scotia. Seedlings and transplants were grown in one of four plant growth chambers for 60 d (beech, paper birch, red maple, black cherry) or 100 d (white pine, hemlock, sugar maple) under CO2 levels of 400 or 700 μL•L−1. Plants were then harvested for biomass and growth determinations. The results showed that the biomass of beech, paper birch, black cherry, sugar maple, and hemlock significantly increased in elevated CO2, but the biomass of red maple and white pine only marginally increased in these conditions. Furthermore, there were large differences in the magnitude of growth enhancement by increased levels of CO2 between species, so it seems reasonable to predict that one consequence of rising levels of CO2 may be to increase the competitive ability of some species relative to others. Additionally, the three species exhibiting the largest increase in growth with increased CO2 concentrations were the shade-tolerant species (i.e., beech, sugar maple, and hemlock). Thus, elevated CO2 levels may enhance the growth of relatively shade-tolerant forest trees to a greater extent than growth of shade-intolerant trees, at least under the light and nutrient conditions of this experiment. We found no evidence to suggest that the age of tree seedlings greatly affected their response to elevated CO2 concentrations.
Rating Eucalyptus vigor and the risk of insect infestation: leaf surface area and sapwood:heartwood ratio
Authors: Paine T. D. , Malinoski M. K. , Scriven G. T.
Published: February 2008

Phoracanthasemipunctata (Fab.) colonizes and kills stressed Eucalyptus spp. in both managed and unmanaged stands in southern California. Stressed trees frequently manifest thinner crowns, with less foliage surface area, than more vigorous trees. This is reflected in reduced conducting sapwood and a lower sapwood:heartwood ratio. Four species of Eucalyptus at four sites were examined, and correlation analyses of leaf surface area to sapwood area were conducted. Using E. cladocalyx as a model, trees in a stand suffering high tree mortality showed significantly lower sapwood:heartwood ratios than trees in stands with beetle activity restricted to dead limbs but evincing little tree mortality. This index could be utilized to identify high-risk stands for implementation of silvicultural management practices.
Distribution of carbon and nutrients and fluxes of mineral nitrogen after clear-felling a Pinusradiata plantation
Authors: Smethurst P. J. , Nambiar E. K. S.
Published: February 2008

The effects of clear-felling and slash removal on the distribution of organic matter and nutrients, fluxes of mineral N, and soil water and temperature were studied in a 37-year-old Pinusradiata D. Don plantation, on a sandy Podzol in southeastern Australia. Slash, litter, and the top 30 cm of soil combined contained 1957 kg N•ha−1, of which slash and litter contained 12 and 25%, respectively. Therefore, loss of slash and litter due to burning or other intensive site preparation practices would substantially reduce the N capital at the site. During the first 18 months after clear-felling, soil water content in the clear-felled area was up to 50% higher than in the uncut plantation, but there were only minor differences in soil temperature. Slash removal decreased the water content of litter, but had little effect on the water content or temperature of the soil. In the uncut plantation, N mineralized in litter and soil was completely taken up by the trees. Following clear-felling, rates of N mineralization increased in litter after 4 months, and in soil after 12 months, but changes were less pronounced with slash removal. After clear-felling, increased mineralization and the absence of trees (no uptake) led to increased concentrations of mineral N in both litter and soil, 64–76% of which was leached below the 30 cm soil depth prior to replanting. Despite leaching, concentrations of mineral N after clear-felling remained higher than those in the uncut plantation for at least 3 years.
Effects of slash and litter management on fluxes of nitrogen and tree growth in a young Pinusradiata plantation
Authors: Smethurst P. J. , Nambiar E. K. S.
Published: February 2008

The effects of slash and litter management practices on soil water and temperature, fluxes of mineral N, needle water potential, and tree nutrition and growth were studied in a young Pinusradiata D. Don plantation growing on a sandy Podzol in southeastern Australia. Treatments were slash and litter retained (SL), litter only retained (L), litter ploughed (LP), and slash and litter removed (SLR). Soils without slash or litter cover (LP and SLR) were up to 4 °C warmer on average than soils overlaid by slash or litter and were subjected to greater extremes of temperature. Treatments had relatively little effect on soil water content and needle water potential in trees. Carbon in surface soil increased from 1.14 to 1.83% after incorporation of litter by ploughing, but decreased to 1.37% during the next 40 months. Smaller but significant decreases in C also occurred in other treatments. LP and SLR led to the highest rates of N mineralization in the 1st year. During the first 3 years after clear-felling, rates of N mineralization increased in SL, L, and LP but decreased in SLR. During the 4th year, rates of N mineralization were low (20–30 kg N•ha−1•year−1) in all treatments. Over 4 years, 211, 170, 210, and 147 kg N•ha−1 were mineralized in treatments SL, L, LP, and SLR, respectively. Rates of mineralization and leaching were strongly correlated (R2 = 0.82) and leaching below 30 cm accounted for 75–85% of N mineralized irrespective of treatment. Incorporation of litter by ploughing doubled concentrations of mineral N during the first summer after planting and increased early tree growth. However, rates of N mineralization in the slash and litter treatments, which were high compared with potential rates of uptake, were weakly correlated with tree growth. Factors controlling N supply were of little consequence for tree growth during this early phase of plantation establishment.
Water relations of loblolly pine trees in southeastern Oklahoma following precommercial thinning
Authors: Cregg Bert M. , Hennessey Thomas C. , Dougherty Philip M.
Published: February 2008

Xylem pressure potential, leaf conductance, transpiration, and soil moisture were measured during three summers following precommercial thinning of a 10-year-old stand of loblolly pine (Pinustaeda L.) in southeastern Oklahoma. The stand was thinned to three target basal-area levels: 5.8, 11.5, and 23 m2•ha−1 (control). Soil water potential increased significantly in response to thinning during the summer of each year studied. However, plant water relations were relatively unaffected by the treatments. Significant thinning effects on diurnal xylem pressure potential were observed on only 7 of 55 measurement periods. Treatment differences in conductance and transpiration observed during the first year of the study appeared to be related to differences in light interception and crown exposure. Regression analysis indicated response of leaf conductance and transpiration to predawn xylem pressure potential and vapor pressure deficit was not affected by the thinning treatments. Overall, the results of this study are consistent with a hypothesis in which transpiration, leaf area, and water potential interact to form a homeostatic relationship.
Fern and aster effects on black cherry shelterwood regeneration
Authors: Drew Allan P.
Published: February 2008

Regeneration of black cherry (Prunusserotina Ehrh.) is difficult on northeast United States forest sites that are dominated by hay-scented fern (Dennstaedtiapunctilobula Michx.). The growth of black cherry seedlings beneath fern and whorled wood aster (Asteracuminatus Michx.) ground cover was monitored for eight growing seasons on weeded and unweeded plots following a shelterwood seed cutting. Black cherry seedlings on plots that were weeded to remove ferns during years 2 through 4 were significantly taller than seedlings on unweeded controls by the end of the 6th year. Yet they still were not as tall as the residual ferns not removed by weeding. Black cherry seedlings beneath aster had overtopped the aster by the end of 6 years and were almost twice as tall as black cherry on weeded fern plots. Reduced height growth of black cherry after 6 years indicated the need for overstory removal. The study results underscore the importance of controlling hay-scented fern prior to a shelterwood seed cutting.
Dynamics of foliar N in Douglas-fir after spring and fall application of ammonium nitrate and urea
Authors: Nason G. E. , Pluth D. J. , Hardin R. T. , McGill W. B.
Published: February 2008

We investigated foliar N dynamics after spring and fall application of ammonium nitrate and urea at 200 kg N•ha−1 to an intermediate productivity 38-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand growing in Humo-Ferric Podzols on Vancouver Island. Douglas-fir responded by increasing: the N concentration of existing foliage and both the concentration and content of N in new shoots. Six months after spring fertilization, N concentration in current foliage averaged 30 and 21 % above that of the control for ammonium nitrate and urea, respectively. Nitrogen concentration of current foliage was increased after 2 years in the ammonium nitrate treatment only. When ammonium nitrate was applied in fall, peak N concentration in current foliage occurred after 6 months (in midspring) at 25% above that of the control. Fall application of urea did not affect current foliage N concentration until the next fall when a 19% increase over that of the control was observed. At the first fall after fertilization (seasons of application combined), ammonium nitrate caused a 26% increment over control in N content of current foliage, whereas urea caused a 13% increase. This superiority of ammonium nitrate over urea was attributed to the nitrate ion. The hypothesis that N uptake into foliage from ammonium nitrate would be greater when applied in spring was not supported.
Nitrogen stress alters root proliferation in Douglas-fir seedlings
Authors: Friend Alexander L. , Eide Marvin R. , Hinckley Thomas M.
Published: February 2008

The proliferation of roots in soil microenvironments was studied to gain an understanding of how nitrogen (N) stress affects root growth. By placing one major lateral root (<10% of the root system) of a Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedling into a small pot (microenvironment) and the remaining roots into a large pot, it was possible to manipulate the growth of a small part of the root system while having only minor effects on the growth of the entire seedling. Nitrogen stress was successfully induced by large-pot treatments and resulted in greatly decreased foliage growth and slightly decreased total fine (<2 mm diam.) root growth. Nitrogen stress had minimal effects on total fine root growth, but large effects on the distribution of growth within the root system. Fine roots grew preferentially in high compared with low N microenvironments, and root proliferation in high N microenvironments was enhanced twofold in N-stressed compared with nonstressed seedlings. The root proliferation response of Douglas-fir seedlings to N stress illustrates a potential means of N-stress compensation. It also implies that root distribution among soil microenvironments may depend not only upon chemical activity of nutrient ions in the rooting environment, but also upon nutrient stress in the whole plant.
Response of black spruce (Piceamariana) ecosystems to soil temperature modification in interior Alaska
Authors: Cleve Keith Van , Oechel Walter C. , Hom John L.
Published: February 2008

This paper reports results of a study designed to examine the control that soil temperature exerts on soil processes associated with nutrient flux, and in turn, on tree nutrition in interior Alaska black spruce ecosystems. Approximately 50 m2 of forest floor in a 140-year-old black spruce ecosystem, which had developed on permafrost, was heated to 8–10 °C above ambient temperature. This perturbation amounted to approximately a 1589 degree-day seasonal heat sum (above 0 °C), 1026 degree-days above the control total of 563 degree-days. The forest floor, surface 5 cm of mineral soil, and soil solution were compared with those of an adjacent control plot to evaluate the change in nutrient content and decomposition rate of the forest floor. The nutritional response to soil heating of current black spruce foliage also was evaluated. Soil heating significantly increased decomposition of the forest floor, principally because of an increase in biomass loss of the O21 layer. The increased decomposition resulted in greater extractable N and P concentrations in the forest floor, higher N concentrations in the soil solution, and elevated spruce needle N, P, and K concentrations for the experimental period. These results are discussed in light of the importance of soil temperature and other state factors that mediate ecosystem function.
Organic sulfur in throughfall, stem flow, and soil solutions from temperate forests
Authors: Homann Peter S. , Mitchell Myron J. , Miegroet Helga Van , Cole Dale W.
Published: February 2008

In the assessment of S cycling in forest ecosystems, solutions passing through the forests are normally analyzed for inorganic SO4; other forms of S are rarely considered. In this study, organic S (estimated as the difference between total S and SO4-S) was measured in canopy and soil solutions from eight forest stands spanning a broad range of overstory and soil types. Organic-S concentrations varied among the different types of solutions and among the forests, with values ranging from 0 to 50 μmol S•L−1. Organic S was ≤10% of total S in precipitation, 5 to 54% in throughfall, 1 to 50% in stem flow, 16 to 46% in O-horizon solution, 11 to 21% in A- or E-horizon solutions, and 0 to 29% in B-horizon solutions. Organic S was positively correlated with organic C and organic N in Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and red alder (Alnusrubra Bong.) soil solutions and in Douglas-fir stem flow (r2 = 0.68 to 0.96, p < 0.001 ). Inclusion of solution organic S in nutrient cycling budgets can alter estimates of S transfers within forests and S transport out of some forest ecosystems.
Growth of western red cedar seedlings in relation to microtopography, forest floor nutrient status, and fireweed and salal on clear-cut sites in coastal British Columbia
Authors: Messier Christian , Kimmins James P.
Published: February 2008

The growth of western red cedar (Thujaplicata Donn) seedlings was studied in relation to microtopography, to forest floor nutrient status, and to fireweed (Epilobiumangustifolium L.) and salal (Gaultheriashallon Pursh) abundance on 4-year-old logged and burned sites dominated by salal on northern Vancouver Island, British Columbia. These relationships were sought to determine some possible factors at the microsite level that influence the growth of western red cedar on recently clear-cut sites. Western red cedar growth and fireweed abundance and height were significantly greater in depressions than on flats and mounds, but these differences were not related to any major differences in forest floor pH, cellulose decomposition, total N and P, and available NH4+, NO3−, and phosphate P as measured using resin bags. The ecological significance of and possible reasons for the lack of correlation found between (i) western red cedar and fireweed growth and (ii) many measures of forest floor nutrient status are discussed.
Variable-quality form in mature jack pine stands: quantification and relationship with environmental factors
Authors: Morris Dave M. , Parker William H.
Published: February 2008

The purpose of this study was to determine quantitatively to what extent various stem, crown, and branching attributes conformed to subjective evaluations of form for jack pine (Pinusbanksiana Lamb.) in northwestern Ontario and which environmental variables were associated with the form-related variation. Six fire-origin stands established on deep soils were selected on the basis of their form and subjectively evaluated as good (2), medium (2), or poor quality (2). Ten dominant trees were randomly chosen from each stand, and 26 attributes were determined for each sampled tree. These attributes were categorized as growth (2), stem form (6), crown form (6), or branch characters (12). Data on surrounding stand conditions and microsite were also collected. Climatic factors for each stand were interpolated from nearby weather station data. These data were analyzed by canonical discriminant analysis. The first function separated the poor-quality stands from the other two classes, while the second function separated the average- from the good-quality stands. Important variables in the first canonical function were related to stem and crown characters, whereas branch characters were also important in the second canonical function. First and second canonical discriminant axis scores were used as two new summary variables representing quantified estimates of jack pine form and were regressed against environmental data. While competition and spacing variables explained much of the observed variation, climatic and soil moisture variables were also important. From the present results it is unclear whether these variables affect form directly or indirectly by modifying competition and spacing variables over the course of stand development.
Gain efficiency in short-term testing: experimental results
Authors: Li Bailian , Williams Claire G. , Carlson W.C. , Harrington Constance A. , Lambeth C.C.
Published: February 2008

Height growth of loblolly pine (Pinustaeda L.) was measured in trees subjected to one of five irrigation and fertilization regimes in a closely spaced genetic test for 3 years. Shoot components of 3rd-year annual height increment were measured over two contrasting treatments. Juvenile height and number of stem units in summer growth length in the fully irrigated and fertilized short-term test regime exhibited (i) the highest juvenile-mature correlations (family mean correlation = 0.41–0.68), (ii) high individual-tree heritabilities (0.38–0.44), which were two- to three-fold higher than older tree values in a conventional genetic test of the same families, (iii) high genetic stability across two extreme short-term test treatments (genetic correlation = 0.61–0.80), and (iv) an efficiency in genetic gain per generation of 81–87% relative to selection on height at age 8 years.
The influence of soil texture and aggregation on carbon and nitrogen dynamics in southwest Oregon forests and clearcuts
Authors: Borchers Jeffrey G. , Perry David A.
Published: February 2008

Soil texture and aggregation on two old, poorly vegetated clearcuts and adjacent forests in southwest Oregon were investigated for their influence on loss of soil carbon (C) and nitrogen (N) in disturbed ecosystems with different soil parent material and texture. We determined C and N concentrations in five particle size fractions to detect changes in the more labile components of soil organic matter. The extent to which the labile components were protected from microbial degradation was tested by estimating increases in N availability (anaerobic incubation) after soil aggregates were sonically disrupted. In comparisons of silt loam and sandy loam soils, the coarser soil had lower total C and N concentrations, lower levels of available N in sonically disrupted soil, and significantly greater decreases in available N associated with clear-cutting; nevertheless, C and N losses from the clearcut with fine-textured soil may have been greater, as shown by lower C and N concentrations in silt and clay particle size fractions. The silt loam soil appeared to have a larger pool of physically protected, labile N, which acts as a "slow-release" mechanism that sustains available N at preharvest levels.
Decomposition and nutrient dynamics of ponderosa pine needles in a Mediterranean-type climate
Authors: Hart Stephen C. , Firestone Mary K. , Paul Eldor A.
Published: February 2008

A litter-bag technique was used to measure decay rates and assess changes in organic and inorganic constituents of ponderosa pine (Pinusponderosa Laws.) needle litter during decomposition over a 2-year period in old- and young-growth forests in the Sierra Nevada of California. Rates of mass loss were among the lowest reported for temperate and boreal forests, with annual decomposition constants of about 0.08 and 0.18 year−1 for the old- and young-growth forests, respectively. Apparently, the temporal separation of warm temperatures and moist conditions found in Mediterranean-type climates severely limits decomposition in these coniferous forests. In the old-growth forest, comparison of estimates of tree nutrient uptake with net releases of nutrients from fine litter during their 1st year of decomposition suggests that recent litter fall potentially acts as a significant source of P, Mg, and K for tree uptake in this forest; in contrast, recently fallen litter acts as a net sink for N, S, and Ca. Despite initially lower indices of litter quality for litter originating from the old–growth relative to the young–growth forest, no significant difference in decomposition rates of these two litter age-classes was found when placed at either site. This result does not support the hypothesis that decreases in decomposition rates during forest development are driven by decreases in the quality of litter fall.
Biomass and nutrients in an Engelmann spruce–subalpine fir forest in north central Colorado: pools, annual production, and internal cycling
Authors: Arthur Mary A. , Fahey Timothy J.
Published: February 2008

Biomass and nutrient dynamics were examined in a subalpine Piceaengelmannii Parry–Abieslasiocarpa (Hook.) Nutt. forest within Loch Vale watershed in north central Colorado by quantifying annual above- and below-ground production, biomass, nutrient pools, and internal nutrient transfers. Subalpine forest covers only 6% of the watershed, and the values reported here refer only to the forested area. Total ecosystem biomass was 42 kg•m−2, of which 30% was soil organic matter, 33% was detrital biomass (including deadwood and forest floor), and 36% was living biomass. Total forest biomass (not including soil organic matter) was 28.9 kg•m−2, of which root biomass was 11%. Net primary production was 520 g•m−2•year−1, of which fine root production was about 27% and foliar production was 30%. Much more N was recycled via fine root turnover than via aboveground litter fall (1.6 versus 0.9 g•m−2•year−1), whereas four times more Ca was returned via litter fall than via fine roots. Compared with other temperate coniferous forests, this subalpine forest had low production. Nutrient resorption contributed between 35 and 38% of the annual requirements of N, P, and K, but only 9% of Ca and 12% of Mg. Although a higher percentage of annual N requirement was met by resorption, this forest used N less efficiently than a similar forest in southwestern Alberta.
Estimation of individual tree volume by importance sampling and antithetic variates from the cylindrical shells integral
Authors: Lynch Thomas B. , Chang Shen-Then , Chandler John P.
Published: February 2008

A method of estimating individual tree volume by importance sampling is developed that is based on the cylindrical shells volume integral. The cylindrical shells volume integral conceptualizes a tree stem as being a solid of revolution comprising a collection of thin cylinders. Previous applications of importance sampling to individual tree volume estimation have been based on the method of slices integral, in which the tree stem is viewed as a solid of revolution comprising a collection of thin disks. Both approaches provide unbiased estimates of individual tree volume for any monotonic tree taper, if it can be assumed that the tree is circular in cross section. An advantage of the cylindrical shells approach is that total tree height need not be measured to accomplish the estimation process, as would be required when using importance sampling estimators based on the method of slices integral. Tree volume estimation via importance sampling based on the cylindrical shells integral requires measurement of stump cross-sectional area, which is usually more easily obtained than total or merchantable height measurements. Both approaches require one or more upper stem diameter measurements. Computer simulation shows that use of antithetic variates with importance sampling reduces the variance of the volume estimate significantly when a paraboloid is used as a proxy taper function.
Spatiotemporal distribution of epicormic shoots and their architecture in branches of Fraxinuspennsylvanica
Authors: Remphrey W.R. , Davidson C.G.
Published: February 2008

Epicormic shoots in the branch systems of Fraxinuspennsylvanica var. subintegerrima (Vahl) Fern, (green ash) were more common on lower order shoots and arose periodically over a number of years, resulting in a greater number in older crown regions. Nevertheless, considerable variation existed among trees, ranging from 3 to 34 epicormic shoots per branch sample. Epicormic shoots were generally located near the distal end of parent shoots, suggesting their origin from persistent buds in these regions. The mean divergence angle of epicormic shoots was almost 10° greater than that of nonepicormic shoots. Mean length did not differ between epicormic and nonepicormic shoots, but the length of daughter terminal shoots extending epicormic shoots was considerably less than the length of those extending nonepicormic shoots. The number of lateral shoots produced by the two shoot types did not differ. The significance of epicormic shoot production to crown development and maintenance is discussed.
Crown and basal area relationships of open-grown southern pines for modeling competition and growth
Authors: Smith W.R. , Farrar Jr. R.M. , Murphy P.A. , Yeiser J.L. , Meldahl R.S. , Kush J.S.
Published: February 2008

Data were collected on open-grown loblolly pine (Pinustaeda L.), longleaf pine (Pinuspalustris Mill.), and shortleaf pine (Pinusechinata Mill.) and analyzed to provide predictive equations of crown width and maximum potential basal area growth for crown competition and growth and yield models. The measurements were taken on 115 open-grown loblolly pine trees and 76 shortleaf pines in southeastern Arkansas. The longleaf pine data consisted of 81 open-grown trees from southern Alabama, Georgia, and Florida. A circle and an ellipse were tested as geometric models of the vertically projected crown. No significant differences between the tree shapes were found based on analyses of length and azimuth of the largest crown diameter, and the circle was chosen as an appropriate model. This indicated that only the distance between trees, not their orientation to one another, need be included in models of crown competition based on crown contact. Predictive equations of mean crown width based on diameter at breast height were fitted for each species for use in models of crown competition. A Chapman–Richards growth rate function with an intercept term was fit to periodic annual inside-bark basal area growth based on initial inside-bark basal area to provide empirical estimates of maximum basal area growth rates for growth and yield modeling of the given species. Additionally, equations to predict double bark thickness as a function of diameter at breast height were fit for each species to facilitate the use of the equations with outside-bark measurements of diameter.
Clonal differences in biomass characteristics, coppice ability, and biomass prediction equations among four Populus clones grown in eastern North Dakota
Authors: Tuskan Gerald A. , Rensema Timothy R.
Published: February 2008

Differences in biomass characteristics and biomass prediction equations were quantified for four hybrid poplar clones: 'Siouxland', 'Robusta', 'Eugenei', and 'Northwest'. Twenty trees per clone were destructively sampled, separated into component parts, and compared using analysis of variance and regression techniques. Significant differences in clonal means were detected for all biomass components. The functional relationship, however, between standing-tree measurements and biomass yields did not generally vary among clones. There were differences in regression equation slopes among clones for leaf green weight, limb green weight, and leaf dry weight. These differences appear to be related to the annual infection of the clone 'Northwest' by Melampsora leaf rust. All clones coppiced satisfactorily despite a late summer harvest. Clonal differences did exist in coppice ability and sprout growth vigor.
Genetic variation in plagiotropic growth in a provenance hybrid cross with Piceaabies
Authors: Johnsen Øystein , Skrøppa Tore
Published: February 2008

Plagiotropism (angle departure from orthotropic growth) was measured on 360 Norway spruce (Piceaabies (L.) Karst.) clones propagated in 2 subsequent years. The clones were members of 20 full-sib families (18 clones per family) from a provenance hybrid factorial cross involving 10 parents of Norwegian (N) and 10 parents of east-European (EE) origin. The clones from the EE × EE crosses showed an average of 17° and 20° in plagiotropism, those from the N × N group showed 3° and 7° in plagiotropism, while the hybrids (EE × N and N × EE) showed 8° and 13° in plagiotropism in 1988 and 1989, respectively. A large family variation was found in the EE × EE and the hybrid groups (11 and 8.5% of total variation, respectively), but variation was small (3.5%) in the N × N group. The clonal component accounted for 10, 12, and 8.5% of total variation in EE × EE, hybrids, and N × N, respectively. Among the plagiotropic clones, some were heterogeneous with a large within-clone variation and others were homogeneous. The year × family and year × clone components were rather large in EE × EE (5 and 9% of total variation, respectively) but smaller in the hybrids and smallest in N × N. The clones with best growth were not among those with the worst plagiotropic growth. The clonal material is ideal for use in future studies on the genetic and physiological regulation of maturation.
Spatial and temporal enlargement of trunk cankers of Phytophthoracinnamomi in red oak
Authors: Robin Cécile , Desprez-Loustau Marie-Laure , Delatour Claude
Published: February 2008

Phytophthoracinnamomi Rands is the agent of ink disease on northern red oak (Quercusrubra L.). Cortical cankers on the trunk are the visible symptoms. The fungus causes necrosis of the cambium and phloem, and the tree reacts by forming xylem callus curls. These features can be dated aposteriori on cross sections. The aim of this study was to describe the spatial and temporal development of cankers on cross-sectioned infected oaks. For each lesion, dates of cambium necrosis and formation of callus were recorded at different heights. The following parameters were measured for each lesion: age, height, rate of development, and length and duration of necrosis and canker. Two hundred sixty-three lesions, on 14 trees, were studied. Trees did not exhibit cankers before 9 years of age. All visible trunk cankers could be related to a collar lesion. Phytophthoracinnamomi spreads upwards and can persist for several years, being active seasonally. In this study cambium necrosis occurred preferentially during the first flush. Twenty-nine percent of the lesions were healed over at the collar after 1 year. The collar was less susceptible than the trunk. The other lesions spread rapidly in the cambium of the trunk, which was very vulnerable. They then progressively healed. Therefore, the canker progress curve was bell shaped.