Some effects of long-term ozone fumigation on Norway spruce

Summary Potted cuttings of a 12-year-old Picea abies tree were fumigated with ozone, 100 or 300 g O₃· m^–3 (50 or 150 ppb O₃) being added to charcoal-filtered air during the 1985 growing season for a total of 1215 h. The wax structure of ozone-fumigated needles was no different from that of controls. Because flattened wax structures and fused wax fibrils also occurred in controls, these phenomena could not serve as bioindications for the ozone concentrations applied. A smooth layer was found beneath the soluble wax layer and covered needle surface and stomatal openings of ozone-fumigated needles to a greater extent than in controls. Wax quantity was considerably reduced by fumigation with 300 g O₃ · m^–3. Leaf pigments (as extracted with the wax) were less abundant in needles treated with 300 gO₃; the smooth layer probably contributed to the impeded extraction of pigments.     

Some effects of long-term ozone fumigations on Norway spruce

Summary Potted cuttings of a 12-year-old, and grafts of an 80-year-old, Norway spruce (Picea abies (L.) Karst.) were subjected to 100 or 300 g O₃·m^–3 for 1215 h (45 h of daylight per week) during the growing season of 1985. At the end of the fumigation the plants did not exhibit any visible signs of injury. Whereas in the fumigation with 100g O₃·m^–3 we did not detect any significant change in gas exchange, 300 g O₃·m^–3 did alter the CO₂ uptake after 27 weeks, and in one clone transpiration was also altered. Stomatal reaction to a change of light suggested sluggishness, but the change was not statistically significant.     

Effect of acid irrigation and liming on root growth of Norway spruce

The effect of acid irrigation and liming on fine root growth of Norway spruce (Picea abies [L.] Karst.) was studied in an approximately 80-year-old forest stand in southern Germany (Höglwald). Root growth was measured mainly on root windows and in addition by soil core sampling. Root growth rate showed a typical pattern in the course of a year with a maximum in August. Acid irrigation depressed root growth rate, whereas liming, particularly in combination with acid irrigation, markedly increased root growth in the humic layer and the upper 0–5 cm of the mineral soil. The treatment effects on root growth in the mineral soil below 5 cm were small and not significant. Root growth rate was not correlated with the concentration of aluminium (Al) or the molar ratio of calcium (Ca) to Al in the soil solution. The results suggest that inhibition of root growth by acid irrigation is a direct effect of high proton concentrations in the irrigation water, and that enhancement of root growth by liming is caused by an improved supply of mineral nutrients and higher biological activity.     

Genetic host-tree effects on the ectomycorrhizal community and root characteristics of Norway spruce

A greenhouse experiment was used to study the effects of host genotype on short root formation and ectomycorrhizal (ECM) fungal community structure in Norway spruce (Picea abies (L.) Karst.). Rooted cuttings representing 55 clones were inoculated with a mix of vegetative hyphae of five ECM fungal species (Laccaria sp., Amphinema byssoides, Piloderma sp., Cadophora finlandia, Paxillus involutus). After one growing season, the ECM fungal community structure was determined by amplifying the fungal internal transcribed spacer (ITS) of ribosomal DNA directly from ECM root tips. Restriction profiles of obtained amplicons were then compared to those of the inoculated strains. Spruce clones differed in their ECM fungal community composition; we found a statistically significant clone-specific effect on ECM fungal diversity and dominating fungal species. Nevertheless, the broad sense heritabilities of the levels of Laccaria sp., Piloderma sp. and A. byssoides colonisations as well as the ECM fungal community structure were low (H ²?=?0.04?0.11), owing to the high within-clone variation. As nitrogen concentration of needles correlated negatively with ECM fungal richness, our results imply that in the experimental conditions nutrient acquisition of young trees may benefit from colonisation with only one or two ECM fungal species. The heritability of short root density was moderate (H ²?=?0.41) and highest among all the measured shoot and root growth characteristics of Norway spruce cuttings. We suggest that the genetic component determining root growth and short root formation is significant for the performance of young trees in natural environments as these traits drive the formation of the below-ground symbiotic interactions.     

The ectomycorrhizal community structure in high mountain Norway spruce stands

The species composition of ectomycorrhizal (ECM) fungal communities can be strongly influenced by abiotic and biotic factors, which determine interactions among the species such as resource partitioning, disturbance, competition, or relationships with other organisms. To verify whether ectomycorrhization of the root tips and composition of the ECM community in Norway spruce vary according to site features and if ECM species peculiar to these environmental variables can be detected, ten comparable stands differing in bedrock pH and exposure were selected and studied. The results demonstrated that tips vitality and ectomycorrhization degree do not change significantly either on the same tree, or among trees growing in the same stand, whereas they differ greatly with bedrock pH and exposure, even if no spatial or temporal trend were found. ECM species composition revealed instead a significant connection with the two environmental features, with a few species significantly associated to them. The results suggest that pH/exposure patterns play a primary role in the adaptive selection of ECM species constituting the consortium.     

Pervasive growth reduction in Norway spruce forests following wind disturbance

Background

In recent decades the frequency and severity of natural disturbances by e.g., strong winds and insect outbreaks has increased considerably in many forest ecosystems around the world. Future climate change is expected to further intensify disturbance regimes, which makes addressing disturbances in ecosystem management a top priority. As a prerequisite a broader understanding of disturbance impacts and ecosystem responses is needed. With regard to the effects of strong winds – the most detrimental disturbance agent in Europe – monitoring and management has focused on structural damage, i.e., tree mortality from uprooting and stem breakage. Effects on the functioning of trees surviving the storm (e.g., their productivity and allocation) have been rarely accounted for to date.

Methodology/Principal Findings

Here we show that growth reduction was significant and pervasive in a 6.79·million hectare forest landscape in southern Sweden following the storm Gudrun (January 2005). Wind-related growth reduction in Norway spruce (Picea abies (L.) Karst.) forests surviving the storm exceeded 10% in the worst hit regions, and was closely related to maximum gust wind speed (R² = 0.849) and structural wind damage (R² = 0.782). At the landscape scale, wind-related growth reduction amounted to 3.0 million m³ in the three years following Gudrun. It thus exceeds secondary damage from bark beetles after Gudrun as well as the long-term average storm damage from uprooting and stem breakage in Sweden.

Conclusions/Significance

We conclude that the impact of strong winds on forest ecosystems is not limited to the immediately visible area of structural damage, and call for a broader consideration of disturbance effects on ecosystem structure and functioning in the context of forest management and climate change mitigation.     

The effects of enhanced UV-B radiation on physiological activity and growth of Norway spruce planted outdoors over 5 years

The responses of Norway spruce [Picea abies (L.) Karst.] to enhanced UV-B radiation during the 5-year treatment performed outdoors have been subjected to ecophysiological and growth analysis. The plants were exposed to UV-B radiation, simulating 17% ozone depletion. Ecophysiological parameters were monitored three times a year on three needle age classes, while growth was analysed at the end of each growth season. Spruce exhibited great variability in the amounts of photosynthetic pigments and methanol-soluble UV-B absorbing compounds, light use efficiency, photosynthesis and respiratory potential. The needle, branch and plant biomass production was not significantly affected during the 5-year treatment. The repeated-measures procedure comparing growth parameters through subsequent seasons, revealed a decrease of branch diameter under enhanced UV-B, which could be interpreted as a cumulative UV-B effect. The effects of UV-B radiation depended on needle development stage, interaction with environmental conditions and stresses. A reduced negative effect of UV-B radiation was observed during the prolonged drought in 2003, which was hypothesised as an alleviating effect. The tolerance of Norway spruce to elevated UV-B was to a large extent due to the high content of methanol-soluble UV-B absorbing compounds that was related neither to environmental conditions, including UV-B dose, nor to the developmental stage of the needles. The current year needles exhibited a tendency to increased production of UV-B absorbing compounds under elevated UV-B radiation. The outdoor study performed under variable environmental conditions showed great complexity of spruce response to enhanced UV-B.     

Divergent growth of Norway spruce on Babia Góra Mountain in the western Carpathians

Growth divergence – i.e. the expression of divergent growth trends of neighboring trees – has certain implications for dendrochronological research, for instance in the context of climate reconstructions but also in terms of estimating net ecosystem productivity. Thus, understanding the underlying mechanisms is essential to extend our fundamental dendroecological knowledge. In this context, the Picea genus plays an important role since several of its species were reported to exhibit growth divergence. Here, we investigate a well sampled Norway spruce (Picea abies (L.) Karst) data set for growth divergence comprising ring-width and Blue Intensity measurements from seven sites on Babia Góra Mountain, at the border between Poland and Slovakia. By means of Principal Component Gradient Analysis, inter-series correlations, and climate growth relationships, we are able to show that I) Norway spruce on Babia Góra expressed growth divergence since the 1970s, II) the definition of groups increased the strength of population signals and the stability of climate-growth relationships, and III) Blue Intensity appeared as a more robust proxy for environmental conditions. We discuss soil heterogeneity, genetics, and air pollution as possible underlying mechanisms, thereby indicating further research avenues to obtain a better understanding of growth divergence.     

The impact of spruce aphids on nutrient flows in the canopy of Norway spruce

1 This study investigated the effects of honeydew from aphids in the canopy of Norway spruce (Picea abies (L.) Karst.) on the nitrogen chemistry of throughfall using a rainfall simulation experiment. Throughfall collected beneath infested trees was compared with that from beneath uninfested trees, while standardizing the quality and quantity of the precipitation and plant age. 2 Honeydew excreted by Cinara pilicornis (Hartig) and C. costata (Zett.) significantly increased the concentrations of dissolved organic carbon (DOC) and hexose-C in throughfall. The average concentrations of nitrogenous compounds (NH₄-N, NO₃-N) in throughfall collected beneath infested trees were significantly lower than beneath uninfested trees. 3 Multiple regression analysis indicated that the amount of rain and NH₄-N concentrations were the best predictors of the concentrations of dissolved organic nitrogen (DON) in throughfall. Parameters that were closely associated with the level of infestation (DOC, hexose-C concentrations) did not have a direct relationship with DON. About 40% of the reduction in the concentration of DON in the throughfall was attributed to aphid–micro-organism interactions. 4 Particle amino nitrogen (PAN)-concentrations were highest under infested trees in July after aphid numbers had declined, indicating a concomitant decline in microbial biomass after honeydew becomes a limiting resource. 5 The comparison of the concentrations of different nitrogen compounds in throughfall of infested and uninfested trees indicated that aphids affect the carbon and nitrogen cycles in the phyllosphere by providing energy that fuels the metabolism of the micro-organisms. These processes seem to occur very rapidly. 6 We discuss the significance of the results and the prospects of linking the ecology of micro-organisms and herbivores with flows of nutrients through the canopy of trees.     

Abrupt growth changes in Norway spruce and Yezo spruce near an industrial district in Hokkaido, Japan

 Increments in the radii of Norway spruce (Picea abies Karst.) and Yezo spruce (Picea jezoensis Carr.) trees that revealed symptoms of a decline in growth were analyzed by dendrochronological methods in an attempt to correlate past reductions in growth with their main causes. The trees were growing at different sites near the industrial district of Tomakomai, Hokkaido. A skeleton plot method was used to construct a series of pointer years that revealed the number of trees with a clear reduction in growth or recovery from such a reduction. An analysis of “abrupt growth changes” demonstrated that at least two periods of growth reduction were common to a large number of Norway spruce trees. The reduction events were related to the records of industrial activity near the forest and meteorological data. The growth reduction in the 1970s coincided with the start of operation of certain local factories, and its extent was related to the distance from the industrial region. By contrast, a reduction in growth in 1984 was detected at all the Norway spruce sites and the extent was approximately the same at all sites. This phenomenon was related to extreme drought conditions. Growth of Yezo spruce trees was less sensitive to industrial activity and to drought than that of Norway spruce. Thus, differences in response to air pollution and drought were observed between the two species. Received: 20 February 1996 / Accepted: 29 April 1996     

The effects of aluminium and Paxillus involutus Fr. on the growth of Norway spruce [Picea abies (L.) Karst.]

Norway spruce [ Picea aides (L.) Karst.] seed lots were obtained from populations growing on an acid soil in the Black Forest, West Germany (acid), and a calcareous soil in the Schwabische Alb, West Germany (calc). Seedlings were grown in sterile perlite culture containing 0–6 mM aluminium. Hypocotyl extension was inhibited by aluminium in the calcareous seedlings, hut not in the acidic seedlings. In a longer term experiment acidic and calcareous plants were grown for 10 weeks in perlite. Some of the tubes were inoculated with the fungus Paxillus involutus Fr. (designated F +) and some were not (F -). Aluminium sulphate solutions were then added to the tubes to raise the aluminium concentrations to 0–6 mM. Plants were harvested after a further 10 weeks. Fungus was associated with the roots in F+ plants, but mycorrhizas did not form. Growth of acid(F -) was somewhat stimulated by aluminium treatment, but that of calc(F -) was greatly reduced, and the plants were chlorotic. The presence of a rhizospherie fungus (F +) enhanced the growth of the calcareous plants, but had little effect on the acidic plants. Shoot analyses suggested that the greater aluminium sensitivity of the calcareous plants involves an inability to exclude aluminium or to maintain normal levels of calcium and magnesium uptake in its presence. The presence of rhizospheric fungi reduced the effects of aluminium.     

Induction of volatile terpene biosynthesis and diurnal emission by methyl jasmonate in foliage of Norway spruce

Terpenoids are characteristic constitutive and inducible defense chemicals of conifers. The biochemical regulation of terpene formation, accumulation, and release from conifer needles was studied in Norway spruce [Picea abies L. (Karst)] saplings using methyl jasmonate (MeJA) to induce defensive responses without inflicting physical damage to terpene storage structures. MeJA treatment caused a 2-fold increase in monoterpene and sesquiterpene accumulation in needles without changes in terpene composition, much less than the 10- and 40-fold increases in monoterpenes and diterpenes, respectively, observed in wood tissue after MeJA treatment (D. Martin, D. Tholl, J. Gershenzon, J. Bohlmann [2002] Plant Physiol 129: 1003-1018). At the same time, MeJA triggered a 5-fold increase in total terpene emission from foliage, with a shift in composition to a blend dominated by oxygenated monoterpenes (e.g. linalool) and sesquiterpenes [e.g. (E)-beta-farnesene] that also included methyl salicylate. The rate of linalool emission increased more than 100-fold and that of sesquiterpenes increased more than 30-fold. Emission of these compounds followed a pronounced diurnal rhythm with the maximum amount released during the light period. The major MeJA-induced volatile terpenes appear to be synthesized de novo after treatment, rather than being released from stored terpene pools, because they are almost completely absent from needle oleoresin and are the major products of terpene synthase activity measured after MeJA treatment. Based on precedents in other species, the induced emission of terpenes from Norway spruce foliage may have ecological and physiological significance.     

Effect of growth rate on mean microfibril angle and cross-sectional shape of tracheids of Norway spruce

The variation of the mean microfibril angle (MFA) and the shape of the cross-section of lumen with the distance from the pith in fast grown Norway spruce were studied by X-ray scattering and optical microscopy. The samples were from stems of a clone of Norway spruce [ Picea abies (L.) Karst.] grown in a fertile site at Nurmijärvi, southern Finland Both the mean MFA and the circularity index of the lumen of the fast-grown trees decreased more gradually as the distance from the pith increased than those in reference trees grown in a medium fertility site. However, in mature wood the mean MFA reached the same level in fast-grown trees as in reference trees (5°–10°) but the cross-sections of the cells remained more circular in fast-grown trees than in reference trees. The dependence of the mean MFA on the distance from the pith was similar for earlywood and latewood, but the values of the mean MFA of latewood were systematically smaller than those of earlywood. Two different X-ray diffraction geometries were compared from the points of view of biology and data analysis.     

The effects of artificial soil frost on cambial activity and xylem formation in Norway spruce

We studied the effects of artificial soil frost on cambial activity and xylem formation on 47-year-old Norway spruce [Picea abies (L.) Karst.] trees grown on medium fertile site type (with moraine soil) in eastern Finland (62°42′N; 29°45′E). Different soil frost treatments applied were: (1) natural snow accumulation and melting (control, CTRL); (2) artificial removal of snow from soil surface during two consecutive winters (OPEN); and (3) snow clearing and insulation (FROST), which was in other ways similar to OPEN, but the ground was insulated in early spring to delay soil thawing. Each treatment was replicated in three blocks, and two sample trees in each plot were repeatedly microcored during growing seasons of 2006–2007 for the analysis of the onset, cessation and the duration of xylem formation. The phases of tracheid differentiation (tracheids in radial enlargement, secondary cell wall formation, and mature tracheids) were measured from the microcores of 2007. The intra-ring growth and wood density variables were analysed based on X-ray densitometry. In FROST in 2006, xylem formation started a week later than in the other treatments. In 2007, no difference was found between the treatments. The discrepancy in results between the two study years may be explained by between-years variation in weather, i.e., the winter was colder in 2005/2006 than in 2006/2007. No effects of soil frost treatments on tracheid differentiation and on most of the intra-ring growth and density variables were discovered. Our results suggest that the delayed thawing of moraine soil may slightly affect the onset, timing and duration of xylem formation in Norway spruce. However, the effects of delayed soil frost may depend also on the soil type and become more evident with increasing water holding capacity of the soil.     

Effects from shear stress on morphology and growth of early stages of Norway spruce somatic embryos

The shear stress effect on directional expansion of pro embryogenic masses (PEMs) and suspensor cell development of somatic embryos of Norway spruce (Picea abies) at the proliferation stage was studied by a direct and quantitative image analysis system. The experimental system allowed for detailed observations of the effect of hydrodynamic shear stress in rotating and deforming liquid cultures of proliferating Norway spruce somatic embryos. Briefly, somatic embryos at an early development stage comprised only of clusters of meristematic cells without suspensor cells were fixed on an alginate film. The alginate film was affixed on the bottom of a flow cell and the somatic embryos were subjected to laminar flow through the chamber of the flow cell. Magnified images of the cell clusters were collected every 24 h. The image data was processed based on a normalized cross‐correlation method, capable of measuring morphological and size features of individual cell clusters in both temporal and spatial domains. No suspensor cells developed in the cell clusters under shear stress of 140 s^?1 for the duration of the experiments. Cell clusters in the control cultured in stationary liquid conditions developed suspensor cells after 5–9 days in culture. Furthermore, the radial growth of meristematic cell clusters was inhibited by shear rates of 86 and 140 s^?1, corresponding to shear stress of 0.086 and 0.14 N/m², compared to growth under stationary conditions. The shear rate showed a significant negative correlation to growth rate. Control group showed no preference for direction during growth under static conditions. Biotechnol. Bioeng. 2010; 105: 588–599. © 2009 Wiley Periodicals, Inc.     

Effects of growth differences due to geographic location and N-fertilisation on wood chemistry of Norway spruce

We studied the effect of long-term nitrogen fertilisation on wood chemistry at two boreal sites in Finland: the northern site (Kemijärvi) and the southern site (Heinola). N-fertilisation was repeated in five-year intervals from the 1960s. Norway spruce (Picea abies L. Karst.) trees that had been planted in 1938 and 1954, in the northern and the southern site, respectively, were harvested in October 2002. Altogether 20 trees, in five different size classes, either unfertilised or fertilised, were felled. Wood sections at breast height, consisting of five consecutive annual rings, from six (Kemijärvi) or five (Heinola) points with different distances from the pith were examined. Differences in growth between the northern and southern sites were marked in favour of the southern site. In the northern site fertilisation had clearly increased the diameter growth, while in the southern site fertilisation had no effect. Nitrogen fertilisation resulted in slight changes in wood chemistry that included increased nitrogen concentrations in the northern site and extractives in the southern site. Stem wood had higher concentrations of extractives, starch, and uronic acids, and lower concentration of cellulose, in the northern than in the southern site. Changes in the stem wood chemistry along radial axis were marked. The changes in wood chemistry are discussed in relation to the physiological function and also how the changes can influence the suitability of wood for different end-use purposes.     

The influence of ultraviolet-B radiation on the growth, pigment production and chlorophyll fluorescence of Norway spruce seedlings

Norway spruce (Picea abies (L.)Karst.) from seven seed sources was grown in a greenhouse with 8.3 and 14.7 kJ·m⁻²·d⁻¹ m UV-B_BE (biologically effective UV-B: 280–320 nm) irradiation, and with no supplemental irradiation as control. The seedlings total biomass (dry weight) and shoot growth decreased with high UV-B treatment but spruce from low elevation seed sources were more affected. The seedlings grown at the highest UV-B irradiance (14.7 kJ·m⁻²·d⁻¹) showed from 5 to 38% inhibition of total biomass and 15 to 70 % shoot growth inhibition. Norway spruce populations from higher altitude seed sources manifested greater tolerance to UV-B radiation compared to plants from low altitudes. Changes in phospholipids and protective pigments were also determined. The plants grown at the lower UV-B irradiance (8.3 kJ·m⁻²·d⁻¹) showed greater ability to concentrations UV-B-absorbing pigments then control plants. Chlorophyll a fluorescence parameter R_fd, (R_fd=(F_m-F_s)/F_s) showed a significant decrease in needles of UV-B treated plants and this correlated with the altitude of seed source. Exposure to UV-B affect levels of the ratio of variable to maximum fluorescence (F_v/F_m). Results from this study suggest that the response to increased levels of UV-B radiation is depended upon the ecotypic differentiation of Norway spruce and involved changes in metabolites in plant tissues.