Effects of Mg(OH)2-fertilization on nutrient cycling in a heavily damaged Norway spruce ecosystem (NE Bavaria/FRG)

Main objective of this study was to test the effects of Mg(OH)₂-fertilization in a Norway spruce ecosystem showing severe symptoms of Mg-deficiency.The site is characterized by high atmospheric inputs with deposition rates of 1.25 kg H, 42 kg S, and 32 kg N per ha and year. The typic Dystrochrept derived from granite is acidified down to greater depths. The pH-values in soil solution of the organic surface layer and the upper mineral soil are around 3.5. Concentrations of Al, SO₄ ^2-, and especially NO₃ ^- and DOC are very high. The element balance indicates a significant influence of N-inputs and processes of N-turnover on the chemical status of the soil and probably on tree nutrition. Nitrification in the upper mineral soil leads to a transformation of a major part of NH₄ ⁺ into NO₃ ^-, which is quantitatively leached, resulting in an ecosystem-internal H⁺-production of 1.8 keq ha^-1yr^-1. NO₃ ^- and SO₄ ^2- govern the seepage output from the ecosystem.Mg(OH)₂ fertilization resulted in manifold increased Mg²⁺ concentrations in soil solution down to 70 cm soil depth and to a significant increase of pH down to 25 cm mineral soil depth. Nitrate concentrations were elevated after fertilization, but decreased within 15 months below the level of the control plot. As a mean over the whole experimental period, N-output was not increased by fertilization. Despite an elevated internal proton production due to nitrification, acid buffering in the soil was clearly increased, but enhanced Al-mobilization was not observed. Mg/Al- and Ca/H-ratios in soil solution indicate much more favourable conditions for fine root growth. Fertilization also increased the amount of exchangeable Mg down to 40cm mineral soil depth. Mg contents in current-year needles increased after three vegetation periods. Thirty months after application, only 10% and 4% of the fertilized Mg had left the organic surface layer and the mineral soil with seepage water output, respectively.     

Conductance of needle and twig axis phloem of damaged and intact Norway spruce (Picea abies (L.) Karst.) as investigated by application of14C in situ

Summary Phloem conductance of¹⁴C-labelled assimilates was investigated in natural stands of Norway spruce showing substantial damage from needle yellowing and needle loss disease. Terminal current-year shoots of a branch were allowed to fix¹⁴CO₂ (300–600 ppm in air) and carbon dioxide net uptake was monitored with a gas analyser. The difference between¹⁴C-uptake and the amount of radiocarbon determined in the photosynthesizing needles was interpreted to reflect assimilate export from the needles to the axis of the tree. Compared with an undamaged control tree,¹⁴C-export from the assimilating needles was not impaired in the yellowing tree and only slightly reduced in the tree showing needle loss. Incorporation of¹⁴C into starch increased significantly during autumn particularly in the tree showing needle loss. Import of radiocarbon from the¹⁴C-labelled phloem sap in twig axes and needles older than 1 year was used as a measure of phloem conductivity of older sections of a branch which showed considerable damage. Carbon uptake by these older plant parts was more pronounced than in undamaged twigs. In the case of older needles enhancement of¹⁴C-incorporation suggested an increased sink strength, while the same phenomenon in the twig axes was interpreted as a consequence of partially impaired conductivity of individual sieve elements resulting in an inhomogeneous velocity of phloem transport. The hypothesis is put forward that curtailed viability of the sieve cells is responsible for a delay of transport, which is compensated for by an augmented production of phloem elements from the cambium.     

Short-term pigment changes in Norway spruce needles

The photosynthetic pigment contents and the chlorophyll fluorescence induction in Norway spruce [ Picea abies (L.) Karst.] needles were monitored at 3 h intervals over a 10 day period. This covered 6 days of high insolation, one day of low insolation, followed by three more days of high insolation. During the first six days only small changes in mean pigment contents were observed but we interpret them as suggesting a daily rhythm in total chlorophyll content with two maxima and minima. The day of low insolation was paralleled by larger pigment changes, mostly an increase in chlorophyll b along with a decrease in carotenoid content. With the resumption of high insolation, pigments gradually return to their previous levels. During the entire period chlorophyll a fluorescence induction remained relatively constant. These short-term responses may reflect features of thylakoid organization in relation to pigment content and suggest possible long-term adaptive mechanisms in non deciduous conifers.     

Revitalization experiments in magnesium deficient Norway spruce stands in Austria

Amelioration of degraded forest ecosystems on acidic substrates showing the new type of forest decline is a major goal of forest management. A number of experiments show positive effects of Mg-application to systems suffering from Mg-deficiencies. The current paper compares experiments conducted in the Austrian part of the Bohemian Massif, where both effects on soil solution chemistry and effects on plant nutrition, vitality and growth were investigated. It turned out that any type of Mg-source is able to improve Mg-nutrition of trees; both a neutral salt like KIESERITE as well as alkaline reacting magnesite and dolomite derived materials. A positive reaction of vitality and growth could however only be induced with dolomitic lime or magnesite. Using mineral NPK fertilizers, even with high Mg-content, induced Mg-deficiencies and led to nutritional imbalances. In addition significant NO₃ ^--leaching occured. On the other hand an organic slow release fertilizer (BACTOSOL*) amended with magnesite derived fertilizers (BIOMAG**) led to balanced nutrition and a fast recovery of tree health status, as judged by crown transparency, vitality index and growth rates. In both cases, when either magnesite derived compounds or combinations with the organic slow release fertilizer were applied, NO₃ ^--leaching occured only during the first three years after fertilization. The leaching rates declined afterwards to values comparable to unfertilized plots, while Mg-content of the soil solution could be elevated compared to the CONTROL, showing the sustainability of proper fertilization.     

Karyotype of Norway spruce by multicolor FISH

The chromosomes (2n = 2x = 24) of Norway spruce are very large since their size reflects the huge amount of genomic DNA (2C = 30 × 10⁹ bp). However, the identification of homologous pairs is hampered by their high degree of similarity at the morphological level. Data so far presented in the literature were not sufficient to solve all the ambiguities in chromosome identification. Several genomic Norway spruce DNA clones containing highly repetitive sequences have been identified and characterised in our laboratory. Three of them were selected for fluorescent in situ hybridization (FISH) experiments because of their strong signals and suitability for chromosome identification: PATR140 hybridized at the centromeric site of three chromosome pairs; PAF1 hybridized in six subtelomeric and two centromeric sites; 1PABCD6 co-localized with the subtelomeric sites identified by PAF1. The statistical analysis of microscopic measurements of chromosomes in combination with the FISH signals of these probes allowed the unambigous construction of Norway spruce karyotype. We also compared the karyotype of Norway spruce with that of other spruce species to infer the number and kind of rearrangements that have occurred during the evolution of these species.Communicated by D.B. Neale     

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.     

Photoinactivation of catalase in needles of Norway spruce

Catalase IEC 1.11.1.6) activity in Norway spruce ( Picea abies [L.] Karst.) needles was examined under different environmental conditions. When shade-adapted spruce trees were exposed to full sunlight or to high light intensities in growth chambers, the catalase activity decreased. Under continuous light the activity was reduced in comparison to the control grown in light/dark cycles. The reduction of the activity was not temperature dependent. Under field conditions the activity was higher in hranches oriented north than in those oriented south. A diurnal rhythm with a maximum in the night was delected. The reduction in catalase activity also occurred in young white needles of Picea ahies vur. argenteospica . which are free of chlorophyll. It is concluded that in Norway spruce needles there is a ligh:-dependent photoinactivation of catalase. which is not temperature-dependent.     

Experimental evidence of a deleterious soil microflora associated with Norway spruce decline in France and Germany

Norway spruce (Picea abies (L.) Karst.) seedlings were grown in a glasshouse pot experiment in soils from 11 declining and 7 healthy spruce stands from France and Germany. In soils from 9 declining stands, seedlings showed decline symptoms (needle yellowing). Soil pasteurization suppressed the symptoms, and reinoculation of the pasteurized soil with a rhizospheric extract from the corresponding stand re-induced yellowing. This suggests that a deleterious soil microflora is associated with spruce decline. The occurrence of this microflora seems to be correlated with the main chemical characteristics of the soils (low pH, low saturation of the adsorbing complex, low exchangeable Ca²⁺ and Mg²⁺, and high level of exchangeable Al). ei]R F Huettl     

In-situ soil solution chemistry in an acid forest soil as influenced by growing roots of Norway spruce (Picea abies [L.] Karst.)

A new approach for non-destructive monitoring of soil solution chemistry in high spatial and temporal resolution for rhizosphere studies is presented. In a 5×10 mm grid, 30 micro suction cups (1mm) were installed in a rhizotron with Norway spruce (Picea abies [L.] Karst.) growing in low pH B-horizon soil. Roots grew through the grid, closely passing the suction cups. Soil solution composition before, during and after root passage was determined. For K⁺ and Mg²⁺ a significant decrease of soil solution concentration near root tips and elongation zones was observed, indicating a marked uptake of these elements. Mg²⁺ concentration was also significantly lowered when the root system aged, suggesting that this ion might also be taken up in older parts of the root system. No influence of growing roots was found on Na⁺-concentrations.     

Magnesium deficiency treatment causes reductions in photosynthesis of well-nourished Norway spruce

In order to investigate effects of magnesium deficiency on Norway spruce [Picea abies (L.) Karst.] photosynthesis, 100 well-nourished 5-year-old spruce trees were grown in sand culture, individually supplied with circulating nutrient solutions. Mineral nutrients were added to the nutrient solutions in optimal quantities and optimal relations to nitrogen. Magnesium was supplied at 0.203, 0.041 and 0.005 mM in order to simulate optimal nutrition, moderate deficiency and severe deficiency. Parameters of photosynthetic gas exchange, chlorophyll, magnesium and starch concentrations were determined in current-year and 1-year-old needles during one growing season. By mid May — 6 months after onset of the Mg deficiency treatments in late autumn — CO₂-assimilation rates of 1-year-old needles were significantly decreased independent of the severity of the deficiency treatment, whereas the chlorophyll concentrations did not differ from the controls. The occurrence of yellowing symptoms during July did not further influence the Mg deficiency effect on photosynthesis. In contrast to 1-year-old needles, significant reductions of photosynthesis and chlorophyll in current-year needles were only caused by severely deficient Mg supply. Mg deficiency affected carboxylation efficiency but not light use efficiency. From the accumulation of starch in the needles, up to 30-fold of the controls, the conclusion has been drawn that reactions of CO₂-fixation were affected by reduced carbohydrate export. The light-dependent pigment reduction, leading to the typical tipyellowing of needles, clearly reflects a secondary effect of Mg deficiency.     

Root and needle litter decomposition responses to enhanced supplies of N and S in a Norway spruce forest in southwest Sweden

The effects of additions of ammonium sulfate (NS) on the decomposition of litter derived from Norway spruce roots (< 2 and 2 - 5 mm in diameter) in the humus and mineral soil layers (0 - 15 cm) of a Norway spruce stand in southern Sweden were investigated over a 6-year period. To this purpose, litterbags were incubated in the humus layer and in the mineral soil in June 1996, with roots collected from NS and control (C) plots incubated in the NS and C plots, respectively. The N concentrations in fine roots (< 2 mm) in the NS- plots were higher than those in 2 - 5 mm roots in both humus and mineral soil layers. In the humus layer, N concentrations in the fine roots in the C- and NS- plots were 12.8 and 15.7 mg g ^{? 1}, respectively. By the end of the fifth year the < 2 mm roots in humus layer had lost 48.5 and 50% of their mass in the C and NS plots, respectively, while the corresponding values for the 2 - 5 mm diameter class were 44 and 54%. The fresh root litter may be a sensitive indicator to responses to enhanced N and S deposition, although decomposition rates of both litter types are affected.     

The response of Norway spruce seedlings to simulated acid mist

Four pot experiments are reported in which Norway spruce ( Picea abies (L.) Karst) seedlings, of different nutrient status, were treated with acid mist for one growing season in open-top chambers (OTCs). Combinations of H⁺, SO₄²⁻, NH₄⁺ and NO₃⁻ were applied at different frequencies of application and supplying different doses of S and N kg ha⁻¹. Plant growth, visible injury, frost hardiness and nutrient status were observed. These experiments were undertaken to improve our understanding of the interaction of environmental factors such as nutrition and mist-exposure frequency on seedling response to N and S deposition.
Both acidity (pH 2·7) and SO₄²⁻ ions were necessary to induce visible injury. Mist containing SO₄²⁻, H⁺ and to a lesser extent NH₄⁺ significantly reduced winter frost hardiness. Increasing the misting frequency, and to a lesser extent the overall dose, increased the likelihood of acid mist causing visible injury and reducing frost hardiness. Post-planting stress, low N status and needle juvenility increased the likelihood of acid mist causing visible injury. Increased plant vitality, adequate N status and growth rate reduced the likelihood of acid-mist-induced reductions in frost hardiness.
Principles underlying the responses of spruce seedlings treated in controlled conditions to acid mist are discussed.     

Effects of ozone on organic acids in needles of Norway spruce and Scots pine

Summary The effect of ozone, needle age, and season on the pH of homogenate and acid contents of Scots pine and Norway spruce needles is presented. In addition enzyme activities of cytochrome C-oxidase (cyt. C-ox), phosphoenolpyruvate-carboxylase (PEPC), shikimic acid-dehydrogenase (SHDH) and malate-dehydrogenase (MDH) were measured in Scots pine needles. In freshly sprouted spruce needles the level of quinic acid is high and the pH of the needle homogenate is low. Shikimic acid starts at low levels, increases with increasing needle age and becomes dominant, whereas the quinic acid content decreases. Malic acid has a marked seasonal trend; no trend was found in citric acid. Ozone (200 g/m³) decreased shikimic acid and quinic acid, whereas pH, malic acid and citric acid increased. Ozone (100 g/m³) had a similar effect, except in the current-year spruce needles. In Scots pine needles ozone led to increased enzymatic activities of cyt. C-ox, PEPC and SHDH, and a decrease in the activity of MDH. This effect was more pronounced in summer than in autumn, but the visible damage was greater in autumn. These effects can be found with other stresses and are not specific for ozone.     

Deterioration of Norway spruce vitality despite a sharp decline in acid deposition: a long‐term integrated perspective

Since the late 1970s, several long‐term ecological studies were conducted to better understand the biogeochemical functioning of Norway spruce stands in the Ardennes as these nutrient‐poor ecosystems were subject to high levels of acid deposition and exhibited symptoms of tree health decline. Between 1978 and 2009, acid deposition declined sharply, especially sulfur and to a lesser extent nitrogen deposition. The aim of this study was (i) to determine if the Norway spruce stands recovered after the reduction of acid deposition and (ii) to explain why such a recovery occurred or not. Therefore, we collected data from different projects carried out in the Ardennes to characterize the long‐term temporal trends in soil solution chemistry, foliar nutrition, and crown condition. In parallel, a model describing the nutrient cycling in forests (NuCM) was calibrated and used to check the consistency of the observed temporal trends and to explain them. The soil solution concentration of most of the elements decreased between 1978 and 2002, which was ascribed to a decrease in atmospheric deposition. For potassium, a decline in the exchangeable pool was also showed based on the simulation carried out with NuCM. As nitrogen (N) deposition remained at an elevated level, Norway spruce stands were progressively saturated in N and mineral nutrition became more and more unbalanced. Except the foliar N and Al concentration that remained constant and increased respectively, the foliar concentration of all other nutrients decreased between 1993 and 2009, which can be explained by the decrease in ion concentration in solution. These nutritional disorders weakened trees and were probably exacerbated during the 2003 summer drought, after which symptoms of vitality loss progressively appeared. In these N‐saturated ecosystems, the N cycle was disrupted by this health decline, which increased NO₃^? leaching reinforcing soil acidification and risk of aluminum (Al) toxicity.     

Development of biomass proportions in Norway spruce (Picea abies [L.] Karst.)

This study tests the hypotheses that (1) the above-ground structure of Norway spruce (Picea abies [L] Karst.) is derivable from the functional balance theory, and that (2) crown ratio is a key source of structural variation in trees of different age and social position. Twenty-nine trees were measured in three stands (young, middle-aged, and mature), with three thinning treatments (unthinned, normal, and intensive) in the two older stands. There was a strong linear relationship between the total cross-sectional area of branches and that of stem at crown base. Foliage mass was linearly related with stem basal area at crown base. Also an allometric relationship was found between foliage mass and crown length. The mean length (weighted by basal area) of branches obeyed an exponential function of crown length. The parameters of most of these relationships were independent of slenderness (tree height/breast height diameter) and tree age However, total branch cross-sectional area per stem cross-sectional area in the young trees was greater than in the older trees. The young trees also had slightly shorter branches than predicted by the mean branch length equation. This was probably caused by branch senescence which had not yet started in the young stand. The older trees had a relatively long lower crown segment which was growing slowly and senescing. It was proposed that a segmented crown structure is characteristic of shade tolerant tree species, and that the structural model could be further developed by making the two segments explicit.     

Basta tolerance as a selectable and screening marker for transgenic plants of Norway spruce

The bar gene conferring resistance to the herbicide Basta (containing phosphinothricin) was transferred to embryogenic cultures of Picea abies by particle bombardment and transformants were selected on Basta medium. In total, 83 9-month-old transgenic plants of Picea abies from six transformed sublines were analysed for continued tolerance to Basta. PCR analysis showed that the bar gene was present in all transformed plants but not in the control plants. Northern blot analysis showed differences in expression level among plants from the same subline as well as among sublines. A simple biotest for screening for Basta tolerance based on the colour change of detached needles induced by Basta was developed. The tolerance to Basta varied among the plants from different sublines. Needles from four of the sublines were resistant to 100 mg l⁻¹ phosphinothricin, a concentration inducing yellowing in control needles, while plants from the other two sublines were on average two to four times as resistant as untransformed control plants. The biotest enables rapid semi-quantitative monitoring for continued transgene expression in long-lived tree species. Received: 21 October 1999 / Revision received: 24 January 2000 / Accepted: 24 January 2000     

Distribution of lead in mycorrhizal and non-mycorrhizal Norway spruce seedlings

Non-mycorrhizal spruce seedlings (Picea abies Karst.) and spruce seedlings colonized with Lactarius rufus (Scop.) Fr. or two strains of Paxillits involutus (Batsch) Fr. were grown in an axenic silica sand culture system with frequently renewed nutrient solution. After successful mycorrhizal colonization, the seedlings were exposed to 1 μM PbCI₂ for 19 weeks. The degree of infection in all of the mycorrhizal treatments approached 100% during the experiment and was not affected by exposure to Pb. However, the number of root tips per root dry weight and the shoot: root ratio, both in the non-mycorrhizal and the mycorrhizal seedlings, had decreased after the 19 week treatment with PbCl₂ Using X-ray microanalysis, the distribution and concentration of Pb in the tissues of mycorrhizal and non-mycorrhizal root tips were compared. In the mycorrhizae of seedlings exposed to Pb no significant accumulation of Pb in the hyphal mantle or in fungal cell walls of the Hartig net were detected. Lead accumulated primarily in the cortex cell walls both of non-mycorrhizal and mycorrhizal root tips. No significant difference of Pb concentrations in root cortex cell walls of non-mycorrhizal and mycorrhizal seedlings was found; except for seedlings colonized with Paxillus involutus strain 537. However, at the endodermis no effect of mycorrhizal fungal colonization on the Pb tissue concentration was detected. The presence of the fungal sheath did not prevent Pb from reaching the root cortex. The endodermis acted as a barrier to Pb radial transport in both mycorrhizal and non-mycorrhizal seedling roots.