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Picea × darwyniana Björk & Goward was recently proposed to replace Picea albertiana S. Brown as the representative taxon for the hybrid offspring of Picea glauca (Moench) Voss and Picea engelmannii Parry ex Engelm., but should be considered invalid for three reasons. First, the proponents failed to document in any way that the P. albertiana isotypes were Picea glauca × mariana Little & Pauley hybrids, as they claimed. Secondly, the P. albertiana isotypes lacked pubescent twigs, purple markings on their seed cones, and denticulate cone-scale margins, which are characteristics of P. glauca × mariana. This indicates a misinterpretation of the P. albertiana parentage. Lastly, P. × darwyniana appears to be an example of P. albertiana ssp. ogilviei Strong & Hills. As the latter is an earlier and validly published name, P. × darwyniana is an illegitimate replacement for plants within the P. glauca × engelmannii (=P.a. ssp. albertiana) and P. engelmannii × glauca (=P.a. ssp. ogilviei) circumscriptions based on naming priority. [ABSTRACT FROM AUTHOR]

Eastern dwarf mistletoe ( Arceuthobium pusillum Peck) parasitizes the branches of white spruce ( Picea glauca [Moench] Voss) and ultimately kills this host species. Previous studies of host needle physiology generally focused on trees experiencing infections of moderate severity; here, we expanded upon previous research to investigate the morphological, physiological, and biochemical properties of needles from white spruce trees experiencing the full range of infection severities. We found that the impact of parasitism on host needle parameters did not scale uniformly with infection severity. Rather, parasitism reduced host needle size distal to infection and resulted in more negative carbon isotope ratios across all infection severities. Reduced foliar nitrogen and chlorophyll content were only evident in trees with moderate or severe infection, while photosynthetic capacity was depressed in only severely infected trees. Furthermore, while some impacts were confined to infected host branches, others, such as smaller needles and reduced photosynthetic capacity, were also evident in branches showing no visible signs of infection. We conclude that symptoms of infection appearing only after infection worsened in severity or appearing in uninfected branches may in whole or in part also be manifestations of a decline in resource availability and vigor of the whole tree. [ABSTRACT FROM AUTHOR]

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Fluorapatite-solubilizing bacteria were isolated from the hyphosphere of the ectomycorrhizal (ECM) fungus Wilcoxina sp., a dominant species in the Picea glauca (Moench) Voss rhizosphere. Hundreds of strains isolated from the ascomycete Wilcoxina sp. could dissolve tricalcium phosphate, while only 27 of them could produce clarification halos on fluorapatite-amended solid medium. Most of the fluorapatite-solubilizing strains belonged to the Burkholderia genus. Scanning electron microscopy observations have shown that these efficient phosphate-solubilizing bacteria (PSB) were able to completely solubilize fluorapatite crystals within 22 h. The efficient PSB Burkholderia sp. strain 205 and Curtobacterium sp. strain 168 were tested for their ability to associate with a genetically distant fungal host while fulfilling their phosphate-solubilizing function. Burkholderia sp. strain 205 successfully associated with the basidiomycete Laccaria bicolor (Maire) P.D.Orton when hydroxyapatite was the only phosphorus source available to the fungus, while there was no bacterial development when Laccaria bicolor could access soluble phosphorus as well. Optical microscopic observation of Laccaria bicolor associated with Burkholderia sp. revealed extensive colonization of fungal hyphae by the bacterium. These results suggest an important role of bacteria - ECM fungi associations in white spruce phosphate nutrition. [ABSTRACT FROM AUTHOR]

In Isle Royale National Park, heavy moose browsing over the past 100 years has suppressed the regeneration of many tree species, gradually resulting in a shift towards more open forests and savannas. By 1996, 16% of the forests at the southwestern end of Isle Royale had become savanna and another 20% of forests were starting to have canopy breakup. The changes in understory vegetation brought about by savanna formation have received little attention, even though the future of moose and wolf populations on Isle Royale is tied to these vegetation changes. This study examined the vegetation of savannas ranging in age (date since formation) from <10 years to 80 years to examine how the ground flora changes over time from initial forest canopy breakup, to extensive grassland, and finally to a zootic subclimax dubbed 'moose-spruce savanna.' Ordination techniques were used to describe plant communities and to identify environmental variables that influence vegetation development. Nonparametric multiplicative regression was used to predict how these variables influenced individual plants and structure within the communities. Plant communities had a notable shift from forest herbs to ruderal species, especially non-native plants. This succession was influenced strongly by the underlying bedrock and hydrology-altering moisture regimes and plant communities. Picea glauca (Moench) Voss. and Poa pratensis L. competed in a dynamic inhibitory relationship. The former facilitated forest plants while the latter out-competed other plants and promoted open swards. These interactions are dramatically changing the character of Isle Royale's upland plant communities and will have important trophic consequences for the island. [ABSTRACT FROM AUTHOR]

The present study documents the changes in carbon and nitrogen metabolites occurring in apical buds and previous year stems of white spruce seedlings ( Picea glauca [Moench] Voss) with contrasting growth phenotypes (tall vs. small) after transfer to short day (SD; 8 h) photoperiod to induce bud formation. Concentrations of total nonstructural carbohydrates markedly increased in the developing buds within the days after transfer to SD, mainly as a result of increased concentrations of monosaccharides such as glucose, fructose, and pinitol. At the same time, starch levels declined, with the resulting carbohydrates presumably used to meet early carbon requirements of the SD-induced apical bud. Concentrations of glutamine, glutamic acid and proline also decreased immediately after transfer to SD in both organs. Later stages of SD-induced bud formation were characterized by an increase in starch, sucrose, and glutamine concentrations in previous year stems, concomitant with an increase in the steady-state levels of UDP-glucose pyrophosphorylase and glutamine synthetase protein. In contrast, arginine levels increased after 2 weeks of SD exposure, indicating a transition in arginine metabolism at the time of initiation of shoot stem primordia and bud elongation. Higher accumulation of total nonstructural carbohydrates and total amino acids in previous year stems of small trees could indicate lower sink strength of apical bud during its development, which could in turn impact subsequent tree growth. [ABSTRACT FROM AUTHOR]

White spruce ( (Moench) Voss) cone crops were measured from 1986 to 2011 in the Kluane region of southwestern Yukon to test the hypothesis that the size of cone crops could be predicted from spring and summer temperature and rainfall of years t, t - 1, and t - 2 . We counted cones in the top 3 m of an average of 700 white spruce trees each year spread over 3-14 sites along 210 km of the Alaska Highway and the Haines Highway. We tested the conventional explanation for white spruce cone crops that implicates summer temperatures and rainfall in years t and t - 1 and rejected it, since it explained very little of the variation in our 26 years of data. We used exploratory data analysis with robust multiple regressions coupled with Akaike's information criterion corrected (AICc) analysis to determine the best statistical model to predict the size of cone crops. We could statistically explain 54% of the variation in cone crops from July and August temperatures of years t - 1 and t - 2 and May precipitation of year t - 2. There was no indication of a periodicity in cone crops, and years of large cone crops were synchronous over the Kluane region with few exceptions. This is the first quantitative model developed for the prediction of white spruce cone crops in the Canadian boreal forest and has the surprising result that weather conditions 2 years prior to the cone crop are the most significant predictors. [ABSTRACT FROM AUTHOR]

An endoconidial, black meristematic taxon gen. et. sp. nov. (Dothideales) from the black subicula found on twigs of declining white spruce, (Moench) Voss, in Alberta is described. It is morphologically distinguishable from other endoconidial taxa by the conidioma composed of clumps of endoconidial conidiogenous cells, scattered meristematically dividing cells, dematiaceous hyphae, abundant brown, granular matrix materials, and sometimes plant tissue. Endoconidia also occur in conidiogenous cellular clumps that are not organized into a conidioma but develop directly from stromatic cells on the bark. In culture, it forms similar endoconidial conidiomata and also a mycelial, blastic synanamorph that superficially resembles . is a member of the Dothideales and shows phylogenetic affinities to a clade of conifer-stem and -needle pathogens, including and , although no teleomorph was found either on the natural substrate or in culture. It has not been determined whether A. arboricola is pathogenic to its host, but the occurrence of abundant intracellular hyphae in the host periderm suggests that the fungus is at least parasitic. [ABSTRACT FROM AUTHOR]

CO2–light interactions can influence the competition among boreal plants, but are poorly understood. We investigated the effect of such interactions on the growth and biomass of 1-year-old black spruce (Sb) (Picea mariana (Mill.) BSP) and white spruce (Sw) (Picea glauca (Moench) Voss) grown with CO2 concentrations ([CO2]) of 360 and 720 µmol·mol–1 under 30%, 50%, and 100% light, in greenhouses. There were significant two-way and three-way interactions. Root collar diameter (RCD) of Sw decreased with decreasing light, while in Sb, there was no significant difference in RCD for plants grown under 50% or 30% light. Height was greater for plants grown under 100% light than if the plants were shaded. Elevated [CO2] increased RCD by 33% and enhanced stem volume by 67%, 98%, and 84% under 100%, 50%, and 30% light, respectively. The CO2 enhancement of total biomass was relatively higher under lower light, and greater for Sb than Sw. Elevated [CO2] decreased specific leaf area under 50% light only. Root mass was generally higher under 100% light than when shaded. Elevated [CO2] increased the root mass of Sb under 100% light, but decreased it under 30% light. Elevated [CO2] decreased the shoot/root ratio under 100% light, but increased it under 30% light. Our data suggest that raising [CO2] will likely increase species competitiveness under low light conditions, and that the increase will be greater in species that are relatively shade tolerant. [ABSTRACT FROM AUTHOR]