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.     

Variation in Soil Nitrate Concentrations in Two N-Saturated Norway Spruce Forests (Picea abies (L.) Karst.) in Southern Bavaria

Persistently high Nitrogen (N) deposition may have caused widespread N saturation in Central Europe’s forests. Simple and inexpensive methods are required for estimating the N status. This study suggests that the current N status of forest ecosystems can be estimated by measuring CaCl₂-extractable nitrate concentrations in the soil below the main rooting zone. We tested this possibility using a large number of samples (135 in total) in a nested sampling design in two homogeneous Norway spruce forests in southern Bavaria. This approach was accompanied by a small scale survey with suction cups (N = 54) in one forest. Nitrate concentrations determined by soil extracts varied widely (coefficients of variance 95 and 125%) and were well comparable with those of the simultaneous investigation of seepage water. Site and stand conditions explained only a small portion (<10%) of the total variation. Mineral soil nitrate concentrations were not spatially dependent at the medium and large scales (about 10 m to several km) in both forests. Therefore the reliability of estimates at these scales depends mainly on the sample size. At the small scale (<about 10 m) large variation in nitrate concentrations and a considerable spatial dependency could be observed. Therefore intensive sampling is necessary at short distances in order to estimate the mean adequately. From our results, we deduct possibilities and limitations of nitrate inventories as a tool for regional assessment of the N status of forests.     

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.     

Response of Picea abies (L.) Karst. Provenances to sulphur dioxide and aluminum: A pilot study

Seedlings of six Picea abies provenances were exposed to Al, SO₂ and A1+SO₂ for 12 weeks. A molaric Ca/Al ratio of 0.05 was chosen by using 1.68 mM Al. On the average, concentration of SO₂ was 335 μg m^?3. Shoot and root growth were measured and needle discoloration was scored for different pollution regimes. Plant response to different environmental stresses differed significantly among the provenances used and showed marked provenance x treatment interactions. It is noteworthy that the high intraspecific variation of the traits investigated could cause misleading conclusions in nongenetic studies if inappropriate plant material is employed.     

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.     

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.     

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.     

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.     

Effects of acid irrigation and liming in a norway spruce stand (Picea abies [L.] KARST.)

Acid irrigation (pH 2.7 to 2.8; mean annual input 4.1 kmol H⁺ ha^?1 as H₂SO₄) has caused significant changes in the chemistry of the soil of a mature Norway spruce stand (Picea abies [L.] KARST.) after 4 years of treatment. In the surface humus layer around 20% of the exchangeable Ca, Mg, K and Mn ions were leached. This was connected with a decrease of pH and cation exchange capacity. In the mineral soil no changes of pH and cation adsorption were observed. However there was a significant increase of Al³⁺ ions in the soil solution, exceeding 20 mg L^?1, mainly caused by dissolution of Al-hydroxides and Al-hydroxosulphates. Also the concentrations of ionic Cu, Zn and Cd were nearly doubled. Manganese concentrations are fluctuating according to periods with and without acid irrigation, showing reduction and oxidation phases. In contrast to microorganisms, certain moss species and Oxalis acetosella, the mature spruce stand was not severely damaged up to now. It is hypothesized that Ca/Al and Mg/Al ratios of single horizons are insufficient for characterizing Al stress in the field. Liming (4 Mg ha^?1) led to a significant increase of dissolved organic C, which is associated with mobilization of metals such as Pb, Cu and Al in organic complexation. Also nitrification increased in the surface humus layer. As a consequence the nitrate concentrations in the seepage water exceeded 250 mg NO₃ L^?1.     

Radial Distributions of Ph in Stems of 6-Year-Old Spruce Trees (Picea Abies (L.) Karst.) Grown for 2 Years in Ph- Contaminated Soil}

Concentrations and total quantities of Pb in annual growth rings of 6-year-old Picea abies trees were determined after two years of growth in Pb-contaminated soil. Xylem rings grown after Pb addition to the soil did not show highest Pb concentrations. Peak concentrations of Pb were found in inner, older rings. Radial distribution patterns of total Pb quantities in the rings were different from those of Pb concentrations in the rings. Relatively small quantities were found near the pith and in the outermost rings whereas larger amounts occurred in rings grown in the years just before or after the Pb treatment started. The results were compared to data of a previous harvest of spruce trees from the same experiment after one year of treatment. Radial distributions of Pb concentrations did not change in the period of one year between the first and the second harvest but concentration levels varied. The radial distributions of Pb concentrations were no chronological records of temporal variations in soil Pb levels. Neither concentrations nor quantities of Pb in growth rings were reliable indicators of the year when Pb was added to the soil. The results question the use of such data for biomonitoring of historical changes in environmental Pb pollution levels.     

Sulfuric acid rain treatment of Picea abies (Karst. L): Effects on nutrient solution,throughfall chemistry,and tree nutrition

To determine acid rain effects on nutrient solution, throughfall chemistry and nutrition of Picea abies, three years old saplings were treated with sulfuric acid (pH 2.7 and 2.4; 200 ml/tree and day) three times a day during a period of 10 days. The major effects on nutrient solution chemistry include significant increases of total acidity and sharp decreases in contents of phosphorus. Besides, the leaching of K, Ca and Mg out of the canopy clearly increases with precipitation acidity, resulting in significant lower Mg-contents of acidic treated spruce needles.     

Short-Term Influence of Clinker Dust and Wood Ash on Macronutrients and Growth in Norway Spruce (Picea abies) and Scots Pine (Pinus sylvestris) Seedlings

The effects of clinker dust and wood ash on Norway spruce and Scots pine seedlings were compared in buried pots. Clinker dust (0.5 kg m^?2) and wood ash (0.5 kg m^?2) were applied to the surface of a nutrient-poor mineral soil. In the second year, the increase in soil pH by the dust and ash were larger than in the first year. Both alkaline treatments caused a large increase in the needle potassium (K) concentration. An excess of soil K relative to magnesium (Mg) was observed by decreased Mg concentration in needles shortly after treatment. However, Mg concentration in needles stayed in the sufficiency range. Current results confirmed earlier findings that despite a positive effect on base cation nutrition, wood ash has a low potential for increasing the biomass of forest stands on mineral soils due to the N limitation in these soils.     

Impacts of (NH4)2SO4 Deposition on Norway Spruce (Picea Abies [L.] Karst) Roots

The effects of enhanced (NH₄)₂SO₄ (NS) deposition on Norway spruce (Picea abies [L.] Karst) fine root biomass, vitality and chemistry were investigated using root-free in-growth cores reproducing native organic and mineral soil horizons. The cores were covered and watered every 2 weeks with native throughfall or throughfall supplemented with NS to increase deposition by 75 kg ha^-1 a^-1 NH₄ ⁺-N (86 kg ha^-1 a^-1 SO₄2--S). The in-growth cores were sampled after 19 months and assessed for root biomass, necromass, length, tip number, tip vitality and fine root chemistry. Root biomass and fine root aluminium (Al) concentration were negatively correlated, but NS deposition had no effect on root growth or root tip vitality. NS deposition caused increased fine root nitrogen (N) concentrations in the organic horizon and increased Calcium (Ca) concentrations in the mineral horizon. Fine root biomass was higher in the organic horizon, where fine root Al and potassium (K) concentrations were lower and Ca concentrations higher than in the mineral horizon. Results highlighted the importance of soil stratification on fine root growth and chemical composition.     

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 influence of Mg fertilization on growth and mineral contents of fine roots in (Picea abies [Karst] L.) stands at different stages of decline in NE-Bavaria

The effect of various Mg-fertilizers (MgSO₄; calcined dolomite) on root growth and mineral composition of 40 yr old Norway spruce at different sites and stages of decline was studied. Two years after fertilization, density of living fine roots of Mg-deficient trees had significantly increased on fertilized compared to non-fertilized plots. Only fertilization of calcined dolomite appeared to induce new root formation in the upper mineral soil. No such changes were observed for healthy looking trees at a second experimental site, where base saturation of the bulk soil was also low but trees were sufficiently supplied with Mg. At the third experimental site where foliar analyses reflected a luxurious Ca and Mg but an insufficient K nutrition at high Mg and Ca saturation of the bulk soil, calcined dolomite caused an increase of root growth due to a reinforced antagonism between Ca and Mg competing with K uptake. In general, at the experimental sites the fine root necromass decreased when base saturation of the bulk soil increased. The elemental contents of fine roots from the minenal soil of all three sites under investigation indicated that fine root growth in the mineral soil is strongly related to the root Ca and Mg contents. Root Ca contents seemed to be mainly a function of the Ca availability in the soil. Since there was no close relationship between fine root growth and the Ca/Al molar ratio in living fine roots, Al toxicity may not completely account for the differences in root growth and nutrition on the experimental sites.     

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.     

Effects of Elevated Ozone Concentrations on Thai Jasmine Rice Cultivars (Oryza Sativa L.)

This study investigated the effects of O₃ on growth, yields and physiological characteristics of Thai Jasmine rice cultivars. Rice was exposed to O₃ for 7 h day^?1 in a closed chamber for 113 days, beginning from seedling until harvest. O₃ concentration in each chambers was controlled at 0 ppb, 50 ppb, 100 ppb, 150 ppb and at the ambient level. Effects of O₃ on leaf area index (LAI) became obvious at maturity when LAI significantly decreased in the treatments under elevated O₃ concentrations. Results in shoot biomass indicated that shoot length was more affected by O₃ than shoot dry weight. Root length rather than dry weight was significantly reduced in all cultivars. The most severe damage of O₃ was found in photosynthetic components, namely chlorophyll and carotenoid contents, and rate of net photosynthesis. Yield components were also strongly affected by O₃. The highest reduction in filled seed per ear was found in the Pathumthani 1 cultivar by 78% when it was exposed to 150 ppb O₃ compared to the control (0 ppb). Similarly, 100-grain weight was also reduced as much as 12.3% in this cultivar.     

Crown Condition and Nutrient Status of Red Spruce (Picea Rubens Sarg.) in West Virginia

The appearance, foliar nutrient status, and soil nutrient availability were determined for 9 trees in each of 39 red spruce stands in West Viginia. Visual evaluation of crown conditions for all 351 trees sampled resulted in median values of 5% for discoloration and 10% for defoliation. The most common symptom of discoloration was needle chlorosis, found on the upper surface of collected branches. Defoliation generally occurred beginning with the older year-classes of needles and progressed outward toward the branch tips. The levels of discoloration and defoliation varied to such an extent among stands, plots, and trees within a plot that a single causal agent was not likely responsible for the observed symptoms. Foliar nutrient levels were compared to observed crown condition but were inconclusive in proving a definite relationship between crown condition and any individual nutrient; levels of foliar N and P were negatively correlated to defoliation, but not to discoloration or live crown ratio; yet, foliar K was negatively correlated to both discoloration and defoliation and positively correlated to live crown ration. While individual sample trees exhibited symptoms of reduced health and vigor, the majority of red spruce sampled during the course of this study appeared healthy.     

Effects of Selected Surfactants on Nutrient Uptake in Corn (Zea mays L.)

Surfactants in herbicide formulations eventually enter soil and may disrupt various processes. Research examined effects on nutrient uptake in corn caused by surfactants, herbicides, and surfactant-herbicide combinations applied to silt loam and silty clay loam soils in the greenhouse. Surfactants evaluated were Activator 90, Agri-Dex, and Thrust; herbicides were glyphosate, atrazine, and bentazon. Corn was planted in fertilized soils with moisture content maintained for optimum growth. Foliage (V8 growth stage) was collected for elemental analyses. Nutrient uptake differed with soil texture. Nutrient uptake from silty clay loam was more affected by surfactants and/or herbicides than in silt loam. Potassium uptake was significantly (P = 0.05) decreased in silt loam only by Thrust but uptake of phosphorus (P), potassium (K) calcium (Ca), sulfur (S), copper (Cu), and zinc (Zn) decreased by ≤30% in silty clay loam treated with surfactants. Surfactants and/or herbicides may interact with soil texture to affect nutrient uptake. Long-term field studies to validate changes in nutrient uptake and grain yields after annual applications of surfactants plus herbicides are needed.     

Effects of Perchlorate Stress on Growth and Physiological Characteristics of Rice (Oryza sativa L.) Seedlings

The main objective of the present study is to measure the levels of heavy metals in important fruit species such as apple, apricot, and nectarine and their nine, five, and six cultivars, respectively. This work investigates the accumulation of Fe, Cu, Zn, Ni, Cd, Pb, and Cr in flowers of above species, to measure the levels of heavy metal contamination. The obtained results revealed that amounts of heavy metals significantly varied among cultivars at the same species and were within the permissible amounts in general. The Cd was not detected in apricot, nectarine, and the most of apple cultivars. Results for floral Fe, and also for Cu and Zn, which are the most important micronutrients for fruit production, suggest that levels of these elements might be used for assessing the storage of these elements during the previous season. We assume that the production of apple, apricot, and nectarine is safe, and there is no risk of contamination with heavy metals.