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.     

Responses of Pinus sylvestris and Picea abies Seedlings to Limited Phosphorus Fertilization and Treatment with Elevated Ozone Concentrations

Scots pine ( Pinus sylvestris L.) and Norway spruce [ Picea abies (L.) Karst.] seedlings were exposed to high phosphorus (HP) or low phosphorus (LP) availability for one growing season in the open field, and to combined P availability and elevated ozone (O 3 ) concentrations (0, 55, 110 and 210 ppb for Scots pine and 0, 40, 75 and 150 ppb for Norway spruce, respectively) for 28 days in controlled laboratory chambers. Compared with HP, the LP treatment reduced Scots pine current-year (C) shoot and root dry masses and Norway spruce total dry mass, whereas the highest O 3 concentrations increased the magnesium concentration of Scots pine C needles and P concentrations of the C needles of both tree species. Chlorophyll a, a+b and carotenoid concentrations of Scots pine C needles were significantly higher in the LP treatment compared with HP under the highest O 3 concentration (210 ppb). In the mesophyll tissue of C needles of both tree species, LP treatment increased the size of mitochondria and elevated O 3 -induced granulation of chloroplast stroma and disintegration of cytoplasm. Exposure to elevated O 3 concentrations increased swelling of chloroplast thylakoids and reduced the amount of vacuolar tannin in the LP Scots pine C needles. The results suggest disturbances in needle photosynthetic machinery due to acute exposure to the combination of elevated O 3 and low P availability. However, clear additive effects were found only in needle P concentrations < 1 mg g -1 in short-term O 3 exposure.     

Effect of Thinning and Phlebiopsis gigantea Stump Treatment on the Growth of Heterobasidion parviporum Inoculated in Picea abies

The spread of Heterobasidion parviporum Niemelä & Korhonen in roots of Norway spruce was studied in three unthinned first rotation stands of Norway spruce [Picea abies (L.) Karst.] on former agricultural land in south-western Sweden. Heterobasidion parviporum was inoculated at stump height into the trunk of 135 standing trees in a randomized block design. One year after inoculation, two-thirds of the trees were thinned out and one-third was left standing. Half of the stumps left by thinning were treated with spores of Phlebiopsis gigantea (Fr.) Jül and half were left untreated. The spread of H. parviporum was examined both 3 and 5 yrs after inoculation. The rate of spread of H. parviporum and the proportion of infected roots were found to be significantly higher in the root systems of the stumps than in those of the standing trees. Treatment with P. gigantea had no significant effect on the development of H. parviporum in the stumps. There was a tendency 5 yrs after inoculation, however, for a lower proportion of H. parviporum-infected roots in the stumps treated with P. gigantea than in the untreated stumps. In conclusion, thinning of infected Norway spruce was found to increase the rate of spread of H. parviporum in the root systems of the infected trees, which could increase the risk of a rapid build-up of infection in the remaining stand.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

Survival and Growth of Picea abies Regeneration after Shelterwood Removal with Single- and Double-grip Harvester Systems

Three stands in Sweden were followed for 7 yrs to study the survival and growth of Norway spruce [Picea abies (L.) Karst.] regeneration after shelterwood removal with single- and double-grip harvester systems. The height of all seedlings within circular plots was recorded before and after final cutting. The tallest seedling and one randomly selected seedling on each circular plot were permanently marked and their annual height growth was measured each year during the period 1993-1999. No significant differences between single- and double-grip harvester systems were found with respect to their effects on regeneration density, survival or annual height growth. The annual height growth of the individual seedlings after shelterwood removal was significantly correlated with seedling height before shelterwood removal. Significant differences were found in annual height growth between seedlings with high and low vitality. Logging damage did not affect the annual height growth. Several practical conclusions were drawn. First, the choice of harvester system does not affect seedling height growth or survival after shelterwood removal. Secondly, the removal of a 200 m³ shelterwood with 200 stems ha^-1 does not seem to constitute a serious problem for seedling survival and growth. Finally, estimated vitality and seedling height both seem to be fairly good predictors of postrelease survival and growth.     

Critical Factors Affecting Ex Vitro Performance of Somatic Embryo Plants of Picea abies

The potential to use somatic embryos for large-scale propagation of elite genotypes, for integration into breeding programmes and for connecting breeding and mass propagation, is receiving much attention. However, before the methods are applied it is important that the plants regenerated via somatic embryogenesis grow as expected, i.e. as seedlings or cuttings. Growth of somatic embryo plants is under a cumulative influence of a number of treatments given during the in vitro phase and during the ex vitro establishment phase. The aim of this study was to identify treatments with a negative influence on the subsequent growth of somatic embryo plants of Norway spruce (Picea abies L. Karst.). Based on the results, the time of contact with abscisic acid during somatic embryo maturation and the length of continuous light treatment (CLT) during the first growth period strongly affect the height growth during two successive growth periods. In both cases longer treatments exerted negative effects. Based on these results a new method was set up, which includes: (1) prematuration treatment of the suspension culture in a growth regulator-free medium, by which the maturation step is synchronized and contracted; and (2) a two-phase germination treatment, first on a solidified medium and then in a liquid medium. This treatment avoids extended CLT during the first growth period. Another advantage of the two-phase germination treatment is a better root-system development. Somatic embryo plants produced according to this method can be transferred directly from in vitro conditions to the greenhouse.     

Radial,Height and Volume Increment Variation in Picea abies (L.) Karst. Stands with Varying Thinning Intensities

Variation in radial increment at different stem heights was compared with stem volume increment and height increment using thinning experiments of Picea abies (L.) Karst. in southern Finland. The magnitude of growth variation was similar on trees from different crown classes and stand densities. However, there was higher autocorrelation in the codominant and intermediate trees and trees on dense plots. The relationship between short-term volume increment and radial increment variation at breast height was not affected by thinnings. While short-term growth variation was similar at different stem heights, some evidence was found for differences in medium-term variation between radial increment at breast height and volume increment. Height increment reacted to unfavourable climatic events later than radial and volume increment. Radial and volume increments were negatively correlated to temperature and positively correlated to precipitation of the current summer. Height increment was positively related to current early summer temperature, but negatively to temperature of the previous summer.     

Autumn Fertilization in the Nursery Affects Growth of Picea abies Container Seedlings After Transplanting

Second-year Norway spruce seedlings [Picea abies (L.) Karst.] grown in containers were divided into three fertilization levels in August [5, 15 and 25 mg nitrogen (N) seedling^?1]. The resulting foliar concentrations of N were 11.0, 13.1 and 15.8 g kg^?1, respectively. Seedling height (mean 26.0 cm) did not differ among treatments. The next spring, the seedlings were tested in two experiments. (1) The seedlings were transplanted into pots containing sandy soil in the greenhouse, where they were fertilized with either pure water or nutrient solution (22 mg N l^?1). (2) The outplanting performance of the autumn-fertilized seedlings was tested on a sandy field. In the greenhouse experiment, the autumn fertilization level affected height growth and root egress of the seedlings significantly, but less than fertilization with a nutrient solution after planting. In the field experiment, during the first season after transplanting shoot growth of the seedlings increased with the level of autumn fertilization. After the second and third seasons, the seedling stem volume was highest with the highest level of autumn fertilization. These results suggest that, by improving the preplanting nutrient status of seedlings, the growth of shoot, stem diameter and root biomass can be enhanced after planting, especially on nutrient-poor soils. However, heavier autumn fertilization than that used here may yield a greater and more persistent increment in growth.     

Effects of Seedbed Substrates on Regeneration of Picea abies from Seeds

The effects of seedbed substrates on the emergence and mortality of Norway spruce [ Picea abies (L.) Karst.] on clear-cuts were studied in a sowing experiment. Seven intact substrates as well as scarified plots on the same types of substrates were considered. The experiment took place at two locations in south-east Norway, during three consecutive years. Of intact substrates, Sphagnum spp. was found to be the best for emergence and litter was found to be the second best. Microhabitats dominated by feather mosses, Dicranum spp., Vaccinium myrtillus or Deschampsia flexuosa were poor environments for emergence. However, after two to three seasons, survival in per cent of emerged seedlings was more or less equal among all substrates. Emergence was higher on scarified plots than on intact substrates, and except for Sphagnum substrates, survival was equal or better. For scarified plots, the original substrate did not influence the emergence of seedlings, but mortality after the second summer differed owing to original substrate. The best substrates for scarification were V. myrtillus and D. flexuosa , while mortality was highest for plots that were originally dominated by Sphagnum . Weather conditions influenced the suitability of the substrates as seedbeds, as did the location of the plots.     

Potential Effects of Temperature on Early Reproductive Development and Progeny Performance in Picea abies (L.) Karst

In order to enhance cone production in Norway spruce [Picea abies (L.) Karst] seed orchards have been established in more southerly, warmer sites in Norway. This has led to concern and some evidence that seedlings obtained from parent trees grown at warmer sites may not be well adapted if planted in northern regions. Selective events during sexual reproduction in the warmer climate may select for traits not well adapted for cold climates. This study describes ovule and male gametophyte development, fertilization and proembryo and early embryo development under six different temperature regimens of warm or cold, warm-cold or cold-warm, and compares development in relation to temperature sums in degree days (dd) and calendar date. The outside treatment in a cold climate in Norway served as the control, and normal development and few ovule abortions and abnormalities were observed. In no treatments were abnormalities in male gametophyte development observed. In treatments in which trees were kept in the greenhouse throughout the study or moved during the study from the outside to inside the greenhouse, a higher incidence of megagametophyte, egg or embryo abortion was generally observed.     

Community of Aphyllophorales and Root Rot in Stumps of Picea abies on Clear-felled Forest Sites in Lithuania

The community of Aphyllophorales fungi in stumps of Picea abies (L.) Karst. and the occurrence of root rot caused by Heterobasidion annosum were investigated at 38 clear-felled sites in Lithuania. Fruit-bodies were recorded on 36.0% of the 3924 examined stumps. The most common were Bjerkandera adusta, Phlebiopsis gigantea, Fomitopsis pinicola, Gloeophyllum sepiarium, Stereum sanguinolentum, Trametes zonata and H. annosum. All species occurred in stumps both with and without established root rot, but B. adusta, F. pinicola, G. sepiarium, T. zonata and Trichaptum abietinum occurred less often in stumps containing root rot, while H. annosum was encountered more often. Greater numbers of fruit-bodies were found on stumps cut in summer than on those cut in winter. The fruiting became most abundant 3-4 yrs after the trees were felled. The abundance of nearly all Aphyllophorales correlated positively with the stump diameter, and on larger stumps, fruit-bodies of several different fungi were more common. The number of stumps containing H. annosum root rot in different sites varied from 9.8% to 68.8%, and was 27.6% on average. The incidence of root rot correlated neither with the age nor with the density of the felled stand, but it correlated negatively with the proportion of deciduous trees within a stand.     

细胞分裂素和硝酸铵对欧洲云杉不定芽伸长的影响

报道细胞分裂素和硝酸铵对欧洲云杉不定芽伸长过程的影响.采用5年生的欧洲云杉1个无性系不定芽丛来研究玉米素和硝酸铵对不定芽生长的影响.试验3种诱导类型(玉米素浓度分别为6.84、13.68、20.52 μmol·L-1,激动素浓度0.69 μmol·L-1,培养4周),玉米素最高浓度处理诱导的伸长芽数量最多,在4个无生长调节剂继代培养过程中,加入了1个硝酸铵浓度逐渐增加的继代培养过程.经不含生长调节剂的低浓度的硝酸铵(2.5 mmol·L-1)培养基的继代培养后转入含有细胞分裂素的诱导培养基,下一个继代培养基补充的硝酸铵浓度分别为2.5、7.5、12.5、17.5 mmol·L-1,8周(2个继代培养)后转入含有硝酸铵浓度为2.5 mmol·L-1的培养基培养.硝酸铵浓度为7.5 mmol·L-1的处理可形成数量最多的不定芽,这对于采用不同浓度的玉米素进行诱导的处理结果是一致的,但随着硝酸铵的浓度增至12.5 mmol·L-1和17.5 mmol·L-1时则不定芽的数量减少.欧洲云杉的胚轴外植体经1次或多次诱导后,细胞分裂素(BA、激动素、玉米素、2iP)促进了不定芽的分化和发育,其中BA由于可诱导产生大量的不定芽而成为最有效的细胞分裂素.玉米素虽然诱导不定芽相对弱一些,却在BA多次诱导后可促进芽的伸长.这对获得具有形成不定芽能力并可扩繁的芽丛非常重要.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Influence of Shelterwood Density on Survival and Height Increment of Picea abies Advance Growth

Abstract

The increases in the arithmetic mean diameter at breast height (dbh) of the 100, 200, 300 and 400 largest stems ha^?1 by dbh associated with six different thinning regimens for periods up to 35 years were compared, by analyses of variance, to the corresponding stem fractions in unthinned stands using permanent sample plot data. In addition, the expected mean dbh of these stand fractions at future points in time was modelled, based on site and stand data obtained at the time of the first thinning. Thirty-five years after the first thinning, the thinning from below regimens resulted in actual increases (a measure affected by both the thinning intensity and the thinning method), compared with the unthinned stands, in the mean dbh for the 100, 200, 300 and 400 largest stems ha^?1 of 2.6–9.0 cm. The corresponding genuine increases (a measure principally affected solely by the thinning intensity) were 4–11 cm. The functions predicting the future dbh of these stand fractions yielded good fits.     

Variation in Tree Size and Resistance to Ceratocystis polonica in a Monoclonal Stand of Picea abies

Tree resistance to the pathogenic blue-stain fungus Ceratocystis polonica was studied in a monoclonal stand of Norway spruce [ Picea abies (L.) Karst.] in relation to tree social status and diameter at breast height (DBH). The DBH distribution of the 33-yr-old stand ranged from 5 to 35 cm. There were clear differences in tree height between the suppressed (DBH 7.4-10.3 cm), codominant (DBH 11.8-17.4 cm) and dominant (DBH 18.6-23.9 cm) tree classes. The resistance was tested by mass inoculating trees with a low (400 inoculations m -2 , 60 cm inoculation belt) or high (400 inoculations m -2 , 120 cm inoculation belt) dosage. The small, suppressed trees were more susceptible to inoculation than the codominant and dominant trees, based on the amount of blue-stained and occluded sapwood, lesion length and dead cambium/phloem. A threshold in tree social status or tree size may be important in the overall resistance to fungal infection.     

Effects of Previous High N Addition on Nutrient Conditions in Above-ground Biomass of a Picea abies Stand in Sweden

The effect of different thawing procedures on seedling quality in Norway spruce (Picea abies) was evaluated. Freezer-stored seedlings were thawed rapidly for 20 h by immersion in water with an initial water temperature of 8°C or thawed more slowly by gradually increasing the temperature in storage over a period of 8 weeks. Seedlings from these treatments were also compared with seedlings thawed rapidly overnight at 15°C. Frost tolerance, carbohydrate content and the time of bud break were used as indicators of the vitality of the seedlings. Seedlings thawed rapidly in water or air showed significantly better frost tolerance after storage than slowly thawed seedlings. The contents of sucrose and raffinose in seedlings thawed rapidly were also significantly higher than in seedlings thawed more slowly. Bud break occurred later in seedlings thawed rapidly than in slowly thawed seedlings. Rapid thawing in water may be a good method to ensure the delivery of high-quality thawed seedlings throughout the planting season.     

Functions for Biomass Estimation of Young Pinus sylvestris,Picea abies and Betula spp. from Stands in Northern Sweden with High Stand Densities

New silvicultural regimes with high within-stand competition require new functions for estimation of standing stock and growth of biomass components, since the allometry of trees is changed by light competition. This paper presents functions for estimation of the aboveground biomass dry weights for stem wood, stem bark, branches and leaves of young (diameter at breast height <10 cm) Scots pine (Pinus sylvestris L.), Norway spruce [Picea abies (L.) Karst.] and birch (Betula pendula Roth. and Betula pubescens Ehrh.) trees growing in dense mixed stands. The functions were derived from a sample consisting of 84 Scots pine, 43 Norway spruce and 66 birch trees from six stands in northern Sweden with high stand densities (>10000 st ha^-1). The logarithmically transformed power function displayed a good ability to stabilize the variance of dry weights and showed a good fit to the material (0.37< R ² <0.99). A comparison with the most commonly used biomass functions in Sweden today showed that they overestimated the weight of stem wood and branches, while the weight of foliage was underestimated. The nature of these discrepancies suggested that the precision of biomass estimations might also be improved for young trees at wider spacing.     

沙床育苗技术对杉木苗木生长影响的研究

对采用沙床育苗法培育的杉木轻基质容器苗的生长量、生物量、根系形态和出圃率等进行对比研究的结果表明:轻基质容器苗地径、侧根数、高径比在贝江河林场、西山林场和咸水林场等3个种子园的良种苗间均存在极显著差异。轻基质容器苗的苗高、地径、侧根数、地下鲜重、根冠比和出圃率分别为37.3 cm、5.5 mm、13.5条、5.1 g、0.29和94.5%,表明轻基质容器苗根系发达,出圃率高,对提高造林成活率和良种利用率具有重要意义。沙床培育轻基质容器苗技术利于培育出高质量和高出圃率的良种壮苗,宜在苗木培育与生产中大力推广。     

Reconstructing 100-150 years of logging history in coastal spruce forest (Picea abies) with special conservation values in central Norway

Coastal spruce forests of central Norway harbour a unique assemblage of epiphytic lichens and are given high priority with respect to conservation of biodiversity. To assess the historical impact of logging during the last 100-150 yrs, 31 remnant stands were studied by means of tree-ring analysis of 2199 trees and the decay stage of 1605 stumps. No stands had been clear-cut, but all had been selectively logged at least twice during the last 150 yrs. Total harvested timber volume ranged from 65 to 409 m³ha-¹ (31-124% of present-day standing volume) and the selective logging kept standing volume low (40-200 m³ha-¹) during 1890-1930. Present-day stand characteristics were strongly correlated with site productivity and topographic position within the ravine valleys. Low amounts of dead wood at sites with high historical logging activity was the only consistent relationship found after covariance of site productivity, topographic position and deciduous trees were taken into account. The results indicate that old-growth stand characteristics, such as reversed J-shaped age distributions and dead wood in advanced decay classes, can be obtained 100-150 yrs after intensive selective logging.     

Effects of aluminium and calcium on Picea abies seedlings

Newly‐germinated Norway spruce seedlings were grown for 15 weeks in pots of iron podzol soil that received additions three times a week of nutrient solution containing six levels of Al (0, 0.37, 0.74, 1.5, 3.0 or 6.0 mM) and two levels of Ca (0.09 or 0.46 mM). The Ca concentrations in shoots and roots decreased with increasing Al levels. Growth was suppressed at 0.74 mM Al in the nutrient solution, which gave 0.5 mM Al in saturated soil extracts at the end of the experiment.