Effect of wood ash application on the biomass distribution and physiological state of Norway spruce seedlings on sandy soils

The effect of wood ash applied as a fertiliser (0.25, 0.5 and 1 kg m^–2) to nutrient poor sandy soil on 4-year-old Norway spruce (Picea abies) growing in small-scale sample plots was studied. Analyses carried out with roots, stems, needles and shoots of different age showed that an increase in the pH level and K and Ca concentrations and a decrease in N and P concentrations in the soil was accompanied by a disbalance of nutrients in tree compartments. Stimulation of pigment synthesis in Norway spruce needles was observed, and no disbalances occurred in the pigment system (Chl a/Chl b, TChl/Car) guaranteeing normal process of photosynthesis. Biomass responses to wood ash application depended on the age of needles and shoots, being only slightly notable in current year organs. Inhibition of height growth of seedlings, but stimulation of root biomass was established.     

Diastereomeric stilbene glucoside dimers from the bark of Norway spruce (Picea abies)

As part of a long-term study of the chemical defenses of Norway spruce (Picea abies) against herbivores and pathogens, a phytochemical survey of the phenolics in the bark was carried out. Eight stilbene glucoside dimers, designated as piceasides A-H (1a-4b), were isolated as four 1:1 mixtures of inseparable diastereomers. Their structures were determined by extensive spectroscopic means including 1D (1H and 13C) and 2D NMR (1H-1H COSY, HSQC, HMBC, ROESY) spectra, and were supported by enzymatic hydrolysis and computational analysis.     

Distinct sources of gene flow produce contrasting population genetic dynamics at different range boundaries of a Choristoneura budworm

Populations are often exposed to multiple sources of gene flow, but accounts are lacking of the population genetic dynamics that result from these interactions or their effects on local evolution. Using a genomic clines framework applied to 1,195 single nucleotide polymorphisms, we documented genomewide, locus‐specific patterns of introgression between Choristoneura occidentalis biennis spruce budworms and two ecologically divergent relatives, C. o. occidentalis and Choristoneura fumiferana, that it interacts with at alternate boundaries of its range. We observe contrasting hybrid indexes between the two hybrid zones, no overlap in “gene‐flow outliers” (clines showing relatively extreme extents or rates of locus‐specific introgression) and variable linkage disequilibrium among those outliers. At the same time, correlated genomewide rates of introgression between zones suggest the presence of processes common to both boundaries. These findings highlight the contrasting population genetic dynamics that can occur at separate frontiers of a single population, while also suggesting that shared patterns may frequently accompany cases of divergence‐with‐gene‐flow that involve a lineage in common. Our results point to potentially complex evolutionary outcomes for populations experiencing multiple sources of gene flow.     

Expression of a Bacillus thuringiensis cry1Ab gene in transgenic white spruce and its efficacy against the spruce budworm (Choristoneura fumiferana)

A synthetic version of the cry1Ab gene from Bacillus thuringiensis (Bt) was introduced into white spruce (Picea glauca) by microprojectile bombardment. A plasmid carrying the cry1Ab gene, driven by a ubiquitin (maize) promoter, was co-transferred with a plasmid containing the gus–nptII fusion gene as a screenable selection marker. Molecular analysis of the transgenic lines showed a high level (more than 90%) of co-integration of the cry1Ab gene with the screenable marker. A wide range of expression levels of the cry1Ab gene and corresponding endotoxin was obtained. Accumulation of the Cry1Ab protein was evaluated in embryogenic tissue, the needles of somatic seedlings and in the needles of 5-year-old field-grown trees of individual lines. Laboratory and field insect feeding trials suggest that several spruce transgenic lines were lethal to spruce budworm larvae.     

Stable carbon isotopes as indicators of increased water use efficiency and productivity in white spruce (Picea glauca (Moench) Voss) seedlings

The relationship among water use efficiency (WUE), productivity and carbon isotopic composition (δ¹³C) in white spruce (Picea glauca (Moench) Voss) seedlings was investigated. Sixteen hundred seedlings representing 10 controlled crosses were planted in the field in individual buried sand-filled cylinders. The soil water content in the cylinders was measured using time domain reflectometry over two growing seasons and seedling water use determined by water balance. Two watering treatments were imposed: irrigation and dry land. There was significant (1.6–2.0%c) genetic variation in needle δ¹³C. Ranking of crosses in terms of δ¹³C was generally maintained over watering treatments and there was not a significant genetic versus environmental interaction. There was a positive correlation between δ¹³C and both intrinsic and long-term WUE (more positive δ¹³C with increased WUE) and between δ¹³C and productivity, suggesting a correlation due to variation in photosynthetic capacity. Root to shoot ratios did not increase in water-stressed plants, indicating that responses to drought were primarily at the level of gas exchange, rather than through morphological changes. Our results indicate that it should be possible to use δ¹³C as a surrogate for WUE and to select white spruce genotypes for high WUE without compromising yield.     

Genetic diversity in a seed production population vs. natural populations of Sitka Spruce

Isozyme analysis was applied to estimate the level of variation and the genetic structure of a seed-production population (i.e., seed orchard) and 10 range-wide natural populations of Sitka spruce (Picea sitchensis (Bong.) Carr.). Gene diversity and heterozygosity estimates were comparatively high in both the seed orchard and the natural populations studied. The seed orchard population showed a significantly higher number of alleles per locus and percentage of polymorphic loci. Though not significant, mean heterozygosity of the seed orchard was higher than that observed for all natural populations. Genetic distance analysis indicated that the seed-orchard population was genetically similar to three natural populations from which the parent trees were selected. Parent trees sampling breadth has been identified as the major cause for the observed increased level. The impact of recurrent selection and seed orchard biology and management on maintaining the genetic diversity is discussed.     

Assessment of soil calcium status in red spruce forests in the northeastern United States

Long-term changes in concentrations of available Ca in soils of redspruce forests have been documented, but remaining questions aboutthe magnitude and regional extent of these changes have precluded anassessment of the current and future status of soil Ca. To addressthis problem, soil samples were collected in 1992—93from 12 sites in New York, Vermont, New Hampshire, and Maine toprovide additional data necessary to synthesize all availableresearch results on soil Ca in red spruce forests. Sites werechosen to encompass the range of environmental conditionsexperienced by red spruce. Concentrations of exchangeableCa ranged from 2.13 to 21.6 cmol_ckg^–1 in the Oa horizon, and from 0.11 to 0.68cmol_c kg^–1 in the upper 10 cm of theB horizon. These measurements expanded the range of exchangeable Ca reported in the literature for both horizons in northeastern redspruce forests. Exchangeable Ca was the largest Ca fraction in theforest floor at most sites (92% ofacid-extractableCa), but mineral Ca was the largest fraction at the three sites that also had the highest mineral-matter concentrations. Theprimary factor causing variability in Ca concentrations among siteswas the mineralogy of parent material, but exchangeable concentrationsin the B horizon of all sites were probably reduced by acidicdeposition. Because the majority of Ca in the forest floor isin a readily leachable form, and Ca inputs to the forest floor from the mineral soil and atmospheric deposition have beendecreasing in recent decades, the previously documented decreasesin Ca concentrations in the forest floor over previous decades mayextend into the future.     

Effect of mycorrhizal inocula on the growth of Sitka spruce seedlings in different soils

Summary Different mycorrhizal fungi were tested for their effectiveness in promoting growth of Sitka spruce seedlings, in two contrasting soils, in a glasshouse pot experiment. In nursery soil,Laccaria amethystina significantly improved growth of seedlings in comparison toL. laccata. Seedlings inoculated with a forest isolate ofThelephora terrestris were significantly larger than those inoculated with a nursery isolate when grown in forest soil. The effectiveness ofComplexipes moniliformis in forest soil was poor in comparison to other mycorrhizal fungi. Strains aswell as species of mycorrhizal fungi affect seedling growth differently. These effects are further influenced by soil type.     

Ethylene synthesis and growth in embryogenic tissue of Norway spruce: Effects of oxygen, 1-aminocyclopropane-1-carboxylic acid, benzyladenine and 2,4-dichlorophenoxyacetic acid

Ethylene production from an embryogenic culture of Norway spruce ( Picea abies L.) was generally low. ca 2.5 nl g⁻¹ h⁻¹, whereas 1-aminocyclopropane-1 -carboxylic acid (ACC) concentration was high, fluctuating between 50 and 500 nmol g⁻¹ during the 11-day incubation period. Hypoxia (2.5 and 5 kPa O₂) rapidly inhibited ethylene production without subsequent accumulation of ACC. Exogenous ACC (1, 10 and 100 μ M ) did not increase ethylene production, but the highest concentrations inhibited tissue growth. Ethylene (7 μl I⁻¹) did not inhibit growth either when supplied as ethephon in the medium or in a continuous flow system. Benzyladenine (BA) had little effect on ethylene production, although it was necessary for sustaining the ACC level. Omission of 2.4-dichloro-phenoxyacetic acid (2.4-D) from the medium caused ethylene production to increase from about 2.5 to 7 nl g⁻¹ h⁻¹ within the 11-day incubation period. Although 2.4-D did not specifically alter the endogenous level of ACC, the lowest ACC level, 33 nmol g⁻¹, was observed in tissue treated with 2.4-D (22.5 μ M ) and no BA for 11 days. Data from this treatment were used to estimate the kinetic constants for ACC oxidase, the apparent K_m was 50 μ M and V_max 2.7 nl g⁻¹ h⁻¹. Growth of the tissue was strongly inhibited by 2.4-D in the absence of BA, but weakly in the presence of BA (4.4 μ M ). The results suggest that ethylene or ACC may be involved in the induction of embryogenic tissue and in the early stages of embryo maturation.     

The Liphook Forest Fumigation Project: an overview

The aim of the Liphook Project was to assess the effects of SO₂ and O₃, singly and in combination, on coniferous forest ecosystems. More than 4000 trees of Scots pine (Pinus sylvestris), Norway spruce (Picea abies) and Sitka spruce (P. sitchensis) were fumigated for nearly 4 years using an open-air fumigation technique especially developed for the purpose. The technique eliminated artifacts due to chambers and enabled a variety of effects of the pollutant gases on forest ecosystems to be studied. Most symptoms of forest decline did not occur, but each species reacted in a different way to SO₂ stress, providing no evidence for universal forest decline symptoms. However, some of the mechanisms hypothesized to underlie forest declines were observed as an effect of SO₂ treatment, though others were not, notably any major effect of O₃. The results are assessed against proposed regulatory standards (critical loads and levels) for the protection of forest ecosystems against pollution.