bluuebunny/crossref_metadata_2025 huggingface dataset:
Approximating natural landscape pattern using aggregated harvest
Authors: Carlson Matthew , Kurz Werner A.
Published: April 2008

Successful implementation of the natural disturbance model for timber harvest is hindered by the lack of strategies to approximate landscape fire pattern. In the forests of Alberta, Canada, the fire regime is dominated by large fires that create large regions of same-aged forest. Current forestry practices disperse harvest blocks across the landscape, causing increased fragmentation as compared with fire. Aggregating harvest blocks is one potential strategy to improve approximation of natural landscape pattern. We used a simulation approach to compare landscape pattern created by aggregated harvest strategies, the current dispersed harvest approach, and the natural disturbance regime for a 270 000 ha forest landscape in northeastern Alberta. Compared with dispersed harvest, aggregated strategies increased compatibility with natural landscape pattern by reducing fragmentation. Capacity to aggregate harvest declined when the constraint of maintaining a constant proportion of deciduous to coniferous harvest was included. We conclude that aggregated harvest can improve implementation of the natural disturbance model by bringing several landscape metrics closer to the conditions that fall within the natural range of variability. Aggregated harvest alone, however, performed poorly at maintaining interior old forest, emphasizing that an explicit old-forest strategy is also required.
The effect of collector size on forest litter-fall collection and analysis
Authors: McShane M. C. , Carlile D. W. , Hinds W. T.
Published: April 2008

Litter fall is commonly collected for a variety of ecological studies. This study was designed to test the effect of collector size on the precision of forest litter-fall estimates and on the time involved in laboratory sample sorting. Collectors varied in size from 0.010 to 0.933 m2 and were physically nested, the smaller units within larger units. Ten of these collector combinations were randomly placed on a 1-ha plot in a Douglas-fir/western hemlock (Pseudotsugamenziesii (Mirb.) Franco/Tsugaheterophylla (Raf.) Sarg.) stand in H. J. Andrews Experimental Forest. Collections were made monthly and records were kept of the time required to sort the litter into needles, epiphytes, and miscellaneous categories. Based on a definition of precision as ±10% of the mean, 90% of the time, results indicate (i) that the cost of obtaining precise estimates of needle fall decreases with decreasing collector size to 0.010 m2, (ii) that collectors of any size can be used to obtain estimates of total litter fall if the number of collectors required to obtain precise results is determined, and (iii) that precise estimates of epiphyte biomass require large numbers of samplers and are not cost effective.
Sensitivity of Pinusponderosa foliage to airborne phytotoxins: use in biomonitoring
Authors: Rice Peter M. , Boldi Robert A. , Carlson Clinton E. , Tourangeau Phillip C. , Gordon Clarence C.
Published: April 2008

Pinusponderosa Laws. foliage from a relatively nonpolluted area (SO2 ≤ 5.2 μg/m3, annual average) was compared with foliage from a more polluted area (75 μg/m3, annual maximum average) over a 6-year period. Total sulfur and fluoride concentrations, frequencies of basal needle injury and healthy needles, and percent needle surface area affected (chlorotic and necrotic) classified as tip necrosis, mottle, and total necrosis were substantially higher at the polluted site and were judged to be sensitive characteristics. Two years following study inception, the first 700 MW of a planned 2100-MW coal-fired electric generating facility began operating in the nonpolluted area. No consistent changes were noted in the foliar characteristics measured in the nonpolluted area since power-plant start-up, and it is concluded that the facility's emissions did not measurably impact the pine ecosystem during the early years of operation.
Effect of light, nitrogen fertilization, and mycorrhizal fungi on growth and photosynthesis of lodgepole pine seedlings
Authors: Ekwebelam S. A. , Reid C. P. P.
Published: April 2008

Seedlings of lodgepole pine (Pinuscontorta Dougl.) were grown for 10 weeks without eetomycorrhizae in the greenhouse at three levels of irradiance (low, medium, and high) and ammonium nitrate (3, 62, and 248 ppm N). At 10 weeks, inoculation with either Pisolithustinctorius (Pers.) Coker and Couch or Suillusgranulatus (L. ex Fr.) O. Kuntze was superimposed on light and nitrogen treatments, and the seedlings were grown for an additional 6 weeks. Mycorrhiza formation increased with increase in irradiance, while fertilization with 62 ppm N resulted in greater mycorrhiza formation than either 3 or 248 ppm N. Further, inoculated plants had significantly greater biomass and took up more phosphorus than nonmycorrhizal seedlings. Inoculation with P. tinctorius and S. granulatus resulted in photosynthetic rates of 1.87 and 1.85 mg CO2•dm−2•h−1, respectively, significantly greater than nonmycorrhizal plants (1.41 mg CO2•dm−2•h−1). Although the increase in growth of the mycorrhizal seedlings was associated with increased photosynthesis, the magnitude of this response depended on specific combinations of irradiance and nitrogen fertilization. These results emphasize the importance of interactions among irradiance, nitrogen fertilization, and mycorrhiza development in the growth of containerized seedlings.
Modeling methods for a two-state system with continuous responses
Authors: Hamilton Jr. David A. , Brickell James E.
Published: April 2008

A probabilistic two-step method of analysis is described that overcomes the problems associated with using a single model to analyze data drawn from a two-state system. The two steps of the analysis are (i) to determine the probability that an observation with given characteristics falls in each of the two states of the system and (ii) to estimate the response of the dependent variable in each of the two states as a function of characteristics of observations. Estimating cull volume in standing trees provides an example. This analysis results in two component models that more closely describe the process of interest than is possible with any single model. Statistically sound approximations to confidence intervals and tests of hypotheses for the parameters of each of the component models may be computed.
Population studies of white spruce. I. Effects of self-pollination
Authors: Fowler D. P. , Park Y. S.
Published: April 2008

The effects of self-pollination in white spruce, Piceaglauca (Moench) Voss, were examined in 20 trees in three populations. The most drastic effect is the increased frequency of empty seeds which averages over 90%, and is 5 to 22 times higher than that from comparable cross-pollinations. The average numbers of embryonic lethal equivalents, although highly variable for individual trees, averaged 8.0, 9.1, and 12.9 for the three populations. Self-pollination also resulted in slightly lower germination and reduced survival. The total number of lethal equivalents affecting seed yield, germination, and survival to age 17 years is estimated as 12.6. The effect of selfing on growth becomes evident at age 2 years and increases to age 17 years when seedlings from self-pollinations averaged 44.5% shorter and 63.7% smaller diameter than seedlings from unrelated matings.
Phenotypic selection in Betulapapyrifera
Authors: Stanton Brian J. , Canavera David S.
Published: April 2008

Phenotypically superior trees of Betulapapyrifera Marsh, were identified on the basis of their breast height stem diameters in two even-aged stands in western Maine. The growth superiority of each of the candidate trees was evaluated further using one of three different selection methods. Two methods were based on mean annual volume increment and differed in regard to their use of comparison trees. Selected trees were those which grew the most volume throughout the life of the stand. In the third procedure, periodic basal area increment was compared with the estimated basal area increment using an equation incorporating crown surface area as an independent variable. Trees rated as most superior were those which produced the largest increment in relation to crown size. Open-pollinated progenies of selected and control trees were evaluated for height growth and stem diameter in a greenhouse trial. Although significant differences in height existed among the selection methods, no one method was successful in identifying trees whose progenies, as a group, were significantly taller than the average of the control progenies.
Using derived demand techniques to estimate Ontario roundwood demand
Authors: Nautiyal J. C. , Singh B. K.
Published: April 2008

Derived demand for roundwood created by the three major forest-products industries in Ontario from 1952 to 1980 was estimated from the production functions of the industries. The Cobb–Douglas function represents the lumber and the veneer and plywood industries, and the constant elasticity of substitution (CES) function represents the pulp and paper industry. In all three industries, the derived demand for roundwood is price inelastic. A theorem that the sum of partial price elasticities of derived demand when output of the final product is held constant is equal to zero has been proved. Demand by the lumber industry showed regular fluctuations throughout the 29-year period of study, while that by the other two industries rose steadily except for a few slumps.
Nitrogen accumulation in a chronosequence of red alder communities along the Hoh River, Olympic National Park, Washington
Authors: Luken J. O. , Fonda R. W.
Published: April 2008

Alnusrubra Bong, dominates the first 65 – 80 years of a sere that is initiated naturally on the terraces of the Hoh River. Stands of 14, 24, and 65 years were studied to determine to what extent the Alnus stage enriched the nitrogen inventory of the site. Bare sandbars deposited by the river had a mean of 783 kg/ha nitrogen. Alnus communities caused an increase in the nitrogen inventory so that, by 65 years, total community nitrogen was 4659 kg/ha, soils held 3594 kg/ha N in the upper 45 cm, and Alnus trees held 942 kg/ha N. The nitrogen contents of the soil, Alnus wood, bark, and branches, grasses, total aboveground biomass, total belowground biomass, and sticks less than 1 cm diameter all showed significant increases from 14 to 65 years. The A. rubra stage is an important link in the nutrient inventory between unvegetated, recently deposited sandbars and the climax coniferous forests dominated by Tsugaheterophylla (Raf.) Sarg. and Piceasitchensis (Bong.) Carr.
Balsam fir foliage regressions are age dependent
Authors: Baskerville G. L.
Published: April 2008

The dimensional relationship of foliage weight to stem diameter, or height, in balsam fir (Abiesbalsamea (L.) Mill.) is shown to be strongly age dependent across a range of ages from 5 to 91 years. The relationship changes in a manner that makes extrapolation of regressions from one age-class to another extremely dangerous.
Variance estimation from systematic samples in Minnesota timber stands
Authors: Reber Carol A. , Ek Alan R.
Published: April 2008

A 402 permanent-plot inventory of the University of Minnesota Cloquet Forestry Center was used to assess the adequacy of systematic samples for estimating population variance. The inventory plots were arranged in the form of four approximately equal-size systematic samples or clusters. The design was systematic sampling with multiple random starts. Population variances were estimated for number of trees, basal area, and volume per hectare for four different measurements spanning 17 years. Results indicate that the individual random starts and the aggregate of 402 plots treated as a simple random sample provide estimates of variance comparable to those obtained by treating the inventory as a cluster sample design. This report plus reports in the literature suggest that plots in the Lake States that are at least 80 to 362 m apart are likely to provide useful estimates of population variances and sampling errors for common forest-survey variables.
Effect of fertilization on free amino acid concentrations in black spruce and jack pine containerized seedlings
Authors: Kim Y. T. , Glerum C. , Stoddart J. , Colombo S. J.
Published: April 2008

Greenhouse-grown black spruce and jack pine container seedlings were fertilized weekly with a 20–8–20 fertilizer at four concentrations during the fall. Seedlings were sampled when 23 weeks old towards the end of the greenhouse cultural period to determine the effect of fertilization on the free amino acid concentrations. All amino acids, except tryptophan, showed significant increases in concentration with higher levels of fertilizer; the concentration of tryptophan decreased with increasing fertilizer concentration. Amino acids with the highest concentrations in black spruce were arginine, glutamic acid, and proline, while in jack pine, besides these three, aspartic acid and glutamine were also found in high concentrations. Black spruce had significantly higher amino acid concentrations than jack pine. The concentrations of certain free amino acids may be more sensitive indicators of seedling nitrogen status than total foliar nitrogen.
Effect of flooding on growth, stem anatomy, and ethylene production of Pinushalepensis seedlings
Authors: Yamamoto F. , Kozlowski T. T. , Wolter K. E.
Published: April 2008

Flooding of soil for 43 days greatly altered growth and stem anatomy and increased ethylene production by stems of 10-month-old Pinushalepensis seedlings. Flooding reduced the dry weight increment of seedlings primarily as a result of decay of roots and, to a lesser extent, inhibition of growth of roots and needles. Flooding did not influence height growth of seedlings but increased stem diameter, largely because of an increase in bark thickness at all stem heights and stem hypertrophy associated with proliferation of phloem parenchyma cells and an increased amount of intercellular space in the phloem. The effects of flooding on xylem increment varied appreciably with stem height. In the submerged portion of the stem, flooding greatly reduced the number of tracheids laid down per radial file. Flooding also slightly reduced the number of tracheids produced in the portion of the stem just above the water level. In the upper stem, however, flooding had little effect on xylem increment and on tracheid production for the first 29 days but increased both thereafter. Flooding also induced formation of short, thick-walled, rounded tracheids resembling those in compression wood. However, these tracheids developed an S3 wall layer, which is absent in well-developed compression wood. Flooding also increased the number of longitudinal resin ducts as well as the number and size of the xylem rays. The basic density of stem segments was lower in flooded than in unflooded seedlings, largely because of the high proportion of parenchyma cells and more intercellular spaces in the wood and bark of flooded seedlings. Flooding greatly increased production of 1-amino-cyclopropane-1-carboxylic acid by roots and ethylene by stems. The capacity for production of ethylene increased faster in stem segments just above the water line than in submerged portions of stems. However, the capacity for ethylene production as a flooding response declined progressively with increase in stem height above the basal whorl of branches. The data indicated an important regulatory role of ethylene in altering growth and stem anatomy of woody plants.
Simultaneous total and merchantable volume equations and a compatible taper function for loblolly pine
Authors: McTague John P. , Bailey Robert L.
Published: April 2008

Loblolly pine (Pinustaeda L.) is an important source of raw material for the forest products industry of Santa Catarina, Brazil. Data from 159 trees were used to develop a simultaneously estimated total and merchantable volume equation, which treats total volume as a special case of merchantable volume with Dm, the diameter limit, equal to zero. By imposing a restriction on the parameters of the total and merchantable volume equation, a compatible taper function was derived that predicts diameter at breast height when merchantable height equals 1.3 m. The taper function possesses an analytic point of inflection in the lower portion of the stem.
Evaluation of physical properties of several growing media for use in aerial seeding containers
Authors: Lennox Tanya L. , Lumis Glen P.
Published: April 2008

Several personally blended and commercially prepared growing media were evaluated as potential substrates for coniferous tree seedlings in specialized seeding containers (aerial darts). Water retention curves were developed using a porous pressure plate apparatus. Bark–vermiculite–sand and Ball Growing Mix II retained less water at pressures from 0 to 0.1 MPa than all other media observed. At pressures less than 20 × 10−3 MPa the greatest water retention was in Pro-mix A, while above 33 × 10−3 MPa the greatest water retention was in bark–vermiculite. As the proportion of bark in bark–vermiculite was increased, the air space increased significantly but water retention was unaffected. Addition of a hydrophilic gel to media containing a surfactant significantly increased water retention. The easily available water, water buffering capacity, and air space were unaffected by gel but total porosity increased in some of the media. When the surfactant was excluded the addition of gel at the recommended rate did not significantly increase water retention. As the concentration of gel increased there was an increase in water retention, a linear increase in total porosity, a slight increase in air space, a decrease in easily available water, and no change in water buffering capacity. Media amended with gels of different absorbing capacities retained water similarly, releasing approximately 50% of the absorbed water at pressures less than 10 × 10−3 MPa.
Provenance variation among different populations of Pinusstrobus from Canada and the United States
Authors: Genys J. B.
Published: April 2008

Eastern white pine (Pinusstrobus L.), represented by 117 seed sources from different parts of its range in Canada and the United States, was studied for 2 years in a nursery and 14 years at two plantations in Maryland. In the Piedmont Plateau, these populations ranged in survival from 38 to 100%, in height from 3.0 to 8.2 m, and in diameter from 4.3 to 16.8 cm. In the Coastal Plain, they varied in survival from 25 to 100%, in height from 3.0 to 7.8 m, and in diameter from 3.6 to 15.5 cm. Heights and diameters were strongly correlated; both these characteristics were correlated inversely with the latitude (r ranged from −0.38 to −0.67) and directly with the altitude of the seed source (r = 0.22 to 0.31). The latter correlation, however, included a latitudinal component because most high-elevation trees came from the south. Heights in Maryland at 16 years were significantly correlated with heights of similar populations at younger ages studied in 10 other plantations in the eastern United States (r = 0.32 to 0.73) and to the date of bud set by 1-year-old trees (r = 0.23 to 0.51). The most outstanding in growth rate were some sources from Tennessee, Kentucky, and North Carolina. Also, among the northern sources two populations from Norfolk County, Ontario, were distinctly superior.
Sap yields, sugar content, and soluble carbohydrates of saps and syrups of some Canadian birch and maple species
Authors: Jones A. R. C. , Alli I.
Published: April 2008

During the spring of 1984 and 1985, white birch (Betulapapyrifera Marsh), sweet birch (B. lenta L), and yellow birch (B. alleghaniensis Britt.) were tapped to determine sap yields and syrup characteristics. These properties were compared with sap yields and syrup produced from sugar maple (Acersaccharum Marsh) and red maple (A. rubrum L). The sap flow seasons were as follows: white birch, 23 days (April 7–29, 1984) and 29 days (April 5 – May 3, 1985); sweet birch, 26 days (1984); yellow birch, 25 days (1985). The sap flow season for the maple species was much earlier than the birch species. Maple sap flow seasons were as follows: sugar maple, 16 days (March 28 – April 12, 1984) and 45 days (March 10 – April 23, 1985); red maple, 44 days (March 11 – April 23, 1985). Sap yields were as follows: white birch, 80.5 L in 1984 (1.0% sap) 51.0 L in 1985 (1.0% sap); sweet birch, 48.0 L in 1984 (0.5% sap); yellow birch, 28.4 L in 1985 (0.5% sap); red maple, 30.6 L in 1985 (2.3% sap); sugar maple, 53.5 L in 1985 (4.5% sap). Sap analyses showed the average total carbohydrate content of all birch saps and all maple saps was 9.2 and 24.5 g/L, respectively. The average sugar contents of the syrups from the birch saps and the maple saps were 302 and 711 g/L, respectively. The average pH of birch and maple saps were similar but the average pH of the syrups obtained from the birch saps was substantially lower than that of the syrups obtained from the maple saps.
Variations in photosynthetic, anatomical, and enzymatic leaf traits and correlations with growth in recently selected Populus hybrids
Authors: Ceulemans R. , Impens I. , Steenackers V.
Published: April 2008

Several photosynthetic, anatomical, and enzymatic leaf traits were studied on 1- and 2-year-old fast growing Populus clones representing interspecific hybrids of P. deltoides, P. trichocarpa, and P. maximowiczii. Growth performance of the clones was studied with container-grown plants and for 5 years in the field. Considerable variation in photosynthetic, anatomical, and enzymatic leaf traits was found, but variation in growth differences among the clonal groups was minimal. Photosynthetic photon flux density saturated net photosynthesis of 1-year-old container-grown plants was significantly correlated with shoot height growth, but none of the other leaf traits measured showed a significant correlation with any of the growth characteristics. Clonal groups could be segregated by taxonomic and genetic affinities with hierarchical clustering and principal component analysis. Although enzymatic and biochemical traits (area leaf weight, ribulose-bisphosphate carboxylase and phosphoenolpyruvate carboxylase activities, protein content) and adaxial stomatal frequency can be used to discriminate among clonal groups, no significant regression of these leaf traits on growth performance was observed.
Observations on pollination in loblolly pine
Authors: Brown Sheryl Diane , Bridgwater F. E.
Published: April 2008

Insitu observations of Pinustaeda L. strobili in a 26-year-old grafted seed orchard showed that emergence of pollination droplets began on unpollinated strobili as they approached full receptivity and declined thereafter. Droplets reemerged throughout the receptive period primarily during the early morning or evening until pollinated, after which they did not emerge again. Droplet reemergence for a given ovule was independent of other ovules on the same strobilus. Rainfall was found to effect pollination. Ovules pollinated during rain did not subsequently display pollination droplets.
Soil CO2 evolution in Florida slash pine plantations. I. Changes through time
Authors: Ewel Katherine C. , Cropper Jr. Wendell P. , Gholz Henry L.
Published: April 2008

Soil CO2 evolution rates were measured in slash pine (Pinuselliottii) plantations of three ages in north Florida. At the mature (29-year-old) plantation, which had a closed canopy and a well-developed forest floor of litter and humus overlying the mineral soil, C storage in detritus in the mineral soil was relatively low and soil C release was relatively high (13.0 t•ha−1•year−1). C release was highest (22.7 t•ha−1•year−1) at the clear-cut site, presumably because of high temperatures and rapid decomposition of detritus added during the harvest, and lowest (8.2 t•ha−1•year−1) at the 9-year-old plantation. For a range of forest sites, soil CO2 evolution rates and the magnitude and direction of changes after harvesting show latitudinal variation that probably depends not only on the amount of C contained in dead organic matter in the soil and its decomposition rate but also on the treatment of slash left after harvesting.
Potential prediction bias in regression and discriminant analysis
Authors: Verbyla David
Published: April 2008

not available
Shoot elongation and growth plasticity in incense-cedar
Authors: Harry David E.
Published: April 2008

When nursery-grown seedlings of Calocedrusdecurrens (Torr.) Florin from diverse genetic origins were watered regularly throughout the summer, shoot elongation of leaders and branches continued into fall. By contrast, growth of seedlings watered less frequently slowed earlier but accelerated rapidly after watering. This pattern was similar for all seedlings, regardless of their origin. Calocedrusdecurrens, in the Cupressaceae, lacks the distinct spring flush that is typical of many temperate conifers, mostly in the Pinaceae. Although new growth on Calocedrus shoots is clearly visible in the spring, there is no distinct demarcation along the stem between the growth that occurs during successive years. Elongation of several leaf internodes near the shoot tip in fall is arrested over winter and is not completed until the following spring. Hence, shoot growth is a more or less continuous process characterized by changes in tempo that are influenced primarily by current environment. This pattern of developmental plasticity may contribute to the nature and extent of genetic variation observed within Calocedrusdecurrens.
Cross-sectional area relationships in root systems of loblolly and shortleaf pine
Authors: Carlson William C. , Harrington Constance A.
Published: April 2008

The relationship between cross-sectional root area at groundline and composite root area (the sum of the areas of the first-order lateral roots plus the area of the taproot subtending the most distal lateral root) was examined in 3- to 9-year-old loblolly and shortleaf pine (Pinustaeda L. and P. echinata Mill.). For both species, root area at groundline and composite root area were highly correlated, and the slopes in equations relating the two root areas were close to 1.0. These results imply that (i) the pipe model of tree form is appropriate for young root systems, and (ii) the development of basal stem diameter is directly related to root system development.
Influence of tree stress and site quality on the induced defense system of loblolly pine
Authors: Paine T. D. , Stephen F. M.
Published: April 2008

Even-aged loblolly pines growing in plantations on different sites were inoculated with Ceratocystisminor, a fungus associated with the southern pine beetle, to determine if the inducible defense system of the trees was affected by plant quality or growing conditions. Overtopped trees produced smaller hypersensitive lesions than dominant or codominant trees. There was no discernible effect of previous exposure to the fungi on the subsequent ability of the tree to respond to inoculation. A temporal effect was observed in trees growing on the better well-drained site but was not seen in trees on the poorer site with waterlogged soil.
Importance of current photosynthate to new root growth in planted conifer seedlings
Authors: van den Driessche R.
Published: April 2008

A series of experiments were conducted to examine the importance of current photosynthate for development of new roots in planted conifer seedlings and to assess the possible importance of carbohydrate reserves. Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and Sitka spruce (Piceasitchensis (Bong.) Carr.) seedlings, labelled with 14CO2 in October, contained 14C in old roots but little in new roots when placed into growing conditions in January. New roots of seedlings labelled after 12 days growth in January were highly radioactive, indicating that current photosynthate was the primary carbon source for new roots. These results agreed with an experiment in which the amount of new root growth of 1 + 1 Douglas-fir transplants was proportional to light intensity. Net photosynthesis (Pn) of similar Douglas-fir nursery stock was inadequate to supply carbon for respiration and new root growth at 200 μE•m−2•s−1, although new root growth occurred. The ability to achieve gas exchange from the moment of planting in moist soil was evident from photosynthesis measurements and transpiration weighings, but although preconditioning affected new root growth in lodgepole pine (Pinuscontorta Loud.), no relationship between new root growth and Pn was observed.
Responses of root systems of young Pinussylvestris and Piceaabies plants to water deficits and soil acidity
Authors: Bartsch N.
Published: April 2008

Responses of the root systems of two conifer species (Pinussylvestris L. and Piceaabies (L.) Karst.) in a strongly acidic mineral soil and in a soil with normal acidity to increasing water deficits and subsequent rewatering were examined in a growth chamber experiment. Two-year-old greenhouse seedlings were transplanted into transparent acrylic containers (rhizotrons) positioned at an angle of 45° in wooden boxes. During the 12-week test duration, the following root parameters were measured in intervals of 2 to 4 days: root elongation rate, number of growing roots, root diameter, development of root hairs, root browning, and the development of mycorrhizae. The test plants, the spruces more so than the pines, in the strongly acidic soil were limited in their ability to react to changes of the water supply. Of the examined root parameters, the root elongation rate and the number of growing roots showed the most distinct reactions.
Growth of containerized jack pine seedlings inoculated with different ectomycorrhizal fungi under a controlled fertilization schedule
Authors: Gagnon J. , Langlois C. G. , Fortin J. A.
Published: April 2008

Containerized jack pine (Pinusbanksiana Lamb.) seedlings were grown in a peat moss – vermiculite substrate and inoculated at sowing with pure cultures of three ectomycorrhizal fungi. After 18 weeks of growth in the greenhouse, seedlings inoculated with Laccariabicolor had 97% of their short roots mycorrhizal, while those inoculated with Hebelomacylindrosporum had 36% of their rootlets mycorrhizal. No mycorrhizae were obtained with Rhizopogon sp. After both 12 and 18 weeks of growth with the fertilization schedule used, seedlings colonized with L. bicolor and H. cylindrosporum were significantly smaller than those inoculated with Rhizopogon sp. or control seedlings. After 18 weeks of growth, the available nitrogen (N) content of the substrate was considerably greater with L. bicolor inoculated seedlings than with control seedlings, whereas the available phosphorus (P) content of the substrate was the same for these two treatments. Also, after 18 weeks, seedlings mycorrhizal with L. bicolour had a. greater concentration (%) of N and P in their tissues than control seedlings; however, they contained fewer milligrams of N and P than control seedlings. From our results on substrate fertility of mycorrhizal seedlings, we state that it is possible to induce mycorrhiza formation of jack pine seedlings with L. bicolor when substrate fertility in available N and P is less than or equal to 39 and 60 ppm, respectively, and that it is possible to maintain L. bicolor mycorrhizae when N and P fertility is less than or equal to 24 and 28 ppm, respectively. From analysis of tissue nutrient content in mycorrhizal seedlings, it appears that the appropriate N and P concentrations to maintain mycorrhiza formation of jack pine seedlings with L. bicolor are less than or equal to 1.6 and 0.2%, respectively.
The root–fungus interface as an indicator of symbiont interaction in ectomycorrhizae
Authors: Massicotte H. B. , Ackerley C. A. , Peterson R. L.
Published: April 2008

Seedlings of Alnuscrispa (Ait.) Pursh, Alnusrubra Bong., Eucalyptuspilularis Sm., and Betulaalleghaniensis Britt. were grown in plastic pouches and subsequently inoculated with Alpovadiplophloeus (Zeller & Dodge) Trappe & Smith (two different strains), Pisolithustinctorius (Pers.) Coker & Couch, and Laccariabicolor (R. Mre) Orton, respectively, to form ectomycorrhizae insitu. Alnus seedlings were inoculated with Frankia prior to inoculation with the mycosymbiont. The interface established between A. crispa and A. diplophloeus was complex, involving wall ingrowth formation in root epidermal cells and infoldings in Hartig net hyphae. Alnusrubra – A. diplophloeus ectomycorrhizae had an interface lacking epidermal cell wall ingrowths but with infoldings in Hartig net hyphae. The interface between E. pilularis –. tinctorius consisted of branching Hartig net hyphae between radially enlarged epidermal cells lacking wall ingrowths. Ectomycorrhizae between B. alleghaniensis and L. bicolor developed unique interfaces with radially enlarged epidermal cells near the apical meristem, which synthesized dense vacuolar deposits. Very fine branchings occurred in Hartig net hyphae.
Allelopathic interference in the seedbed of Pinus jeffreyi in the Sierra Nevada, California
Authors: Yoder-Williams M. P. , Parker V. T.
Published: April 2008

Wyethiamollis Gray (Asteraceae) dominates extensive areas within the mixed conifer forest of the eastern Sierra Nevada, California. Large (>20 ha) patches form when overgrazing follows canopy fires. No regeneration of conifers is found in these patches even after removal of grazing. Survival of planted pines in Wyethia patches is 50% less than that in non-Wyethia areas and stem height is reduced 33%. Laboratory bioassays using live tissue extracts show an allelopathic effect as measured by radicle elongation: 24% reduction in lettuce seedlings and 67% reduction in Pinusjeffreyi Grev. & Balf. seedlings. While seed predation on pines is 27% higher in non-Wyethia areas, field-germinated pine seeds overwintered in Wyethia litter exhibited a 34% reduction in germination and 33% reduction in root growth.
Mechanical stability of black spruce in the clay belt region of northern Ontario
Authors: Smith V. G. , Watts M. , James D. F.
Published: April 2008

Black spruce (Piceamariana (Mill.) B.S.P.) is an important pulpwood species that grows on peatland sites in the clay belt region of northern Ontario. The mechanical stability of spruce found on these sites is crucial in determining how tall a stand can grow before losses due to windthrow become excessive. In this study, the stability of a sample of 58 black spruce trees, in stands of various height and density classes, was measured by winching them over and determining their critical turning moment. Regression analysis was used to express critical turning moment as a function of tree height, dominant stand height, and stand stocking. An analysis was carried out to estimate turning moments due to static wind action on the sample trees and predicting the wind speeds required to produce the static force needed to cause windthrow. A comparison of the measured critical turning moments to the estimated wind-generated critical turning moments was used to identify the wind speeds that have enough static force to cause windthrow. A table of critical wind speeds, based on a reference wind, is given for black spruce stands of various heights and densities. Based on these wind speeds and winds associated with periodic storms, black spruce stands can be expected to become susceptible to windthrow once dominant stand height reaches 20 to 21 m. Stand stability increases with stand density owing to the greater ability of dense stands to dissipate incoming winds and the added stability of interlocking root systems. These results suggest that the black spruce stands growing on peatland sites in the clay belt should be harvested before dominant stand height reaches a maximum of 20 to 21 m to avoid excessive losses due to windthrow.
A rapid, multisample technique for detection of trace elements in trees by energy-dispersive X-ray fluorescence spectroscopy
Authors: Maclauchlan L. E. , Borden J. H. , Cackette M. R. , D'Auria J. M.
Published: April 2008

A new method is presented for studying the distribution of trace elements in trees. A tree core is removed, sectioned into very thin slices (≤400 μm), and analyzed directly using X-ray fluorescence spectroscopy. The technique offers a number of advantages, including minimal sample preparation time, elimination of contamination or leaching, and rapid simplified data analysis. Analysis of 10 or more samples per annual ring is possible. Application of the technique in two studies (first, using trees as indicators of airborne pollutants and second, analyzing pesticide residues in trees) is described. In the first study there were significant correlations between seasonal airborne pollution levels and the levels of lead and zinc detected in the phloem tissue of red alder, Alnusrubra Bong. In the other study, the technique was used to analyze arsenic content in lodgepole pines, Pinuscontorta var. latifolia Englemann, treated with monosodium methanearsonate. Vertical arsenic profiles in treated trees indicated accumulations of arsenic near the site of injection at the base of the bole and in the foliage. Differential radial uptake was also apparent.
Classification trees: a new discrimination tool
Authors: Verbyla David L.
Published: April 2008

Classification trees are discriminant models structured as dichtomous keys. A simple classification tree is presented and contrasted with a linear discriminant function. Classification trees have several advantages when compared with linear discriminant analysis. The method is robust with respect to outlier cases. It is nonparametric and can use nominal, ordinal, interval, and ratio scaled predictor variables. Cross-validation is used during tree development to prevent overrating the tree with too many predictor variables. Missing values are handled by using surrogate splits based on nonmissing predictor variables. Classification trees, like linear discriminant analysis, have potential prediction bias and therefore should be validated before being accepted.
Boron fertilization, ectomycorrhizal colonization, and growth of Pinusechinata seedlings
Authors: Mitchell R. J. , Garrett H. E. , Cox G. S. , Atalay A. , Dixon R. K.
Published: April 2008

Shortleaf pine (Pinusechinata Mill.) seedlings inoculated with Pisolithustinctorius (Pers.) Coker and Couch or left uninoculated were grown in book planters for 16 weeks. Seedlings were fertilized with 25 μg mL−1 of borate applied to the foliage as a mist, to the soil as a solution, or to both the foliage and the soil. B applied to the foliage or to the soil significantly increased ectomycorrhizal colonization of roots and seedling growth. Growth of uninoculated seedlings was not enhanced by B fertilization. The lack of growth response of uninoculated seedlings as contrasted with increased infection and growth of inoculated seedlings suggests that B affects the fungal symbiont or the plant host–symbiont combination to a greater extent than the plant host alone.
Canopy dynamics and growth of Pinusradiata.: I. Effects of irrigation and fertilization during a drought
Authors: Linder S. , Benson M. L. , Myers B. J. , Raison R. J.
Published: April 2008

A field experiment was commenced in 1983 in a 10-year-old plantation of Pinusradiata (D. Don) in the Australian Capital Territory to study the effects of varying levels of nutrition and water availability on the physiological processes controlling tree growth. The effects of treatments were accentuated by marked differences in precipitation during the first 2 years of the study. Tree canopies grew rapidly during the wet summer of 1983–1984, particularly with the addition of fertilizer. During the following dry summer transpiration by the large canopies rapidly depleted soil water, leading to severe water stress on nonirrigated plots. This stress restricted the expansion of new foliage, induced heavy shedding of foliage older than 1 year, and prevented stem growth during most of the summer. The stems of nonirrigated trees decreased in diameter for 4 months, and in the fertilized stand several trees died, while others suffered crown dieback. In the dry year, stem volume increments varied between 17 and 45 m3 ha−1 with the different treatments.
Detection of bark lesions caused by Phytophthoracinnamomi in Eucalyptusmarginata with the plant impedance ratio meter and the Shigometer
Authors: Tippett Joanna T. , Barclay Joanne L.
Published: April 2008

A new instrument, the plant impedance ratio meter (PIRM), has been used to determine the extent of lesions caused by Phytophthoracinnamomi Rands in Eucalyptusmarginata Sm. The performance of the PIRM, which measures electrical admittance (the inverse of impedance) of plant tissues at two frequencies (from which an impedance ratio is calculated), was evaluated and compared with that of the Shigometer. The electrical admittance measured at 1 and 10 kHz (PIRM) and the electrical resistance (Shigometer) of healthy tissue varied with both the depth of tissue probed and the water status of stems. However, the impedance ratios (calculated from the admittance values) remained relatively constant for healthy tissue and changes were independent of depth of probing. Hence, changes in ratios indicated a change in tissue condition or necrosis rather than changes in either tissue water content or depth of probing. The impedance ratios recorded for healthy bark tissues were consistently higher than those for the P. cinnamomi lesions in E. marginata. Trends in electrical resistance measured across the boundaries of the lesions with the Shigometer were variable depending on lesion age. The PIRM was used successfully to detect P. cinnamomi lesions in E. marinate and lesion fronts were predicted to an accuracy of ± 7.2 mm (n = 150), lesions being up to 1.0 m long at the time stems were harvested.
Genetic variation in response to nitrogen fertilizer levels in tamarack families
Authors: Wyandanch J. M. , Morgenstern E. K.
Published: April 2008

The response of 20 open-pollinated tamarack (Larixlaricina (Du Roi) K. Koch) families from five populations to three nitrogen fertilizer levels was investigated in a greenhouse for 20 weeks. Measurements included height, root collar diameter, and dry weights. Variation among populations and the population × nitrogen interaction were not significant. Nitrogen and family effects and family × nitrogen interaction were significant for all characters studied. Stability analyses using the methods of Eberhart and Russell, Hühn, and Wricke gave similar results. The families could be divided into groups performing well at either high or low nitrogen levels or at all levels. Due to its evolution in unstable environments, tamarack appears to maintain a genetic system of adaptation based on a high level of flexibility.
Loblolly pine seedling root anatomy and iron accumulation as affected by soil waterlogging
Authors: McKevlin M. R. , Hook D. D. , Mckee Jr. W. H. , Wallace S. U. , Woodruff J. R.
Published: April 2008

Loblolly pine seedlings were grown under flooded and drained conditions in a greenhouse pot study. Flooded roots developed aerenchyma tissue within the stele between the xylem poles, extending from the phloem outward to the pericycle. Large intercellular spaces were present in the pericyclic parenchyma within the phellogen of flooded woody roots. Flooded stems exhibited lenticel hypertrophy. Large intercellular spaces in the cortex were continuous with intercellular spaces in the pericyclic parenchyma of the root. Flooding of roots generally resulted in accumulation of Fe on the epidermal surface and in as well as between cortical cell walls inward to the endodermis. Fe accumulated in and between the precursor phloem cells and became more evident in the region of maturation. In roots with secondary thickening, little Fe was visible in the phloem but was present in helical secondary walls of tracheids. Fe also accumulated on and in bordered pits of root tracheids. Results suggest that flooded loblolly pine seedlings possess a limited internal aeration system and that diffusion of oxygen into the root system may be responsible for the presence of oxidized Fe within the stele.
Stomatal characteristics and transpiration of three species of conifer seedlings planted on a high elevation south-facing clear-cut
Authors: Livingston N. J. , Black T. A.
Published: April 2008

Douglas-fir (Pseudotsugamenziessi (Mirb.) Franco), western hemlock (Tsugaheterophylla (Raf.) Sarg.), and Pacific silver fir (Abiesamabalis (Doug.) Forbes) seedlings were planted in the spring as 1-0 container-grown plugs on a south-facing high elevation clear-cut located on Mount Arrowsmith, Vancouver Island, British Columbia, and their stomatal responses to environmental and physiological variables were determined over two successive growing seasons. The stomatal responses of all three species to changes in environmental variables and time did not differ over the 2 years nor were there differences in response between seedlings planted a year apart. A simple multiplicative boundary-line model that related seedling stomatal conductance (gs) to measurements of hourly average solar irradiance, air temperature, vapour pressure deficit, and average root zone soil water potential accounted for over 70% of the variability in gs. When the number of hours from sunrise was included as an independent variable, over 85% of the variability in gs could be explained. Daily seedlings transpiration rates on a projected leaf area basis were successfully estimated by summing the product of the calculated average gs and D/(RvT′) where D is the vapour pressure deficit, Rv is the gas constant for water vapour, and T′ is the absolute air temperature.
Gas exchange characteristics and water relations of Larixoccidentalis
Authors: Higgins Stewart S. , Black R. Alan , Radamaker Gary K. , Bidlake William R.
Published: April 2008

Photosynthetic, transpirational, and stomatal responses to light, temperature, humidity, and plant moisture stress were measured for greenhouse-grown seedlings of Larixoccidentalis Nutt. Light saturation was 550 μmol photons•m−2•s−1; light and CO2 compensation points were 26 μmol photons•m−2•s−1 and 59 μL CO2•L−1, respectively. Light-saturated photosynthetic rate was over 7 μmol CO2•m−2•s−1 with a temperature optimum between 18 and 23 °C. Photosynthesis, transpiration, and stomatal conductance to water vapor declined as xylem pressure potential decreased from −1.5 to less than −2.5 MPa; above −1.5 MPa no effect was observed. Stomatal conductance declined with increasing leaf to air vapor density difference. Stomatal conductance increased with increasing irradiance. Nighttime stomatal conductance was about 50% of the daytime maximum conductance regardless of xylem pressure potential. When plants were well watered, the ratio of xylem pressure potential to transpiration (XPP/E) decreased by 1.5 × 10−3 MPa•(μg H2O•cm−2•s−1)−1 with each mg H2O•cm−2 that had been transpired. After 7 days of drought, however, XPP/E decreased at 7.9 × 10−3 MPa•(μg H2O•cm−2•s−1)−1 per mg H2O•cm−2. These characteristics are compared with other conifers and are used to suggest differences between growth patterns of L. occidentalis and sympatric species.
Leader size and number of leaf primordia as factors in timing of terminal bud flush in black spruce and tamarack
Authors: Lieffers V. J.
Published: April 2008

Black spruce (Piceamariana (Mill.) B.S.P.) and tamarack (Larixlaricina (Du Roi) K. Koch) in a peatland in north central Alberta were examined twice weekly for terminal bud flush, length of leader, and cessation of leader elongation. Time of terminal bud flush of black spruce, which has determinate bud growth, was negatively correlated with the final length of leader. Differences in timing of flush of terminal buds of individual trees between 1984 and 1985 were negatively related to the ratio of leader length in 1984 to that in 1985. It is proposed that part of the variability in time of bud flush is related to the number of leaf primordia in the expanding bud. Buds with large numbers of leaf primordia flushed earlier than buds with few primordia. Time of terminal bud flush of tamarack, which has indeterminate bud growth, was poorly correlated with the final length of leader.