bluuebunny/crossref_metadata_2025 huggingface dataset:
Early testing of jack pine. I. Phenotypic response to spacing
Authors: Magnussen S. , Yeatman C. W.
Published: April 2008

Six-year results of stem and branch size, stem form, and branch angle in four local jack pine seed lots showed the expected changes caused by variations in available growing space. Spacing, age, and their interaction had significant effects on all traits examined. Tree height was the only variable in which seed lot differences were of practical importance. Offspring from a bulked plus-tree seed lot were significantly taller than offspring from average trees. This difference was more pronounced and persistent among dominant trees in the trial. Statistically significant, but practically unimportant, seed lot × spacing interactions were seen in the diameters of stem and branches. More pronounced interactions are expected to exist among for example half-and full-sib progenies. Juvenile spacing trials are recommended in forest tree breeding programs as they allow assessment under conditions comparable to those in older trials.
Early testing of jack pine.: II. Variance and repeatability of stem and branch characters
Authors: Magnussen S. , Yeatman C. W.
Published: April 2008

Results on within-tree repeatability and among-tree variances of branch angle, stem and branch traits at age 6 years are presented from an intensively managed jack pine trial in the Petawawa National Forestry Institute's nursery (Ontario, Canada). Four local seed lots were tested at spacings of 2, 1, and 0.5 m. The expected response to changing growing space was observed in the mean values of all quantitative traits. Seedlot effects were unimportant. A method to estimate a tree's "genetic" value from multiple measurements is presented. The method is based on phenotypic residuals from analysis of covariance and the within-tree repeatability of a trait. Heteroscedacity of environmental and within-tree variances in the original data was removed in most traits by the procedure applied. Improvement of jack pine timber quality by breeding for wider branch angle is feasible within the four seed lots judged upon a standard deviation of 7° among trees and a within-tree repeatabilities between 0.22 and 0.36. Branch length and branch diameter were less promising traits for improvement.
Extrapolation of synoptic meteorological data in mountainous terrain and its use for simulating forest evapotranspiration and photosynthesis
Authors: Running Steven W. , Nemani Ramakrishna R. , Hungerford Roger D.
Published: April 2008

A model for calculating daily microclimate conditions in mountainous terrain is presented. Maximum–minimum daily air temperatures, precipitation, and dew point are extrapolated from valley stations to adjacent mountain slopes, after making elevation- and aspect-related corrections. The model (MT-CLIM) produces estimates of daily incoming shortwave radiation, air temperature, humidity and vapor pressure deficit, and precipitation for any mountain study site. MT-CLIM was tested against measured meteorological data on six study sites consisting of three north–south slope pairs in western Montana. Correlations between predicted and observed daily conditions on the six study sites for the period April–November 1983 were air temperature, R2 = 0.88–0.92 with standard errors <0.48 °C; relative humidity R2 = 0.63–0.72 with standard errors <15%; radiation R2 = 0.60–0.78 with standard errors <100 W m−2. To test the utility of the model, data from MT-CLIM were used to run the DAYSTRANS/PSN model of evapotranspiration (ET) and photosynthesis (PSN) for western coniferous forests. Seasonal ET calculated from MT-CLIM data deviated by less than 5% from ET calculated from measured meteorological conditions on the six sites. Estimates of seasonal PSN agreed to within 10% of estimates derived from measured meteorological data on all sites except one. For each of the north–south slope study pairs, the combined MT-CLIMDAYTRANS/PSN simulation predicted that north slopes would have higher (5–31%) seasonal PSN than the comparable south slopes, which agrees with observed patterns of forest productivity in this semiarid region.
Syllepsis in Larixlaricina: analysis of tree leaders with and without sylleptic long shoots
Authors: Powell G. R.
Published: April 2008

Nonsylleptic and lightly, moderately, and heavily sylleptic leaders with 0 and 1–8, 9–17, and 18–38 sylleptic long shoots, respectively, were cut from 8-year-old Larixlaricina (Du Roi) K. Koch trees. The leaders showed considerable crookedness but degrees of crookedness were not significantly different among leader classes. Leaders of all classes bore sylleptic short shoots. These sylleptic short shoots were largest at midleader locations and larger on leaders with sylleptic long shoots than on nonsylleptic leaders. The terminal buds on many sylleptic short shoots were of long-shoot type. Some sylleptic short shoots with such buds occurred in mid- and proximal-leader positions, whereas lateral buds of the long-shoot type occurred only in distal-leader positions. Sylleptic long and short shoots greatly increased the numbers of leaves on the leaders. This leaf increase occurred principally on the proximal halves of the leaders where leader diameters also increased. Larger amounts of xylem accounted for most of the diameter increases. Subtending leaf to lateral axis distances increased acropetally among lateral buds and sylleptic shoots, but for the latter, these distances were greatest in the middle parts of the respective zones of occurrence. The large variety of developmental pathways for lateral axes on leaders was discussed.
Decomposition rates and nutrient dynamics in small-diameter woody litter in four forest ecosystems in Washington, U.S.A.
Authors: Edmonds Robert L.
Published: April 2008

Decomposition rates and nutrient dynamics in small-diameter woody litter (twigs, cones, and branches) were studied in four ecosystems in western Washington: high elevation Pacific silver fir (Abiesamabilis (Dougl.) Forbes) and low elevation Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), western hemlock (Tsugaheterophylla (Raf.) Sarg.), and red alder (Alnusrubra Bong.). Conifer twigs decomposed faster (k = 0.14–0.24 year−1) than cones (k = 0.09–0.12 year−1) and branches (k = 0.03–0.11 year−1). Decomposition constants were related better to initial lignin/initial N ratios (r = −0.64) than initial lignin concentrations. N was generally the least mobile nutrient while K was the most mobile. Many nutrients were strongly immobilized in conifer fine woody litter, including N, Mg, Mn, and Ca. There was little immobilization of N in red alder branches. N release from decomposing woody litter appears to be controlled by a critical C/N ratio. This critical C/N ratio, however, was not constant and increased as the substrate decomposition rate increased.
Marginal analysis and cost effectiveness in seed orchard management
Authors: Thomson Thomas A. , Lester Donald T. , Martin Jeanne A.
Published: April 2008

We use marginal analysis for three seed orchard management decisions. First we consider the roguing of a seed orchard established with many untested trees. We show that inferior parents should be rogued to the point where the number of orchard trees times the average expected volume gain of trees from seed produced by that orchard is maximized. Marginal analysis also is useful where one must choose the number of trees to establish in an orchard planted after progeny tests have identified superior parents. The cost of establishing many ramets to meet early seed production goals can be balanced with the projected value of seed. For the example presented, an additional orchard tree is cost effective if its seed is needed at an orchard age of 12 to 15 years. Finally, we use marginal analysis to determine whether to induce a seed orchard to increase its seed production when there is an excess demand for seed. This decision is guided by balancing the cost of the induction treatment with the combined effect of expected increase in seed harvest, the amount of genetic gain, and the discount rate. We present a four-quadrant decision diagram for estimating this balance. In designing tree improvement programs, these analytical techniques can be applied to proposed alternatives as one way to structure decision making and to provide comparable economic assessments from which cost-effective choices can be made.
Tensile force required to pull the main line during out haul in lateral extraction using the Gandai cable logging system
Authors: Ohsato Shoichi , Okawara Shoji
Published: April 2008

The Gandai cable logging system was developed mainly for the operations of selective cutting, small-area clear-cutting, and thinning. The chokerman has to pull a main line on the uphill slope for the lateral extraction during these operations. The parabolic cable theory, which is commonly used for the design of cable logging systems in Japan, was used to derive the general equation for the tensile force required by the chokerman. The minimum value of the tensile force can be obtained by using a graphic solution.
Air and soil temperature limitations on photosynthesis in Engelmann spruce during summer
Authors: DeLucia Evan H. , Smith William K.
Published: April 2008

The relative importance of air and soil temperature as potential limitations to photosynthesis during summer was assessed in Engelmann spruce over its natural elevational range in southeastern Wyoming. Low photosynthetic rates measured at constant temperature, irradiance, and vapor pressure deficit were highly correlated with low minimum (night) air and soil temperature, but at different times during the early summer growth period. Substantial and irreversible reductions in photosynthesis occurred after exposure to night air temperatures of −4 to −5 °C that occurred through mid-June. After middle to late June, decreased photosynthetic rates were correlated with low soil temperature. Correlation analyses indicated that subfreezing air temperature followed by an extended period of low soil temperature were the primary limitations to photosynthesis in early summer. Additional laboratory and field experiments corroborate these field observations.
Relationships between tree crown, stem, and stand characteristics in unthinned loblolly pine plantations
Authors: Sprinz Peter T. , Burkhart Harold E.
Published: April 2008

Empirical and theoretical relationships between tree crown, stem, and stand characteristics for unthinned stands of planted loblolly pine (Pinustaeda L.) were investigated. Readily measured crown variables representing the amount of photosynthetic area or distance of the translocation process were identified. Various functions of these variables were defined and evaluated with regard to efficacy in predicting stem and stand attributes. Linear models were used to evaluate the contribution of the crown variables in predicting stem and stand characteristics. The stem attributes modeled included basal area, basal area growth, diameter at breast height, and diameter growth, while the stand attributes modeled were basal area, basal area growth, arithmetic mean diameter, and mean diameter growth. Crown diameter and crown projection area were particularly important in contributing to model fit and prediction of individual stem characteristics, while sum of crown projection areas was found especially important in stand level equations. As these crown measures developed over time so did corresponding stem and stand attributes.
Root sprouting in American beech: production, survival, and the effect of parent tree vigor
Authors: Jones Robert H. , Raynal Dudley J.
Published: April 2008

Root sprout age-class distributions around American beech trees were measured to characterize production of sprouts under closed canopies. Annual mortality of root sprouts was estimated by static and cohort life table analyses. Sprouts around parent trees with and without beech bark disease were compared to test for effects of lowered parent vigor on sprout production and vigor. Age-class distributions were highly variable, indicating episodic production of sprouts. Trends in the data suggested that (i) for individual parent beech trees, the number of sprouts per age-class decreased exponentially as sprout age increased; and (ii) parent trees with larger diameters had more sprouts, more sprout age-classes, but greater variability in age-class distribution. Life table analyses indicated uniform per capita mortality rates for clumps of sprouts but decreasing mortality with age for individual sprouts within clumps. Low parent vigor, due in part to beech bark disease, was weakly correlated with reduced sprout production, but diseased trees maintained populations of older sprouts that differed little from sprouts associated with nondiseased trees.
Induction of adventitious buds and sprouts on birch seedlings (Betulapendula Roth and B. pubescens Ehrh.)
Authors: Rinne P. , Kauppi A. , Ferm A.
Published: April 2008

The ability of decapitated Betulapendula Roth and Betulapubescens Ehrh. seedlings to form adventitious buds and sprouts was investigated under both laboratory and field conditions, and the occurrence of adventitious buds on stumps of naturally growing adult B. pubescens was also studied. However, all the buds on the stumps proved to be axillary in origin. Disbudding of seedlings induced the development of callus and adventitious bud differentiation in both species. The morphogenetic ability of B. pendula seemed to be very much better than that of B. pubescens, while young plants produced adventitious buds sooner and in greater numbers than older ones. Regeneration occurred both in greenhouses and in the field. Adventitious buds were observed in the callus that formed between the phloem and wood and in wounded areas of the stem about 40 days after decapitation, and some started to sprout about 20 days later. The first leaves of the sprouts were small and structurally simple. The results show that although B. pubescens and B. pendula do not normally produce adventitious buds, they have preserved the ability to form them. Regeneration from these buds is probably important for survival in certain special cases when the seedling is not able to sprout from its dormant buds for some reason.
Changes in light intensity and soil temperature as a result of forest decline on Camels Hump, Vermont
Authors: Perkins T. D. , Vogelmann H. W. , Klein R. M.
Published: April 2008

Light intensity, measured by the anthracene–benzene technique, significantly increased in the montane boreal forest of Camels Hump mountain, Vermont, since the mid- 1960's. The region of increased light corresponds to those elevations where red spruce (Picearubens Sarg.) has declined significantly over the same time period. Soil temperature measured at 15 cm has increased and there is higher week-to-week variability than in the 1960's, especially where canopy decline is most severe.
Compatible crown ratio and crown height models
Authors: Dyer Michael E. , Burkhart Harold E.
Published: April 2008

Several published crown ratio and crown height models were fitted to plantation loblolly pine tree data, but none were considered entirely adequate. A nonlinear model form that yields logical estimates is presented. Required inputs are stand age, tree diameter, and tree height. Both ordinary least squares and seemingly unrelated regression (SUR) were used to estimate model parameters. Cross equation constraints with the SUR procedure result in compatible estimates of crown ratio and crown height for a tree of given height.
Developmental processes in tree root systems
Authors: Coutts M. P.
Published: April 2008

Factors that influence the primary and secondary growth of roots are reviewed in relation to the development of the form of tree root systems. The development of occasional root apices of larger than average diameter is important because they form the main axes that undergo secondary thickening and become permanent members of the woody root system. The formation of these large apices is influenced by injury to, or reduced growth or dormancy of, the subtending main root axis and by proximity to the shoot. The base of the taproot and laterals is seen as a region strongly influenced by shoot activity, resulting in the formation of additional large root apices and enhanced secondary thickening to form the zone of rapid taper in trees, and in the formation of storage organs in some herbaceous species such as radish. The main root axes compete for assimilates and dominance is established between them at an early age. The unequal growth of competing lateral roots is influenced by the local environment of the roots of primary structure. The role of root apices on secondary growth is discussed with reference to work on herbaceous species. In trees the local environment has some direct effects on the root cambium, but such effects appear to be less important than the activity of the roots of primary structure. A hypothesis is developed incorporating the Japanese Pipe Theory for the allocation of assimilates for the secondary growth of tree roots.
Understanding root growth capacity: theoretical considerations in assessing planting stock quality by means of root growth tests
Authors: Burdett A. N.
Published: April 2008

Laboratory assays for measuring the root growth capacity (RGC) of forest tree seedlings were first developed in the belief that root extension immediately after planting is a major determinant of establishment success. An assumption underlying the development of these tests was that root growth under standardized conditions in the laboratory is indicative of root growth under the generally quite different and often highly variable conditions in the field. Evidence in support of this assumption is slight. Recently, it has been proposed that RGC affects seedling performance, not directly, but by virtue of a correlation with cold hardiness or other types of stress resistance that directly affect performance. For this hypothesis, also, the evidence is slight. There is a need for a clearer understanding of the relationship between RGC and seedling establishment to decide how best to measure and interpret RGC as a gauge of stock quality. This is illustrated by a discussion of the optimum conditions for measuring RGC and of the quantitative relationship between RGC and early performance of planted stock.
Needle conductance and root egress of containerized Scots pine and Norway spruce seedlings after surface and deep planting
Authors: Högberg Karl-Anders
Published: April 2008

Surface planting and deep planting were compared with respect to water uptake and root development in the early stage of field establishment. The material consisted of containerized Scots pine (Pinussylvestris L.) and Norway spruce (Piceaabies (L.) Karst.) seedlings. For both species, surface planted seedlings showed less root egress 5 weeks after planting compared with deep planted. Needle conductance was lower for surface planted than deep planted pine seedlings. For pine seedlings high correlation was found between root egress and needle conductance 5 weeks after planting for surface planting but not for deep planting. It is concluded that surface planting increases the water stress risk during establishment. Evaporative water loss from the root ball and the upper soil layers is discussed as the main cause to this effect.
Vertical root distributions of northern tree species in relation to successional status
Authors: Gale M. R. , Grigal D. F.
Published: April 2008

Measurements of root biomass, number, diameter, and length by soil depth for northern tree species were assembled from 19 published papers, yielding a total of 123 vertical root distributions. Species were classified into three tolerance classes based on successional status. A nonlinear function, Y = 1 − βd, where Y is the cumulative root fraction from the soil surface to depth d in centimetres, was fit to the data for each excavation. The regression coefficient, β, was considered to be a measure of vertical root distribution and was used as a response variable to test whether significant differences in vertical root distributions existed among tolerance classes. Early successional or intolerant species had a significantly greater proportion of roots occurring deeper than did late successional or tolerant species. Differences in vertical root distributions are presumed to be related to the inherent genetic potential of early successional species for deep exploitation of a more homogeneous substrate, resulting from either geologic deposition or nutrient and water redistribution following forest disturbance. Early successional species are also able to adapt to sites limiting in water and nutrients because of their ability to exploit larger volumes of soil. Late successional or shallow-rooted species are better adapted to sites where resources are concentrated near the soil surface as the result of biocycling and soil development.
Basal and maintenance respiration of mycorrhizal and nonmycorrhizal root systems of conifers
Authors: Marshall John D. , Perry David A.
Published: April 2008

We measured CO2 efflux from root systems of mycorrhizal and nonmycorrhizal conifer seedlings planted in silica sand and maintained in darkness for 11 to 15 days. We first compared methods of isolating the root system for root respiration measurement using Douglas-fir seedlings (Pseudotsugamenziesii (Mirb.) Franco). Shoot excision effectively isolated the root system and affected total root respiration only slightly. We used this technique to compare respiration rates of mycorrhizal and nonmycorrhizal root systems of ponderosa pine (Pinusponderosa Laws.) seedlings. Some seedlings were uninoculated; others were infected with an ectomycorrhizal species (Laccahalaccata or Hebelomacrustuliniforme) or an unidentified ectendomycorrhizal species. After shoot excision, respiration rates declined within 48 h to a "maintenance" respiration rate. Over the next several days, the respiration rate continued to decline to a much lower "basal" rate typical of nonphotosynthetic seedlings depleting their reserves. The maintenance respiration rate of the Laccaria-infected seedlings was significantly lower than those of the other treatments. The basal respiration rates of the two ectomycorrhizal treatments (Laccaria and Hebeloma) were lower than those of the other groups. Such reductions in respiration rate might strongly affect root longevity and whole-plant carbon budgets.
Mycorrhizal and pathological associations of dematiaceous fungi in roots of 7-month-old tree seedlings
Authors: Wilcox Hugh E. , Wang C. J. K.
Published: April 2008

Colonizing behaviors of five dematiaceous fungi that variously form ectomycorrhizal, ectendomycorrhizal, or pseudomycorrhizal associations with roots were studied at pH 3.0 and 5.7. Species selected were five Hyphomycetes, viz., the three new species Phialophorafinlandia, Chloridiumpaucisporum, and Phialocephalafortinii; the well-known Phialocephaladimorphospora; and Cenococcumgeophilum. Control seedlings and those inoculated with C. paucisporum, P. fortinii, and C. geophilum were badly stunted and showed little growth at pH 3, whereas moderate growth of roots and seedlings was exhibited by ectendomycorrhizal P. finlandia and pathogenic P. dimorphospora. At pH 5.7, P. fortinii seedlings were mostly dead and those with P. dimorphospora were more sparsely developed than at pH 3. The controls as well as the remaining fungal associations were healthy at pH 5.7. Phialophorafinlandia and C. paucisporum associations were ectendomycorrhizal but C. geophilum associations were ectomycorrhizal. The nature of the mycorrhizal association, whether ecto- or ectendo-mycorrhizal, was largely controlled by the host. Structures such as sclerotia were determined by the fungus. Anatomical features of the various associations are shown in accompanying photographs.
Analysis of some sources of error in methods used to determine fine root production in forest ecosystems: a simulation approach
Authors: Kurz W. A. , Kimmins J. P.
Published: April 2008

Fine root production rates are most commonly calculated from periodic measurements of live and dead fine root biomass. The accuracy of production estimates based on this method is very sensitive to violations of the inherent assumptions, particularly the assumption that the processes of fine root production and mortality are temporally separate. A simple model was used to simulate data for a variety of seasonal patterns of live and dead fine root biomass. Fine root production and mortality rates were calculated from these simulated data using two different computational methods. Comparison of the calculated rates with the known rates (the rates used to generate the seasonal patterns) revealed that violations of the above assumptions can result in inaccurate rate estimates. When fine root production and mortality occur simultaneously within a sampling interval, the calculated production rate will greatly underestimate the true value. Additional error in the rate estimates may result from sampling error associated with the fine root biomass data. The model suggested that sampling error can cause either overestimation or underestimation of fine root production.
Mycorrhizae, mycorrhizospheres, and reforestation: current knowledge and research needs
Authors: Perry D. A. , Molina R. , Amaranthus M. P.
Published: April 2008

Although not a panacea, management of mycorrhizae and associated organisms is an important reforestation aid. Its three major components are protection of the indigenous soil community and evaluation of inoculation needs, integration of inoculation programs into existing reforestation technology, and research. Clear-cutting frequently results in reduced mycorrhizae formation, particularly when reforestation is delayed and no other host plants are present to maintain fungal populations. Implications of such reductions for reforestation vary with environmental factors and tree species. Adequate mycorrhiza formation is especially critical for ectomycorrhizal trees growing on poor soils or in environments where seedlings must establish quickly to survive. It may also be important where early successional, noncrop plants do not support the same mycobiont as the crop. In such circumstances, a self-reinforcing trend may develop, with poor mycorrhiza formation reducing seedling survival and poor tree stocking leading to further loss of mycorrhizal inocula. Inoculating nursery seedlings with mycobionts holds promise for improving outplanting performance only if site-adapted fungi are used. A practical alternative is to improve nursery practices to enhance natural populations of mycorrhizal fungi. Seedlings leaving the nursery with diverse mycorrhizae may perform better than those leaving with only one or a few nursery-adapted types. Research is needed in three broad areas: on adaptations of mycorrhizal fungi to particular environmental factors; on interactions between tree seedlings and processes occurring within the sphere of influence of roots (the rhizosphere) or of mycorrhizal roots (the mycorrhizosphere); and on the role of mycorrhizae and associated organisms in ecosystem structure and processes, particularly nutrient cycling, plant-plant interaction, and soil structure.
The influence of low soil temperature on the growth of vesicular–arbuscular mycorrhizal Fraxinuspennsylvanica
Authors: Andersen C. P. , Sucoff E. I. , Dixon R. K.
Published: April 2008

Green ash (Fraxinuspennsylvanica Marsh.) seedlings were either inoculated with Glomusetunicatum or not inoculated and grown for approximately 5 weeks under glasshouse conditions to permit root colonization with vesicular–arbuscular (V–A) mycorrhizae. Two experiments were conducted to characterize V–A mycorrhizae influence on seedling growth at low root temperature. In experiment 1, seedlings were subjected to four root zone temperatures ranging from 7.5 to 20 °C for 24 days to measure leaf area and plant height on intact seedlings. In experiment 2, seedlings were exposed to root temperatures of 12.0, 16.0, and 20.0 °C for 30 days and seedlings were destructively harvested at 6-day intervals to measure growth variables and biomass distribution. Results of experiments 1 and 2 were similar. In experiment 1, leaf area growth of mycorrhizal seedlings was significantly greater than nonmycorrhizal controls at all temperatures. Relative leaf area growth rate was greater in mycorrhizal than nonmycorrhizal seedlings at 7.5 and 11.5 °C, similar between treatments at 15.5 °C, and greater in nonmycorrhizal seedlings at 20.0 °C, differences possibly resulting from the larger size of mycorrhizal seedlings at the start of the temperature treatments. In experiment 2, temperature treatments were imposed on seedlings of the same size. Mycorrhizal seedlings had greater leaf area growth rates and relative leaf area growth rates than nonmycorrhizal seedlings at all temperatures. Phosphorus concentrations and total P content in roots and leaves did not differ significantly between mycorrhizal treatments at any temperature; however, mycorrhizal seedlings had consistently greater leaf P content than nonmycorrhizal controls. Glomusetunicatum actively stimulates green ash growth at moderately low root temperatures.
Combined effect of soil nitrogen and phosphorus on nodulation and growth of Robiniapseudoacacia
Authors: Reinsvold Robert J. , Pope Phillip E.
Published: April 2008

Black locust (Robiniapseudoacacia L.) is a fast growing leguminous tree capable of forming a symbiotic association with Rhizobium spp. Since nodulation of legumes is often affected by available soil nutrients, a greenhouse study was conducted to determine the combined influence of different levels of added nitrogen and phosphorus on nodulation, N2 fixation, and growth of black locust. Black locust seedlings were grown in pots for 30, 60, and 105 days in 16 nutrient combinations (4 levels of P × 4 levels of N). All pots were inoculated with rhizobial isolate B143. As the level of P was increased, the number of nodules per plant, nodular dry weight, shoot height, and dry weights of stem, leaves, and total plant also increased. In contrast, the number of nodules and nodular dry weight were inhibited at high (100 mg N kg−1) and low (0 mg N kg−1) levels of added N as compared with the medium levels (25 and 50 mg N kg−1). In addition, the interaction between the N and P factors was significant for plant and nodule dry weights, acetylene reduction rates, and foliar concentrations of N and P.
Influence of soil compaction and vesicular–arbuscular mycorrhizae on root growth of yellow poplar and sweet gum seedlings
Authors: Simmons G. L. , Pope P. E.
Published: April 2008

A greenhouse study was conducted to determine the influence of soil compaction on root growth of yellow poplar (Liriodendrontulipifera L.) and sweet gum (Liquidambarstyraciflua L.) seedlings grown in association with the mycorrhizal fungi Glomusmacrocarpum Tul. and Tul. or G. fasciculatum (Thaxt) Gerd. and Trappe. Seedlings were transplanted into pots that contained silt loam compacted to bulk densities of 1.25, 1.40, or 1.55 Mg m−3. Fungal chlamydospores or control filtrates were used to inoculate seedlings. Weight and length of yellow poplar roots were significantly greater at the lower bulk densities than at the highest bulk density, but fibrosity of the root system was unaffected by increasing bulk density. Weight, length, and fibrosity of the sweetgum root system decreased significantly with each increase in bulk density. Inoculated yellow poplar seedlings had greater root weight at each bulk density than noninoculated seedlings, but root length was not influenced by mycorrhizal treatments at higher bulk densities. Fibrosity of yellow poplar roots varied by mycorrhizal treatment at each bulk density. Results indicate that for yellow poplar, compaction effects may outweigh mycorrhizal benefits at higher bulk densities. At each bulk density, sweet gum seedlings inoculated with G. fasciculatum showed the greatest root growth, suggesting that effects of compaction can be alleviated for sweet gum by inoculation with this mycorrhizal fungus.
Ectomycorrhizal and ectendomycorrhizal associations of Phialophorafinlandia with Pinusresinosa, Picearubens, and Betulaalleghaniensis
Authors: Wilcox H. E. , Wang C. J. K.
Published: April 2008

Mycorrhizal associations formed by Phialophorafinlandia in Pinusresinosa were both ectomycorrhizal and ectendomycorrhizal with randomly distributed clusters of spherical hyphae within cells of the cortex. The ectomycorrhizal condition was common for short distances in the apices of short roots and in smaller diameter long roots, but intracellular invasion from the Hartig net occurred proximal to this zone, resulting in an ectendomycorrhizal structure. In large diameter long-root branches both conditions were found at different positions along the root axis. In addition, sclerotia-like inclusions occurred in the inner cortical cells, often radially opposite to the protoxylem. Mycorrhizal associations in Picearubens and Betulaalleghaniensis were predominantly ectomycorrhizal in all roots; sclerotial bodies could be present in the inner cortex of both hosts. The Hartig net extended to the endodermis in the spruce, but it surrounded only the epidermis in birch. The epidermal cells of birch ectendomycorrhizae elongated radially and obliquely to the root surface, but in spruce the mycorrhizal condition had no effect on radial dimensions of cortical cells.
Armillaria root rot in Wisconsin aspen sucker stands
Authors: Stanosz G. R. , Patton R. F.
Published: April 2008

Roots of 50 healthy-appearing dominant or codominant aspen suckers were examined for signs of Armillaria root rot in each of nine stands (three each 3, 9, or 15 years after clear-cutting). Lesion numbers, sizes, and positions were also recorded for two of these stands of each age. Infection had occurred by rhizomorph penetration, mycelial growth through roots from parent stumps, and by contact with colonized roots and was only infrequently associated with obvious injuries. Rot incidence increased as a function of stand age, with > 70% of sampled trees affected in 15-year-old stands. More lesions per infected tree and shorter distances from stems to nearest lesions also occurred in the 15-year-old stands. There colonization extended to stem bases in > 25% of infected root systems and to within 10 cm of stem bases in > 50%. Results indicate the potential for losses caused by Armillaria root rot in aspen sucker stands as they continue to develop and approach harvest age.
Armillaria root rot in aspen stands after repeated short rotations
Authors: Stanosz G. R. , Patton R. F.
Published: April 2008

Aspen suckers and stump/root-collar sprouts were sampled in short-rotation plots established by the U.S. Forest Service in Minnesota and by the Petawawa National Forestry Institute in Ontario. Roots exhibited lesions and decay typical of Armillaria root rot. Infection had occurred by direct rhizomorph penetration, entry of rhizomorphs through stubs of previously cut sprouts, and growth of mycelium through proximal parent roots. Stump/root-collar sprouts were more frequently colonized than suckers. Incidence was highest in the Minnesota plot, sampled 5 years after the start of the third 8-year rotation, where 11 of 12 stump/root-collar sprouts and 12 of 18 suckers were infected (77% overall). After three or more rotations of 4 or 5 years in both locations, sprouting was severely reduced and sproutless stubs from previously cut sprouts were invariably colonized. After successive rotations in all plots, decreases in stem numbers and sizes have occurred. Thus, Armillaria root rot may limit rotation length and the number of times aspen stands can be successfully vegetatively regenerated.
Chemosystematic studies in the genus Pinus. VI. General survey of the leaf oil terpene composition of lodgepole pine
Authors: Rudloff E. Von , Lapp Martin S.
Published: April 2008

The leaf terpene composition of 645 individual lodgepole pine trees and 79 bulked samples from 111 different sites or provenances and from one putative and three western jack pine populations (10 trees each) were analyzed by gas chromatography. Numerical analysis by a centroid cluster analysis of the mean squared Euclidean distances was carried out, and percentile distributions of the individual terpenes were plotted. The data obtained confirmed the previous subdivision into the major terpene pattern types A, B, and C (or H) and five subgroups (based on the high modes in bimodal distributions); four additional subgroups were added. Except for typical coastal populations, inter- and intra-populational terpene pattern variation was high. Centroid clustering and assignment of terpene types and subgroups lead to some distinct geographical groupings. Coastal populations (ssp. contorta) were found to be rather unifornm and only a minor difference appears to exist between northern and southern populations. Those near Haines, Alaska, the Skeena Valley, southeastern Vancouver Island, and the Puget Sound showed intermediacy with interior (ssp. latifolia) stands. The Fort Bragg (ssp. bolanderi) and Samoa populations from northern coastal California contained many trees with unique terpene patterns. The interior populations (ssp. latifolia) were highly variable and inverse frequencies of the type A (high near the coast) and type B (high in and near the Rocky Mountains) were recorded in several west-east transects. Introgression with jack pine, as measured by the frequency of type C/H patterns, was extensive in northeastern Alberta and the Peace River area of British Columbia. However, some difficulty in describing recent introgression was encountered. A unique (possibly archaic) population was encountered at Petitot River. The ssp. murrayana from the southern Cascades of Oregon and northern California could not be distinguished from ssp. latifolia further north by the terpenoid data.
Fungi associated with seeds of eastern white pine and white spruce during cone processing and seed extraction
Authors: Mittal R. K. , Wang B. S. P.
Published: April 2008

Using standard moist-blotter and potato-dextrose-agar tests, 13 species of fungi were isolated from seeds and cone scales of Pinusstrobus and 17 species from Piceaglauca. Most fungi were common to both hosts but varied considerably in prevalence on seeds during cone processing and seed extraction. Alternariaalternata, Aureobasidiumpullulans, Cladosporiumcladosporoides, C. herbarum, Fusariumsporotrichioides, Mucorhiemalis, Penicilliumaurantiogriseum, and Rhizopusnigricans were associated with more seeds than other species identified. In closed cones on trees the seeds were usually free from fungi that developed and spread during cone processing and seed extraction. Seeds extracted from cones that were kept on the forest floor showed more fungal contamination than those brought to the laboratory immediately after collection. Seed moisture content gradually decreased, while germination increased between cone collection and final seed conditioning.
Tree species and urea treatment effects on sulfur and metals in throughfall and stemflow of some eastern Canadian forest stands
Authors: Mahendrappa M. K.
Published: April 2008

Concentrations and quantities of S, Al, B, Cu, Fe, Mn, Ni, Pb, and Zn were determined in throughfall (TF) and stemflow (SF) samples collected from 1971 to 1981 in six softwood and three hardwood stands located at the Acadia Forest Experiment Station in central New Brunswick, Canada. Analyses were carried out using freeze-dried total solids in samples of TF, SF, and rainwater. The respective volume weighted average concentrations (for 1971–1981) of Al, B, Cu, Fe, Mn, Ni, Pb, and Zn in the bulk precipitation were 18, 3, 5, 18, 45, 0.56, 27, and 96 μgL−1. The volume weighted average concentration of S in rainwater for the 1971–1981 period was 1.30 mg L−1. In the TF of each species the concentrations of Mn and B were significantly higher than those in rainwater, whereas the reverse was true for the concentrations of Ni, PB, and Zn. There were significant differences among species in both concentrations and deposition rates of various elements. Fertilizer treatment of the stands had significant effects on the quantities of nutrients cycled as TF. The concentrations of various elements in the SF samples were consistently higher than those in the rainwater. The deposition rates of these, however, were comparatively less than those in TF. The quantities of elements cycled in SF differed significantly among species. The ratios of the quantities of nutrients cycled by TF and SF combined and those in the rainwater indicate that Zn is absorbed from rain by the tree canopies, and Mn, Cu, and B are released. The results suggest that the quantities of S and metals cycled in forest ecosystems are functions of tree species and of the nutritional status of tree species.
La variabilité alloenzymatique des hêtraies dans les sous-domaines medio- et eu-atlantiques d'Europe
Authors: Comps B. , Barrière G. , Merzeau D. , Letouzey J.
Published: April 2008

One hundred and four beechwoods located in the Atlantic range of western Europe have been analysed for four polymorphic enzymatic markers. The most diverse populations are mainly found in southern regions (Spain, Pyrenees, Aquitaine), the Pyrenean ones being characterized by the greatest diversity. Allelic variations are noticeable from west to east and then towards the north; they are mostly independent from ecological parameters. Only one locus (peroxydases 1) seems to depend on selection effect (greater polymorphism at high altitude); however, the very important total diversity of Pyrenean beechwoods may be a response, at least partly adaptative, to the large variety of microhabitats found within mountain populations.
Distribution of pine wilt disease with respect to temperature in North America, Japan, and Europe
Authors: Rutherford T. A. , Webster J. M.
Published: April 2008

In regions of North America and Japan where the pinewood nematode, Bursaphelenchusxylophilus, and its insect vectors occur, pine wilt disease in susceptible pines appears to be expressed only where the mean air temperature exceeds 20 °C for protracted periods. In these warm areas, susceptible pines grow disease-free only at the cooler, high elevations. Pines resistant to pine wilt transcend the 20 °C temperature threshold without becoming diseased. There are no reports of susceptible pines dying of pine wilt in those regions of Europe, North America, or Japan where mean summer air temperatures are less than 20 °C, despite the presence of pinewood nematode and its vectors in these regions. Bursaphelenchusxylophilus is found throughout most of North America; has been reported from Siberia, China, and France; and is regarded as an introduced pathogen in Japan. We hypothesize that it occurs throughout most taiga forests of the northern hemisphere where predominantly cool climates prevent widespread expression of pine wilt disease. The cool climates of much of Europe, North America, and Asia mitigate against the occurrence of pine wilt disease should B. xylophilus be inadvertently introduced. Susceptible pines that are transplanted from cool to warm regions will be at risk to the disease.
Statistical efficiency of six progeny test field designs on three loblolly pine (Pinustaeda L.) site types
Authors: Loo-Dinkins Judy A. , Tauer C. G.
Published: April 2008

The environmental variance, defined in this study to include all nonfamily variances, associated with family mean estimates for height were compared among six progeny test field designs on three loblolly pine (Pinustaeda L.) progeny test sites in southeastern Oklahoma and southwestern Arkansas. Twenty-five-tree (or 30-tree) square (or almost square) plots, 5- and 10-tree row plots, 5-tree noncontiguous plots, 2-tree row plots, and single-tree plots were compared. The 5-tree noncontiguous, 2-tree, and single-tree plot designs consistently resulted in lower environmental variance associated with family means than the larger plots. The noncontiguous plot design resulted in environmental variances almost as low as those for the single-tree plot design, except on a site with a strong gradient. The environmental variance associated with family means was as small with 30 trees per family arranged in single-tree or 5-tree noncontiguous plots as with 60 trees per family arranged in 5-tree row plots on the most uniform site.
Some climatic aspects of biomass productivity of white spruce stem wood
Authors: Jozsa L. A. , Powell J. M.
Published: April 2008

Biomass productivity was determined for white spruce (Piceaglauca (Moench) Voss) in the boreal forests of Alberta, the Northwest Territories, and Manitoba. Comparisons were made between southern and northern locations, between eastern and western transect locations, and between older (200 + years) and younger (110 years) trees. At 13 sampling locations, X-ray densitometric tree ring data were obtained from the base of the stem, breast height, and from five points equidistant along the stem. Markedly higher stem wood biomass productivity was found for the 110-year-old trees than for the 210-year-old trees in Alberta; average ring weights were 3.8 and 1.2 g for the first 100 years of growth in 1 cm thick disks at breast height. These results suggest that climatic warming since the end of the Little Ice Age (ca. 1850) has resulted in higher biomass productivity in the Canadian boreal forest.
Effect of root competition and nitrogen on growth and mineral content of Abiesfraseri
Authors: Warren Stuart L. , Skroch Walter A. , Hinesley L. Eric
Published: April 2008

Three-year-old (3 + 0) Fraser fir seedlings (Abiesfraseri (Pursh) Poir.) were grown in a controlled-environment chamber under four N regimes, with and without root competition from orchard grass (Dactylisglomerata L.) or white clover (Trifoliumrepens L.). New shoot, stem, and root growth of Fraser fir were harvested 30, 60, and 90 days after budbreak. In the absence of root competition, dry weight and N content increased in a significant curvilinear manner with increasing N. With root competition, dry weight decreased linearly with increasing N, while N content increased linearly with increasing N levels. Responses of P and K content varied with seedling part. Cal content was not affected by root competition, while Mg content decreased in all seedling parts for trees grown with root competition. Orchard grass decreased growth and nutrient accumulation more than white clover.
Fire damage, mortality, and suckering in aspen
Authors: Brown James K. , DeByle Norbert V.
Published: April 2008

Relationships among fire characteristics, fire damage, tree mortality, and sucker response in Populustremuloides Michx. are described. Circumference charred averaged more than 75% on trees killed and less than 50% on live trees. Average char heights ranged from 0.5 m in low severity fire to 1.5 m in high severity fire. Logistic regression analysis showed that probability of mortality was strongly related to diameter at breast height (dbh), char height, and circumference charred. Char heights of 30 cm had a 90% probability of killing aspen less than 25 cm dbh. Bark thickness at breast height and 10 cm aboveground, which relates to fire resistance, related strongly to tree dbh. Bark thickness was the same at sidehill, downhill, and uphill positions. Minimal flame heights required to kill aspen with 90% probability ranged from 10 cm for a 10-cm dbh tree to 60 cm for a 25-cm dbh tree. Number of suckers per hectare on three burns varied from 9 880 to 57 570 the 1st year following fire and from 7 060 to 21 240 4 years after the fire. Depth of sucker origin ranged from 0.2 to 18 cm and was related to fire severity. Sucker density varied greatly between plots and was not significantly related to fire severity.