bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of liming on the nutrition, vigor, and growth of sugar maple at the Lake Clair Watershed, Québec, Canada
Authors: Moore Jean-David , Camiré Claude , Ouimet Rock
Published: April 2011

In the 1980s, sugar maple (Acer saccharum Marsh.) dieback was observed across its range in Quebec. In spite of the recovery of the majority of stands during recent years, some have continued to show signs of dieback progression. At the Lake Clair Watershed experimental station, a study was undertaken to evaluate the effect of liming on the nutrition, vigor, and growth of sugar maple in an acid soil, poor in available Ca and Mg. A completely randomized experiment was established and selected sugar maples were treated in 1994 with dolomitic lime in amounts of 0, 0.5, 1, 2, 5, 10, 20, or 50 t·ha-1. Four years after the lime application, improvements in foliar concentrations of N, P, Ca, and Mg were noted. Liming increased the radial growth of sugar maple by 45% for rates from 1 to 10 t·ha-1and by 90% for rates of 20 t·ha-1, compared with the control trees. The beneficial effects of lime on dieback appeared only very slightly at the third and fourth years after treatment. The negative impact of liming on sugar maple K nutrition could be mitigated by application of potassium sulphate.
Genetics of cold hardiness in a cloned full-sib family of coastal Douglas-fir
Authors: Anekonda T S , Adams W T , Aitken S N , Neale D B , Jermstad K D , Wheeler N C
Published: April 2011

Variation in cold-hardiness traits, and their extent of genetic control and interrelationships, were investigated among individuals (clones) within a single large full-sib family of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) from Oregon. Cold injury to needle, stem, and bud tissues was evaluated in fall 1996 and spring 1997 following artificial freeze testing of detached shoots collected from 4-year-old ramets (rooted cuttings). Variation among clones in cold-injury scores was significant (p < 0.01) for all shoot tissues in both fall and spring and averaged about three times the magnitude previously observed among open-pollinated families of this species. Thus, improving cold hardiness by within-family selection appears to hold much promise. Striking similarities in relative magnitudes of heritability estimates and genetic correlations in the full-sib family, compared with breeding populations, support the following hypotheses about the quantitative genetics of cold hardiness in this species: (i) heritability of cold hardiness (both broad-and-narrow-sense) is stronger in the spring than in the fall; (ii) cold hardiness of different shoot tissues in the same season is controlled by many of the same genes; and (iii) genetic control of fall cold hardiness is largely independent of cold hardiness in the spring.
Effects of root wrenching on leaf mineral content ofPrunus aviumandCastanea sativaseedlings
Authors: Hipps N A , Samuelson T J , Farman L G
Published: April 2011

The roots of wild cherry (Prunus avium L.) and sweet chestnut (Castanea sativa Mill.) seedlings grown from seed in a nursery bed were cut by passing a wedge-shaped blade horizontally through the soil (wrenched) at 20 cm depth on 10 July (early) or 12 August (late) or on both dates. Nitrogen concentrations in leaves of C. sativa and P. avium seedlings were severely reduced by early or late root wrenching, and except for the early wrenched C. sativa, seedlings had not fully recovered by the end of the growing season compared with the controls. Phosphorus concentrations also were reduced in the leaves of both species by wrenching treatments, but were similar to those found in undisturbed seedlings by the end of the season. The effects of wrenching treatments on the concentrations of potassium, manganese, and calcium in leaves of either species were generally negligible. The reduction in concentrations and total foliar content of nitrogen and phosphorus caused by the wrenching treatments in leaves of these species did not have a negative effect on growth following outplanting.
Interactions of airborne methyl jasmonate with vegetative storage protein gene and protein accumulation and biomass partitioning inPopulusplants
Authors: Beardmore T , Wetzel S , Kalous M
Published: April 2011

In young poplar (Populus nigra Muench × Populus maximowiczii A. Henry) plants, vegetative storage proteins (VSPs), the bark storage protein (BSP), and (or) wound-inducible 4 protein (WIN4) mRNAs were present in the apical and basal leaves and in the basal leaves, respectively. VSPs accumulated in the apical leaves and to a lesser extent in the stem. The response of the plants to 20 µM airborne methyl jasmonate (MJ) was examined in four parts ( apical and basal leaves, stem, and roots) in both short-term (within 72 h) and long-term (1, 2, 3, and 4 weeks) experiments. In the short-term, MJ-treated plants either induced or increased the part-specific expression of win4 and bsp, and accumulation of BSP and (or) WIN4. In the long-term, MJ treatment resulted in part-specific alterations in protein and nitrogen concentration and further altered BSP and WIN4 accumulation. The MJ-treated plants increased both the biomass allocation to the stem, without a change in the relative growth rate, and the tolerance low temperature (-2°C). Together, these results suggest the BSP and WIN4 are both involved in short-term N cycling and that exogenous MJ treatment promotes changes in nitrogen metabolism in poplar.
Application of ectomycorrhizal fungi in rooting of Scots pine fascicular shoots
Authors: Niemi Karoliina , Salonen Maija , Ernstsen Arild , Heinonen-Tanski Helvi , Häggman Hely
Published: April 2011

The ectomycorrhizal fungi, Pisolithus tinctorius (Pers.) Coker & Couch and three Paxillus involutus (Batsch) Fr. strains, were used to enhance in vivo rooting in fascicular shoots of 49 Scots pine (Pinus sylvestris L.) genotypes representing seed families from southern and northern Finland. Inoculation with specific fungi either increased the rooting percentage or accelerated root formation expressed as an increased number of adventitious roots per cutting. Only one of the six seed families gave no positive response. The relationship between the in vitro production of free and conjugated forms of indole-3-acetic acid (IAA) by the fungi and rooting was also investigated. Pisolithus tinctorius was the only significant producer of IAA in the absence of exogenous tryptophan. All the Paxillus involutus strains also synthesized both free and conjugated IAA but did that actively only from exogenous tryptophan. In vitro production of IAA did not correlate with root induction in vivo, but the rooting responses depended on the fungus strains and the Scots pine seed families and (or) genotypes within families. This indicates that in vitro IAA production capacity cannot be the only criterion when selecting ectomycorrhizal fungi for rooting in vivo and that specific genotype-genotype interactions play a key role in root initiation.
A long-term study of tree seedling recruitment in southern Appalachian forests: the effects of canopy gaps and shrub understories
Authors: Beckage Brian , Clark James S , Clinton Barton D , Haines Bruce L
Published: April 2011

We examined the importance of intermediate-sized gaps and a dense shrub layer on tree seedling recruitment in a southern Appalachian deciduous forest. We created 12 canopy gaps under two contrasting understory conditions: 6 gaps were dominated by the dense, shade-producing shrub, Rhododendron maximum L., while the remaining gaps were relatively open. Density of first-year and >first-year seedlings was monitored for 5 years in transects extending from adjacent undisturbed forest through the experimental gaps. We concurrently measured the understory light environment, soil moisture, litter biomass, and seed rain. Neither species diversity nor richness consistently increased following gap formation. Acer rubrum L. responded consistently to canopy gaps with increased seedling densities while most other species, including both shade-tolerant and shade-intolerant species, did not. Seedling densities were especially low and unresponsive to gap formation in areas dominated by R. maximum. Understory light levels were consistently low beneath R. maximum and did not increase with canopy gap formation. Our results suggest that dense shrub cover can neutralize recruitment opportunities in canopy gaps, that seed rain often limits recruitment in gaps, and that canopy gaps that are larger or include understory disturbance are needed to maintain diversity in these forests.
Population density influences assessment and application of site index
Authors: MacFarlane David W , Green Edwin J , Burkhart Harold E
Published: April 2011

The height growth of dominant trees in plantations is often assumed to be independent of initial planting density. This assumption allows for the use of dominant tree height as an index of site quality. We found that this assumption was false for the seven tallest trees in 184 even-aged loblolly pine (Pinus taeda L.) stands, planted at nine initial planting densities, at four different geographic locations. A strong, highly significant negative correlation was found between dominant height and initial planting density for stands 14 and 16 years of age. This leads to large differences in predicted site index for stands with different initial planting densities planted at the same geographic location. Use of these site indices to predict yield produced large differences in predicted yield (m3/ha) at age 25. These results provide strong evidence for density-dependent height growth, even for dominant trees in the stand, and suggest that site index, used as a measurement of site quality, is confounded with stand density.
Genotypic variation in carbon isotope discrimination and gas exchange of ponderosa pine seedlings under two levels of water stress
Authors: Olivas-García J Miguel , Cregg Bert M , Hennessey Thomas C
Published: April 2011

As part of a program to select ponderosa pine (Pinus ponderosa Dougl. ex Laws.) genotypes for improved drought tolerance, we examined physiological and morphological characteristics of 12 half-sib families of ponderosa pine from four seed sources; New Mexico, South Dakota, Nebraska, and Wyoming. We analyzed genetic variation in carbon isotope discrimination (Δ), photosynthetic gas exchange, needle morphology, and growth of 2-year-old seedlings from the four seed sources grown under two levels of moisture availability. To gain a better understanding of within-provenance variation and identify opportunities to refine selection strategies, we also examined family within seed source variation in the traits. Water stress significantly (P < 0.05) reduced net photosynthesis (A), needle conductance to water vapor (gwv), carbon isotope discrimination (Δ), and growth of the seedlings as compared to well-watered seedlings. However, instantaneous water use efficiency (A/gwv) did not differ between water treatments. Seedlings from New Mexico had significantly lower gwv and higher A/gwv than seedlings from the other sources. Carbon isotope discrimination was lowest for seedlings from New Mexico and Nebraska. Families within seed sources varied significantly in A, gwv, stomatal density, needle length, height increment, and Δ. Carbon isotope discrimination was significantly correlated with gwv but not with A, supporting results from mature trees suggesting that variation in Δ in ponderosa pine is more related to gwv than to A. Seed source × water treatment interactions were not observed for any of the traits analyzed. These results support our previous assertion that genotype × environment interaction in Δ of mature ponderosa pine trees from these sources grown in Nebraska and Oklahoma was related to factors other than moisture availability.
Vertical and temporal distribution of insolation in gaps in an old-growth coniferous forest
Authors: Weiss Stuart B
Published: April 2011

The combination of canopy access at the Wind River Canopy Crane Research Facility, hemispherical photography, and long-term insolation data provided estimates of vertical and temporal distributions of insolation in nine canopy gaps in a 65 m tall Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) - western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest. Yearly insolation (long-term data from Portland, Oreg.) exhibited a sigmoidal pattern with height, with a bright zone (>4200 MJ/m2) above 50 m, a transition zone from 45 to 30 m (2000 MJ/m2), and less rapid decrease from 30 to below 10 m (600 MJ/m2). Intergap variation peaked between 20 and 40 m. Interannual variation of yearly insolation (CV = SD/mean) was about 5% throughout the canopy. Seasonality of insolation was driven by solar angle and cloudiness. Diffuse insolation was 50% of annual above-canopy flux, increasing to nearly 70% at 1.5 m, and diffuse proportion was greater in winter and spring. Hourly simulations under clear and cloudy conditions provided an appropriate time scale for modeling photosynthesis. Estimated leaf area index peaked at 30-35 and 5-10 m but was underestimated (3.7 vs. 9.1 m2/m2from direct measurements) because of foliage clumping. The methods documented highly variable distributions of insolation driven by forest structure, cloudiness, and seasonal changes in solar angle.
The consequences of hierarchy for modeling in forest ecosystems
Authors: Robinson Andrew P , Ek Alan R
Published: April 2011

An overview of forest ecosystem models in the context of hierarchies is presented, considering spatiophysical, mechanistic, temporal, usage, and range resolutions. We argue that models of forest ecosystem dynamics can be treated as inherently hierarchical structures of discrete submodels or modules. These submodels represent distinct but connected processes, such as growth, mortality, or regeneration. This approach has important ramifications for model building, fitting, criticism, and application. It provides new strategies for dealing with common modeling problems, such as component choice, as well as placing in context established modeling strategies. A system of categories that avoids popular and simplistic dichotomies is provided to assist in model classification. The need for more sophisticated techniques at each stage of model construction is demonstrated, and candidate solutions are suggested.
Interspecific variation in susceptibility to windthrow as a function of tree size and storm severity for northern temperate tree species
Authors: Canham Charles D , Papaik Michael J , Latty Erika F
Published: April 2011

Studies of wind disturbance regimes have been hampered by the lack of methods to quantify variation in both storm severity and the responses of tree species to winds of varying intensity. In this paper, we report the development of a new, empirical method of simultaneously estimating both local storm severity and the parameters of functions that define species-specific variation in susceptibility to windthrow as a function of storm severity and tree size. We test the method using data collected following a storm that struck the western Adirondack Mountains of New York in 1995. For intermediate-sized stems (e.g., 40 cm DBH), black cherry (Prunus serotina Ehrh.) and red spruce (Picea rubens Sarg.) showed the highest rates of windthrow across virtually all levels of storm severity, while yellow birch (Betula alleghaniensis Britt.) and sugar maple (Acer saccharum Marsh.) had the lowest rates of windthrow. For much of the range of storm severity, the probability of windthrow for the most susceptible species was at least twice as high as for the least susceptible species. Three of the species, yellow birch, red spruce, and beech (Fagus grandifolia Ehrh.), had significantly lower probability of windthrow at a given storm severity in old-growth stands than in second-growth stands. Our results suggest that the distinctive abundance of these three species in old-growth forests of the Adirondacks is due, at least in part, to their ability to survive the intermediate-scale disturbance events that appear to dominate the natural disturbance regime in this region.
The effects of climate change on the distribution and management ofPicea abiesin southern Scandinavia
Authors: Bradshaw Richard HW , Holmqvist Björn H , Cowling Sharon A , Sykes Martin T
Published: April 2011

The distributions of Picea abies (L.) Karst. and other European forest trees have continuously changed since the last glaciation. Static and dynamic bioclimatic simulation models are used to estimate the degree of climatic control operating on the southern Scandinavian range limits of Picea during the last 1000 years. The results show that the range limit has begun to track climate change more closely than in the past, and a future projection predicts a rapid northward contraction of the present limit. Contracting ranges track climate change more closely than do expanding ranges that are limited by seed dispersal. The physiological mechanism of the climatic control is unclear, but Picea planted beyond its current climatic range limit was seriously damaged during a recent storm. Planting trees beyond their natural climatic range limits can only be advised in areas that become suitable for colonization under a changed climate.
Validating allometric estimates of aboveground living biomass and nutrient contents of a northern hardwood forest
Authors: Arthur Mary A , Hamburg Steven P , Siccama Thomas G
Published: April 2011

Accurate estimates of tree biomass and nutrient content are essential to the development of budgets for forest ecosystems. Aboveground biomass is typically estimated using allometric equations; nutrient content is calculated by multiplying elemental concentrations times the weight of each tree component. Allometric projections have seldom been compared with direct measurements; yet, such comparisons are necessary to assess the accuracy of forest biomass and nutrient estimates. For three 0.25-ha northern hardwood forest plots we compared allometric estimates with direct measurements of aboveground tree biomass and nutrients. Trees on each plot were skidded to a landing where they were chipped or removed whole. Chip vans and log trucks with material from each plot were weighed and subsampled for moisture and nutrient contents. The allometric and measured estimates of aboveground biomass did not differ significantly. Nutrient contents estimated using allometry were not significantly different from direct measurements for Ca, Mg, P, Mn, and Zn but underestimated K (24%), N (16%), and Fe (70%). The allometric approach proved accurate for estimating aboveground biomass; nutrient estimates were less consistent, requiring validation before they can be used with confidence. The direct measurements provide an estimate of uncertainty in biomass and nutrient contents.
Conservation of noble hardwoods in Europe
Authors: Eriksson Gösta
Published: April 2011

This paper is a summary of the work carried out within the European Forest Genetic Resources Programme network on gene conservation of noble hardwoods. The species classified as noble hardwoods are all of minor economic importance in European forestry owing to their low proportion in forests. For commonly occurring species the in situ multiple population breeding system (MPBS) is suggested. Some of the noble hardwoods occur together and whenever possible, their combined gene conservation is suggested. If possible, some of the subpopulations will be extended to 200300 ha to match the objective of gene conservation of associated species. For rarely occurring species, grafting of trees and establishment of plantations of grafts in seed orchards or clonal archives are suggested to increase the effective population size. The progenies from such an orchard or archive are planted in forests. For Castanea sativa Mill., which is a multipurpose species, separate gene conservation of fruit cultivars and populations in nature is suggested. The severe threat from Dutch elm disease makes it necessary to establish hedges of Ulmus species to avoid infection of the disease via Scolytus insects. Whenever possible, MPBS in situ gene conservation of Ulmus glabra Huds. and Ulmus laevis Pall. should be carried out.
Evidence for low genetic diversity and metapopulation structure in Canada yew (Taxus canadensis): considerations for conservation
Authors: Senneville Sauphie , Beaulieu Jean , Daoust Gaëtan , Deslauriers Marie , Bousquet Jean
Published: April 2011

Canada yew (Taxus canadensis Marsh.) is a gymnosperm that grows in the understory of mixed and deciduous forests of northeastern North America. This shrub had no economic importance until the discovery of paclitaxel, or TAXOL®, which is a compound found in plant tissue and used in cancer treatment. With the intensifying harvesting pressure on natural populations of this species, the natural gene pool might be affected. The objective of this study was to estimate the levels of genetic diversity and population structure in Canada yew, before any sizeable effects resulting from harvesting appear. Six natural populations of Canada yew were sampled in Quebec. Genetic diversity was estimated at 22 loci coding for 12 enzyme systems. At the population level, the number of alleles per locus was 1.32, the percentage of polymorphic loci was 26.5%, and the observed heterozygosity was 0.102. These results show that Canada yew is genetically less diverse than other yew species and the great majority of gymnosperms. However, the amount of population differentiation was substantially higher (FST= 10.2%) than that for other conifer and tree species growing in the boreal-temperate zone. Hypotheses related to the biogeography of the species and a likely metapopulation structure are proposed to explain the observed trends.
Characterizing shade tolerance by the relationship between mortality and growth in tree saplings in a southeastern Texas forest
Authors: Lin Jie , Harcombe Paul A , Fulton Mark R
Published: April 2011

We investigated the relationship between shade tolerance and sapling mortality using data collected over 15 years in a mesic forest in southeastern Texas. Seven species representing a range of shade-tolerance classes were included in the study. We used survival analysis to estimate species-specific sapling mortality risk (hazard) as a function of recent growth. We found that shade-intolerant species had higher mortality risk at zero growth than shade-tolerant species. The results strongly support the point that shade tolerance can be characterized by the relationship between sapling mortality and growth.
Decomposition and nitrogen release from decomposing woody roots in coniferous forests of the Pacific Northwest: a chronosequence approach
Authors: Chen Hua , Harmon Mark E , Griffiths Robert P
Published: April 2011

Decomposition of woody roots in Sitka spruce (Picea sitchensis (Bong.) Carrière), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and ponderosa pine (Pinus ponderosa P. Laws. ex C. Laws.) dominated forests in Oregon, U.S.A. was studied using a chronosequence. Roots of five coniferous species were excavated from stumps with ages up to 46 years old. In order of increasing decomposition rate constant (k) the species were Douglas-fir < Sitka spruce < lodgepole pine (Pinus contorta Dougl. ex Loud.) < western hemlock (Tsuga heterophylla (Raf.) Sarg) < ponderosa pine. Variation in the proportion of bark, wood, and resin cores was correlated to these differences. Root wood showed the highest k, root bark the second, and resin cores the lowest. The occurrence of resin cores in woody roots of Douglas-fir, Sitka spruce, and lodgepole pine greatly slowed the decomposition of these species. White rots occurred frequently in ponderosa pine and lodgepole pine, whereas brown rots mostly appeared in Douglas-fir and Sitka spruce. Species with white rot had a higher k than those with brown rot. Decomposing woody roots started to release N after 2030% mass loss, a point when the dead root C/N ratio averaged 140.
Birch foliar responses to simulated acidic fog andSeptoria betulaeinoculations
Authors: Kouterick K B , Skelly J M , Pennypacker S P , Cox R M
Published: April 2011

The effects of simulated acidic fog and inoculation with Septoria betulae Pass. on foliar symptom development and foliar senescence of Betula papyrifera Marsh. and Betula cordifolia Regel seedlings were investigated in 1997 and 1998 under greenhouse conditions. An interactive role may exist between acidic fog events and S. betulae in causing birch foliar browning, a disease reported over the past decade to occur on mature trees growing adjacent to the Bay of Fundy, Canada. Seedlings received applications of simulated fog adjusted to pH 3.2, 4.2, and 5.6 or a no-fog treatment. Inoculation treatments at each fog pH level were accomplished through spray atomization with S. betulae conidial suspensions and by placing naturally infected birch leaves bearing pycnidia of the fungus on plastic nets suspended above seedlings in enclosed chambers. Percent symptomatic leaf area of seedlings inoculated with S. betulae was nearly double that recorded for non-inoculated seedlings. Foliar browning resembled symptoms observed on mature trees in the field. Foliar symptoms were observed on non-inoculated seedlings, with greater severities associated with seedlings exposed to the most acidic fog treatment. Leaf senescence was also greatest for spray-inoculated leaves that had been exposed to the pH 3.2 fog treatment. Pycnidial development was not influenced by the pH of the fog treatments but was greater in all fog treatments than in no-fog treatments. Although both acidic fog and S. betulae infection are able to cause symptoms independently, the data suggest that an interactive role may exist in causing birch foliar browning. However, to obtain the same severity of foliar browning as observed on natural forest-grown trees in the Bay of Fundy region, S. betulae must be present.
Laser point-quadrat sampling for estimating foliage-height profiles in broad-leaved forests
Authors: Radtke Philip J , Bolstad Paul V
Published: April 2011

A technique for estimating the vertical distribution of foliage area in broad-leaved forests was developed. The technique is similar to optical point-quadrat sampling, where estimates are based on heights to the lowest leaves above numerous sample locations beneath a canopy. In optical point-quadrat sampling, heights to lowest leaves are measured with a telephoto lens. Here, heights were measured using a commercially available laser range-finding instrument. The laser point-quadrat technique was tested in field studies conducted under broad-leaved forest canopies in western North Carolina and east-central Minnesota, U.S.A. Foliage-height profiles obtained by laser point-quadrat sampling were consistent with two of four published foliage-height profiles observed in 1995 at the North Carolina field locations. Total leaf area estimates obtained by laser point quadrats were not significantly correlated with values of leaf area index estimated by recent litter fall analyses at the North Carolina and Minnesota field locations. Although further evaluation and refinement of the technique is needed, laser point-quadrat sampling shows promise as a means of obtaining foliage-height profiles at a significantly reduced effort and with greater accuracy than methods commonly in use today.
A plot-based method for rapid estimation of forest canopy chemistry
Authors: Smith Marie-Louise , Martin Mary E
Published: April 2011

In this study we present a rapid method to scale the leaf-level chemistry of forest stands to the whole-canopy level. The method combines simple leaf-level measurements of mass and chemistry with a camera-based technique to estimate the fractional distribution of species' foliage area in a forest canopy. Results using this methodology for the estimation of whole-canopy N concentration (g/100 g) are presented and are shown to be comparable with those derived directly from litter fall collection. The ability to efficiently scale leaf-level traits to whole forest canopies enhances our ability to examine key relationships associated with these traits at various levels from the leaf to the forest stand and, with remote sensing technologies, to larger landscapes.
Role of vegetation and weather on fire behavior in the Canadian mixedwood boreal forest using two fire behavior prediction systems
Authors: Hély Christelle , Flannigan Mike , Bergeron Yves , McRae Douglas
Published: April 2011

Spring and summer simulations were carried out using the Canadian Fire Behavior Prediction (FBP) and U.S. BEHAVE systems to study the role of vegetation and weather on fire behavior in the mixedwood boreal forest. Stands at Lake Duparquet (Quebec, Canada) were characterized as being deciduous, mixed-deciduous, mixed-coniferous, or coniferous, according to their conifer basal area percentage. Sampled fuel loads (litter, duff, woody debris, herbs, and shrubs) and local weather conditions (three different fire-risk classes) were used as inputs in the simulation. The predicted fire behavior variables were rate of spread (ROS), head fire intensity (HFI), and area burned. Results from ANOVA testing showed that both weather and vegetation are not always significant, and the two prediction systems qualitatively attribute the explained variance to these factors differently. The FBP System selects the weather factor as the most important factor for all fire behavior variables, whereas BEHAVE selects the vegetation factor. However, three research burns located in Ontario revealed that BEHAVE was not well adapted to the mixedwood boreal region, whereas FBP predictions were quantitatively close to observed prescribed values. Extreme fire weather is confirmed as producing large and intense fires, but differences in fire behavior among stand types exist across the full range of fire weather. Implications of climate change, vegetation, and seasonal effects on fire behavior and the forest mosaic are discussed.
Root dynamics of southern Ohio oak-hickory forests: influences of prescribed fire and landscape position
Authors: Dress William J , Boerner Ralph EJ
Published: April 2011

This study compares standing root biomass from sequential root cores and new root production in ingrowth cores in three watersheds: an unburned control watershed, a watershed burned once in 1996, and a watershed burned for three consecutive years (19961998). Based on root cores collected on six sampling dates from April through November 1998, maximum standing live root biomass occurred approximately 1 month earlier in the growing season in the site burned three times, presumably because of increased soil temperature after the fires. Standing live fine root biomass was significantly lower in the site burned three times in three of the six sampling dates (April, June, and November) and when averaged over the whole growing season. Most of this effect was due to lesser root biomass in the most mesic landscape position. New root production was measured during three ingrowth core intervals: April to August 1998, August to November 1998, and August 1998 to November 1999. Net production was significantly greater in sample plots in xeric landscape positions during each sampling interval. Overall, differences in standing root biomass were inversely correlated with fire-induced changes in N mineralization and increased soil temperature after burning shifted the phenology of root biomass accumulation earlier in the growing season.
Mycorrhizae confer aluminum resistance to tulip-poplar seedlings
Authors: Lux Heidi B , Cumming Jonathan R
Published: April 2011

Aluminum (Al) toxicity may limit the growth and nutrient acquisition of sensitive tree species in regions receiving acidic deposition. Symbioses between tree roots and mycorrhizal fungi may offset the negative impacts of Al in the root zone. Liriodendron tulipifera L. (tulip-poplar) is an important tree species in the Appalachian Mountains of the southeastern United States and may be at risk from the high levels of acidic deposition in that area. Mycorrhizal and non-mycorrhizal tulip-poplar seedlings were exposed to Al levels of 0, 50, 100, and 200 µM in sand culture for 6 weeks. Mycorrhizal plants accumulated two to seven times the shoot and root biomass of non-mycorrhizal plants and demonstrated no decreases in biomass with Al exposure. Non-mycorrhizal plants exhibited significant reductions in biomass at and above 100 µM Al. Aluminum toxicity in non-mycorrhizal plants appears to be the result of the disruption of P translocation to leaves and Ca, Mg, P, Cu, and Zn uptake in roots. Mycorrhizal plants accumulated 2 and 1.5 times the concentration of Al in shoots and roots, respectively, indicating that Al resistance was not associated with the exclusion of Al from the plant. Patterns of labile Al in solution, nutrients, and Al accumulation in tissues suggest that arbuscular mycorrhizal fungal ecotypes may alter the form or compartmentation of Al within the rhizosphere and plant, thus protecting seedlings from the effects of exposure to Al in the soil solution.
Tree ring area measurements using morphological image analysis
Authors: Soille Pierre , Misson Laurent
Published: April 2011

This paper describes a semiautomatic methodology for measuring the areas of annual tree rings. The cross section of a tree stem is first prepared by sanding and dipping into polyethylene glycol to prevent it from cracking. A digital grey-scale image of the resulting stem disk is then acquired by a scanner at the spatial resolution of 600 dots per inch. This image is processed by a series of morphological image processing transformations so as to automatically outline the tree rings. User interaction is restricted to the correction of extraneous or missing boundaries generated by disturbing features such as knots and low-contrast or very narrow rings. The methodology has been developed for Picea abies (L.) Karst., and its applicability to other species is discussed.
Ectomycorrhizal mushroom response to partial cutting in a western hemlock - western redcedar forest
Authors: Kranabetter J M , Kroeger P
Published: April 2011

We examined epigeous ectomycorrhizal mushroom richness and productivity after partial cutting in a western hemlock (Tsuga heterophylla (Raf.) Sarg.) - western redcedar (Thuja plicata Donn ex D. Don in Lamb.) forest of northwestern British Columbia. Mushrooms were collected throughout the fruiting season (July to October) for 3 years, starting 5 years after partial cutting, from plots with mesic soil conditions and residual basal areas ranging from 23 to 69 m2/ha for western hemlock and 0 to 26 m2/ha for western redcedar. Partial cutting had no apparent effect on mushroom phenology over the 3 years. Significant block interactions demonstrated that reductions in basal area of western hemlock could lead to positive, neutral, and negative responses in mushroom richness, biomass, and number of fruiting bodies. These responses were related to stand structure and the potential differences in tree vigour after partial cutting. In addition, there was weak evidence that western redcedar, a host for vesicular-arbuscular mycorrhiza, had a negative effect on average taxon richness. The study demonstrated that partial-cutting systems could allow some timber removal without necessarily reducing ectomycorrhizal mushroom communities.
Role of selection versus historical isolation in racial differentiation of ponderosa pine in southern Oregon: an investigation of alternative hypotheses
Authors: Sorensen Frank C , Mandel Nancy L , Aagaard Jan E
Published: April 2011

Continuous populations identified as Pacific and North Plateau races of ponderosa pine (Pinus ponderosa P. Laws. ex C. Laws.) are parapatric along the crest of the Cascade Range in southern Oregon. A 3-year common-garden study of bud phenology and seedling vigor was performed to estimate the nature and magnitude of differentiation between races, to characterize the transition zone between them, and to relate responses between and within races to topography and climate. Principal component (PC) analyses identified two significant character complexes, PC-1 (phenological traits) and PC-2 (size traits), that explained 73% of the geographic race-related variation. The races were differentiated in two regards. First, PC-1 scores, which were highly correlated with frost-free season and summer-winter temperature differential, displayed a sharp discontinuity in the transition zone. Second, PC-2 scores were significantly correlated with physiographic and climatic variables in the North Plateau but not in the Pacific race, even though these variables had greater ranges in the latter. The data supported a narrow, adaptive transition between races for a complex of traits probably related to cold hardiness, and provided evidence that plant vigor traits were more closely adapted to environments in the North Plateau than in the Pacific region, possibly as a consequence of past climatic-stress selection in the former and competitive-stress selection in the latter.
Growth, morphology, and gas exchange in white spruce (Picea glauca) seedlings acclimated to different humidity conditions
Authors: Roberts Jessica J , Zwiazek Janusz J
Published: April 2011

The study examined the effects of different relative humidity conditions at germination, early growth, and following cold storage on morphological and physiological characteristics of white spruce (Picea glauca (Moench) Voss) seedlings. Seedlings that were grown for 18 weeks following seed germination at the lower, 30% RH (RHinitial) treatments were shorter and had smaller stem diameters, shorter needles with more epicuticular wax, and a greater density of needles per centimetre stem, compared with the 80% RHinitialseedlings. After 18 weeks of growth under 30, 50, and 80% RH, the seedlings were hardened off, stored for 8 weeks at 3°C and planted in pots in growth chambers under 42 and 74% relative humidity (RHsubsequent). Under 74% RHsubsequentconditions, the lower RHinitialseedlings flushed sooner and had higher growth rates compared with the higher RHinitialseedlings. When the higher RHinitialseedlings were placed under 42% RHsubsequentconditions, their bud flush was delayed, and subsequent growth rates were lower compared with the lower RHinitialseedlings. When measured at 40% RH, seedlings subjected to lower RHinitialhad higher net assimilation rates and stomatal conductance compared with the seedlings acclimated to higher RHinitialhumidity. It was concluded that the humidity conditions present during early seedling growth following germination significantly affect their morphological and physiological characteristics during the second growth season.
Substitution in global wood imports in the 1990s
Authors: Uusivuori Jussi , Kuuluvainen Jari
Published: April 2011

In this paper substitution between the main categories of imported wood and between imported and domestic wood raw material is studied empirically using a cost-function approach and a panel data set of the world's 36 most important wood-importing countries in 19901997. A subcost function for the optimal mix of different timber inputs and estimable cost share functions are derived. The results suggest that as industrial consumption of wood continues to grow, international trade becomes an increasingly important source of wood for the world's forest industries. Cross-price elasticities of derived demand based on maximum-likelihood estimation show that substitution between different categories of imported wood in world imports is fairly low. By contrast, substitution between imported wood and domestically produced wood is higher. Long-run own-price and cross-price elasticities are larger in absolute terms than short-run elasticities. Because of fairly strong substitutability between domestic and imported wood in the long run, the effects of national forest conservation may be transferred globally via international trade.
Spatial stochastic modeling of resin yield from pine stands
Authors: Nanos Nikos , Tadesse Wubalem , Montero Gregorio , Gil Luis , Alia Ricardo
Published: April 2011

The spatial structure of resin-yield in maritime pine stands in central Spain was studied on two different scales and with data from two tapping periods (1998 and 1999). For the fine scale, Moran's I and the K function were used to study within-stand spatial variation. We found that in one plot, trees separated by distances of less than 5 m had similar production. The K function results showed that the distribution of trees did not depart significantly from complete spatial randomness. For a much larger scale, data was available from 37 and 59 ten-tree plots for years 1998 and 1999, respectively. Partial (monthly) yields were also measured. The experimental variograms for the mean plot production showed that a large percentage of the total variance was spatially structured. Furthermore, the experimental variograms for the partial yields revealed changes in the spatial structure of this phenomenon within the same year. Spatial stochastic modeling was shown to be an effective and economic modeling strategy. Temporal variation should be included in future work, with the use of geostatistical space-time models.
Do soil fauna increase rates of litter breakdown and nitrogen release in forests of British Columbia, Canada?
Authors: Cárcamo H A , Prescott C E , Chanway C P , Abe T A
Published: April 2011

The objective of this study was to improve our understanding of the role of soil invertebrates in the breakdown of litter, cycling of nitrogen, and growth of seedlings in forests of British Columbia by comparing two experimental approaches. First, in the laboratory, breakdown of birch leaves was slightly higher in the presence of millipedes in the microcosms of forest floor collected from two coastal forests. Presence of smaller animals (mesofauna) and contaminant Diptera larvae did not hasten litter breakdown in microcosms made from forest floor from either a sub-boreal or a coastal forest. In general, inorganic nitrogen release was higher in the presence of fauna, but results were highly variable. Growth of seedlings was slightly greater in the coastal microcosms that included millipedes. In the second approach, a field experiment was conducted using intact forest floor cores enclosed with one of three mesh sizes (54 µm, 1 mm, and 5 mm) and defaunated with liquid nitrogen. Comminution of birch leaves, and to some extent, greater inorganic nitrogen release occurred in sacs that allowed access to larger animals compared with sacs with fine mesh that excluded them. Although differences among treatments were small, the results from both approaches agree and indicate that soil invertebrates increase rate of breakdown of forest litter and cycling of nutrients in coastal forests.
The characteristics of woody debris and sediment distribution in headwater streams, southeastern Alaska
Authors: Gomi Takashi , Sidle Roy C , Bryant Mason D , Woodsmith Richard D
Published: April 2011

Large woody debris (LWD), fine woody debris (FWD), fine organic debris (FOD), and sediment deposition were measured in 15 steep headwater streams with five management and disturbance regimes. Clear-cut channels logged in 1995 contained large accumulations of logging residue that initially provided sites for sediment storage. Half of the LWD in clear-cut channels was recruited during and immediately after logging. Woody debris from logging activities remains in young growth conifer channels 37 years after logging. Numbers of LWD in clear-cut and young conifer channels were significantly higher than in old-growth channels, although numbers of FWD pieces were not significantly different because of higher recruitment from old-growth stands. Channels that experienced recent (1979 and (or) 1993) and earlier (1961 and (or) 1979) scour and runout of landslides and debris flows contained less LWD and FWD, although large volumes of LWD and FWD were found in deposition zones. The volumes of sediment stored in young alder and recent landslide channels were higher than in the other channels. Because of the recruitment of LWD and FWD from young alder stands, the ratio of sediment stored behind woody debris to total sediment volume was higher in young alder channels compared with recent landslide channels. Numbers of LWD and FWD pieces in all streams were significantly correlated with the volumes of sediment stored behind woody debris. Timber harvesting and soil mass movement influence the recruitment, distribution, and accumulation of woody debris in headwater streams; this modifies sediment storage and transport in headwater channels.
Distribution, hosts, and site relationships of Armillaria spp. in central and southern Ontario
Authors: McLaughlin J A
Published: April 2011

This study investigated the species, geographic distribution, host range, site relationships, and impacts of Armillaria in central and southern Ontario. Rhizomorphs and infected wood samples were collected at 110 of 111 sites. Six species were identified by polymerase chain reaction or diploidhaploid pairings. Armillaria gallica Marxmuller & Romagn. was most commonly isolated and had the broadest host range. It was seldom isolated from conifers but often from oaks. It was the species most often found on moist sites and showed strong preference for calcareous soils. Armillaria calvescens Bérubé & Dessureault was rarely isolated from conifers but often from maples, where it commonly caused butt rot. It was found most often on coarse loamy or fine, well-drained, fresh sites. Armillaria ostoyae (Romagn.) Herink. had the second broadest host range. It was seldom found on sugar maple (Acer saccharum Marsh.) but dominated on conifers, especially on dryfresh, rapidly drained sandy to coarse loamy sites. It was not found on sites with finer soils. Armillaria sinapina Bérubé & Dessureault and Armillaria gemina Bérubé & Dessureault were found in more northerly parts of the study area on noncalcareous sites. Armillaria sinapina often caused butt rot and was often found on poorly drained sites. Armillaria gemina was found only on hardwoods. Armillaria mellea (Vahl:Fr.) Kummer s.st. was found on dead hardwoods at four locations.
Decomposer invasion rate, decomposer growth rate, and substrate chemical quality: how they influence soil organic matter turnover
Authors: Hyvönen Riitta , Ågren Göran I
Published: April 2011

The physical structure of litter can be introduced into decomposition models in several ways. We have used the continuous-quality theory to analyse three models: (i) initial quality of litter or growth rate of decomposers depends on the physical structure of litter, (ii) decomposer colonization rate of litter depends on litter shape and size, and (iii) a constant decomposition rate, i.e., no effect of litter shape and size. Our analysis shows that it is important to separate the physical factors affecting access to carbon (C), i.e., decomposer colonization rate, from the chemical characteristics of litter in decomposition models. Soil C stores predicted with models based on the colonization rate of decomposers are much less sensitive to the shape and size of coarse woody litter than predictions based on the two other approaches. The effect of temperature on steady-state soil C storage is greater for litter that is colonized rapidly than for litter that is colonized slowly. The decomposition of litter types like needles, fine roots, and field-layer vegetation is therefore more sensitive to temperature changes than the decomposition of stems and coarse roots, and this difference is more pronounced at high temperatures than at low temperatures.