bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling the incidence and severity of hemlock dwarf mistletoe in 110-year-old wind-disturbed forests in Southeast Alaska
Authors: Trummer L M , Hennon P E , Hansen E M , Muir P S
Published: April 2011

Amodel was developed to predict the severity of dwarf mistletoe (Arceuthobium tsugense (Rosendahl) G.N. Jones) in western hemlock trees (Tsuga heterophylla (Raf.) Sarg.) that developed within forests of Southeast Alaska that experienced near-catastrophic windthrow in the late 1800s. The model suggests that the degree of dwarf mistletoe severity on western hemlock trees was significantly and positively correlated with levels of dwarf mistletoe infection and basal area (m2/ha) in large and small residual trees that survived the wind disturbance. No significant relationships were found between severity level and any other factors, including site productivity, density of coexisting Sitka spruce (Picea sitchensis (Bong.) Carr.), or slope. The model demonstrates the overriding importance of infected residual trees to predict future severity of dwarf mistletoe; greater size and infection level of residual trees results in greater dwarf mistletoe levels on regenerating hemlock crop trees. The model, derived from 76 plots on Kuiu Island, was tested in 18 plots on Chichagof Island, providing a preliminary validation. Slower rates of dwarf mistletoe spread and intensification in forests of southeastern Alaska, as compared with similar coastal forests south of Alaska, provide an opportunity for managers to manipulate the parasite to desired levels in managed forests.
Soil seed bank dynamics of pin cherry in a northern hardwood forest, New Hampshire, U.S.A.
Authors: Tierney Geraldine L , Fahey Timothy J
Published: April 2011

The soil seed bank of the low-value, pioneer tree pin cherry (Prunus pensylvanica L.f.) appears to increase markedly after multiple, large-scale disturbance events, which may result in interference with the growth of high-value species. Seven northern hardwood forest sites of varying age and disturbance history in the White Mountains of New Hampshire were examined to quantify the patterns of accumulation and depletion of the pin cherry soil seed bank. The pin cherry seed bank accumulated in a predictable fashion based on pin cherry stem abundance. High- and low-density populations accumulated approximately 440 and 1900 viable seeds per pin cherry stem, respectively. Depletion of the seed bank appeared to be negligible in stands between age 40 and 60, and moderate (30% loss over 20 years) in stands between age 95 and 115. Short (e.g., 60-year) harvest rotation times may triple the size of the pin cherry soil seed bank, causing proliferation of this species with consequences for ecosystem and community dynamics, whereas longer rotation times of 120 years may allow enough depletion of the seed bank to stabilize population sizes.
Effects of conifer release with glyphosate on summer forage abundance for deer in Maine
Authors: Vreeland J K , Servello F A , Griffith B
Published: April 2011

Effects of conifer release with glyphosate on summer forage availability for large herbivores in northern forests have received relatively little study. We determined effects of glyphosate treatment of clearcuts on abundance of summer foods for white-tailed deer (Odocoileus virginianus) at 1 and 7-10 years posttreatment. We measured the abundance (percent cover in a 0- to 1.8-m height stratum) of five forage classes for deer (leaves of deciduous trees, leaves of deciduous shrubs, forbs, grasses, ferns) on 12 clearcuts (six treated, six untreated) to determine 1-year effects and on 10 clearcuts (five treated, five untreated) to determine 7- to 10-year effects. Abundance of leaves of deciduous trees was greater on untreated sites (38 versus 11%) at 1 year posttreatment, but the difference was less (18 versus 12%) at 7-10 years posttreatment (age × treatment interaction, P = 0.005). Leaves of deciduous shrubs exhibited a similar pattern. Abundance of forbs was similar (13-14%) at 1 year posttreatment but greater on treated sites (29 versus 15%) at 7-10 years posttreatment (P = 0.03). Grasses and ferns were less abundant than other forage classes. Overall, glyphosate application initially decreased the abundance of leaves of deciduous trees and shrubs used as food in summer, but the longer term positive effects on forb abundance may result in little net change in overall habitat value.
Phenology of Vaccinium spp. in a black spruce (Picea mariana) plantation in northwestern Ontario: possible implications for the timing of forest herbicide treatments
Authors: Moola F M , Mallik A U
Published: April 2011

This study reports on the phenology of 180 vegetative and 180 reproductive shoots of lowbush blueberry (Vaccinium angustifolium Ait.) and velvet leaf blueberry (Vaccinium myrtilloides Michx.) in a young black spruce (Picea mariana (Mill.) BSP) plantation near Thunder Bay, northwestern Ontario. Leaves of both species emerged in mid-May and remained uniformly green until mid-August. By late August, the majority of tagged shoots had turned red and were beginning to deteriorate. Approximately 30% of tagged shoots lost their leaves by 25 September in both V. angustifolium and V. myrtilloides. Patterns of leaf development in V. angustifolium and V. myrtilloides suggest that Vaccinium spp. may be less susceptible to foliar-applied herbicides if applications are made during or following the period of leaf senescence (i.e., between late August and late September). However, delayed treatment may be impractical in conifer plantations, since the time of leaf senescence and abscission of blueberry coincides with that of many target species.
Aphid infested Norway spruce are "hot spots" in throughfall carbon chemistry in coniferous forests
Authors: Stadler Bernhard , Michalzik Beate
Published: April 2011

Throughfall chemistry in deciduous and coniferous forests is characterized by a high spatial and temporal variability, the sources of which are largely unknown. Aphids on Norway spruce (Picea abies (L.) Karst.) produce large quantities of honeydew, which is rich in sugars. We investigated the effect of changes in aphid abundance on throughfall carbon chemistry of Norway spruce using a rainfall simulation experiment. Aphid numbers in the experiment paralleled field infestations. Infested trees showed significantly higher concentrations of dissolved organic carbon (DOC) and hexose-C in throughfall solutions compared with uninfested trees. There was also a pronounced seasonal trend in the concentrations of these carbon compounds with highest concentrations recorded at the time of peak aphid abundance at the end of June - beginning of July. The throughfall from a spruce tree showed no spatial (center vs. periphery) differences in DOC and hexose-C concentrations. The number of aphids on a tree was the best predictor of the carbohydrate concentration of throughfall, explaining more than 60% of the variability. During the period of aphid infestation (May-September) average estimated field fluxes of DOC in throughfall collected under heavily infested trees ("hot spots") were 11.6 and 240 times higher than those recorded under moderately and uninfested trees, respectively. The results implicate herbivores as a major potential source of the spatiotemporal heterogeneity in flows of nutrients in forests.
Effects of drought stress and severe pruning on the reaction zone induced by single inoculations with a bark beetle associated fungus (Ophiostoma ips) in the phloem of young Scots pines
Authors: Croisé Luc , Dreyer Erwin , Lieutier François
Published: April 2011

The objective of this study was to test the effect of water stress and pruning on the resistance of young Scots pines (Pinus sylvestris L.) to a bark beetle associated fungus. Six-year-old potted trees were either pruned (70% of needles removed) or subjected to several successive episodes of severe water stress, prior to inoculation of inner bark with the fungus Ophiostoma ips (Rumb.) Nannf., which is usually associated with the bark beetle Ips sexdentatus Boern. Well-watered, nonpruned trees served as controls. Predawn needle water potential reached -2.5 MPa and net CO2 assimilation rates were reduced to almost zero during each water stress episode. The length of the reaction zones around inoculation points reached 3-4 cm after 3 weeks. It was higher during Spring than during Autumn. Impact of water stress on the length of the reaction zone was very limited and independent of the number of drought episodes that had been imposed prior to inoculation. The only visible change was a slight decrease when the inoculation was done during the period of maximum water stress intensity. Growth of the pathogen in the phloem was not affected by water stress. Correspondingly, pruning had no effect on either of these two parameters. Induced reaction zones accumulated monophenolic compounds that were undetectable in unwounded phloem. These included pinocembrin and pinosylvin and its monomethylether known to contribute to the defence against the fungus. Neither drought nor severe pruning induced any change in the nature or concentrations of these compounds in the unwounded phloem or in the reaction zone.
Nitrous oxide production in two forested watersheds exhibiting symptoms of nitrogen saturation
Authors: Peterjohn William T , McGervey Richard J , Sexstone Alan J , Christ Martin J , Foster Cassie J , Adams Mary B
Published: April 2011

A major concern about N saturation is that it may increase the production of a strong greenhouse gas, nitrous oxide (N2O). We measured N2O production in two forested watersheds, a young, fertilized forest (WS 3) and an older, unfertilized forest (WS 4), to (i) assess the importance of N2O production in forests showing symptoms of N saturation; (ii) estimate the contribution of chemoautrophic nitrification to total N2O production; and (iii) examine the relative importance of factors that may control N2O production. During the study period, mean monthly rates of N2O production (3.41-11.42 µ N ·m-2·h-1) were consistent with measurements from other well-drained forest soils but were much lower than measurements from N-rich sites with poorly drained soils. Chemoautotrophic nitrification was important in both watersheds, accounting for 60% (WS 3) and 40% (WS 4) of total N2O production. In WS 3, N2O production was enhanced by additions of CaCO3 and may be constrained by low soil pH. In WS 4, N2O production on south-facing slopes was exceptionally low, constrained by low NO3 availability, and associated with a distinct assemblage of woody vegetation. From this observation, we hypothesize that differences in vegetation can influence N cycling rates and susceptibility to N saturation.
Insect defoliators as major disturbance factors in the high-altitude balsam fir forest of Mount Mégantic, southern Quebec
Authors: Filion Louise , Payette Serge , Delwaide Ann , Bhiry Najat
Published: April 2011

Tree-ring data from a mature balsam fir forest, located at the top of Mount Mégantic (elevation 1100 m), southern Quebec, suggest that insect defoliators were major disturbance factors in the development of high-altitude balsam fir forests. A comparison between the radial growth trend of balsam fir (Abies balsamea (L.) Mill.), a host species of the spruce budworm (Choristoneura fumiferana Clem.), and paper birch (Betula papyrifera Marsh), a nonhost species, showed that several growth depressions in the balsam fir chronology corrresponded to documented spruce budworm outbreaks in southern Quebec in the 1910s, 1950s, 1970s, and possibly in the 1870s. Tree mortality was extensive during the last infestation because of the relatively old age (>60 years) of many balsam fir and, possibly, to the cumulative impact of defoliation. The tree-ring series from paper birch showed several drops in radial growth after the 1930s, possibly related to the large-scale birch dieback that occurred in eastern North America. Macrofossil data (insect remains) from one sample of the uppermost organic soil layers (F horizon) confirm the presence of the spruce budworm at the study site. The ecological role of insect defoliators is discussed in the context of the high-altitude balsam fir forests in northeastern North America where abiotic disturbances are considered the primary controlling factors in stand dynamics.
Decline and physiological response to foliar-deposited salt in Norway spruce genotypes: a comparative analysis
Authors: Hansen Jon Kehlet , Saxe Henrik , Ræbild Anders , Neilsen Christian Nørgård , Simonsen Jens Peter , Larsen J Bo , Wellendorf H
Published: April 2011

Severe spruce decline in Denmark at the end of the 1980s led to investigations of the physiology and genetics of the decline and the importance of sea salt deposition. Narrow-sense heritability of health in a progeny trial with 8-year-old Norway spruce families (Picea abies (L.) Karst.) was 0.58. Broad-sense heritability in a seed orchard with clones from ortets of southeastern European origin was 0.53. The health of the ortets correlated with family and clone health. Health of families and clones were not correlated. The health of three spruce provenances in the progeny trial varied from 6.3 to 7.7 on a 0-9 scale. Salt stress responses of 12 two-year-old open-ollinated families from the above clones were investigated after dipping branches into different salt solutions. Photosynthesis and transpiration decreased with increasing salt deposition, respiration increased, and water use efficiency increased initially and decreased later. Correlations between field health and physiological salt responses suggested that airborne salt predisposes to spruce decline rather than triggers it. Health of Norway spruce is unlikely to be improved by salt-resistance selection in the laboratory but may be improved by low transpiration and high water use efficiency selection. Visible injuries were primarily determined by the amount of salt taken up.
Age trends in genetic parameters of wood density in young Norway spruce
Authors: Hylen Gro
Published: April 2011

Age trends of phenotypic, environmental, and additive genetic variance and heritability were estimated for overall density and its components earlywood and latewood densities and latewood proportion. The objective was to acquire information for both individual and cumulated rings from ring number 3 to 12 counted from the pith. Age-age correlations were calculated for cumulated density traits only. The wood density data were obtained with X-ray analysis of increment cores from 47 open-pollinated families of Norway spruce (Picea abies (L.) Karst.). The families had earlywood and latewood with significant differences in density for individual and cumulated rings and consequently for overall density. The latewood proportion had significant family variation for cumulated rings but not for all individual rings. Large fluctuations in environmental variance caused fluctuations in heritability estimates for successive rings. A strong decrease in environmental variance for all cumulated traits, especially from ring 3 to 5, resulted in a steady increase in heritability estimates. The latewood density had the highest heritability estimates and latewood proportion the lowest for both individual and cumulated rings. Overall density and the cumulated components at cambial age 12 showed strong genetic correlations with their respective traits at all younger ages.
Comparison of growth and physiology of layers and naturally established seedlings of black spruce in a boreal cutover in Quebec
Authors: Paquin Raynald , Margolis Hank A , Doucet René , Coyea Marie R
Published: April 2011

Growth and physiology of layers versus naturally established seedlings of boreal black spruce (Picea mariana (Mill.) BSP) were compared 15 years after a cutover in Quebec. During the first 8 years, height growth of seedlings was greater than that of layers, averaging 10.4 and 7.0 cm/year, respectively. For the last 5 years, annual height growth of layers and seedlings did not differ (25 cm/year; p > 0.05). Over the entire 15-year period, total height growth of seedlings (251 cm) was greater than that of layers (220 cm), although total height did not differ (p > 0.05) over the last 6 years. During the 15th growing season, there were no differences (p > 0.05) for predawn shoot water potential, stomatal conductance, net photosynthesis, intercellular to ambient CO2 ratio, water use efficiency, and hydraulic conductance between layers and seedlings. For diurnal shoot water potential, seedlings showed slightly less stress than layers on two of the four sampling dates. Thus, in the first few years following the cutover, the slower growth observed for layers indicated that they had a longer acclimation period following the cutover. Afterwards, similar height growth, total height, and physiological characteristics of the two regeneration types indicated that layers can perform as well as naturally established seedlings.
Conversion of a natural broad-leafed evergreen forest into pure and mixed plantation forests in a subtropical area: effects on nutrient cycling
Authors: Lian Yuwu , Zhang Qishui
Published: April 2011

Conversion of natural broad-leafed evergreen forests into pure and mixed plantation forests in a subtropical area in China is a common practice in forest management. We investigated the effects of this conversion on litterfall, litter decomposition, and nutrient cycling. Monthly deposition of total N, P, K, Ca, and Mg through throughfall, stemflow, and various components of litterfall was investigated and compared over 3 consecutive years from January 1989 to December 1991 for both forests. The total annual fine litterfall over 3 years of observation was 4.8 t/ha in a pure plantation conifer forest of Chinese-fir (Cunninghamia lanceolata), 7.1 t/ha in a mixed plantation forest of Chinese-fir and Schima superba, and 13.3 t/ha in a natural broad-leafed evergreen forest of Castanopsis kawakamii, respectively. The contributions of litterfall to the total nutrient fluxes were greater than those of throughfall and stemflow for all five nutrient elements in two contrasting forests of Chinese-fir and C. kawakamii. The results of this study demonstrate that natural broad-leafed evergreen forest has a greater capability of nutrient return, coupled with higher rates of litter decomposition and nutrient release, larger soil nutrient pools, and higher nutrient availability, than pure forest, suggesting that conservation of a natural forest is a necessary measure for maintaining woodland soil quality and primary productivity.
Evaluation of temperature models for predicting bud burst in Norway spruce
Authors: Hannerz Mats
Published: April 2011

Spring bud development was assessed on cuttings of 17 Norway spruce (Picea abies (L.) Karst.) clones for up to 7 years at two sites in southern and central Sweden. The ability of various temperature models to predict bud-burst timing was analysed. All temperature-based models resulted in significantly better predictions than the null model, day number. Temperature sum (TS) based on a linear response to temperature above a defined threshold, gave a more precise prediction than forcing units based on a logistic response to temperature. The most precise model could predict bud burst to within 2 days, and it included TS with a threshold of 5°C and a start day arbitrarily chosen between January and March. The models were not improved by incorporating chilling, in terms of chilling days (number of days with mean temperature <5°C) or chilling units. It is suggested that chilling requirement is fulfilled already in December under normal winter conditions in southern and central Sweden. Ranking of clones in bud-burst timing was stable over years and sites. For routine measurements of phenology in applied breeding programmes, it is proposed that standard reference material is thoroughly tested for temperature reactions and that this reference material be used each time new material is tested. With this procedure, an accurate estimate of required temperature sum for bud burst can be obtained from a 1-year assessment.
Spatial patterns of aerobic limit depth and oxygen diffusion rate at two peatlands drained for forestry in Alberta
Authors: Silins U , Rothwell R L
Published: April 2011

The spatial variability of soil aeration (aerobic limit depth and oxygen diffusion rate (ODR)) among different drainage ditch spacings and at various distances from drainage ditches was examined at two peatlands drained for forestry in north-central Alberta. Drainage lowered mean water table levels (p < 0.001) at both peatlands. Lower water table levels within drained areas were associated with greater aerobic limit depths (p < 0.001) and greater ODR (p < 0.001 at Saulteaux River; p < 0.027 at Wolf Creek) compared with undrained areas of both peatlands. Spatial patterns of aerobic limit depth and ODR indicated strong spatial variability of soil aeration in the immediate vicinity of drainage ditches. However, little sensitivity of soil aeration to different ditch spacings was evident. Potential effects of post-drainage subsidence on soil aeration was evident as increased distance of both the aerobic limit, and near-zero oxygen diffusion rates above the water table surface at both peatlands. One effect of post-drainage peatland subsidence may be to increase the thickness of the capillary zone above the water table. However, reduction of aeration within the rooting zone of peatland trees due to subsidence was not observed because of low water tables within the drained areas of both peatlands.
Patterns of seedling and overstory composition along a gradient of hurricane disturbance in an old-growth bottomland hardwood community
Authors: Battaglia Loretta L , Sharitz Rebecca R , Minchin Peter R
Published: April 2011

Disturbance patterns and species composition in the seedling and canopy layers were examined across the range of post-hurricane damage in an old-growth bottomland hardwood forest. Canopy coverage, tip-up number and area, snags, and coarse woody debris were quantified in plots along randomly oriented transects established in bottomland hardwood stands and mixed Pinus taeda L. - bottomland hardwood stands. Wilcoxon rank sum tests of these individual disturbance features indicated greater disturbance in plots containing the early successional species, Pinus taeda, than in mixed bottomland plots without it. Principal components analysis (PCA) using these features illustrated much overlap between the two assemblages and suggested a continuum of canopy and soil disturbance conditions from windthrows along axis I and a continuum of canopy disturbance due to snag formation along axis II. Woody seedlings and trees were inventoried in 30 plots spanning the range of disturbance. Seedling species richness exhibited a rank order increase along axis I. Floristic trends in both seedling and tree layers were significantly correlated with disturbance represented by PCA axis I scores. Removal from the canopy and lack of successful recruitment of Pinus taeda, a former canopy dominant, suggest that the hurricane has shifted this old-growth floodplain forest to a different successional state.
Drying and storage of prechilled Douglas fir, Pseudotsuga menziesii, seeds
Authors: Muller C , Falleri E , Laroppe E , Bonnet-Masimbert M
Published: April 2011

Douglas fir, Pseudotsuga menziesii (Mirb.) Franco, seeds exhibit relative dormancy as they do not germinate at suboptimal temperature (15°C), whereas at optimal temperature (20°C) some germination occurred. Thus, germination at 15°C was chosen to estimate dormancy release. In the first experiment, seeds were prechilled at 32% moisture content (MC) for 0-34 weeks at 3°C. Long chilling treatments enhanced germinability and, more markedly, germination speed both at 20°C and at 15°C. Seeds pretreated for the longest periods were then dried to 6.7% MC and stored up to 6 months without any detrimental effect on germination at 15°C. In the second experiment, seeds from a second seedlot were prechilled for 18 weeks and then stored at three different MCs over a period of 17 months. Seeds stored at the lowest MC (6.7%) germinated fastest and to the highest percentage both at 15 and 20°C. In the nursery, seedling emergence tests confirmed results from this experiment. In most cases, comparisons between seeds prechilled at controlled MC before storage and those stratified with the traditional method resulted in better performance of the first ones, both in the laboratory and in the nursery.
Nonlinear regression approach to estimating Johnson SB parameters for diameter data
Authors: Kudus Kamziah Abd , Ahmad M I , Lapongan Jaffirin
Published: April 2011

A nonlinear regression approach is proposed to estimate the parameters of the Johnson SB distribution. This method was compared to five other methods; these were the four percentile points method, the Knoebel-Burkhart method, the linear regression method, the maximum likelihood (Newton-Raphson) method, and the modified maximum likelihood method through simulation. The performance of the nonlinear regression method was also investigated by using the real diameter data collected from 20 even-aged sample plots of the Acacia mangium Willd. plantation in Sandakan, Sabah, measured annually from age 2 to 8 years. Goodness-of-fit tests based on empirical distribution function (namely the Kolmogorov-Smirnov statistic, Cramer - von Mises statistic, and the Anderson-Darling statistic) were used in selecting the most superior parameter estimation method. Results suggested that the nonlinear regression method was superior for estimating parameters of the Johnson SB distribution for diameter data in terms of bias, root mean square error, and goodness-of-fit tests.
Effects of residual overstory on aspen development in Minnesota
Authors: Huffman Ronald D , Fajvan Mary Ann , Wood Petra Bohall
Published: April 2011

The effects of different amounts of residual canopy on stand development of quaking aspen (Populus tremuloides Michx.) were examined in a chronosequence of 32 stands spanning 6-10 years since harvest. Residual canopy covers ranged from 0 to 65%, and residual basal areas ranged from 0 to 14.4 m2/ha. Aspen regeneration densities ranged from 7130 to 43 672 stems/ha. Regeneration stem density was affected primarily by residual canopy cover (R2 = 0.27, P = 0.0001) and secondarily by stand age (R2 = 0.09, P = 0.004). Aspen density decreased significantly with increasing residual canopy cover for 7-year-old and 8-year-old regeneration. Residual canopy cover did not significantly affect aspen density in 9-year-old regeneration (R2 = 0.02, P = 0.579) but was negatively related to total height of 9-year-old codominant aspens (R2 = 0.49, P = 0.002). Canopy cover was a more accurate representation of the amount of shade the regeneration received than the density or basal area of residual trees. However, the low value of the coefficient of determination from a multiple-regression model indicates that considerable variation in stem densities and height was unexplained by residual canopy cover, even though it was the best predictor of the variables measured.
Effects of rainfall acidity and ozone on foliar leaching in red spruce (Picea rubens)
Authors: Sayre Roger G , Fahey Timothy J
Published: April 2011

The effects of acid rain and ozone on the leaching of chemicals from the canopy of red spruce (Picea rubens Sarg.) saplings was measured over a 4-year treatment period. The saplings were exposed to various levels of ozone and to acid rain (pH 3.1, 4.1, and 5.1) using open-top chambers. No effects of ozone treatments on canopy leaching were observed. Significant effects of rainfall pH on canopy leaching of Ca2+ and Mg2+ were observed, and post-hoc analysis indicated that these effects were associated only with the most acidic treatment (pH 3.1). In the low pH treatment (high NO3- and SO42-) significant canopy retention of both NO3- and SO42- were observed. The observed increase in base cation leaching flux from the red spruce canopy in the low pH treatment was particularly prominent early in the growing season (June) probably reflecting incomplete cuticle formation in the young foliage. Although the annual magnitude of extra Ca2+ leaching from the canopy of red spruce trees in the low pH treatment was small relative to the foliar calcium pool (about 10%), if this leaching preferentially depletes a physiologically important pool, it may influence tree health.
Yield and financial losses associated with a jack pine budworm outbreak in Michigan and the implications for management
Authors: Conway Bradley E , Leefers Larry A , McCullough Deborah G
Published: April 2011

Stand-level merchantable volume and financial losses resulting from a 1991-1993 jack pine budworm (Choristoneura pinus pinus Freeman) outbreak were quantified for 99 jack pine (Pinus banksiana Lamb.) stands in the Raco Plains area of the Hiawatha National Forest. Associations between standing value loss and stand inventory variables were evaluated. Stands were stratified into management groups based on age, site index, and stocking. Differences in standing value loss among groups were examined. Total standing merchantable volume loss and gross value loss were estimated to be 19 500 m3 and $289 800, respectively, for the 1480-ha sample area. Standing merchantable volume loss averaged 13.3 m3/ha or 14% of standing volume. Standing value loss within stands averaged $194/ha. Losses were concentrated in only a few stands with eight stands accounting for over half the total standing value loss. Standing value loss was positively associated with stand age and basal area and negatively associated with the proportion of open-grown, full-canopied "wolf" trees in the stand. A significant interaction in standing value loss was observed between age-class and site index class. No significant differences in standing value loss were observed among stocking classes. Results confirm overstocked stands over 50 years of age should be prioritized for harvest.
Reversal of human-induced vegetation changes in Sequoia National Park, California
Authors: Roy D Graham , Vankat John L
Published: April 2011

We resampled 76 permanent plots that had been established in the woodlands and forests of Sequoia National Park in 1969. Our objectives were to describe vegetation changes in the tree and shrub layers and determine the effects of prescribed burning that began in the 1960s. We compared changes in species importance and tree size class distributions between sample dates and between burned and unburned plots. Species composition had remained similar in all nine vegetation types sampled except in the ponderosa pine forest where Pinus ponderosa Dougl. ex P. & C. Laws. decreased in importance from 28 to 15% and Abies concolor (Gord. & Glend.) Lindl. increased from 18 to 31%. Structural changes were more common, as tree density decreased in the blue oak woodland (19%), and live oak woodlands (15%), as well as in ponderosa pine forest (41%), white fir forest (5%), giant sequoia groves (39%), and red fir forest (24%). Decreases in density were greater in burned plots but occurred in unburned plots as well, indicating that prescribed fire and self-thinning contributed to decreases in density. Tree density was unchanged in the lodgepole and subalpine forests, but increased in the Jeffrey pine forest (58%). The decreases in tree density represent a reversal of earlier trends.
Regeneration alternatives for upland white spruce after burning and logging in interior Alaska
Authors: Densmore R V , Juday G P , Zasada J C
Published: April 2011

Site-preparation and regeneration methods for white spruce (Picea glauca (Moench) Voss) were tested near Fairbanks, Alaska, on two upland sites which had been burned in a wildfire and salvage logged. After 5 and 10 years, white spruce regeneration did not differ among the four scarification methods but tended to be lower without scarification. Survival of container-grown planted seedlings stabilized after 3 years at 93% with scarification and at 76% without scarification. Broadcast seeding was also successful, with one or more seedlings on 80% of the scarified 6-m2 subplots and on 60% of the unscarified subplots after 12 years. Natural regeneration after 12 years exceeded expectations, with seedlings on 50% of the 6-m2 subplots 150 m from a seed source and on 28% of the subplots 230 m from a seed source. After 5 years, 37% of the scarified unsheltered seed spots and 52% of the scarified seed spots with cone shelters had one or more seedlings, but only 16% of the unscarified seed spots had seedlings, with and without funnel shelters. Growth rates for all seedlings were higher than on similar unburned sites. The results show positive effects of burning in interior Alaska, and suggest planting seedlings, broadcast seeding, and natural seedfall, alone or in combination, as viable options for similar sites.
Fungal associates of Buprestis aurulenta in western Oregon
Authors: Garcia Carlos M , Morrell J J
Published: April 2011

Associations between the golden metallic beetle, Buprestis aurulenta L., and wood-destroying fungi were explored with adult beetles collected from log decks. A variety of fungi were isolated from the beetle bodies by four methods. A total of 863 isolations were made from 59 females and 21 males. There was no significant difference between the microflora associated with male and female adult beetles. Hyphomycetes constituted 91.4% of all isolates. Zygomycetes and yeasts represented 5.8% of the total number of isolates. Basidiomycetes were infrequently isolated (2.8%), suggesting that this buprestid does not consistently vector decay fungi into woody debris.
Effects of overstory and understory competition and simulated herbivory on growth and survival of white pine seedlings
Authors: Saunders Mike R , Puettmann Klaus J
Published: April 2011

The interactive impact of overstory canopy closure, understory brush control, and simulated white-tailed deer (Odocoileus virginianus Zimmermann) herbivory (i.e., clipping) on growth and survival of underplanted white pine (Pinus strobus L.) seedlings was examined. Clipping was conducted in April 1996 and 1997 at three intensities (control, 0% previous year's growth removed; lightly clipped, terminal and 50% previous year's growth removed, and heavily clipped: 100% of previous-year's growth removed) and three frequencies (never clipped, clipped once, clipped 2 years in a row). Decreasing overstory canopy closure and brush competition generally increased growth of seedlings under all clipping regimes, with heavily clipped seedlings showing the least benefit of reduced competition. Although first-year height growth was stimulated after light-intensity clipping, this effect did not persist the following year, and these trees still were significantly shorter than controls at the end of the experiment. Diameter growth was reduced at any clipping intensity or frequency, and remained below controls throughout the experiment. Seedling mortality was higher without brush control and after clipping. Results suggest that increased overstory and understory competition reduced seedling growth and survival. In regards to clipping, initial height growth stimulation may result from (i) resource reallocation away from diameter and root growth and (or) (ii) hormonal redistributions from loss of apical control in the seedling. Since both high competition levels and increased herbivory reduced seedling vigor, we suggest that understory brush control and deer protection (e.g., budcapping) go hand in hand to regenerate white pine.
The spatial pattern of a Juniperus communis var. depressa population on a continental dune in subarctic Québec, Canada
Authors: Houle Gilles , Duchesne Mario
Published: April 2011

We performed a nearest-neighbor analysis to determine the population dispersion pattern and the association between males and females in a Juniperus communis L. var. depressa Pursh population occupying a continental dune in subarctic Quebec, Canada. The overall dispersion pattern was contagious, and males (or females) were proportionately as likely to have a male as they were to have a female nearest neighbor. Crown size was positively related to nearest-neighbor distance for the male-male comparison only, suggesting a somewhat stronger intrasex competition between males. Nearest-neighbor distance increased with crown size (significantly related to age) suggesting a change in the intensity of aggregation with age possibly related to self-thinning. Higher mortality as a result of stronger male-male competition could explain the female-biased sex ratio and the absence of spatial segregation between sexes. The overall contagious dispersion pattern in the population may be related to the fact that most seed cones fall directly underneath the mother plant. Birds can eat the cones of J. communis and thus disperse seeds. However, these seeds are deposited in clumps, a process that may also explain contagion within the population.
Leaching of nutrient cations from the forest floor: effects of nitrogen saturation in two long-term manipulations
Authors: Currie William S , Aber John D , Driscoll Charles T
Published: April 2011

Nitrogen saturation results in greater mobility of nitrate, which in turn is often correlated with concentrations of nutrient cations in soil solution and streamwater. At the Harvard Forest, U.S.A., under long-term NH4NO3 inputs, a Pinus resinosa Ait. forest has exhibited signs of N saturation more rapidly than a mixed-Quercus forest. We test the hypothesis that increased nitrate leaching causes increased concentrations of nutrient cations in soil solution. Over 2 years (years 6 and 7 of treatment) we measured SO42-, NO3-, Cl-, Ca2+, K+, Mg2+, Na+, H+, and NH4+ in throughfall solution and in forest-floor (Oa) leachate. Concentrations of NO3- in forest-floor leachate increased with rates of N amendment and correlated positively with cation concentrations, with stronger overall correlations in the pine forest: r2 values were 0.51 (pine forest) and 0.39 (oak forest) for Ca2+, 0.45 (pine) and 0.16 (oak) for K+, and 0.62 (pine) and 0.50 (oak) for Mg2+. In summer and fall, the oak forest showed some negative relationships between nutrient cation leaching and rate of N amendment. These contrasts showed retention of cations and N to occur together in an N-limited system, whereas increased nitrate mobility occurred with increased cation losses in an N-saturated system.
Vegetation management on grass-dominated clearcuts planted with Norway spruce in southern Sweden
Authors: Nilsson Urban , Örlander Göran
Published: April 2011

A field experiment was established between 1989 and 1993 to study the effects of competing vegetation on growth of planted Norway spruce (Picea abies (L.) Karst.) seedlings. Effects of clearcut age, scarification (mounding), herbicide treatment, and seedling stock type were investigated 5 years after planting. On fresh clearcuts, amounts of vegetation were negligible, whereas 2.1-3.7 Mg·ha-1 was found on 4-year-old and older clearcuts. Soil temperatures were about 10% higher in mounds than in undisturbed ground, while herbicide and clearcut age only marginally affected soil temperatures. Seedlings planted on old clearcuts showed significant reductions in growth due to interference from vegetation. Five years after planting, the reduction in growth corresponded to about 1 year's growth. Most of the interaction between seedlings and vegetation occurred during the first 2 years after planting. Thus, scarification was just as effective as repeated herbicide treatments in reducing competition from vegetation. Differences in periods of drought between years could largely explain variation in leading shoot length. However, leading shoot length was affected in the same way irrespective of vegetation control treatments. Five years after planting, the relative differences in diameter between bare-root and containerized seedlings were the same as at the time of planting.
Testing for effects of stump fumigation with chloropicrin on vegetation in an early seral Douglas-fir stand
Authors: Wilson M V , Ingersoll C A , Thies W G
Published: April 2011

The biocide chloropicrin has been suggested for the control of laminated root rot (caused by Phellinus weirii (Murr.) Gilb.), a widespread and economically important disease of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests. This study investigated the effects of chloropicrin use on vegetation. A 65-year-old stand in northwestern Washington dominated by Douglas-fir was harvested by clear-cutting in 1988. At time of harvest, the stand was severely affected by laminated root rot. After harvest, plots were either left unfumigated or fumigated with 3.0-18.2 kg of chloropicrin per 0.04 ha. We used multivariate analyses to investigate the effect of chloropicrin on the abundance of vegetation, accounting for pretreatment plot differences. Five years after harvest and fumigation, no significant differences in vegetation composition or cover were found. Chloropicrin fumigation significantly increased diversity (Hill's measure) but not richness. Of the 10 most abundant species, only two showed significant effects: higher levels of chloropicrin application led to lower Veronica serpyllifolia L. var. serpyllifolia cover and to more Linnaea borealis L. cover. The power of statistical tests to detect effects of chloropicrin on vegetation was high (0.75-0.99) for large effect sizes, lending confidence to the conclusion that chloropicrin use caused few prominent adverse effects.
Long-term effects of jack pine budworm outbreaks on the growth of jack pine trees in Michigan
Authors: Conway Bradley E , McCullough Deborah G , Leefers Larry A
Published: April 2011

Growth of jack pine (Pinus banksiana Lamb.) trees from the Raco Plains area in the Upper Peninsula of Michigan was examined over an 18-year period (1978-1995) that included two jack pine budworm (Choristoneura pinus pinus Freeman) outbreaks. Specific volume increments were calculated for 84 trees grouped into three classes based on their status in 1996; 36 trees were undamaged, 24 trees had been recently top-killed, and 24 trees had been recently killed. Average growth was converted to proportion of previous years' growth for three periods: before the 1983-1985 outbreak, between the 1983-1985 and 1991-1993 outbreak, and after the onset of the 1991-1993 outbreak. Differences in growth over these periods among undamaged, recently top-killed, and recently killed trees were evaluated. Growth did not differ among the three groups before the 1983-1985 outbreak. From 1983-1990, undamaged and recently top-killed trees grew significantly more than recently killed trees. There was no difference in average growth from 1983 to 1990 between undamaged and recently top-killed trees. Growth of undamaged trees was significantly greater than growth of recently top-killed trees following the onset of defoliation from the 1991-1993 outbreak. Patterns of growth loss suggest that a history of defoliation stress from multiple budworm outbreaks was an important determinant of tree mortality.
Aboveground production and nutrient circulation along a flooding gradient in a South Carolina Coastal Plain forest
Authors: Burke Marianne K , Lockaby B Graeme , Conner William H
Published: April 2011

Relative to effects of flooding, little is known about the influence of hydrology-nutrient interactions on aboveground net primary production (NPP) in forested wetlands. We found that nutrient circulation and NPP were closely related along a complex physical, chemical, and hydrologic gradient in a bottomland hardwood forest with four distinct communities. Aboveground biomass, NPP, biomass partitioning to stem production, growth efficiency, and soil macronutrient availability were greatest in the flooded zone, possibly because of the stable hydrologic regime. In the wet transition zone, trees were least productive, nutrient use efficiency was highest, and N retranslocation from foliage before abscission was "complete." Wet and dry transition zones had the lowest litterfall quality. Soil organic matter was negatively correlated with extractable NH4-N plus NO3-N before in situ incubations and positively correlated with litterfall lignin/N ratios. Lignin/P and C/N ratios were positively correlated with exchangeable soil Ca and Mg, cation exchange capacity, and clay content and negatively correlated with extractable soil P. We concluded that periodic flooding and associated widely fluctuating soil chemistry resulted in disequilibrium between the plant community and environmental conditions, which led to nutrient deficiency and low NPP in the transition zones compared with the continuously flooded and mesic zones.
Forest inventory with optimal two-phase two-stage sampling schemes based on the anticipated variance
Authors: Mandallaz Daniel , Ye Ronghua
Published: April 2011

This work presents optimal sampling schemes for forest inventory. The sampling procedures are optimal in the sense that they minimize the anticipated variance for given costs or conversely, the anticipated variance is the average of the design-based variance under a local Poisson model for the spatial distribution of the trees. The resulting optimal inclusion rules are either probability proportional to size, in one-stage procedures, or a combination of probability proportional to prediction and probability proportional to error, in two-stage procedures. Best feasible approximations of the exact optimal sampling schemes are also given.
Genetic variation in growth, carbon isotope discrimination, and foliar N concentration in Picea mariana: analyses from a half-diallel mating design using field-grown trees
Authors: Johnsen Kurt H , Flanagan Lawrence B , Huber Dudley A , Major John E
Published: April 2011

We performed genetic analyses of growth, carbon isotope discrimination (delta13C), and foliar N concentration using a half-diallel subset of a 7 × 7 complete diallel planted on three sites ranging in water availability. Trees were 22 years old. Heritabilities; general and specific combining abilities; as well as phenotypic, genetic, and environmental correlations were calculated using the best linear unbiased prediction and restricted maximum-likelihood methods. The four traits measured showed variable levels of genetic control. The calculated heritablilities for the traits were as follows: height, 0.39 ± 0.22 (estimate ± SD); diameter, 0.14 ± 0.10; delta13C value, 0.54 ± 0.26; and foliar N, 0.00. Phenotypic correlations were moderate (r = -0.35), genetic correlations were strong (r = -0.97), and environmental correlations were weak (r = -0.18) between height growth and delta13C. The strong negative genetic correlation between delta13C and growth supports earlier work with a subset of families indicating photosynthetic differences caused genetic variation in delta13C. Inbreeding greatly decreased growth while not impacting delta13C. High heritability, lack of inbreeding depression, and low environmental correlations indicate that a major proportion of delta13C genetic control may be relatively simple. Because delta13C is highly heritable, highly genetically correlated to growth, less environmentally sensitive than growth, and has the possibility of early selection, the trait is a good candidate trait for indirect selection for growth.
The birdseye figured grain in sugar maple (Acer saccharum): literature review, nomenclature, and structural characteristics
Authors: Bragg Don C
Published: April 2011

Little is known about the "birdseye" figured grain of sugar maple (Acer saccharum Marsh.). This paper clarifies and expands the discussion of birdseye sugar maple by describing the similarities and differences with figured grains in other species, as well as discussing important features of its peculiar anatomy. Sections are also provided that discuss the proposed causes of the birdseye grain, detail birdseye sugar maple's geographic distribution, and address what is known about genetics and birdseye maple. Possible variations on the birdseye theme (e.g., roundeye, fingernail, cat's paw, distorted) are documented, and a new set of descriptive terminology is established. Finally, further observations and speculations on the birdseye phenomena are provided, and research directions are suggested.