bluuebunny/crossref_metadata_2025 huggingface dataset:
Initial quantitative characterization of soil nutrient regimes. I. Soil properties
Authors: Kabzems R. D. , Klinka K.
Published: January 2008

Previous attempts to characterize soil nutrient regimes of forest ecosystems have been qualitative evaluations utilizing vegetation and (or) topographic features, morphological soil properties, and mineralogy of soil parent materials. The objective of this study was to describe and provide initial data for quantitative classification of soil nutrient regimes in some Douglas-fir ecosystems on southern Vancouver Island. A multivariate classification using forest floor plus mineral soil mineralizable N and exchangeable Mg quantities was proposed for the four nutrient regimes (poor, medium, rich, and very rich) recognized in this study. Significant differences in mineralizable and total N existed between the four identified soil nutrient regimes. The previous N fertilization of two study sites did not seem to change soil N status sufficiently to alter the classification. The differences in nutrient availability were more distinct when forest floor and mineral soil properties, expressed on an areal basis, were summed. There were no significant differences in exchangeable Ca and Mg for the poor and medium soil nutrient regimes. The humus form of the forest floor was an important characteristic for identifying soil nutrient regimes in the field; however, the nutrient quantities of the forest floor reflected differences in bulk density and depth and did not effectively distinguish between regimes.
Phosphorus allocation in flooded loblolly pine seedlings in relation to iron uptake
Authors: McKevlin M. R. , Hook D. D. , McKee Jr. W. H. , Wallace S. U. , Woodruff J. R.
Published: January 2008

To determine whether P allocation in loblolly pine (Pinustaeda L.) seedlings is related to uptake of Fe2+ and its subsequent oxidation and precipitation out of the transpiration stream, newly germinated and 1 -year-old loblolly pine seedlings were grown in flooded and drained pots in a glasshouse for 24 to 28 weeks. The foliage of the younger seedlings grown in flooded pots exhibited P deficiency symptoms and had lower P concentrations, averaging 63% of those for drained seedling foliage. The older seedlings did not develop P deficiency symptoms but flooding resulted in P concentrations in the foliage averaging only 66% of those for drained seedlings. In both newly germinated and 1-year-old seedlings, P concentrations of the roots from flooded pots were 158 and 25% higher, respectively, than those of the roots from drained pots. Flooding also resulted in significantly higher Fe concentrations in all seedling components. Fe concentrations in roots were positively correlated with P concentrations in roots and negatively correlated with P concentrations in stems and foliage. Implications are that excessive concentrations of Fe in and on the roots interfered with the movement of P into stems and foliage.
Stability of resistance among Pinuscontorta provenances to Lophodermellaconcolor needle cast
Authors: Ying Cheng C. , Hunt R. S.
Published: January 2008

Lophodermellaconcolor needle cast was rated in 41 lodgepole pine (Pinuscontorta) provenance trials in the central and southern interior of British Columbia. Moist, low-elevation sites were most severely affected while sites at high elevation and in dry climatic zones were free of L. concolor. Lodgepole pine populations exhibited a high degree of stability (low site by provenance interaction) and genetic variability in resistance to L. concolor. These characteristics favor selecting resistant seed sources and incorporating them into genetically improved stock. Most provenances, other than those from the interior British Columbia and Alberta geographic region, were extremely susceptible to L. concolor. Susceptibility to L. concolor increased with the elevation of provenance for those provenances of interest to silviculturalists and tree improvement specialists in the interior of British Columbia.
Mixed integer programming improves spray operation planning
Authors: Melachrinoudis Emanuel , Rumpf David , Venegas Ramon
Published: January 2008

The spruce budworm is the most destructive pest of spruce and fir forests in the northern United States and Canada. To counter the insect, the Maine Forest Service has, for the last decade (1975–1985), conducted a large-scale spray operation in Maine's northern and eastern forests. The operation involves the use of several types of aircraft flying from several airfields to spray hundreds of target areas. A minimum cost mixed integer programming model was developed to determine the airfield locations, the number of types of aircraft, and the flight plans to best conduct the spray operation. The model extends and complements a microcomputer linear programming model previously developed for and used by the Maine Forest Service. The savings obtained by the mixed integer programming model can be seen by the included comparison of their results.
Syllepsis in Larixlaricina: association of sylleptic branching with cross-sectional stem growth and stem form of saplings
Authors: McCurdy W. D. , Powell G. R.
Published: January 2008

The effect of sylleptic branching on past stem growth of 8-year-old Larixlaricina (Du Roi) K. Koch saplings was investigated in relation to the lengths of long shoots borne on sylleptically and proleptically originated lateral branches over a 4-year period. Over time, the sylleptic crown component accounted for increasing proportions of the total crowns of saplings exhibiting syllepsis. The total length of all long shoots in the crown increased linearly from lightly to heavily sylleptic saplings. However, groups of branches of sylleptic origin declined in average shoot vigour more rapidly than did groups of branches of proleptic origin in the same height-growth increment. Annual wood ring production and total stem cross-sectional areas at various positions along the main stem were positively correlated with the proleptic, sylleptic, and total branching components occurring above those positions. Wood production along the stem was greater, more uniform and the resultant stem more conical in heavily sylleptic saplings than in lightly sylleptic saplings. The role of syllepsis in crown and main stem development was discussed in relation to plus-tree selection for tree improvement purposes.
Water stress of Pinusponderosa in relation to foliage density of neighboring plants
Authors: Petersen Terry D. , Maxwell Bruce D.
Published: January 2008

The relationship of predawn needle water potential of ponderosa pine (Pinusponderosa Dougl. ex Laws.) and the foliage density of neighboring plants was examined after experimental gradients of foliage were established on two sites in northwestern Montana. In late summer, soil water content linearly decreased in relation to the amount of foliage of herbs and shrubs. Predawn needle water potential of pine seedlings planted along the gradient ranged from −0.5 MPa when competitor foliage was near zero to less than −3.0 MPa when such foliage was more extensive. Even when neighboring plants had a small amount of transpiring foliage at this time of year, the pine seedlings had an increased level of water stress.
A better seed and litter trap
Authors: Hughes Jeffrey W. , Fahey Timothy J. , Browne Bryant
Published: January 2008

Collection of litter fall (leaves and seeds) over a known surface area is an integral part of many ecological studies. We describe a litter trap that is very durable and inexpensive yet is quickly constructed from readily available materials. The trap is easily emptied, light in weight, and easily positioned at any height or orientation, even on steep, rocky slopes. In addition, the trap is highly stable in strong winds, is unaffected by winter storms or fallen trees, and functions well in forest stands of different successional development. Other features include 100% retention of collected litter, a 15-L capacity, a 0.25-m2 collection surface, sharply delineated edges to minimize edge effect, rapid drainage following rainfall, and resistance to predation on fallen litter. The trap efficiently collects seeds as small as 1 mm in diameter.
In defense of the polycross
Authors: Fowler D. P.
Published: January 2008

In Pinaceae species, except for Tsuga, the small number of pollen grains that actually compete in the generative process limits the possible reproductive bias that can result from using the polycross mating design for estimating genetic parameters. For species in which the number of competing pollen grains is 3 or less and where the number of males represented in the pollen mix is 20 or more, reproductive bias is within acceptable limits even if one male were to be favored over all others. Reproductive bias in other species, or where less than 20 males are represented in the mix, can be effectively reduced by diluting the pollen mix with dead pollen.
Analyzing treatment effects on Douglas-fir seedling survival with an extreme value regression model
Authors: Maguire Douglas A. , Maguire Christine C.
Published: January 2008

First year survival patterns in a cohort of natural Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings were assessed with an extreme value regression model. Extreme value distributions were fit to the data, assuming equal scale parameters among treatments but allowing location parameters to vary. The regression approach using indicator variables facilitated statistical comparison of survival curves among several habitats and treatments.
Uptake and persistence of the herbicide glyphosate (Vision®) in fruit of wild blueberry and red raspberry
Authors: Roy D. N. , Konar S. K. , Banerjee S. , Charles D. A. , Thompson Dean G. , Prasad R.
Published: January 2008

Field studies on the uptake and persistence of glyphosate (N-(phosphonomethyl)glycine) on wild blueberry (Vacciniummyrtilloides Michx.) and red raspberry (Rubusstrigosus Michx.) under boreal forest (Matheson, Ont.) conditions were undertaken. Uptake studies indicated that less than 10% of glyphosate penetrated the fruit in the first 9 h postapplication. Results of the persistence studies showed a gradual decline in residue levels with time. Times to 50% dissipation for glyphosate residue as determined by curvilinear regression analyses were <20 days (95% confidence limit of 8–26 days) and <13 days (95% confidence limit of 6–14 days) for blueberry and raspberry fruit, respectively. Initial residue levels dissipated to approximately 4 and 6% after 61 and 33 days for the blueberry and raspberry, respectively. Results also showed that at no time during the study period did glyphosate levels in either substrate dissipate to below the maximum permissible residue level (0.01 ppm) as established by Health and Welfare Canada.
The role of the Douglas-fir beetle and wood borers in the decomposition of and nutrient release from Douglas-fir logs
Authors: Edmonds Robert L. , Eglitis Andris
Published: January 2008

The role of insects in the decomposition of and nutrient release from Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) logs was studied in the Cedar River Watershed near Seattle, Washington. In April 1976, two large-diameter (average diameter at breast height, 41.7 cm) and two small-diameter (average diameter at breast height 26.3 cm) trees were felled. Three pairs of 91 cm length sections were cut from each tree. Half the sections were covered with window screening to prevent insect entry. The number of Douglas-fir beetle (Dendroctonuspseudotsugae Hpk.) attacks on each section, as well as the frass production, were monitored. After 10 years, decomposition rates were determined by mass loss. Douglas-fir beetles attacked large-diameter (23 attacks/m2) and small-diameter (27 attacks/m2) log sections at similar rates. Total frass production was also similar (33.6 g•m−2 for large logs and 32.6 g•m−2 for small logs). Large-diameter unscreened log sections tended to decompose faster (k = 0.050 per year) than small diameter unscreened logs (k = 0.026 per year) owing to the presence of wood borers (Monochamusscutellatus (Say)) in the larger logs. Screening of logs to reduce insect attack tended to reduce the rate of decomposition. A brown rotting fungus (Oligoporusplacentus (Fr.) Gilb. and Ryv.) fruited on unscreened large-diameter logs. Wood borers had a greater influence on log decomposition than Douglas-fir beetles. Frass produced by the Douglas-fir beetle contributed very little to litter fall and nutrient cycling. After 10 years there was a net release of N, P, K, Ca, and Mn from decomposing logs. Only Mg was immobilized in large-diameter logs.
Twin-camera fixed-base photography of tree plots: possibilities and accuracy of a system
Authors: Gagnon P. A. , Agnard J. P.
Published: January 2008

This paper investigates the stability and accuracy of a system using twin-camera fixed-base photography for the photogrammetric measurement of tree heights. Using basic matrix equations that relate photograph coordinates to ground coordinates, the general effects of errors of orientation parameters on tree heights are determined for the specific geometry of the system. It is shown that the most critical factor is the φ-inclination (the inclination of the camera along the axis perpendicular to the fixed base). The actual accuracy of the orientation parameters of each diapositive is then determined using a first-order analytical plotter (BC-1), with five stereopairs of tree plots taken at a nominal scale of 1:800. Because of the small base–height ratio, the standard deviations of the orientation parameters (ω, φ, κ) along the X, Y, and Z axes of each camera are high: between 10cc and 20cc (1cc = 0.01 grade). However, the cumulated effect of all the factors gives an accuracy within 30 cm for a tree height of 10 m. Compared with the effect of the relative orientation error in φ, the other factors have an almost negligible effect. Thus, important uncertainties concerning a practical system of deriving quantitative information from tree plots by photogrammetric means are clarified. Directions of further development are also indicated.
Animal vectors of Arceuthobiumamericanum seed in Manitoba
Authors: Punter David , Gilbert Jeannie
Published: January 2008

Long-distance dispersal of Arceuthobiumamericanum Nutt. ex Engelm. seed by animals was investigated in Grand Beach Provincial Park, Manitoba, where passerine migration routes traverse stands of dwarf mistletoe infected Pinusbanksiana Lamb. Small mammals appear to be insignificant as vectors in Manitoba as no seeds were found on any of the 193 individuals trapped. In contrast, 5.5% of 146 birds netted in 1986 and 5.1% of 59 netted in 1987 carried seed. Three species are reported carrying seed for the first time: brown creeper (Certhiaamericana), Swainson's thrush (Catharusustulatus), and red-breasted nuthatch (Sittacanadensis). Seeds were also found on five gray jays (Perisoreuscanadensis) and three dark-eyed juncos (Juncohyemalis), species for which numerous records of dwarf mistletoe seed transport already exist. Swainson's thrushes and dark-eyed juncos are potential disseminators of A. americanum seed into jack pine stands in northern Ontario and the Great Lakes States during years when seed discharge and migration overlap.
Allozyme variation of bishop pine associated with pygmy-forest soils in northern California
Authors: Millar Constance I.
Published: January 2008

Two races of bishop pine (Pinusmuricata D. Don) meet in a narrow contact zone near sea level along the Sonoma County coast, northern California. The races previously were identified by foliar ("blue" in north, "green" in south), monoterpene, and allozyme differences. Disjunct stands of blue bishop pine were observed at higher elevations along a ridge south of the contact zone on patches of infertile pygmy-forest soils. Green bishop pine grew on fertile soils 0.5 km from the pygmy-forest patches. The frequency of trees with blue foliage in pygmy-forest stands was 0.73–0.86. One ridgetop stand south of the contact zone on fertile soils also had blue foliage. Allozyme differences at 7 of 46 loci distinguished blue and green races on different soils. Ridgetop blue and green stands were clearly related allozymically to lower elevation blue and green races in the same region. Selection for tolerance to soil conditions in the pygmy forest appears to maintain blue bishop pine in ridgetop pygmy forests.
Elemental concentrations in tree rings by PIXE: statistical variability, mobility, and effects of altered soil chemistry
Authors: McClenahen James R. , Vimmerstedt John P. , Scherzer Amy J.
Published: January 2008

Concentrations of up to 14 elements were determined from increment cores by proton-induced X-ray emission for dated series of annual rings of plantation Liriodendrontulipifera L. All trees were treated in 1965 with 841, 224, and 280 kg/ha of elemental N, P, K, respectively, and with either 0, 1683, or 3366 kg/ha of elemental Ca applied as pulverized agricultural limestone. Intraring elemental concentrations were not significantly different between earlywood and late-wood. Statistical variability of proton-induced X-ray emission elemental determinations was greatest for Al, Si, Cl, Cu, and Zn; concentrations of P, K, Ca, Mn, and Sr were least variable. Estimated standard errors among cores within trees averaged less than those among trees on a uniform site. Element mobility was tested in xylem core samples taken in 1965 and 1986. Liming significantly increased P, S, K, Ca, and Zn and decreased Mn in pre-1965 xylem. Retroactive liming effects were not detected for Mg, Al, Fe, Sr, or Ba; liming responses of Si, Cl, and Cu were unclear. Significant differences in elemental concentration independent of liming were detected between the 1965 and 1986 sampling times for P, K, Ca, Mn, Zn, Sr, and Ba. Of these, differences in P, K, and Mn may be due largely to heartwood formation between sampling times. Exchangeable Ca and Mg, followed by pH, were the most important soil variables in significant regressions with xylem elemental concentrations; only weak relationships were found with foliar elemental concentrations. Concentrations of Al, Si, Fe, and Cu in L. tulipifera xylem could be useful biomonitors of soil chemical changes by virtue of their apparent immobility; other elements, particularly S and Sr, may also be useful. However, expected time trends, especially as they pertain to heartwood formation, should be taken into account for each element.
Induction of nitrate reductase activity in red spruce needles by NO2 and HNO3 vapor
Authors: Norby Richard J. , Weerasuriya Yohan , Hanson Paul J.
Published: January 2008

The induction of the enzyme nitrate reductase in needles may be a prerequisite for the assimilation of foliar-absorbed nitrogen oxide pollutants by red spruce (Picearubens Sarg.) trees. To test for induction of nitrate reductase, 1-year-old red spruce seedlings were exposed to NO2, HNO3 vapor, or acid mist containing nitrate, and the activity of nitrate reductase in needles was measured. One day after exposure to NO2 (75 nL•L−1) began, nitrate reductase activity was three times greater than that of unexposed control plants. One day after exposure ended, the nitrate reductase activity returned to the control level. Older red spruce seedlings that had been excavated from a spruce–fir stand exhibited a similar pattern of response, but the level of nitrate reductase activity was much lower than that of the 1-year-old seedlings. Nitric acid vapor (75 nL•L−1) also induced nitrate reductase in red spruce needles, and the pattern of response was similar to that with NO2, except that the nitrate reductase activity did not return to control levels until 2 days after exposure ended. Exposure of seedlings to acid mist containing nitrate (pH 3.5 and 5.0) did not result in a change in nitrate reductase activity. These results indicate that red spruce is capable of assimilating NO2 and HNO3 vapor and that hypotheses of forest decline based on foliar assimilation of pollutant nitrogen oxides are tenable.
Jack pine barrens in northeastern New York: postfire macronutrient concentrations, heat content, and understory biomass
Authors: Stergas R. L. , Adams K. B.
Published: January 2008

Macronutrient concentrations (N, P, K, Ca, and Mg), ash, high heat, and ash-free high heat contents were determined for current-year jack pine (Pinusbanksiana Lamb.) foliage, huckleberry (Gaylussaciabaccata (Wang.) K. Koch.) and blueberry (Vacciniumangustifolium Ait.) foliage, and reindeer lichen (Cladoniarangiferina (L.) Web.) thallus in four fire-regenerated jack pine (Pinusbanksiana Lamb.) stands in northeastern New York aged 21, 29, 46, and 67 years. Macronutrient concentrations and heat contents were usually lowest in lichen, but other species patterns differed with the variable. Overall, differences in macronutrient concentrations for each species in an age sequence were not significant. Comparisons of live aboveground understory biomass, macronutrient content, and heat content through the age sequence showed no significant differences, but the influence of stand age may have been masked by large spatial variability. If the wildfires that regenerated these jack pine stands caused serious nutrient losses, the adverse effects were no longer detectable with the methodology used in this study.
A sequential decision plan for the management of the eastern hemlock looper, Lambdinafiscellariafiscellaria (Lepidoptera: Geometridae), in Newfoundland
Authors: Dobesberger E. J.
Published: January 2008

A sequential decision plan based on Wald's sequential probability ratio test for the negative binomial distribution was derived for eastern hemlock looper (Lambdinafiscellariafiscellaria (Guen.)) egg populations in Newfoundland. An average sample number of not more than six midcrown branches was feasible, and both α and β error rates were defined. Monte Carlo simulation of operating characteristic and average sample number values for static and dynamic K of the negative binomial showed that Wald's sequential probability ratio test was acceptable. More eggs were found on midcrown balsam fir (Abiesbalsamea (L.) Mill.) branches than on other sampling substrates, such as ground mosses (mainly comprising Hylocomiumsplendens (Hedw.) B.S.G., Pleuroziumschreberi (Brid.) Mitt., and Ptiliumcrista-castrensis (Hedw.) De Not.), loose bark from paper birch (Betulapapyrifera Marsh.), and crown lichens (primarily Usnealongissima Ach.).
Assessment of patterns of response of tree ring growth of black spruce following peatland drainage
Authors: Dang Q. L. , Lieffers V. J.
Published: January 2008

A new procedure was developed for assessing the effects of drainage on tree ring growth. It uses both the predrainage growth of the drained site and the postdrainage growth on an adjacent undrained site as controls in estimating tree ring growth response following drainage. The procedure allows the calculation, on a yearly basis, of the net response of tree ring growth to peatland drainage. The new procedure was applied to black spruce on six peatlands in central Alberta; these sites were drained in 1966. The average age of trees on the sites ranged from 33 to 107 years at time of drainage. The response patterns were as follows: for the first 3 to 6 years following drainage, the tree ring growth did not increase in response to drainage. After that, the net increase in tree ring growth increased nearly linearly until reaching a maximum 13 to 19 years after drainage. The maximum net increases ranged from 76 to 766% of the projected growth of the trees if the sites had not been drained. The net increases fluctuated near the maximum value thereafter. The year to year fluctuations in tree ring index on the drained sites corresponded to the yearly fluctuations on the natural sites.
Nitrogen-fixing plants in a cut-over lodgepole pine stand of southern British Columbia
Authors: Hendrickson O. Q. , Burgess D.
Published: January 2008

The acetylene reduction assay was used to estimate amounts of nitrogen fixed by Lupinusarcticus Wats. (1.97 kg•ha−1•year−1) and Shepherdiacanadensis (L.) Nutt. (0.78 kg•ha−1•year−1) in a regenerating lodgepole pine (Pinuscontorta Dougl.) stand in southern British Columbia. These amounts appear to be significant, as lodgepole pine ecosystems are generally highly deficient in nitrogen. Thinning of excessively dense pine stands may provide an added growth benefit by increasing nitrogen fixation activity of understory vegetation.
Height growth components in inter- and intra-provenance jack pine families
Authors: Magnussen S. , Yeatman C. W.
Published: January 2008

Duration (D), rate of shoot elongation (RSE), number of stem units (NSU), and mean stem unit lengths (MSUL) of current year's (1987) leaders were analyzed in 18 jack pine (Pinusbanksiana Lamb.) full-sib progenies from nine inter- and nine intra-provenance crosses. The parent material consisted of selected "plus" trees from Ontario, Quebec, Wisconsin, and Michigan provenances. The average within-family variance (phenotypic) of D was on the average 186 days or twice as large as the among-family variance of 90 days. Duration was positively correlated with the number of growing degree-days at the place of parental origin. Tree height and height growth of several crosses significantly exceeded a local check lot, and the provenance effects on heights were predominantly additive (but not the luxuriance of hybrids). In determining annual height growth, it was discovered that D and RSE were roughly equally important, but large differences in RSE were observed among families with almost equal growth duration. The superior height growth of two interprovenance families was attributed to higher growth rates rather than a longer growth period. Although NSU was more important than MSUL in determining final shoot length, a negative correlation between NSU and MSUL complicated the overall significance of NSU. It was concluded that jack pine had sufficient variation in the examined height growth components to facilitate genetic improvement in height growth without adverse effects on periodicity. The provenance hybrids produced sufficiently promising results and additional exploitable phenotypic variation to warrant continued hybridization efforts.
A sequential approach to sampling design for time studies of cable yarding operations
Authors: Howard Andrew F.
Published: January 2008

Comprehensive sampling design including determination of the distribution, number of observations and specification of desired levels of precision is typically ignored in time studies of yarding operations. A computer-based data collection, processing, and analysis system was developed for time studies that permits improved sampling design. Data collection programs were written for continuous timing of yarding operations and downloaded on to hand-held computers equipped with real-time clocks. After each shift of observation, the time study data are uploaded to a portable microcomputer. The data are then processed through a series of programs that provide error checking, cataloging, and formatting in preparation for analysis. Data from three cable yarding operations were used in a study to assess the potential for sequential design and to determine precision levels obtainable from short-duration time studies. Confidence intervals were computed cumulatively and used to assess whether additional observation of a specific machine on a particular site was justified. The data collection, processing, and real-time analysis system shows promise as a technique for improving sampling design of time studies for timber harvesting operations through sequential analysis of the data.
The behavior of nonindustrial private forest landowners
Authors: Hyberg Bengt T. , Holthausen Duncan M.
Published: January 2008

Recent models of nonindustrial private forest landowner behavior have suggested that landowners seek nonmonetary as well as monetary returns from their forest investments. In this paper, landowners are modeled as maximizing utility, which is a function of income and nonpecuniary benefits. We explore the implications of this model for both harvesting and reforestation decisions, present empirical evidence that supports the model, and discuss some policy implications of the model.
Nitrogen fertilization enhances cold tolerance of red spruce seedlings
Authors: DeHayes D. H. , Ingle M. A. , Waite C. E.
Published: January 2008

Red spruce (Picearubens Sarg.) seedlings were treated with one of four concentrations of NH4NO3 (0, 300, 1500, and 3000 kg N•ha−1•year−1) applied to the soil, with and without triple superphosphate, during early, mid-, or late summer. Laboratory freezing assessments indicated that cold tolerance of treated seedlings generally increased with increasing nitrogen (N) uptake, with the exception of the highest N treatment. Seedlings receiving 1500 kg N•ha−1•year−1 were most cold tolerant on most sample dates. In general, these seedlings were hardier than those receiving 300 kg N•ha−1•year−1, which were hardier than unfertilized control seedlings. Seedlings receiving supplemental N also acclimated to cold more rapidly in autumn and deacclimated more slowly in spring than unfertilized controls. Supplemental phosphorus (P) had no influence on cold tolerance, and there was no evidence of a N × P interaction. Significant differences in cold tolerance associated with time of N application (early, mid-, and late summer) were detected in autumn and winter, but not in spring. In general, seedlings receiving N in mid- or late summer were as hardy or hardier than seedlings fertilized in early summer, regardless of the concentration of fertilizer. Significant interactions between N and timing of treatments occurred primarily because N applied in early summer resulted in only a slight increase in cold tolerance, whereas mid- and late summer N application resulted in a substantial increase in cold tolerance. Combined results suggest that it is highly unlikely that either the amount or timing of atmospheric N deposition is responsible for the winter injury frequently observed in red spruce.
A study of interpolation methods for forest fire danger rating in Canada
Authors: Flannigan M. D. , Wotton B. M.
Published: January 2008

Canadian fire control agencies use either simple interpolation methods or none at all in estimating fire danger between weather stations. We compare several methods of interpolation and use the fire weather index in the North Central Region of Ontario as a case study. Our work shows that the second order least square polynomial, the smoothed cubic spline, and the weighted interpolations had the lowest residual sum of squares in our verification scheme. These methods fit the observed data at both high and low fire weather index values. The highly variable nature of the spatial distribution of summer precipitation amount is the biggest problem in interpolating between stations. This factor leads to highly variable fire weather index fields that are the most difficult to interpolate. The use of radar and (or) satellite data could help resolve precipitation patterns with greater precision. These interpolation methods could easily be implemented by fire control agencies to gain a better understanding of fire danger in the region.
Response to water stress of Italian alder seedlings from diverse geographic origins
Authors: Borghetti M. , Cocco S. , Lambardi M. , Raddi S.
Published: January 2008

The morphological and physiological response to water stress was studied in 2-year-old potted Italian alder (Alnuscordata Loisel.) seedlings. Leaf area, transpiration, stomatal conductance, and xylem water potential were measured during May 1987 on seedlings from five geographic sources grown (i) with soil water content close to field capacity and (ii) with a severe drought. Significant differences in leaf area were found, at the end of the experiment, between drought-stressed and well-watered plants. As drought progressed, plants displayed a reduction of xylem water potentials and a decrease in stomatal conductance. However, transpiration did not stop completely, and seedlings were not able to maintain a favourable internal water status. Osmotic potentials for the undiluted cell sap, estimated from pressure–volume curves, were between −0.9 and −1.3 MPa. In June 1988, a similar experiment was carried out using seedlings from only one geographic source. A simultaneous decrease of transpiration, xylem potential, and net photosynthesis was observed in seedlings subjected to the drought treatment. During both experiments, a recovery of physiological parameters was observed, after rewatering. Some differences between provenances were detected. The provenance from Corsica showed the greatest sensitivity to water stress; a seed source from the province of Avellino (Campania, south Italy) was able to maintain a more favourable internal water status, as drought progressed.
Optimal road spacing for multistage cable yarding operations
Authors: Howard Andrew F. , Tanz Jordan S.
Published: January 2008

Equations needed to determine the economically optimal spacing of roads for multistage, one-way to roadside cable yarding were derived. The equations were used in a case study of optimal road spacing on four grapple yarding operations in coastal British Columbia. Two-stage yarding was cheaper and led to closer road spacing than one-stage yarding in all cases. The break-even point for two- and three-stage yarding with respect to road cost was defined as critical road cost. Three-stage yarding provided cost savings and a substantial increase in road spacing once critical road costs were exceeded. Critical road costs for three-stage yarding were within the range experienced in coastal British Columbia for the operations included in the case study. The potential for cost savings and reduced site disturbance from multistage yarding warrants serious consideration of these systems during harvest planning.
Abundance and distribution of rhizomorphs of Armillaria spp. in defoliated mixed oak stands in western Maryland
Authors: Twery Mark J. , Mason Garland N. , Wargo Philip M. , Gottschalk Kurt W.
Published: January 2008

The abundance and distribution of rhizomorphs of Armillaria spp. in the soil were quantified in undisturbed stands and in stands defoliated 1 and 5 years previously by insects. Although the species of Armillaria was not determined, similar mixed oak forests in south central Pennsylvania contain North American biological species VII (Armillariabulbosa Barla.). Several analysis techniques were tested for sensitivity to differences in distribution of rhizomorphs. Rhizomorph distribution within the 0.04-ha study plots was uniform in the undisturbed stands, but was significantly greater near dead trees in the defoliated stands. Total rhizomorph abundance was greater on plots defoliated 5 years before sampling than on more recently defoliated plots, and it was least on undefoliated plots. Rhizomorph density near dead trees was highly correlated with overall rhizomorph density. Greater rhizomorph abundance near recently dead trees or stumps may have important implications for management decisions in the presence of gypsy moth (Lymantriadispar L.) infestations.
Sphagnum-dominated peatlands of the hyperoceanic British Columbia coast: patterns in surface water chemistry and vegetation
Authors: Vitt Dale H. , Horton Diana G. , Slack Nancy G. , Malmer Nils
Published: January 2008

Vegetation from 133 relevés representing a broad spectrum of peatland types from the Prince Rupert area, British Columbia was divided into six relevé groups. The 210 taxa found in these relevés were classified into six species groups. In general, the species groups are related to one another along shade and height (above water level) gradients. Chemical and physiographic gradients that correlate with the relevé distribution pattern on a detrended correspondence analysis ordination are surface water chemistry, shade, and height. In particular, the major gradient influencing the first axis of the ordination is shade. The second axis of the ordination is related to a complex chemical gradient in which hydrogen ion, calcium, and sulphate are the most important components. These chemical changes are influenced by ombrotrophy. Surface water chemistry patterns show enriched ionic conditions on Graham Island (Queen Charlotte Islands), with a decrease inland. Especially important is the decrease of sodium and chloride ion. The peatlands studied include ombrotrophic bogs and soligenous fens. Raised bogs were found in basins, whereas blanket bogs occurred on gentle slopes at the most oceanic site. Pinuscontorta Loud. var. contorta is most abundant on ombrotrophic sites, whereas Chamaecyparisnootkatensis (Lamb.) Spach is dominant in soligenous fens. Soligenous poor fen, characterized by high Sphagnum abundance in lawns and forest islands and pH of 4.4–6.6, is the peatland type most frequently encountered in the study area.
Impact of clone mixture composition on stability of 7th-year mean height in a series of Norway spruce clone tests
Authors: Bentzer B. G. , Foster G. S. , Hellberg A. R.
Published: January 2008

Four mixtures of Norway spruce (Piceaabies (L.) Karst.), each containing 56 clones, were analysed for height at age 7 years at six locations in southern Sweden. The number of clones in each mixture was subsequently reduced in a stepwise manner from 56 to 40, 30, 20, 10, and finally, 5 clones. The reduction process was conducted in three ways: (i) random deletion, (ii) deletion based on height growth, and (iii) deletion based on clone stability. No difference among the means of clone mixtures could be found for 20–56 clones for any elimination procedure tested, and no mixture × location interaction existed despite the number of clones in the mixture or the elimination process used. Location effects were consistently significant, independent of the number of clones in each mixture. Also, replication effects were significant in all cases but one. Random elimination of clones resulted in weak differences between mixture means when 10 and 5 clones were included. Deletion of clones based on lack of stability or inferior height growth only slightly changed the variation pattern compared with when all 56 clones were present in each mixture. Relative height growth performance of clone mixtures with as few as 5 clones appeared to be stable within the region of Sweden that was represented by the trials.
Test of the TRIM inventory projection methods on Wisconsin jack pine
Authors: Leary Rolfe A. , Smith W. Brad
Published: January 2008

Reported is a test of the methodology underlying the trim projection system being used in the Resources Planning Act timber assessment. Nine combinations of density standards and relative density change equations were used to estimate annual volume growth of jack pine (Pinusbanksiana Lamb.). Annual volume growth data from remeasured USDA Forest Service inventory plots in two northern Wisconsin survey units and from industrial continuous forest inventory plots were used to evaluate the combinations. The yield table of Gevorkiantz and Duerr for well-stocked jack pine stands combined with a Riccati relative density change equation gave unbiased estimates of annual volume growth on both an absolute and percent error basis. We conclude that the concepts underlying the TRIM methodology are sound. However, for jack pine in northern Wisconsin only well-stocked or normal yield tables as the density standard and locally calibrated relative density change equations provide unbiased estimates of growth. A jack pine empirical yield table combined with the form of the relative density change equation used in the southern timber supply study underestimated growth by 45.4% (1.39 m3/(ha•year)). An empirical yield table enhanced with the STEMS projection system as a density standard used without a relative density change equation underestimated growth by 65.6% (1.67 m3/(ha•year)). Thus, inappropriate combinations of density standards and relative density change equations may lead to large errors in growth estimates.
The sensitivity of measurement error in stand volume estimation
Authors: Gertner George Z.
Published: January 2008

A method is given for approximating and evaluating the consequences of random and nonrandom errors in the independent variables of a nonlinear tree volume function that is used in the estimation of stand volume based on a simple random sample of plots. Sampling error, regression function error, and measurement error are accounted for with the method presented. An application is given where relatively moderate amounts of measurement error in the independent variables of a tree volume function can cause a relatively large reduction in the accuracy of estimated stand volume.
Growth and foliar nutrient status of black spruce and tamarack in relation to depth of water table in some Alberta peatlands
Authors: Lieffers Victor J. , Macdonald S. Ellen
Published: January 2008

Foliar nutrient status and growth rates of black spruce (Piceamariana (Mill.) B.S.P.) and tamarack (Larixlaricina (Du Roi) K. Koch) were assessed at 21 peatland locations where the water table was affected by roadbed construction. On one side of the road the peatland may have been drained while the other side may have been flooded or unaffected by the road. For both black spruce and tamarack, concentrations of foliar N and S, needle length, and periodic annual increment in basal area were positively correlated with depth to water table. Analysis of pairs of sites (from each side of the road) showed that trees from the site with greater depth to water table had higher concentrations of foliar N and S and greater basal area increment. Foliar concentration of P, K, Ca, Mg, Mn, Al, and Fe were not correlated with depth to water table or growth rate.
Initiation of embryogenic cultures and somatic embryo development in loblolly pine (Pinustaeda)
Authors: Becwar M. R. , Nagmani R. , Wann S. R.
Published: January 2008

Immature zygotic embryo explants (isolated or with intact megagametophytes) from 10 loblolly pine (Pinustaeda L.) clones (7-34, 7-56, 11-9, 11-16, 11-25, 10-1003, 10-1007, 10-1011, 10-1018, and 10-1019) were surveyed for their potential to form embryogenic tissue from the suspensor region of zygotic embryos. After over 14 000 explants were cultured, embryogenic cultures were initiated from explants of 8 of the 10 clones; only explants from clones 11-25 and 10-1019 were not responsive. Embryogenic tissue was initiated from zygotic embryos with intact megagametophytes on MSG basal medium with no exogenous plant growth regulators or with 2–5 mg/L 2,4-dichlorophenoxy acetic acid (2,4-D) and 0–1 mg/L N6-benzyladenine (BA). The highest initiation frequency (5%) was obtained from isolated zygotic embryos of clone 7-34 less than 0.5 mm in length just prior to cotyledon primordia development on DCR basal medium with 3 mg/L 2,4-D and 0.5 mg/L BA. Two types of embryogenic cultures were maintained on medium with 2,4-D and BA: (i) those that contained pre-embryonal masses of cells interspersed with unaggregated suspensorlike cells, but which rarely contained well-formed somatic embryos, and (ii) those that frequently contained well-formed somatic embryos. Somatic embryo development from both types of cultures progressed to a precotyledonary stage on medium with 2.6 mg/L abscisic acid.
Soil solution chemistry of an Adirondack Spodosol: lysimetry and N dynamics
Authors: Shepard J. P. , Mitchell M. J. , Scott T. J. , Driscoll C. T.
Published: January 2008

Solutes were monitored from the soil of a beech–maple forest and an adjacent lake at the Huntington Forest in the Adirondack Mountains of New York. The predominant ions were Ca2+ and SO42−. For soil solutions collected by lysimeters, the highest concentrations of most ions (H+, K+, NH4+, Ca2+, Mg2+, and NO3−) occurred in O horizon leachates, and the lowest concentrations beneath the spodic B horizon. However, Al and SO42− concentrations were highest beneath the B horizon. Concentrations of NO3− showed distinct seasonal variation. Values reached 60 μequiv. L−1 in the spring and decreased to near zero late in the growing season. Coefficients of variation (CV) differed among horizons. The E horizon was generally most variable (CV, 17 to 199%) and the B horizon the least (CV 19 to 166%). Variation was especially high for NO3− and NH4+, which had minimum CVs of 124% and 122%, respectively. Variation in these ions was likely due to the dominant role of biological processes in affecting nitrogen dynamics. Differences in soil solution concentrations among six soil pits were mainly due to spatial variation in soil properties rather than differences among the four types of lysimeters (tension, zero tension, fritted glass, and ceramic plate). Nitrogen species showed the greatest response to the installation of lysimeters, with elevated concentrations of NO3− (120 to 160 μequiv. L−1) observed during the first 2 years after installation. The high temporal and spatial variation of NO3− as well as its generation following lysimeter installation has important implications in assessing nitrogen dynamics of forest ecosystems.
Shoot and root development and dry matter partitioning in Populusgrandidentata, P. tremuloides, and P. × smithii
Authors: Reighard Gregory L. , Hanover James W.
Published: January 2008

Shoot and root development and dry matter partitioning in Populusgrandidentata Michaux, Populustremuloides Michaux, and their hybrid Populus × smithii Boivin were studied in hydroponic culture. Seedlings from intra- and inter-specific crosses having P. tremuloides as the maternal parent grew the tallest. Populustremuloides produced significantly fewer secondary roots than did P. grandidentata and P. × smithii. Rates of root growth in both species and the hybrid were similar after 5 weeks. Populustremuloides had a stem to root ratio twice that of P. grandidentata, whereas the hybrids had ratios that were more like those of their maternal parents.
Preliminary estimates of foliar absorption of 15N-labeled nitric acid vapor (HNO3) by mature eastern white pine (Pinusstrobus)
Authors: Vose James M. , Swank Wayne T.
Published: January 2008

We used a direct approach to quantify foliar N absorption by exposing foliage of mature eastern white pine (Pinusstrobus L.) to 15N-labeled nitric acid vapor (HNO3). Foliage on terminal portions of branches in a 31-year-old white pine plantation was enclosed in 9.0-L teflon film branch cuvettes and exposed to 10, 50, and 100 ppb H15NO3 for 12–30 h. Foliar absorption rates ranged from 0.026 μg 15N•g−1•h−1 at 10 ppb to 0.267 μg 15N•g−1•h−1 at 100 ppb. Extrapolation to the entire canopy resulted in an estimated absorption of 0.30–0.50 kg N•ha−1•year−1 at ambient HNO3 concentrations. In contrast, canopy input–output estimates for the same forest stand indicated a depletion of 2.3 kg•N•ha−1•year−1 by the forest canopy.
Male fertility variation in an open-pollinated plantation of Norway spruce (Piceaabies)
Authors: Xie Chang Yi , Knowles Peggy
Published: January 2008

Male fertility variation in an open-pollinated plantation of Norway spruce (Piceaabies (L.) Karst.) was studied using six polymorphic isozyme marker loci. Significant variation in male fertilities was detected in the seed crops from 81% of the female parents. The ranking of relative contribution of male parents to the offspring varied considerably among seed crops. Pronounced heterogeneity among the fertility estimates of a male parent derived from different seed crops was also observed. The overall male fertility estimates were highly skewed, with less than 23% of trees contributing more than 50% of the male gametes to the seed sample. In addition to postpollination mechanisms, factors associated with pollination such as variation in pollen production and floral phenology among trees likely have contributed to the observed male fertility variation. These results have significant implications in forest tree improvement programs.