Seasonal effects of liming,irrigation, and acid precipitation on microbial biomass N in a spruce (Picea abies L.) forest soil

Summary Seasonal effects of liming, irrigation, and acid precipitation on microbial biomass N and some physicochemical properties of different topsoil horizons in a spruce forest (Picea abies L.) were measured throughout one growing season. The highest biomass N was recorded in autumn and spring in the upper soil horizons, while the lowest values were obtained in summer and in deeper horizons. The clearest differences between the different soil treatments were apparent in autumn and in the upper horizons. Liming increased the microbial biomass N from 1.7% of the total N content to 6.8% (Olf₁ layer) and from 1% to 2% of the total N content in the Of₂ layer. The main inorganic-N fraction in the deeper horizons was NO _inf3 ^sup- . An increase in cation exchange capacity was observed down to the Oh layer, while soil pH was only slightly higher in the Olf₁ and Of₂ layers after liming. The effects of irrigation were less marked. The microbial biomass N increased from 1.7% of total N to 4.8% in the Olf₁ layer and from 1% to 2% of total N in the Of₂ layer. In the Olf₁ layer an increase in C mineralization was observed. Acid precipitation decreased the microbial biomass N in the upper horizons from 4.8% of total N to 1.8% in the Olf₁ layer and from 2% to 0.5% in the Of₂ layer. No significant changes in soil pH were observed, but the decrease in cation exchange capacity may result in a decrease in the proton buffering capacity in the near future.     

Spatial heterogeneity of soil solution chemistry in a mature Norway spruce (Picea abies (L.) Karst.) stand

The determination of the average soil solution concentrations in forest soils is hindered by the spatial heterogeneity of the soil conditions and the stand structure on all scales. The aim of this paper is to investigate the spatial heterogeneity of the soil solution chemistry within a mature stand of Norway spruce and to evaluate the implication of this heterogeneity for the sampling design for soil solutions. The site is a 140 years old Norway spruce stand of 2.5 ha located in the German Fichtelgebirge at 800 m elevation on granitic, deeply weathered bedrock. At 35 cm soil depth, 59 ceramic suction lysimeters (5 cm length, 2 cm diameter) were installed in a systematic grid of 25 · 25 m and soil solution was sampled at 3 dates in June and July 1994. The solutions were analysed for major cations and anions. Semi-variance of the concentrations at a given date revealed no systematic spatial patterns. The coefficients of variance of the element concentrations were between 36 and 298% with highest values for NH₄ ⁺-N. The implications of the observed heterogeneity for the appropriate number of replicates was investigated by Monte Carlo simulations. As an example, the probability that the measured average concentration of SO₄ ^2?-S is outside a ±10% range (related to the ‘true’ 59 lysimeter average) is about 68% if only 3 replicates would have been used, 41% with 10 replicates and 25% with 20 replicates. Due to the generally large spatial heterogeneity of the soil solution chemistry in forest soils the number of lysimeters used must be carefully adjusted to site conditions and the specific question.     

Effects of growing roots of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) on rhizosphere soil solution chemistry

The chemical conditions of the rhizosphere can be very different from that of bulk soil. Up to now, little attention has been given to the problem of spatial heterogeneity and temporal dynamics of rhizosphere soil solution and little is known about the influence of different tree species on rhizosphere chemistry. In the present study, we used micro suction cups to collect soil solution from the rhizosphere of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) seedlings in high spatial resolution and capillary electrophoresis for the determination of major cations and anions. The results indicate, that in a soil with a base saturation of about 20—25% and a pH of 6.5, growing roots of beech and spruce lower the concentrations of nutrient cations and nitrate in the rhizosphere soil solution and decrease significantly the pH. The H⁺ release leads to an enhanced mineral weathering as indicated by an increase of CEC and base saturation and to a mobilization of soluble Al, however, on a very low concentration level. In our experiment rhizosphere effects of spruce have been more pronounced than those of beech, indicating, that with respect to below ground activity young spruce trees have a better competitive power than beech.     

Effect of liming on some chemical,biochemical, and microbiological properties of acid soils under spruce (Picea abies L.)

Summary Soil pH, total organic C, total N, exchangeable Al, available P, CO₂ evolution, microbial biomass C and N, phosphatase and dehydrogenase activities were determined in acid soils sampled under spruce subjected to acid deposition, before and after liming. A slight decrease in pH values was observed from the edge of a tree canopy to the base of the trunk in acid soils. Liming drastically reduced exchangeable Al and increased CO₂ evolution, microbial biomass, and the metabolic quotient. The microbial biomass C to total organic C ratio increased after liming but did not reach 2%, the average value considered valid in soils where the C content is in equilibrium, that is when C inputs are equal to C outputs. The microbial biomass C:N ratio decreased after liming, thus indicating that bacteria became predominant over fungi when soil acidity decreased. Dehydrogenase activity but not phosphatase activity was increased by liming. The decrease in phosphatase activity was not completely related to the increase in available P, but was also dependent on microbial growth and the decrease in acid phosphatase, the predominant component of acid soils.     

Organic and inorganic soil phosphates and acid phosphatase activity in the rhizosphere of 80-year-old Norway spruce [Picea abies (L.) Karst.] trees

Summary Inorganic and organic phosphates (P) were measured in bulk soil, rhizosphere soil and mycorrhizal rhizoplane soil of Norway spruce. Various methods of P extraction and estimation were compared. In addition, acid phosphatase activity and mycelial hyphae length were determined. In soil solutions from various locations, about 50% (range 35%–65%) of the total P was present as organic P. Compared to the bulk soil, the concentrations of readily hydrolysable organic P were lower in the rhizosphere soil and in the rhizoplane soil; this difference was particularly marked in the humus layer. In contrast, the concentrations of inorganic P either remained unaffected or increased. A 2- to 2.5-fold increase was found in the activity of acid phosphatase in the rhizoplane soil in comparison to the bulk soil. There was a positive correlation (r = 0.83^***) between phosphatase activity and the length of mycelial hyphae. The results stress the role of organic P and of acid phosphatase in the rhizosphere in the P uptake by mycorrhizal roots of spruce trees grown on acid soils.     

the accumulation of arsenic,bromine and iodine in needles of norway spruce ( picea abies [L.] karst.) at sites with low pollution

The concentrations of As, Br and I were measured in needles, in the material deposited on the needle surface and in the soil. Results from 8 unpolluted and one polluted continental sites and from one maritime site are reported. The mass of al13 elements on the needle surface is similar to that in the needles. Needle concentrations increase linearly with the needle age class, but net accumulation during the first year is larger than during later years. There are significant correlations between the material on the needle surface and the needle concentrations for As and Br, but not between the soil and the needle concentrations. Bromine values are much higher at the polluted and at the maritime site than at the unpolluted sites.     

Aluminium-induced callose formation in root tips of Norway spruce (Picea abies (L.) Karst.)

The objective of this study was to examine whether aluminium (Al) induces callose formation in roots of Norway spruce as it does in soybean. Spruce seedlings were grown in Al-free nutrient solution under controlled conditions in a growth chamber at pH 3.8. After 21 days 170 μM Al was added or not (controls) to the complete nutrient solution (molar Ca/Al ratio: 0.75). Callose could be detected in outer root-tip cells of Al-treated plants within 3 h, using fluorescence microscopy after staining with aniline blue. Prolonged Al treatment up to 24 h increased both the density of the callose deposits and the number of affected cell layers. Control plants showed no comparable callose deposits. Ultrastructural examinations showed cell-wall appositions in Al-treated root cells but not in controls. The possible implications of Al-induced callose formation for nutrient and water uptake by roots are discussed.     

The effect of lime on microbial activity in spruce (Picea abies L.) forests

Summary The use of lime increased heat output and decreased the C:N ratio (global indicators of biological activity) in the organic horizons of a spruce forest (Picea abies L.) soil. These changes were still present after 18 years. During the same period, the muramic acid content increased slightly, while the concentration of both ergosterol and glucosamine decreases. The ratios of ergosterol or glucosamine to muramic acid decreased significantly after 3 years in the plots that had been irrigated and limed, and after 8 years in the limed non-irrigated plots.     

The influence of stand density and canopy position on sulfur content in needles of Norway spruce (Picea abies L. Karst.)

Analysis of total S in tree foliage has become widely accepted as a means of assessing S pollution of forests when air quality data are lacking. An investigation of total S content of mixed needle samples of different age and canopy height from two stands of young Norway spruce with different densities showed that S-content exceeded the maximum natural S-content (i.e. in the absence of SO₂-pollution) for spruce. Significantly higher average needle S contents were encountered with decreasing stand density. Changed aerodynamic roughness and physiological status of thinned trees indicated combined action of atmospheric and tree physiological variables on S deposition and uptake in forest ecosystems. A marked increase in S content from 1 yr old to older needles and from the lower to the upper canopy was observed.     

Long-term development of element budgets in a Norway spruce (Picea abies (L.) Karst.) forest of the German solling area

To evaluate ecosystem response to changing atmospheric deposition, element budgets were established over the period from 1973 to 1991 for a Norway Spruce (Picea abies (L.) Karst.) site. Budgets for Na⁺, Cl^?, Ca²⁺, Mg²⁺, N, S and H⁺ were based on total deposition and seepage water fluxes. The deposition of Ca²⁺, Mg²⁺, particularly, of S and H⁺ decreased with time, while calculated N deposition remained constant at a high level. The decrease in Ca²⁺ deposition led to a reduction of Ca²⁺ fluxes with seepage water. The decrease of Mg²⁺ deposition did not have an effect on the output fluxes of Mg²⁺. The reversibility of soil and seepage water acidification by reduced S deposition was delayed by the release of previously accumulated soil SO ₄ ^2? . The highest NO ₃ ^? fluxes were observed during the period of 1986 to 1988; NO ₃ ^? fluxes in general demonstrated a considerable annual and periodic variation. Total N accumulation in the ecosystem amounted to nearly 590 kg ha^?1 yr^?1 during the observation period. The major sink of N in the spruce site is the aggrading humus layer. The results emphasize the need for measurements over several years to make conclusions regarding the function of ecosystems in response to atmospheric deposition.     

Element contents of spruce needles (P. abies [L.] Karst.) along an altitudinal gradient in the bavarian alps

One and 3 yr old needles of (Picoa abies [L.] Karst) were analyzed for mineral content and to determine the main nutrients and pollutants. In the Bavarian Alps 70 adult spruce trees were selected along an altitudinal gradient on seven stands from 800 to 1720 m above sea level. The samples, collected at different times of the year, came from the tops of the crowns. The needle analysis showed a severe P and a mild N deficiency. Samples which were washed with chloroform have significantly lower Fe and Ph contents. The low S concentrations of the needles exclude a burden by air pollution caused by SO₂.     

Nutritional status of declining spruce (Picea abies (L.) Karst.): Effect of soil organic matter turnover rate

Foliar analysis was undertaken in two plots of Picea abies (L.) Karst., located in a watershed of Haute Ardenne, Belgium, in order to estimate the decline of the trees. Apart from a general Mg deficiency, the concentrations of the needles were in the same range as those determined in other European stands. Comparisons between healthy and declining trees within each plot revealed a general pattern of decline similar to that observed elsewhere in Western Europe. This was shown as lower Ca, Mg, Zn concentrations and water content and higher N and P concentrations of the needles collected from declining trees. It is concluded that this decline could be due to N over fertilization by the atmospheric deposition. The difference of decline between the two plots was attributed to the turnover rate of the soil organic layer which was less intensive in the most damaged plot.     

Soil microbial activity in the coastal Norway spruce [Picea abies (L.) Karst.] forests of the Gulf of Bothnia in relation to humus-layer quality, moisture and soil types

Relationships between chemical, physical and microbial properties in the humus layer, soil type and crown condition of Norway spruce (Picea abies) were studied in stands located along the Finnish and Swedish coasts of the Straits of the Gulf of Bothnia. Humus layers of ferric podzols had higher basal respiration (BASAL) than those of carbic podzols and higher substrate-induced respiration (SIR) than those of both carbic podzols and dystric gleysols. BASAL and SIR correlated with environmental factors associated with humus-layer fertility; i.e. they were positively associated with pH and extractable K, Mn and P and negatively associated with organic-matter content of the humus layer. A short lag-time was associated with humus-layer fertility and a long lag-time with crown defoliation. Specific respiration increment was lowest at sites with high field moisture and discoloured crowns. The results suggest that on carbic podzols and dystric gleysols poor nutrient status, acidity and lack of oxygen due to excess moisture in the humus layer result in low microbial activity and poor condition of spruce. Received: 8 November 1996     

Ozone and drought stress — Interactive effects on the growth and physiology of Norway spruce (Picea abies (L.) Karst.)

Young trees of Norway spruce (Picea abies (L.) Karst.) were grown in 120 litre pots under two different ozone levels in open-top chambers for three seasons, 1992–1994. The ozone treatments were charcoal filtered air (CF, average 24 h seasonal mean 6.5 ppb) and non-filtered air with extra ozone aiming to track 1.5 times ambient (NF+, average seasonal mean 34 ppb). In addition, half of the spruce trees in Aug – Sep each season recieved a drought period of between five and seven weeks. The remaining half were kept well-watered. The soil water content, the needle water potentials, and the gas exchange as well as the chamber micro climate were measured before, during and after the drought period. Furthermore, the growth of the trees was measured as biomass increase. During the 1993 drought period, where the trees experienced a moderate drought stress, the trees grown in NF+ consumed soil water faster and showed a higher needle conductance compared to CF. However, no negative effects were found on needle water potential or growth. During the more severe 1994 drought stress period we did not find any differences between the two ozone treatments in soil water consumption, needle conductance or needle water potential. There was a significant negative effect of the high ozone treatment on tree biomass of the well-watered trees. Total plant biomass was reduced 18 % and stem biomass was reduced as much as 28 %. The negative effect of ozone on tree biomass was much smaller for the droughted trees.     

Effects of Sulfur Dioxide and Ozone on Ion Uptake of Spruce (Picea abies (L.) Karst.) Seedlings

Shoots of spruce (Picea abies (L.) Karst.) seedlings grown in solution culture were fumigated with sulfur dioxide or ozone, or with a combination of both for 60 days. Dry weights of the shoots exposed to O₃ and SO₂/O₃ were increased over the controls. Uptake rates of calcium, magnesium, potassium and nitrate from the nutrient solutions were altered in dependence on fumigation, time of exposure and stage of plant development. Uptake rates of all ions by the seedlings fumigated with SO₂ first increased, but later on decreased as compared to the control. Fumigation with O₃, or O₃ in combination with SO₂ affected uptake of the various nutrients differently. The effects of the pollutants on the concentrations of calcium and magnesium in the various parts of the seedlings indicate that the changes are not only due to altered water and ion uptake but may be related to various effects in ion transport and plant metabolism.     

On the causes of decline of Norway spruce (Picea abies Karst.) in Central Europe

Abstract. A careful study of the etiology and symptoms of the decline phenomena in stands of silver fir ( Abies alba Mill.), Scots pine ( Pinus sylv L.), European beech ( Fagus silv. L.) and Norway spruce ( Picea abies Karst.) in southern Germany leads to the conclusion that all these diseases, although exhibiting some common features (e.g. premature senescence and shedding of leaves, formation of transparent crowns), vary considerably between species and, within one particular species, between forest regions. It therefore seems plausible to assume, as a first approach, that we have to deal with different types of disease or decline, and consequently also with varying sets of causes or stress factors. This approach can be demonstrated best by reviewing the present knowledge of diseases in Norway spruce.     

Foliar symptoms,ethylene biosynthesis and water use of young Norway spruce (Picea abies (L.) Karst.) exposed to drought and ozone

Four-year old Norway spruce (Picea abies (L.) Karst.) trees were pretreated at low and high water supply, and then placed into a growth chamber containing four compartments so that two levels of ozone exposure, 0.02 and 0.4 Μl l^?1, could be replicated. They were exposed to ozone and drought stress for 59 days, and water use was determined by periodic weighing. Small effects of ozone treatment were detected on new shoot dry weight, and water use by trees receiving the high ozone treatment appeared higher. Both visual symptoms and ethylene biosynthesis showed that drought stress reduced damage to trees exposed to high ozone. Ethylene emission and 1-aminocyclopropane-1-carboxylic acid (ACC) levels increased after 18 days of exposure to 0.4 Μl l^?1 ozone, while visual symptoms were seen at 30 days. After 59 days of exposure to the combined stresses, ethylene and ACC levels were lower, but showed an ozone x water interaction. Most ethylene and ACC were produced by wet trees at high ozone concentration, but dry trees also had high ethylene and ACC levels at low ozone. Levels of needle malonyl-ACC (MACC) were not significantly affected by treatment, and did not change with time, but root MACC levels, which were twice needle levels, were high in wet trees at high ozone concentration, but also high in dry trees at low ozone concentration. These results suggest that drought stress occurring during ozone exposure could be expected to reduce damage to young Norway spruce, and that this damage may be related to ethylene biosynthesis.     

Liming effects on the chemical composition of the organic surface layer of a mature Norway spruce stand (Picea abies [L.] Karst.)

The application of lime in a mature Norway spruce (Picea abies [L.] Karst.) forest in southern Germany induced major changes in the activity of soil organisms and root growth. Since this may influence the chemical compostion of the soil organic matter (SOM) of the organic surface layer, its composition and changes due to the treatment were examined in this study.Fine roots of Norway spruce have a relatively low content of extractable lipids, a low alkyl C content (¹³C CPMAS NMR) and a high ratio of non-cellulosic to cellulosic carbohydrates (NC/CC, carbohydrate determination by MBTH and gas chromatography analyses) as compared to needles. Furthermore, they show high ratios of suberin/cutin compounds (thermally assisted hydrolysis and methylation, (THM)) and high ratios of eicosanic acid/phytadiene I in their lipid extracts (pyrolysis-GC/MS).Liming (4 t ha⁻¹ dolomite) of a Norway spruce organic surface layer decreased the proportion of alkyl C, the alkyl C/O-alkyl C ratio, and the content of extractable lipids. The NC/CC ratio and the abundance of suberin relative to cutin components increased. The contribution of the chlorophyll component phytadiene I decreased in relation to eicosanic acid. These changes are attributed to increased fine root formation in the organic layer after liming. Furthermore, the presence of less degraded lignin (THM, peak ratio of 3,4-dimethoxybenzoic acid, methyl ester/3,4-dimethoxy-benzaldehyde) on the limed plot is explained by the increased input of relatively fresh fine root material. On the other hand, the decrease in the carbon-to-nitrogen ratio may be attributed to the higher microbial activity after liming.     

Chemistry of soil organic matter as related to C : N in Norway spruce forest (Picea abies(L.) Karst.) floors and mineral soils

Due to high nitrogen deposition in central Europe, the C : N ratio of litter and the forest floor has narrowed in the past. This may cause changes in the chemical composition of the soil organic matter. Here we investigate the composition of organic matter in Oh and A horizons of 15 Norway spruce soils with a wide range of C : N ratios. Samples are analyzed with solid‐state ¹³C nuclear magnetic resonance (NMR) spectroscopy, along with chemolytic analyses of lignin, polysaccharides, and amino acid‐N. The data are investigated for functional relationships between C, N contents and C : N ratios by structural analysis. With increasing N content, the concentration of lignin decreases in the Oh horizons, but increases in the A horizons. A negative effect of N on lignin degradation is observed in the mineral soil, but not in the humus layer. In the A horizons non‐phenolic aromatic C compounds accumulate, especially at low N values. At high N levels, N is preferentially incorporated into the amino acid fraction and only to a smaller extent into the non‐hydrolyzable N fraction. High total N concentrations are associated with a higher relative contribution of organic matter of microbial origin.     

The effect of spruce (Picea abies Karst.) on soil development: an analytical and experimental approach

Changes in soil and biogeochemical processes following the replacement, 60 years ago, of part of a deciduous forest by a coniferous stand were evaluated by (i) a balance-sheet approach using soil and biomass element content analyses and the mineral flux, and (ii) the inclusion of test-mineral and resin bags in an integrative experimental approach. The comparison of soils under different stands shows that the change to spruce is inducing physical, chemical and biological modifications in soil properties. Changes in the humus layers lead to a reduction in mineralization and the mobilization of active organic acids in the system. Under spruce, the soil structural stability is reduced as fine clay is dispersed. Soil acidification is increased, linked to a decrease in soil pH and desaturation of the soil exchange complex. Soil mineralogy also indicates this tendency, particularly with an increase in the stability of Al intergrades. The biogeochemical cycle is modified especially for N, S and Al. with large changes in the internal fluxes between the ecosystem components, but the modification of the input-output balance due to spruce introduction is large only for S. The acidification is partly due to a change in litter quality, which inhibits biological activity, and partly because, during the dormant season, evergreen species intercept ‘dry and occult’ depositions from the atmosphere containing acidic or potentially acidic components. Use of test-mineral bags improves understanding and interpretation of the current soil mechanisms. The test mineral, a vermiculite, introduced into the soil or placed in the lysimeter flux very quickly undergoes measurable transformation characterized by desaturation and fixation of non-exchangeable Al in the interlayer zone, easily identified by Al speciation. The acidifying effect of spruce is clearly demonstrated by the experimental approach used, including the characterization of soil solutions by resin bags. All the techniques are complementary and could be used together or individually, depending on the aim of the study.