bluuebunny/crossref_metadata_2025 huggingface dataset:
Chloroplast microsatellites as markers for paternity analysis in Abies alba
Authors: Ziegenhagen B , Scholz F , Madaghiele A , Vendramin G G
Published: April 2011

This study describes the application of previously characterized chloroplast microsatellites as markers for paternity analysis in a conifer species. The investigations were performed on silver fir (Abies alba Mill.) relic trees in an endangered population of the Ore Mountains (Germany). Two relatively isolated adult trees about 30 m apart, as well as 24 naturally regenerated young trees in their direct neighborhood, were analyzed at two chloroplast microsatellite loci. Results reveal the potential usefulness of the markers for paternity analysis.
Relatedness and status number in seed orchard crops
Authors: Lindgren D , Mullin T J
Published: April 2011

Status number is a measure of effective population size that is based on current relatedness only. Formulae are developed for group coancestry (=average coancestry) and status number for seed orchard crops. The formulae consider (1) differences in reproductive success among orchard genotypes, (2) relatedness between pairs of orchard genotypes, (3) inbreeding of orchard genotypes, (4) influence of pollen contamination (considering its relatedness both to itself and to the genotypes in the orchard), and (5) gender differences and sexual asymmetries of orchard genotypes. Properties of status number and other measures of effective number are discussed. They may refer to rate or state, to the reference population or the development of an idealized population, and to different moments in the sexual cycle.
Cavity trees and coarse woody debris in old-growth and managed northern hardwood forests in Wisconsin and Michigan
Authors: Goodburn John M , Lorimer Craig G
Published: April 2011

The effects of uneven-aged management on the availability of coarse woody debris habitat were examined in northern hardwood forests (with and without a hemlock component) in north-central Wisconsin and adjacent western Upper Michigan. Snags, cavity trees, fallen wood, and recent tip-up mounds in 15 managed uneven-aged (selection) stands were compared with levels in 10 old-growth stands and six unmanaged even-aged second-growth stands. Amounts of coarse woody debris in selection stands were generally intermediate between old-growth and even-aged stands. Density of snags >30 cm DBH in northern hardwood selection stands averaged 12/ha, approximately double that found in even-aged northern hardwoods, but only 54% of the level in old-growth northern hardwoods. Highest densities of snags >30 cm DBH occurred in old-growth hemlock-hardwood stands, averaging over 40 snags/ha. For combined forest types, the volume of fallen wood (>10 cm in diameter) was significantly lower in selection stands (60 m3/ha) and even-aged stands (25 m3/ha) than in old-growth stands (99 m3/ha). Volume differences were even more pronounced for large-diameter debris (>40 cm). Cavity tree density in selection stands averaged 11 trees/ha, 65% of the mean number in old-growth stands. Densities of snags (>30 cm DBH) and large-diameter cavity trees (>45 cm) present in selection stands exceeded current guidelines for wildlife tree retention on public forests.
Comparison of communities of ectomycorrhizal fungi in old-growth and mature stands of Douglas-fir at two sites on southern Vancouver Island
Authors: Goodman D M , Trofymow J A
Published: April 2011

An old-growth and a mature stand, each of fire origin and similar in drainage, slope, and exposure, were selected at each of two sites. Soil cores were collected in spring and fall for 2 years in each stand. Ectomycorrhizae were separated into types based on detailed examination of morphology and anatomy. All root tips were separated and counted. Sixty-nine morphological types were distinguished. Nineteen accounted for >1% of the 17 500 root tips examined, and 14 types were found in >5% of the 120 soil cores. Only three types were found in >20% of the cores. Total richness was approximately 100 fungi. Nine codominant mycosymbionts each colonized 2.824% of all tips and together colonized 67% of all tips. Cenococcum geophilum Fr. was the most abundant, followed by a Rhizopogon vinicolor Fr.-like species, an unidentified Piloderma-like species, Lactarius rubrilacteus Hesler & Smith, Piloderma fallax (Libert) Stalpers, and four unidentified species. Old-growth and mature stands had similar richness and diversity of ectomycorrhizal types. There was no evidence that any types were more abundant or frequent in one age-class than in the other.
Fiber length in young hybrid Populus stems grown at extremely different rates
Authors: DeBell Jeffrey D , Gartner Barbara L , DeBell Dean S
Published: April 2011

Length of libriform fibers was measured in rings 2-7 at breast height in 7-year-old hybrid poplar stems from two clones (11-11, a Populus trichocarpa Torr. & Gray x P. deltoides Bartr. ex Marsh. hybrid; and D-01, of unknown taxonomic identity) grown in a controlled test of three spacings (0.5, 1.0, and 2.0 m) on an irrigated and fertilized site in western Washington. In each clone, samples included a very wide range of cambial growth rates, with ring widths from 1 to 19 mm. Growth rate, expressed in several ways, had no consistent effect on fiber length within rings of the same age for rings 2-6. For ring 7, however, there were positive correlations between most growth rate measures and fiber length. Whole-disk fiber length increased with overall growth rate as measured by stem diameter; this apparent anomaly is caused by the fact that fast-growing trees have more of their basal area concentrated in rings further from the pith than do slower growing trees, and these rings have longer fibers compared with rings closer to the pith.
Effects of tree cover, understory vegetation, and litter on regeneration of Douglas-fir (Pseudotsuga menziesii) in southwestern Argentina
Authors: Caccia F D , Ballaré C L
Published: April 2011

The factors and processes that regulate Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) natural regeneration in southwestern Argentina are unknown. We investigated (i) the germination responses of P. menziesii seeds to variations in the radiation and thermal environments imposed by canopy cover and litter, (ii) the effects of litter on seedling emergence, and (iii) the effects of understory vegetation on seedling performance and seed and seedling predation. Seed germination was high in darkness and under canopies. Under a combination of canopy types and litter covers, germination showed a negative correlation with temperature between 23 and 40°C. Germination was not altered by changes in red/far-red ratio. These results suggest that the presence of an overstory canopy promotes P. menziesii seed germination compared with a no-canopy situation (e.g., a clearcut). Litter inhibited seedling emergence by reducing water availability and by acting as a mechanical barrier. Understory vegetation (established saplings) reduced seedling growth and survival. However, our results suggest that direct competition between seedlings and understory vegetation is not the principal force regulating regeneration; indirect effects appear to be of paramount importance because P. menziesii seed and seedling consumption (presumably by rodents) is greatly encouraged by the presence of dense vegetation patches in the understory.
Tree-selection algorithms for optimizing thinning using a distance-dependent growth model
Authors: Pukkala Timo , Miina Jari
Published: April 2011

When a distance-dependent yield model is used in growth simulation and optimization, the stand is described by a plot on which the trees are described by species, DBH, height, age, coordinates, and other characteristics. Optimizing a distance-dependent model requires that the trees to be removed in a thinning treatment be specified individually and that a special algorithm be developed for this selection. This algorithm affects the formulation of the optimization problem. In this study, we compared four different problem formulations for optimizing a distance-dependent yield model: (1) Harvest percentages in different diameter classes were utilized together with a tree-selection algorithm proposed earlier; this algorithm removed trees on the basis of competitive status. The algorithm was fixed, i.e., it was not amenable to numerical optimization. (2) Minimum distances between remaining trees were used as decision variables. (3) Minimum distances were used with harvest percentages and the existing tree-selection algorithm. (4) The tree-selection algorithm was made dependent on two parameters, which were optimized together with harvest percentages in different diameter classes. Based on case optimizations in pure and mixed conifer stands, the fourth formulation was considered to be the best one from the standpoint of simplicity of optimization and in terms of the objective function value.
Carbon isotope dynamics in Abies amabilis stands in the Cascades
Authors: Buchmann N , Hinckley T M , Ehleringer J R
Published: April 2011

Carbon isotope ratios ( delta 13C) of canopy air and carbon isotope discrimination at the ecosystem level were studied in three montane Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes) stands, an old-growth and two younger stands. Spatial and temporal variations of canopy CO2 concentrations ([CO2]) and their delta 13C were strongly related to stand structure. Within the old-growth stand, both daytime canopy [CO2] and canopy delta 13C stayed close to those of the troposphere, either indicating low overall photosynthetic rates or high turbulent mixing. Pronounced periods of photosynthetic drawdown below baseline [CO2] accompanied by more enriched canopy delta 13C were observed for the two younger and denser stands. Canopy [CO2] profiles seemed closely related to changes in soil conditions. Soil respiration rates were positively related to soil temperature, but negatively to soil moisture. delta 13C of soil-respired CO2 stayed relatively constant at -24.55 ± 0.20%oduring the growing season. Significant relationships existed between canopy delta 13C and 1/[CO2] in all three stands. Using the intercepts of these regressions, we calculated an average delta 13C for ecosystem respiration of -26.4 ± 0.1%o. Ecosystem carbon isotope discrimination ( DELTA e), an integrating measure for carbon exchange between the troposphere and the entire ecosystem, stayed relatively constant through time. DELTA e showed no significant stand structure effect (leaf area index, density) and averaged 18.9%o for the old-growth and 19.2 ± 0.2%ofor the two younger stands.
Stochastic simulation of growth loss in thinned balsam fir stands defoliated by the spruce budworm in Newfoundland
Authors: Dobesberger Erhard John
Published: April 2011

A stochastic simulation model was developed to derive a damage function for the spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), and balsam fir, Abies balsamea (L.) Mill., herbivore interaction at the stand level for open-grown trees. Both aggregated and uniform models of attack pattern by late-instar larvae based on k of the negative binomial were evaluated to determine the impact of larval density and attack pattern on the loss in stemwood volume increment of young, thinned balsam fir stands in Newfoundland. Percentage loss in stemwood increment was a nonlinear, negative exponential function of initial larval density. Implementation of control measures to prevent 50% defoliation that is caused by about 14 larvae/branch tip would result in saving 24% of the annual stemwood increment after 1 year of defoliation and about 32% after 2 years of cumulative defoliation. Aggregation of spruce budworm larvae among trees within a forest stand results in less growth loss compared with a uniform pattern of attack. The nonlinear damage function may suggest tolerance and possibly compensatory growth after herbivory by low population levels of the spruce budworm.
Within-ring δ13C spatial variability and interannual variations in wood cellulose of two contrasting provenances of Pinus pinaster
Authors: Nguyen-Queyrens Anne , Ferhi André , Loustau Denis , Guehl Jean-Marc
Published: April 2011

The carbon isotope composition (δ13C) of cellulose extracted from wood samples was measured on 26-year-old maritime pine trees (Pinus pinaster Ait.) of the mesic French provenance Landes and of the drought-resistant Moroccan provenance Tamjoute, all growing at the same location in France. Analysis of spatial variability revealed that intra-ring δ13C values varied over a range of about 0.5%o (mean SD = 0.12%o) for circumference and of about 1%o (mean SD = 0.22%o) for height and that interannual variability of δ13C was 3%o. The successive year-to-year δ13C values on four trees (from 1972 to 1991) were found to roughly parallel the variations of a water stress index, calculated by taking into account climatic variables as well as the level of the water table in the soil: δ13C increased with drought. The two provenances (30 trees per provenance) were compared at a juvenile stage (old rings) and at a mature stage (recent rings). The drought-resistant provenance (Tamjoute) presented lower δ13C values, independent of ring age. Relationships between δ13C and tree height are discussed both at the within- and between-provenance levels.
A 9000-year fire history from the Oregon Coast Range, based on a high-resolution charcoal study
Authors: Long Colin J , Whitlock Cathy , Bartlein Patrick J , Millspaugh Sarah H
Published: April 2011

High-resolution analysis of macroscopic charcoal in sediment cores from Little Lake was used to reconstruct the fire history of the last 9000 years. Variations in sediment magnetism were examined to detect changes in allochthonous sedimentation associated with past fire occurrence. Fire intervals from ca. 9000 to 6850 calendar years BP averaged 110 ± 20 years, when the climate was warmer and drier than today and xerophytic vegetation dominated. From ca. 6850 to 2750 calendar years BP the mean fire interval lengthened to 160 ± 20 years in conjunction with the onset of cool humid conditions. Fire-sensitive species, such as Thuja plicata Donn ex D. Don, Tsuga heterophylla (Raf.) Sarg., and Picea sitchensis (Bong.) Carr., increased in abundance. At ca. 4000 calendar years BP, increases in allochthonous sedimentation increased the delivery of secondary charcoal to the site. From ca. 2750 calendar years BP to present, the mean fire interval increased to 230 ± 30 years as cool humid conditions and mesophytic taxa prevailed. The Little Lake record suggests that fire frequency has varied continuously on millennial time scales as a result of climate change and the present-day fire regime has been present for no more than 1000 years.
Foliage biomass distribution of loblolly pine as affected by tree dominance, crown size, and stand characteristics
Authors: Xu Mingguang , Harrington Timothy B
Published: April 2011

Horizontal and vertical distributions of foliage biomass of loblolly pine (Pinus taeda L.) were analyzed for 30 trees in a plantation that had developed 12 years after several site-preparation treatments in the Georgia Piedmont, U.S.A. Regression analyses indicated that foliage biomass of individual branches increased with branch diameter and with branch relative height. Weibull models were used to characterize foliage biomass distributions and analyses revealed that branch foliage biomass distribution varied with branch-level, tree-level, and stand-level variables. Results indicate that the proportion of foliage biomass occurring within the inner crown increased with branch diameter and relative height. For trees of greater dominance, branch foliage biomass was more evenly distributed across the branch length. With increasing crown ratio of a tree, branch foliage biomass shifted from the inner to the outer crown. For trees of greater dominance, the vertical distribution of crown foliage biomass was more even, whereas less dominant trees shifted their foliage to the top of the crown. For trees of similar dominance, crown foliage tended to shift upward as stand leaf area index increased.
Distribution of arthropods in relation to forest patch size, edge, and stand characteristics
Authors: Jokimäki Jukka , Huhta Esa , Itämies Juhani , Rahko Pekka
Published: April 2011

We studied the abundance of arthropods in relation to forest patch size, edge orientation, distance from the forest - open-land edge, and stand characteristics in pine-dominated forests in northern Finland. Arthropod samples were collected using the sweep-net method. The total catch of arthropods, catches from the field layer and deciduous shrubs, the numbers of flying arthropods, small (<1 mm) arthropods, and the numbers of seven different arthropod taxa (viz. Linyphiidae (Arachnida), Cicadellidae (Homoptera), Diptera, Brachycera (Diptera), Nematocera (Diptera), and Hymenoptera and Ichneumonidae (Hymenoptera)) were lower in large forest patches (>5 ha) than in small patches (5 ha). The edge orientation and the type of adjacent open area (clearcut area or treeless mire) had no impact on the abundance of arthopods in the patches. The distance from the forest edge affected the total abundance of arthropods, small arthropods, flying arthropods, and Coleoptera (especially Cantharidae) in that all decreased in number from the forest edge to the interior of the forest stand. The abundance of many arthropod taxa correlated positively with the numbers of saplings, deciduous shrubs, and spruces. It was clear that the existence of these vegetation characteristics mainly explained the observed differences in the abundance of arthropods between forest patches of different sizes and also between forest edges and stand interiors.
Relationship between soil metal contamination and metal resistance of callus established from mature red maple
Authors: Watmough Shaun A , Hutchinson Thomas C
Published: April 2011

The relationship between metal contamination in surface soil and metal resistance of red maple (Acer rubrum L.) callus was examined by sampling mature trees along a transect extending away from a metal smelter at Rouyn-Noranda, Quebec. Callus tissue, established from shoots, was tested for resistance to zinc (Zn), cadmium (Cd), nickel (Ni), and arsenic (As) (a metalloid). Strong positive linear correlations were found between Zn resistance of callus and total Zn in soil beneath sampled trees (r = 0.83, p < 0.001) at concentrations between 73.4 and 840 mg Zn·kg-1 and between Zn resistance and H2O-extractable Zn (r = 0.83; p < 0.001) at values between 0.3 and 11.8 mg Zn·kg-1. Despite high total concentrations of As in soil, which were between 6.2 and 499 mg·kg-1, there was no significant correlation between As resistance of red maple callus and soil As levels. However, H2O-extractable As concentrations were very low (< 0.11 mg·kg-1). Concentrations of Cd and Ni in surface soil beneath trees were not high, and there were no significant correlations between Cd resistance of callus and soil Cd or between Ni resistance in vitro and soil Ni. The origin of these resistance traits, and their significance to the survival of trees in metal-polluted soils, is discussed.
Validation of SpraySafe Manager, an aerial herbicide application decision support system
Authors: Ray John W , Richardson Brian , Schou Wayne C , Teske Milton E , Vanner Arthur L , Coker Graham WR
Published: April 2011

Spray Safe Manager (SSM) is a computer-based aerial application model, which unlike previous models, has a simple user interface. SSM not only predicts spray deposition but also integrates this data with herbicide-plant dose-response curves. This latter facility allows the operator to predict the size of buffer zone required to avoid damage to sensitive plants outside the spray area and the degree of weed control within the spray block. Validation trials showed that, for a helicopter applied spray, the model tended to overpredict spray deposition on stainless steel plates close to the spray block and underpredict deposition in the region 32-80 m from the centre of the spray release line and on isolated plants. The accuracy of model prediction was greater when the spray was applied using D8-45 nozzles orientated at 90°, than for spray applied using D6 nozzles orientated at 0°. The reasons for this are discussed. The model can also be used to predict possible work rates, hectares sprayed per hour, and potentially as a training tool.
Critical period of interspecific competition for northern conifers associated with herbaceous vegetation
Authors: Wagner Robert G , Mohammed Gina H , Noland Thomas L
Published: April 2011

Using critical-period analysis, we examined the temporal effects of interspecific competition from herbaceous vegetation on seedlings of jack pine (Pinus banksiana Lamb.), red pine (Pinus resinosa Ait.), eastern white pine (Pinus strobus L.), and black spruce (Picea mariana (Mill.) BSP) during the first 5 years after planting. The critical period is the time period during stand development when interspecific competition reduces tree growth. We found both similarities and differences in responses among tree species. Gains in stem volume index associated with increasing duration of vegetation control (expressed by weed-free curves) differed among species. In contrast, declines in stem volume index with increasing duration of competition after planting (expressed by weed-infested curves) were equal among species. Critical periods for stem volume index were shorter for shade-intolerant jack and red pine (1 and 2 years after planting) than for more shade-tolerant white pine and black spruce (1-3 years for spruce and 1-4 years for white pine). Intolerant species had greater absolute stem volume growth, but smaller relative declines from continuous association with herbaceous vegetation (85, 81, 78, and 67% for white pine, black spruce, red pine, and jack pine, respectively). Herbaceous vegetation did not affect survival and had a variable influence on height growth of all species.
Effect of stand density on radial growth of branches of Scots pine in southern and central Finland
Authors: Mäkinen Harri
Published: April 2011

Branch growth dynamics in Scots pine (Pinus sylvestris L.) were studied in 19 thinning experiments in southern and central Finland. Data were collected from 229 trees growing on sites of different fertility with different stand density, age, and canopy position. Radial increments were measured from discs from the base of the thickest branch on every fifth living whorl. Branch growth declined gradually from the upper part of the crown towards the crown base. Near the crown base, the effect of stand density was most apparent and branches remained alive without forming annual rings. After the thinnings, branch growth did not increase, but wider spacing delayed the reduction in branch growth and increased branch longevity. Correlation of branch increment between trees was greater in the upper whorls than in the lower crown. Correlation of the radial increment between whorls of different ages was greater between whorls near each other than between whorls from the upper and lower crown. Variation of the annual increments was similar in the stem and branches. A model was developed for predicting branch increment at different heights in the crown. The best independent variables for indicating branch increment were stem radial increment, height/diameter ratio, and branch age.
Carbon storage of microbes and roots and the flux of CO2 across a moisture gradient
Authors: Pietikäinen J , Vaijärvi E , Ilvesniemi H , Fritze H , Westman C J
Published: April 2011

Living root biomass (tree roots [Formula: see text]2 mm, tree roots >2 mm, and dwarf shrub roots), dead root biomass, microbial biomass carbon (Cmic), and soil surface CO2 flux were investigated in a northern boreal mixed forest. Three study sites were established along a 100-m gradient with differing moisture and soil texture. The amount of total root biomass did not differ across the moisture gradient. The amount of living root biomass averaged 1.46 kg·m-2, and 1.04 kg·m-2 was found as dead roots. Half of living root biomass was fine roots (diameter [Formula: see text]2 mm), and of this fraction, 75% was fine roots of trees. The total amount of Cmic was lower on the dry site (78.5 g C·m-2) compared with the intermediate and mesic sites (95.3 g C·m-2). The Cmic to organic C ratio was 1.4% in the L+F+H horizon, and the ratio increased with increasing depth to 4.1% in the C horizon, which indicated that microbes in the deeper soil horizons decomposed recently deposited root litter or exudates. The storage of carbon in fine roots was four times more than that in Cmic. The soil surface CO2 flux fluctuated seasonally but was similar across the gradient.
Dendroclimatic response of Picea mariana and Pinus banksiana along a latitudinal gradient in the eastern Canadian boreal forest
Authors: Hofgaard Annika , Tardif Jacques , Bergeron Yves
Published: April 2011

To decipher spatial and temporal tree-growth responses to climate change we used tree-ring data from Picea mariana (Mill.) BSP and Pinus banksiana Lamb. along a latitudinal transect in western Quebec. The transect encompassed the distinct transition between mixed and coniferous forests at approximately 49°N. Correlation analyses and principal component analyses were used to identify common spatiotemporal growth patterns, and site- and species-specific patterns since 1825. A moist summer in the year t - 1 and an early start of the current growing season favored growth of both species. A prolongation of the growing season into fall was the most distinguishing factor between the species. A long and gradual climatic gradient shifted to a short gradient with a clear segregation between the southern and northern parts of the transect. This shift, around 1875, was abrupt and characterized by a turbulent climatic period. The observed pattern was likely related to a large-scale shift in the mean position of the Arctic Front that occurred at the end of the 1800s. No discrete climatic setting explained the present switch from mixedwoods to conifers at 49°N. Awareness of such nonequilibrial relations between climate and species distribution is essential when assessing vegetation responses to future climate change.
Environmental resource interactions affect red raspberry growth and its competition with white spruce
Authors: Lautenschlager R A
Published: April 2011

Multifactor experiments were used to study the effects of (1) shade, moisture, and nutrients on above- and below-ground biomass production of red raspberry (Rubus idaeus L.) and (2) intra- versus inter-specific competition for light, nitrogen, and space in interplantings of raspberry and white spruce (Picea glauca (Moench) Voss) seedlings. Interactive effects among the manipulated resources on seedling growth were common. Raspberry biomass increased with increasing moisture and nutrients or with added nitrogen when nitrogen was the only nutrient manipulated. Seventy-three percent shade reduced raspberry biomass production, while production under full sun and 30% shade was similar. Raspberry shoot/root ratio increased with increasing nutrients and shade but decreased with age. In mixed plantings with spruce, when nitrogen was added, raspberry biomass and shoot/root ratio increased at the expense of spruce, while the shoot/root ratio decreased with shade in low-nitrogen plots. Spruce height growth was not affected by light level, nitrogen addition, or competition type; however, spruce diameter and biomass production decreased with competition from both raspberry and spruce and increased with increasing growing space and in low-nitrogen shaded plots where raspberry was less common.
The effects of glyphosate and triclopyr on common bryophytes and lichens in northwestern Ontario
Authors: Newmaster Steven G , Bell F Wayne , Vitt Dale H
Published: April 2011

The effects of two silvicultural herbicides (Vision®, Release®) on bryophytes and lichens were studied in a harvested boreal mixedwood ecosystem. A completely randomized design with 115 plots of 1 m2 allowed direct comparison between herbicides and their effects on community dynamics. Regression models were used to analyze the relationship between herbicide application rates (0.71-6.72 kg active ingredient/ha) and changes in bryophyte and lichen abundance and species richness for 2 years following herbicide application. Results showed that bryophyte and lichen abundance and species richness decreased after herbicide treatments. In general, herbicide applications reduced the diversity of forest mesophytes and weedy colonizers to an ecosystem with only a few species of colonizers. A combination of clustering techniques and ANOVA were used to divide bryophytes and lichens into three ecologically defined response groups: herbicide-tolerant colonizers, semi tolerant long-term stayers from dry open forest, and sensitive forest mesophytes.
What expansion factor should be used in binned probability proportional to size sampling?
Authors: Ducey Mark J
Published: April 2011

In probability proportional to size sampling, including prism cruising and other forms of point and line sampling, calculation of an exact expansion factor requires that size be recorded exactly. When sizes are binned or recorded by class, this information is lost. While several alternatives for calculating the expansion factor have been proposed, theoretical attention has been lacking. A decision-theoretic perspective helps distinguish between the alternatives and offers some support to the use of the arithmetic mean size in calculating the expansion factor, a choice which had previously come under some criticism. However, consistency arguments strongly favor estimators based on squared error loss or minimax principles. Some new alternatives are suggested when prior information about the diameter distribution in a stratum is available.
An efficient Biolistic® transformation protocol for Picea abies embryogenic tissue and regeneration of transgenic plants
Authors: Walter C , Grace L J , Donaldson S S , Moody J , Gemmell J E , van der Maas S , Kvaalen H , Lönneborg A
Published: April 2011

An efficient Biolistic® transformation technology was developed to stably transform Picea abies (L.) Karst. Several embryogenic tissue lines were tested for proliferation on standard embryogenesis media. Transient transformation studies with these lines were performed to optimize the parameters for genetic transformation. Selection conditions for transgenic tissue based on the nptII resistance gene in combination with the antibiotic geneticin were defined such that only transgenic P. abies lines were able to develop. Nontransgenic tissue was completely inhibited under these conditions. Stable integration of a uidA reporter gene and a nptII resistance gene into the genome of P. abies was achieved and more than 200 mature embryos were regenerated for every transformation event. Histochemical and fluorometric analysis indicated strong expression of the uidA gene in transgenic material. ELISA studies to detect and quantify the nptII gene product as well as polymerase chain reaction and Southern blotting confirmed the presence and integration of uidA and nptII genes into the P. abies genome. Transgenic P. abies plants from nine independent transformation events were recovered and are currently growing in a greenhouse for genetically modified organisms, awaiting field release.
Chondrostereum purpureum as a biological control agent in forest vegetation management. II. Efficacy on Sitka alder and aspen in western Canada
Authors: Harper G J , Comeau P G , Hintz W , Wall R E , Prasad R , Becker E M
Published: April 2011

A national research program was established to test the field efficacy of the native fungal pathogen Chondrostereum purpureum (Pers. ex Fr.) Pouzar) for control of hardwood vegetation. During 1995, two fungal isolates were applied as a biocontrol agent to the cut stumps of Populus tremuloides Michx. (trembling aspen) and Alnus viridis ssp. sinuata (Regel) Á. Löve & D. Löve (Sitka alder). Treatments consisted of two formulations (BC, ON) in combination with two fungal isolates (2139, JAM6), blank formulations, cutting only, triclopyr herbicide application, and an uncut control. Analysis of Sitka alder clump mortality indicated isolates JAM6 and 2139 in combination with the BC formulation caused clump mortality of 90 and 88%, respectively. The blank formulation treatments caused the lowest clump mortality and appeared to promote sprouting and growth of Sitka alder when compared with cutting alone. At the aspen installation, the BC formulation with isolate 2139 was found to be the most effective fungal treatment resulting in 84% aspen stem mortality. The results from both installations suggest that C. purpureum efficacy appears to be dependent on the virulence of the isolate and the formulation.
Dry matter amounts and increment in 21- to 91-year-old common alder and grey alder and some practical implications
Authors: Johansson Tord
Published: April 2011

Growth data were collected from 32 stands of common alder (Alnus glutinosa (L.) Gaertn.) and 26 stands of grey alder (Alnus incana (L.) Moench) growing on forest land in Sweden. The stands ranged in latitude from 56 to 60°N and from 58 to 63°N, respectively. The mean ages of common and grey alder stands were 48 (range 21-91) and 40 years (range 21-66), respectively; the mean stand densities were 1114 (range 431-2994) and 1854 stems/ha (range 546-4031), respectively; and the mean diameters at breast height (outside bark) were 21 (range 12-28) and 17 cm (range 9-25). No statistically significant differences in site index were found among the four soil groups in common alder stands or among the three soil groups in grey alder stands. The mean total dry mass above stump level was 152 t·ha-1 with a range of 73-257 t·ha-1 for common alder stands and 139 t·ha-1 with a range of 82-218 t·ha-1 for grey alder stands. Mean annual mass increments outside bark for common and grey alders were 3.5 and 3.4 t·ha-1, respectively. Mean leaf area index was 2.85 for common alder stands and 3.04 for grey alder stands. Mean specific leaf area was 13.3 m2·kg-1 for common alder and 12.8 m2·kg-1 for grey alder. Some recommendations for management of common and grey alder stands are given.
Mass controlled pollination of Eucalyptus globulus: a practical reality
Authors: Harbard J L , Griffin A R , Espejo J
Published: April 2011

Mass production of seed by controlled crossing of selected individuals is an increasingly important method of capturing genetic gain from tree breeding. In Eucalyptus the conventional controlled pollination (CP) method requires at least three separate visits to a flower, and seed is correspondingly costly. This paper reports development of a cost-efficient pollination technique referred to as one-stop pollination (OSP) for application in seed orchards of Eucalyptus globulus Labill. in Chile. Emasculation of the flower at anthesis is followed by slicing the stigma and top of the style to provide a site for pollen adherence. Pollen is applied immediately, followed by isolation of the style from contaminating pollen by covering with a section of tubing. It is then not necessary to revisit until capsule harvest. Seed yield per capsule after OSP treatment was equivalent to that achieved by treating flowers with supplementary pollination at the time of natural stigma receptivity. Only 5% of those flowers pollinated at anthesis without style wounding set a capsule, compared with 69% with OSP. Seed yield for OSP averaged 26 seeds per capsule compared with 12 for open-pollinated samples from the same trees. The effect of orchard location on OSP harvest percentage and seed yield was demonstrated. With application of OSP in the environment of the Chilean orchard, we estimate a sevenfold reduction in seed production cost in comparison to conventional pollination techniques.
Seasonal gas exchange of black spruce using an automatic branch bag system
Authors: Rayment M B , Jarvis P G
Published: April 2011

Four large cuvettes were used to measure whole-branch CO2and H2O vapour exchange at the Boreal Ecosystem-Atmosphere Study, Southern Study Area, Old Black Spruce site. Measurements started before the spring thaw and continued until after the winter freeze-up. Daytime photosynthesis, nighttime respiration, transpiration rate, and branch conductances were zero at the start and the end of the measurement period. Maximum photosynthetic uptake rates were ca. 6 µmol·m-2·s-1(0.02 µmol·g-1·s-1). Maximum nighttime respiration was ca. 0.8 µmol·g-1·s-1. Maximum transpiration rates were ca. 2 mmol·m-2·s-1(7.1 µmol·g-1·s-1). Maximum branch conductance was ca. 35 mmol·m-2·s-1(0.123 mmol·g-1·s-1). A simple model combining light and temperature responses accounted for 80-90% of the day-to-day variation in daytime carbon uptake. Total annual daytime carbon uptake ranged from 151 to 271 g·m-2(530-868 mg·g-1). Total nighttime loss ranged from 12.7 to 15.5 g C·m-2(22.4-27.3 mg C·g-1). Total transpiration ranged from 20.4 to 35.0 kg H2O·m-2(70.2-112.2 g H2O·g-1).
Tree-ring patterns in stems and root systems of black spruce (Picea mariana) caused by spruce budworms
Authors: Krause Cornelia , Morin Hubert
Published: April 2011

Radial growth along the stems and root systems of black spruce trees (Picea mariana (Mill.) BSP) was examined to determine the effects of spruce budworm defoliation. A mixed conifer and pure black spruce stand located in the boreal zone of Quebec, Canada were sampled. Following defoliation, dendrochronological analyses revealed the percent growth reduction in the ring width at different stem heights and throughout the root system. Ring widths of black spruce were found to be reduced during the last three spruce budworm outbreaks. The reduction of the tree-ring width after spruce budworm outbreaks started first in the crown region and was followed by reduction at the stem base. For the whole root system, the ring-width index exhibited a decrease. The root system showed a high sensitivity to defoliation by spruce budworm. Inside the root system, the growth reduction after a spruce budworm outbreak was variable in each root branch. The growth decrease of the pure black spruce stand was less intensive than in the mixed stand.
Variation in response to nutrition in a three-generation pedigree ofPopulus
Authors: Karim S Abdul , Hawkins B J
Published: April 2011

Response to nitrogen (N) and phosphorus (P) was examined in a three-generation pedigree of Populus in 1996 and 1997. In 1996, the first-generation parental clones female Populus trichocarpa Torr. & Gray and male Populus deltoides Bartr. and second-generation male and female F1hybrids were grown in five treatments of varying N:P ratio. In 1997, 29 third-generation F2clones and the first-generation clones were grown with high or low N and P. Variability in response to nutrients existed among and within generations. Growth increased with N supply but not with P supply because of N limitation. On average, the male F1hybrid had the greatest growth and biomass per unit foliar N and P, while the female F1hybrid and P. trichocarpa were intermediate. Populus deltoides was least productive in 1996. Most F2clones had poorer growth than the first-generation clones, but some F2clones were as productive and variation was large. Clones 331-1078 and 331-1122 produced at least as much biomass and biomass per unit foliar N and P as P. trichocarpa, the most productive first-generation clone. With larger screening trials, clones combining high growth rates with low nutrient requirements may be found and selected for use on nutrient-poor sites.
Measurement and modeling of spatially explicit variation in light transmission through interior cedar-hemlock forests of British Columbia
Authors: Canham Charles D , Coates K Dave , Bartemucci Paula , Quaglia Stefan
Published: April 2011

We have characterized canopy geometry and light transmission by the nine dominant conifer and broad-leaved tree species of the interior cedar-hemlock (ICH) forests of northern British Columbia. Our field data were used to parameterize a spatially explicit model of light transmission through mixed-species forests. That model, a component of the forest dynamics simulator SORTIE, was developed for eastern deciduous forests, and this paper presents a test of that model in a very different ecosystem. Our results show that individual crowns of the ICH forests intercepted much more light than species of eastern deciduous forests but that the canopy as a whole allowed greater light penetration, largely because of openings between the relatively narrow, conical crowns of the western conifers. Light transmission by individual crowns was correlated with shade tolerance among the conifers (as in eastern deciduous species), but crown depth was not (in contrast with eastern species). Despite the fundamental differences in the nature of light transmission in the two ecosystems, the SORTIE light model developed for eastern deciduous forests was effective at predicting spatial variation in understory light levels in these western coniferous forests. The goodness of fit of such a simple model suggests that the most important factors regulating spatial variation in understory light levels in these forests are simply the sizes and distribution of nearby trees, and the local sky brightness distribution. Discrete canopy gaps represent a special case in which a region of the canopy is not occupied by crowns.
Intensifying a heuristic forest harvest scheduling search procedure with 2-opt decision choices
Authors: Bettinger Pete , Boston Kevin , Sessions John
Published: April 2011

Forest management problems with even-flow and adjacency considerations are difficult to solve optimally. A heuristic search intensification process, which uses two types of decision procedures, changes to single-decision choices (1-opt moves) and changes to two-decision choices simultaneously (2-opt moves), was used in an attempt to locate feasible and efficient solutions to these problems. One-opt moves involve changing the timing of timber harvests for a single land unit and are commonly used in heuristic techniques. Two-opt moves involve swapping the harvest timing between two land units, which intensify the search process. We apply the procedures to two management problems, one with 40 land units and the other with 700 land units. The goal is to achieve the highest, and most even, flow of timber volume over five time periods, with adjacent units being unavailable for harvest in the same period. One-opt moves, used alone, allowed the search process to produce good feasible solutions to these management problems and to generate a relatively even spread (number) of harvests over the planning horizon. The use of 2-opt moves resulted in better solutions, although the number of harvests per time period remained static. These procedures, used alone, may not be appropriate for all problems, because of their nature and limitations.
Influence of weather at time of pollination on acorn production of Quercus alba and Quercus velutina
Authors: Cecich Robert A , Sullivan Neal H
Published: April 2011

Pistillate flower development and acorn production were observed in small populations of white oak (Quercus alba L.) and black oak (Quercus velutina Lam.) in central Missouri from 1990 to 1997. There were significant year-year differences in the size of flower crops for both species and significant tree-tree differences in black oak. About 7% of the white oak flowers matured into acorns; most flowers aborted by early July, just after fertilization. About 12% of the black oak flowers matured into acorns, but some individual trees never or rarely produced a mature acorn. The number of fertilized flowers in white oak and black oak in early July was positively correlated with acorn production. Over all trees and years, the number of flowers and acorns were significantly correlated. Acorn production varied in relation to weather variables during the time of pollination. Simple regression models were good predictors of white oak acorn production but not of black oak acorn production. Maximum temperature and the number of days with hail had negative effects on acorn production. The number of days of rain during the pollination period was positively correlated with flower survival in black oak but not with white oak.
Provenance hybridization in a diallel mating scheme of maritime pine (Pinus pinaster). I. Means and variance components
Authors: Harfouche Abdelkader , Kremer Antoine
Published: April 2011

Growth and survival from age 1 to 13 years, stem straightness, and resistance to Dioryctria splendidella Herr. Schaff. were assessed in 154 families belonging to interprovenance hybrids of maritime pine (Pinus pinaster Ait.). The hybrids were part of a full 10 × 10 diallel mating scheme. The 10 parental provenances belonging to the three major geographic groups of maritime pine (Atlantic, Mediterranean, and North African) were also included in the experiment as controls. The variance among families within an interprovenance hybrid combination represented only a minor part of the total variance, except for height and survival from age 1 to 3 and resistance to Dioryctria. General combining abilities were more important than specific combining abilities for all traits except for survival during the juvenile stages. General reciprocal effects were only significant for height at age 1 and stem straightness at age 8. A few hybrids between Atlantic and Mediterranean or North African provenances combined the good growth of the former provenance with the excellent stem straightness of the latter ones, suggesting new alternatives for tree improvement.
Cold hardiness in coastal, montane, and inland populations ofPopulus trichocarpa
Authors: McCamant Thaddeus , Black R Alan
Published: April 2011

Freezing tolerance was studied in laboratory and field tests using black cottonwood, Populus trichocarpa Torr. & Gray, clones collected from eight populations within the coastal, montane, and inland regions of the Pacific Northwest. Freezing tolerance varied among different populations and was dependent on growing environment. Clones from coastal populations grown in a coastal common garden (Puyallup, Wash.) had 50% less injury in laboratory tests compared with the same clones grown in an inland common garden (Pullman, Wash.). In contrast, clones from inland populations grown in an inland common garden had 50% less injury in laboratory tests compared with the same clones grown in a coastal common garden. Freezing tolerance also varied between coastal populations. In field tests at the inland common garden, clones from inland and montane populations had less freezing injury compared with clones from coastal populations. Leaves on 50% of the clones with coastal origins were killed by the first fall frosts compared with 25% for clones with inland origins. Subsequently, 50% of the coastal clones exhibited winter injury following the winters of 1993-1994 and 1994-1995 at the inland common garden. Clones from inland populations exhibited little or no winter injury. The specific tissues injured during freezing tests varied among clones. Populus trichocarpa is a species offering considerable variation for selection to local environments, and therefore, the source of material should be an important consideration in hybrid poplar breeding programs.