Studies of extraction damage decay in crops of Picea abies in southern England

Trees in a well-grown crop of Picea abies were subjected to wounding and inoculation with Stereum sanguinolentum at three-monthly intervals over a period of one year. The pattern of fungal colonisation in wood beneath wounds of various types is described.     

Studies of extraction damage decay in crops of Picea abies in southern England

Studies are described in which the pattern of fungal colonisation was examined in the wood at the base of spruce stems which had been damaged at different times over the previous six years during normal log-extraction operations. The mycoflora of the wood and bark of undamaged stems in similar crop conditions was also examined.     

欧洲云杉、黑云杉、白云杉苗期对比试验

选择欧洲云杉3个种源、黑云杉3个种源、白云杉3个种源、青海云杉1个种源进行了不同种、种源的苗期生长性状变异试验。结果表明：云杉不同种、种源间苗期性状差异显著。4个种的1年生苗以苗高进行排序：欧洲云杉〉黑云杉〉白云杉〉青海云杉。欧洲云杉、黑云杉、白云杉各个种的不同种源间有很大的变异及选择潜力。因此在进行云杉引种时,应选择不同的种、种源,才能取得更好的效果。     

Pathogenicity of ophiostomatoid fungi on Picea abies in Slovenia

Pathogenic fungi can survive and develop in living plants, often causing diseases in the host. Some theories speculate that pathogenic ophiostomatoid fungi provide benefits to its vectors – bark beetles – by overcoming the tree's defence mechanisms. This study reports the results of an experiment in south‐eastern Europe in which mature and seedling Norway spruce trees were artificially inoculated with various ophiostomatoid fungi. The aim of the experiment was to determine the relative virulence of ophiostomatoid fungi by assessing the ability of the fungi to stimulate host tree defence mechanisms through inoculation experiments. Experiments were performed by inoculation of Picea abies in seedling and mature trees. The following fungi were used in low‐density and seedling inoculations: Ophiostoma ainoae, O. brunneo‐ciliatum, Grosmannia cucullata and an unidentified Leptographium sp., O. bicolor, O. fuscum, O. piceae, G. penicillata and G. piceiperda. Endoconidiophora polonica was used in mass and seedling inoculations. Various characteristics such as host vitality, blue stain, lesion and resin outflow were measured before and after the trees were felled. E. polonica caused blue stain, induced large lesions and killed some of the mature trees and seedlings, confirming earlier reports that it is a strong wound pathogen. Only E. polonica, Leptographium sp. and O. ainoae caused blue stains in the sapwood of inoculated seedlings. In low‐density inoculations, G. piceiperda induced intense necrosis and had higher values for all the characteristics monitored. Some of the other ophiostomatoid fungi showed a moderate level of pathogenicity. Fungi with the capacity to stimulate a host defence mechanism could play a role in the establishment of bark beetle populations.     

Effect of sulfur-dioxide on protein-SH in needles of Picea abies1

The effect of SO₂ on the SH-groups of proteins in needles of Picea abies is studied. The content of total protein SH and glutathione is estimated with 5.5′-Dithio-bis-nitrobenzoic-acid (Ellman reagent). In addition structural protein SH is measured microspectrophotometrically in sections stained with the SH reagent, mercurochrome. The results indicate that GSH and also total protein SH and structural protein SH are increased in needles of Picea abies growing in SO₂ polluted areas. Compared to needles of trees in relatively unpolluted areas average increases of 2. 33 (GSH), 1.22 (total protein SH) and 1.55 (structural protein SH) are found.     

Uncertainty in detecting climate change impact on the projected yield of black spruce (Picea mariana)

The empirical growth and yield (G&Y) curves used in most timber supply models assume that growth conditions are invariable over time, which may not be correct given the projected future climate. However, errors in G&Y models can be quite large, and we therefore wanted to know the probability of detecting climate change-induced growth anomalies as a departure from current G&Y predictions. The work was carried out in a boreal forest study area in Eastern Canada, where Picea mariana Mill. BSP (black spruce) is the dominant species. Climate change effects were incorporated into G&Y predictions as correction factors obtained from process-based simulations of growth using current or projected climate. Uncertainty in G&Y projections was quantified through the inclusion of sampling and model errors in a bootstrap re-sampling scheme that yielded a percentile distribution of possible differences between G&Y curves that included or did not include climate change effects. Results yielded an average projected increase in productivity of 29% under future climate conditions for the black spruce strata in the study area. The probability of the climate change-modified G&Y predictions being significantly different from the current G&Y projections is 75% when considering the sampling error alone, and of 67% when both the sampling and modelling errors are included. Although incomplete in terms of what sources of error have been included, this study demonstrates the type of information that can be generated on the propagation of uncertainty in G&Y projections and, ultimately, on timber supply.     

Overstorey density influence on the height of Picea abies regeneration in northern Sweden

The study aimed specifically at investigating if canopy opennesswas a better predictor of the height growth of Norway spruce(Picea abies (L.) Karst.) advance regeneration than overstoreybasal area or overstorey standing volume. In 1990, a field experimentwith 3 x 2 factorial design and two replications (blocks) wasestablished in an uneven-aged Norway spruce forest. Plots hada net plot area of 30 x 30 m, each with a 10-m-wide treatedbuffer zone. Three overstorey density levels retained approximately15, 40 and 70 per cent of the pre-harvest overstorey standingvolume and were allotted to the plots. Two types of thinningthat harvested smaller trees or harvested larger trees wererandomly allocated to each pair of overstorey density plots.In mid-June 2000, canopy openness was estimated from hemisphericalphotographs taken at five marked points in the centre of eachof the plots at 0.9 m from ground to the top of the ‘fish-eye’camera lens. Regression results showed that canopy opennesswas a better predictor of height increments of spruce seedlings(0.1< height < 0.5 m), saplings (0.5 height < 2.0m), and small trees (height 2.0 m, diameter at 1.3 m height< 5 cm) than with overstorey basal area (m² ha^–1) oroverstorey standing volume (m³ ha^–1). The height incrementof the spruce advance regeneration was not significantly correlatedto stand basal area or to standing volume. Overstorey basalarea in the net plots was significantly negative (P 0.05) withmean canopy openness estimates, and the r² value was 0.40. Resultsindicated that basal area was not linearly related to canopyopenness as it increased, which might explain the lack of predictivepower of retained basal area on spruce regeneration height indense stands in boreal Sweden.     

Variation in sapwood thickness of Picea abies in Estonia depending on the tree age

Variation of sapwood thickness in terms of a linear measurement and a growth ring count with reference to the age was studied in dominant and suppressed Norway spruce trees. In the trees of both dominance classes the sapwood thickness increased in absolute terms, while its relative portion decreased with the age of the trees growing. Great differences were found in sapwood thickness between dominant and suppressed trees in linear measurements but not in the number of sapwood rings or the rate of the heartwood formation. The number of sapwood growth rings reached 40 in old trees. The index of vigour differed considerably in dominant and suppressed trees.     

The impact of Sirococcus shoot blight on radial and height growth of Norway spruce (Picea abies) in young plantations

The impact of Sirococcus shoot blight on the radial and height growth of Norway spruce in a young plantation (approximately 20 years old) was investigated by examining the increment losses for four infection intensities (classes). The average diameter at breast height of trees in the lightly damaged class was 72% when compared with the average diameter of the healthy trees, whereas moderately and severely damaged tree classes were 67 and 57%, respectively. Using tree ring analysis, the development of radial growth over time due to intensity of infection was studied. Height growth of affected trees was also significantly reduced (up to 43%) compared with the healthy trees, thus indicating a dramatic impact of Sirococcus conigenus on the growth of young Norway spruce.     

Somatic embryogenesis in cotyledons of Picea abies is enhanced by an adventitious bud-inducing treatment

Somatic embryos were obtained from young, isolated cotyledons of Picea abies. A bud-inductive treatment for one week before transfer to a callus induction medium, resulted in a tenfold increase in the percentage of cotyledons in which embryonic tissues could be induced. The degree of expression of somatic embryogeny depends on whether cotyledons are first subjected to a callus-inducing medium or first exposed to a cytokinin treatment followed by a callus-inducing medium. It is hypothesized that two populations of cells exist, both with the inherent potential of becoming embryogenic after treatment with plant growth regulators.     

Induction of tumours by various strains of Agrobacterium tumefaciens on Abies nordmanniana and Picea abies

Abies nordmanniana and Picea abies seedlings were inoculated with a wild‐type (C 58) or an attenuated strain (rooter or shooter mutants) of Agrobacterium tumefaciens. Large tumours were formed on A. nordmanniana in response to the wild‐type and rooter strains, 60–65 % of the seedlings being susceptible. Smaller tumours were formed on Picea abies in response to the wild‐type strain, at least 12% of the seedlings being susceptible. Tumours from both species induced by the wild‐type strain grew in vitro on medium without added phytohormones.     

The threshold of successful attack by Ips typographus on Picea abies: A field experiment

The spruce bark beetle, Ips typographus, was induced to attack Norway spruce by means of pheromone dispensers. The degree of attack on each tree was recorded and the trees were later categorized as surviving or dying, according to the degree of sapwood blue-staining caused by the attacks. A threshold of successful attack was observed; i.e. above a certain number of attacks the trees were successfully invaded by the beetles and their mutualistic blue-stain fungi. The height of this threshold increased with increasing tree vigour, measured as the relative increment of the sapwood cross-sectional area.     

Estimating the frequency of stem rot in Picea abies using an increment borer

The likelihood of detecting decay present in Norway spruce trees when taking bore core samples at breast height or at stump height was analyzed in two stands. The actual numbers of decayed trees were obtained after the trees were felled. More than 80% of the decay extending to breast height level was detected by taking core samples at that level. However, these core samples revealed only 40–70% of the actual amount of decay present at stump height. At stump height a higher portion of the total amount of decay present was revealed. Heterobasidion annosum was detected in 69 and 77% of the decayed trees in the two stands.

Misjudgements occurred mainly where either (i) decay was present at stump height but not at breast height or (ii) when the decay column had a lateral position. At breast height the probability of finding lateral rot columns was higher than at stump height.     

Influence of initial spacing and tree class on the basic density of Picea abies

The effects of initial spacing and tree class on the basic density of Norway spruce were evaluated in a stand on a fertile site in southwestern Sweden. The basic density at 0 and 4 m above ground level was significantly higher for trees planted with an initial spacing of 1.5 m than for trees planted with wider initial spacings. A decrease in initial square spacing from 2.5 m to 1.5 m had little effect, of small practical importance, on the basic density. The density at 0 and 4 m above ground was significantly higher for the suppressed trees than for the intermediate and dominant ones, and for the intermediate trees compared with the dominant trees. Differences in basic density appeared to be due mainly to differences in growth‐ring width. Basic density decreased outwards from the pith to the bark at 1.3 and 4 m above ground.     

Resistance of Picea abies seedlings to infection by Heterobasidion annosum in relation to drought stress

Norway spruce (Picea abies) seedlings, 2–4 years old, were subjected to different degrees of stress. Drought stress affected the predisposition to infection by Heterobasidion annosum in the same way in root wood, stem wood and stem bark. At high water potentials (?3 to ?5 bar) resistance was high, at intermediate levels (- 5 to - 15 bar) it was low but increased again at water potentials below - 8 to - 15 bar. Neither light nor oxygen deficiencies appeared to have adverse effects on resistance. Total length of unsuberized roots was a sensitive indication of strain on the seedlings.     

Effect of Nutrient Optimization on Branch Characteristics in Picea abies (L.) Karst

The number and size of branches are major determinants of log grading. To study the effect of fertilization on branch characteristics in Norway spruce, trees were sampled in a nutrient optimization experiment in northern Sweden. Data were collected from 24 40-yr-old trees from fertilized and control plots after 12 yrs of annual nutrient application. On the fertilized plots, all essential macronutrients and micronutrients were supplied in irrigation water every second day during the growing season. Fertilization increased the number of new branches, but its effect on branch angle and branch mortality was small. Fertilization increased the diameter of the branches that were formed after the initiation of the treatment, but also the diameter of the branches that were formed before the fertilization commenced. Fertilization enhanced the general growth of a tree, but there were no significant changes in the relationships between stem and branch characteristics. Improved growth rate of trees, as an effect of fertilization, may impair branching quality of logs. Such negative effects may, however, to some extent be counteracted by planting density at stand establishment and later thinning regimens.     

Optimizing the Management of a Butt-rotted Picea abies Stand Infected by Heterobasidion annosum from the Previous Rotation

There are no instructions on the management of stands of Norway spruce [ Picea abies (L.) Karst.] in which butt rot caused by Heterobasidion annosum coll. (Fr.) Bref. was not discovered until the time of first thinning. A stochastic simulation model describing the spread of butt rot in a stand of Norway spruce was used with a new submodel describing the butt rot of young trees. Non-linear stochastic optimization was used to determine the most profitable management schedule of a young Norway spruce stand with butt rot. If the initial level of butt rot was 5% or 10%, or the stand was thinned in summer with stump treatment, one thinning with a rotation of 55 yrs was optimal. Two winter thinnings with a rotation of 61 yrs was optimal in an initially healthy stand. Optimizations indicated that silvicultural measures that decrease the transfer of H. annosum to next generation at clear-cuttings could be economically fulfilled.     

Changes in soluble-phenol content of Norway-spruce (Picea abies) phloem in response to wounding and inoculation with Ophiostoma polonicum

The aim of this study was to investigate the temporal changes in Norway-spruce (Picea abies) phloem phenolics during wound-induced response. Two Norway spruces were inoculated with Ophiostoma polonicum and sterile agar; unwounded phloem was simultaneously tested as control. Both unwounded and inoculated phloem were then sampled 6, 11, 21, 30, and 60 days later. Monophenols were analysed by HPLC, and the tanning capacity of the phloem extracts was estimated from their ability to precipitate proteins. The response to inoculation was characterized by radical changes in the phloem phenolic composition. Initially, an increase in (+)-catechin concentration was observed, concomitant with a slow decrease in both glycoside concentrations and tanning capacity. After day 6, this decrease was accelerated in the event of fungus inoculation. The appearance of aglycones did not take place during the decrease in glycosides, but was delayed. The phenolic response of Norway-spruce phloem to inoculation is modulated by the presence of the fungus and is focused on the formation of insoluble compounds.     

Organization and ultrastructure of the dormant cambial zone in compression wood of Picea abies

Summary This electron microscopy study is concerned with the dormant cambial cells in compression wood of Picea abies (L.) Karst. The cambial zone comprised 4–8 rows of fusiform cells. Each radial file contained the group known as Sanio's four, namely an initial, a mother, and two daughter cells. Groups of three, resulting from a failure of a mother or a daughter cell to divide, were also present. Undifferentiated xylem tissue cells occurred singly, in pairs, or in groups of four. These cells and the last-formed tracheids were often enclosed by a common primary wall. The fusiform cells had a large, elongated nucleus, numerous small vacuoles, and a frequently infolded plasma membrane. Golgi apparatus and endoplasmic reticulum were rare, while plastids, amyloplasts, and lipid droplets were common. Cambial ray cells contained much lipid material. The tissues were similar to cambial tissues in normal wood of conifers. The present results can only be interpreted in terms of the single layer of initials and sequence of cell divisions established by Sanio. The initial can be located by several criteria in dormant and active cambial regions in conifers. It could be shown that the existence of the group of Sanio's four is better documented in the literature than has so far been recognized. The occurrence of a variable number of primary cell walls is discussed with reference to the concentration of lignin in the middle lamella of mature xylem.