Adult Norway Spruce Research Articles

Changes in phosphorus concentration in needles of adult Norway spruce - nutrient re-translocation or dilution effect?

Regarding the low availability of phosphorus in soil, tree internal cycling of phosphorus through re-translocation among needles would be a good strategy for conifers to cope with soil phosphorus deficiency and to support new needles in annual growth. Therefore, the relationship between the amount of plant-available phosphorus in the soil and the differences in concentrations of phosphorus among first- and second-year needles (P-difference Ny1 − Ny2) of adult Norway spruce was examined. No significant correlation could be detected between the stocks of available phosphorus extracted using citric acid and P-difference Ny1 − Ny2, even for trees with deficient nutritional status. The temporal variations of P-difference Ny1 − Ny2 at single plots showed the same order of magnitude as the variability between plots. The typically lower concentrations of phosphorus in second-year needles result mainly from an increase in needle weight of older needles. The net phosphorus re-translocation into younger needles appears to be of minor importance.

Intra-annual growth response of adult Norway spruce (Picea abies [L.] KARST.) and European beech (Fagus sylvatica L.) to an experimentally enhanced, free-air ozone regime

Several findings indicate an impact of ozone on stem diameter growth leaving the question unanswered, if and how the intra-annual growth pattern is changed. In this study the hypotheses are tested, that (1) ozone will alter the absolute growth and (2) alter and shift the period of growth activity within a year. Our data originates from the free air ozone fumigation experiment ‘Kranzberger Forst’ in a mixed stand of Norway spruce and common beech near Freising/Germany. Annual and intra-annual growth reactions of a sample of five adult beech and five spruce trees, exposed to double ambient ozone were examined and compared to the same number of untreated reference trees. Diameter increments were measured with plastic diameter girth bands and high-resolution, automatically logging micro-dendrometers, mounted at breast height (1.3 m). We used the increment data from the growth periods 2000 to 2005. The high-resolution micro-dendrometer data were examined by fitting a Weibull function to the standardized annual growth profiles to obtain curve parameters for statistical tests. We estimated the parameters ‘T’ which represents the point of time, when 63% of the annual diameter increment is performed and the parameter ‘m’, the Weibull module, which was used as an indicator for the span of time needed to complete the annual growth. The statistical significance of these curve parameters, together with the absolute diameter increment, was tested by use of mixed regression models. The analysis of the growth curve parameters revealed a significantly altered intra-annual growth pattern of both species induced by ozone. Spruce under ozone showed reduced absolute annual diameter increment and a preponed growth activity compared to untreated trees. Beech’s absolute diameter increment was not affected under ozone, but its growth activity was delayed. For both species, ozone fumigation did not alter the individual length of the annual growing season. These results are discussed with respect to drought, tree ring anatomy and tree allometry. The study shows that ozone is able to change growth behaviour of trees even if increment losses are not obvious.

A close-up view of wood structure and properties across a growth ring of Norway spruce (Picea abies [L] Karst.)

A growth ring of an adult Norway spruce (Picea abies [L] Karst.) was analyzed to a high resolution at the single cell level with respect to structural and mechanical changes during the growth period. For this purpose structural characterization was performed by means of light microscopy, scanning electron microscopy and wide angle X-ray diffraction for investigating the geometry of cells, their cell wall fractions and cellulose microfibril angles (MFA). The mechanical properties were determined in microtensile tests on individual tracheids which had been taken from sequentially cut tangential slices. The results revealed pronounced differences in tensile stiffness between earlywood and latewood cells but only minor differences in tensile stiffness between the cell walls of both tissue types. These comparatively small changes in cell wall stiffness across the growth ring were caused by slight changes in MFA. The findings suggest that trees mainly vary cell size to optimize water transport and mechanical stability during the growth period and that modification of the cell wall organisation plays a minor role.

Polyphenols in the woody roots of Norway spruce and European beech reduce TTC

A common method to determine the vitality of fine root tissue is the measurement of respiratory activity with triphenyltetrazolium chloride (TTC). The colorless TTC is reduced to the red-colored triphenyl formazan (TF) as a result of the dehydrogenase activity of the mitochondrial respiratory chain. However, measurements with woody fine roots of adult Norway spruce and European beech trees showed that dead control roots had a high potential to react with TTC. High reactivity was found in boiled fine roots and the bark of coarse roots, but not in the boiled wood of coarse roots. By sequential extraction of dried and ground adult Norway spruce fine roots, reactivity with TTC was reduced by about 75% (water extraction), 93% (water/methanol extraction) and 94% (water/acetone extraction). The water extract reacted with TTC in the same way as polyphenols such as lignin, catechin and epicatechin. Boiling did not affect the extent to which fine roots of adult trees reduced TTC, whereas it greatly reduced TTC reduction by seedling roots. Application of the TTC test to roots of spruce seedlings subjected to increasing drought showed a progressive decrease in TTC reduction. The decrease in TTC reduction was paralleled by a reduction in O(2) consumption, thus supporting the conclusion that for roots with a low polyphenol content the TTC test provides a valid assessment of tissue vitality. Our results suggest, however, that the TTC test should not be applied to the fine roots of adult trees because of their high content of polyphenolic compounds whose reaction with TTC masks changes in TTC reduction due to changes in the respiratory capacity of the tissue.

Growth of Adult Norway Spruce (Picea abies [L.] Karst.) and European Beech (Fagus sylvatica L.) Under Free-Air Ozone Fumigation

This study attempted to detect the impact of ozone on adult trees of Norway spruce ( Picea abies [L.] Karst.) and European beech ( Fagus sylvatica L.) in an experimental mixed stand in Southern Bavaria, Germany. The aim was to examine whether there is a decrease in growth when trees are exposed to higher than atmospheric concentrations of ozone. This exposure was put into effect using a free-air fumigation system at tree crown level. Growth analysis was carried out on a group of 47 spruce and 36 beech trees, where radial stem increment at breast height - a sensitive index for stress - was measured. The ozone monitoring system allowed values to be obtained for the accumulated ozone exposure (SUM00) of each individual tree, so that their radial increment over three years could be correlated with the corresponding ozone exposure for the same time period. Correlation and regression analysis were then carried out to test the influence of ozone on diameter increment. In both spruce and beech, the initial stem diameter was the most influential factor on radial increment in the following year. A linear model was applied, including the diameter of the preceding year and the ozone exposure of the current year as predicting factors. For spruce trees, a significant negative influence of ozone exposure was found. In contrast, no significant ozone effect on diameter increment of beech was detected. The effect of ozone stress on a large spruce tree can lead to a decrease in potential radial increment of 22 %. The results are discussed in relation to other stress factors such as drought and lack of light.

Evaluation of the stomatal conductance formulation in the EMEP ozone deposition model for Picea abies

It is widely acknowledged that the possible impacts of ozone on forest trees are more closely related to ozone flux through the stomata than to external ozone exposure. However, the application of the flux approach on a European scale requires the availability of appropriate models, such as the European Monitoring and Evaluation Programme (EMEP) ozone deposition model, for estimating ozone flux and cumulative ozone uptake. Within this model stomatal conductance is the key variable, since it determines the amount of ozone absorbed by the leaves. This paper describes the suitability of the existing EMEP ozone deposition model parameterisation and formulation to represent stomatal behaviour determined from field measurements on adult Norway spruce (Picea abies (L.) Karst.) trees in the Central European Alps. Parameters affecting maximum stomatal conductance (e.g. seasonal phenology, needle position, needle age, nutrient deficiency and ozone itself) and stomatal response functions to temperature, irradiance, vapour pressure deficit, and soil water content are investigated. Finally, current limitations and possible alterations of the EMEP model will be discussed with respect to spatial scales of available input data for future flux modelling.

Quantifying ozone uptake at the canopy level of spruce, pine and larch trees at the alpine timberline: an approach based on sap flow measurement

Micro-climatic and ambient ozone data were combined with measurements of sap flow through tree trunks in order to estimate whole-tree ozone uptake of adult Norway spruce ( Picea abies), cembran pine ( Pinus cembra), and European larch ( Larix decidua) trees. Sap flow was monitored by means of the heat balance approach in two trees of each species during the growing season of 1998. In trees making up the stand canopy, the ozone uptake by evergreen foliages was significantly higher than by deciduous ones, when scaled to the ground area. However, if expressed per unit of whole-tree foliage area, ozone flux through the stomata into the needle mesophyll was 1.09, 1.18 and 1.40 nmol m −2 s −1 in Picea abies, Pinus cembra and Larix decidua, respectively. These fluxes are consistent with findings from measurements of needle gas exchange, published from the same species at the study site. It is concluded that the sap flow-based approach offers an inexpensive, spatially and temporally integrating way for estimating ozone uptake at the whole-tree and stand level, intrinsicly covering the effect of boundary layers on ozone flux.

Photosynthesis in rust-infected adult Norway spruce in the field.

• Norway spruce (Picea abies) has been infected by the needle rust Chrysomyxa rhododendri in many regions of the Central Alps with increasing intensities in recent years. Basidiospores formed on leaves of the main host, Rhododendron sp., only penetrate into developing current-year needles of Norway spruce, which leads to shedding of infected needles in the autumn. • Net photosynthesis at ambient CO2 , net photosynthesis vs internal CO2 , pigment and nitrogen concentration were compared, as well as annual radial growth of severely infected and healthy adult Norway spruce under field conditions. • Net photosynthesis at ambient CO2 was significantly decreased (-47%) in infected current-year needles. However, net photosynethesis in uninfected, older (1-yr-old) needles increased, expressed per needle area, per gram of chlorophyll a+b as well as per gram of nitrogen. Annual ring width analysis revealed growth reductions (-25%) of the infected tree in periods of repeated C. rhododendri infections. • Although adult Norway spruce trees dispose of compensatory photosynthetic potentials of older needle age classes, C. rhododendri infections cause a substantial decrease in annual radial growth. If high infection intensities persist we predict serious damage to the subalpine spruce forest.

Wood diameter indicates diurnal and long-term patterns of xylem water potential in Norway spruce

The stem diameter of adult Norway spruce trees was measured to see whether changes in xylem water potential lead to detectable radial deformation of the wood. The dendrometers used in these experiments measured only the dimensional changes of the woody cylinder (sap- and heartwood). Wood diameter was measured close to the ground and just below the living crown. After correction for thermal expansion of dendrometers and wood, diurnal variation of wood diameter ranged between 50 and 180 µm. Psychrometric measurements showed that xylem water potential varied in parallel to wood diameter. Diameter changes were always more pronounced at the higher stem position and exhibited a clear diurnal pattern. During the day, wood diameter decreased with increasing vapor pressure deficit and transpiration rate and with decreasing twig water potential. At night, the wood re-expanded but did not always reach the dimension of the previous day. Pre-dawn wood diameter decreased during periods of soil drought, a process which rapidly stopped and reversed after rain events. On several days, oscillation in wood diameter was observed during the mid-day hours. The oscillation had a period of approximately 50 min and showed a phase shift between different stem heights. All observed patterns of wood shrinkage and expansion were consistent with the hypothesis that xylem water tension leads to an elastic contraction of xylem conduits. The results demonstrate that xylem diameter is more suitable than whole-stem diameter for monitoring changes in xylem water potential.

Water relations of adult Norway spruce (Picea abies (L) Karst) under soil drought in the Vosges mountains: whole-tree hydraulic conductance, xylem embolism and water loss regulation

Relations hydriques chez l'epicea commun (Picea abies (L) Karst) soumis a une secheresse edaphique dans les Vosges : conductance hydraulique totale, embolie du xyleme et regulation des pertes en eau. Les variations de conductances hydrauliques totales (gL) induites par une secheresse ont ete suivies tout au long d'une saison de vegetation dans une parcelle de Picea abies âges de 30 ans. gL a ete calcule a partir de mesures simultanees de potentiels hydriques foliaires et de densites de flux de seve dans les troncs. Le deficit hydrique dans le sol a reduit nettement gL, cette reduction etant probablement localisee dans le compartiment sol-racine. La chute de gL n'a pas induit de diminution importante du potentiel hydrique minimum parce que les densites de flux de seve maximales ont ete reduites proportionnellement a gL. Nous faisons l'hypothese que les valeurs maximales journalieres de flux de seve chez l'epicea sont ajustees en fonction de la conductance hydraulique totale, ceci ayant pour effet de maintenir le potentiel hydrique minimum au dessus du point de dysfonctionnement xylemique cause par la cavitation des tracheides.

Water relations of adult Norway spruce (Picea abies (L) Karst) under soil drought in the Vosges mountains: water potential, stomatal conductance and transpiration

Les effets du dessechement du sol sur le flux de seve, le potentiel hydrique des rameaux, la conductance stomatique et du couvert ont ete analyses dans 2 placeaux d'un peuplement d'epiceas âges de 30 ans. L'un des placeaux a ete soumis a une secheresse par couverture du sol, le second ayant ete irrigue. Le potentiel hydrique de base des arbres du placeau sec est descendu jusqu'a -1,2 MPa. Dans le placeau irrigue, une faible variabilite de la densite de flux de seve a ete observee entre les arbres mesures, les maxima etant de l'ordre de 1,2 a 1,9 dm 3 .dm -2 .h -1 , ce qui correspondait a environ 0,5 mm.h -1 . Dans le placeau desseche, la densite de flux de seve a diminue tout au long de l'ete jusqu'a atteindre au minimum 0,05 dm 3 .dm -2 .h -1 pour certains arbres, la variabilite entre arbres etant beaucoup plus importante que chez les arbres arroses. La transpiration ainsi que la conductance stomatique ont fortement diminue avec la secheresse, la plus grande part de cette reduction ayant ete observee lorsque le potentiel hydrique de base est passe de -0,4 a -0,6 MPa. La conductance du couvert, calculee en inversant la formule de Penman-Monteith, a ete modelisee au moyen d'un modele multi-variable prenant en compte les facteurs climatiques et la secheresse edaphique

Influence of (22S,23S)-homobrassinolide on rooting capacity and survival of adult Norway spruce cuttings.

To determine whether brassinosteroids promote clonal propagation of mature coniferous trees, cuttings of adult Norway spruce (Picea abies (L.) Karst.) trees were harvested in late March, treated with (22S,23S)-28-homobrassinolide (SSHB), and stored at 2 degrees C in darkness until they were planted in May. Treatment of the cuttings with SSHB significantly enhanced the formation of adventitious roots by increasing percent rooting from 50% in the control cuttings to 92% in the 60 ppm SSHB treatment. N(6)-Benzyladenine (BA) stimulated rooting slightly although not significantly, but it counteracted the stimulative effect of SSHB when cuttings were treated with both compounds together. In a second study, the above-ground parts of medium-sized mature clonal Norway spruce trees were pretreated from the end of June till August with SSHB or BA or both. Needle retention of cuttings taken from the pretreated trees the following spring was prolonged until September and the cuttings flushed, but did not root, whereas cuttings from untreated stock plants died before September. No interaction between BA and SSHB was observed. When these pretreatments were repeated the following year on the same mature clonal trees rooting of cuttings was significantly improved in the 5 ppm SSHB treatment.

Nitrate reductase in needles, roots and trunk wood of spruce trees [Picea abies (L.) Karst.

Nitrate reductase (EC 1.6.6.2) activity (NRA), as measured by an in vivo assay, is present in needle leaves and mycorrhizal fine root tips of adult Norway spruce [Picea abies (L.) Karst.] in at least equal amounts on a fresh weight basis, in both adult and 5-year-old trees. NRA could also be demonstrated in trunk wood of deroted trees after fertilization with 5 mM $${\text{NO}}_{{\text{3}}^{\text{ - }} }$$ , exhibiting a longitudinal profile in the trunk. Inducibility in needles can more efficiently be achieved by NO2 (100 μg·m-3) than by 5 mM nitrate, which is effective only in root-amputated trees. A remarkably high level of needle-NRA in unfertilized trees, which are characterized by a very low level of nitrate in the xylem sap, suggests that NRA in spruce needles may in part be constitutive. Organic-N is a major nitrogen source for the needles even in root-amputated trees, indicating pronounced exchange processes between ray parenchyma and trunk xylem, which in turn are modified by the nitrogen source fed to the trunk stump. Intact trees exhibit a very similar amino acid composition of the xylem sap, regardless of whether $${\text{NO}}_{{\text{3}}^{\text{ - }} }$$ or $${\text{NH}}_{{\text{4}}^{\text{ + }} }$$ has been fed. The amino acid pattern of the needles is not thrown out of balance by “flooding” with $${\text{NO}}_{{\text{3}}^{\text{ - }} }$$ and $${\text{NH}}_{{\text{4}}^{\text{ + }} }$$ , which occurs in fertilized derooted trees. This indicates a distinct potential for homoeostasis of nitrogen entrance-metabolism (i.e. NRA and glutamine synthetase activity) in the needles. In the ectomycorrhiza/fine root-system (EMC), marked differences in NRA were observed depending on root-tip diameter and along the longitudinal profile of the fine roots. EMC-nitrate reductase is strongly enhanced by $${\text{NO}}_{{\text{3}}^{\text{ - }} }$$ . Needle-NRA exhibits a circannual rhythm. An early summer maximum is followed by a December minimum. This activity pattern matches well the transitory increase of soluble nitrogen in spring and the total protein maximum in winter. In an indirect way assimilatory NRA may well contribute to nitrogen overfertilization (by consumption of NOX) as one possible cause of the contemporary decline of spruce populations.