Distribution of protozoa in scots pine mycorrhizospheres

The distribution of heterotrophic flagellates, naked amoebae, testate amoebae and ciliates was investigated in habitats created by Scots pine-Paxillus involutus and -Suillus bovinus ectomycorrhizospheres. The protozoa living on plant and fungal surfaces preferred the non-mycorrhizal pine roots over mycorrhizal roots or external mycelium. The testate amoebae were more abundant on external mycelium than on mycorrhizae regardless of the mycorrhizal fungal species. Numbers of protozoa were higher in the different habitats provided by S. bovinus mycorrhizospheres when compared with P. involutus mycorrhizospheres. Interestingly, the quality of the bacterial flora as food for the protozoa was affected by the mycorrhizal fungi even in the soils adjacent to non-mycorrhizal root tips of pine. These results demonstrate that mycorrhizal fungi create habitats differently suitable for protozoa living in boreal forest soil.     

Determination of nitrate in a pine bark substrate

Abstract

An experiment was conducted to evaluate extraction methods for the determination of nitrate in a synthesized pine bark substrate. It was found that prior to nitrate determination, oven dryino of the pine bark sample was necessary followed by rewetting and extraction in a vacuum for 72 hours. Using this technique, about 65% of applied nitrate was recovered.     

Effects of air pollution on the chemistry of surface waxes of scots pine

Surface waxes from Scots pine (Pinus sylvestris) trees from the same provenance, but growing at a polluted and an unpolluted site, were sampled for each year class of needles at least twice during the year.There was no change in the amount of wax per unit area over the lifetime of the needles, but less wax was obtained from trees at the polluted site.Quantitative thin-layer chromatography of the wax gave several components which decreased in amount with time. They were identified as long-chain alcohols and ketones, and comprised only a small proportion of the total wax. The rate of change was greater in polluted air than in clean air, and there was a strong correlation with measured contact angles for water droplets. The degradation in structure observed by scanning electron microscopy may be associated with particular chemical components of the surface wax.     

Throughfall deposition of ammonium and sulphate during ammonia fumigation of a scots pine forest

The estimation of the dry deposition of sulphur dioxide to forests is confounded by the possibility of co-deposition of SO₂ with NH₃ on leaf surfaces. A sector of Scots pine forest was selectively fumigated with NH₃ to give average concentrations up to 15 ppbV (nL L^–1) above ambient, in order to test the hypothesis that increased air concentrations of NH₃ would enhance the dry deposition of SO₂, and the consequent amounts of SO₄ ^2– measured in throughfall below the forest canopy. Ammonia gas, generated by evaporation of concentrated aqueous solution, was released above the canopy in proportion to wind speed when the wind direction was between south and west. Concentrations of NH₃ at canopy height were measured using passive diffusion tubes; throughfall was preserved with thymol and measured weekly. Meteorological data and SO₂ concentrations were recorded continuously, to permit the estimation of dry deposition input. Deposition of NH₄ ⁺ in throughfall over 8 months was increased by up to 40 meq m^–2 relative to control sites upwind of the NH₃ release point, with largest values closest to the release point. Deposition of SO₄ ^2– in throughfall was also enhanced in the fumigated area, by up to 20 meq m^–2, even though average ambient SO₂ concentrations were 2.3 ppbV. The results are discussed in terms of the factors controlling SO₂ deposition on forest surfaces, the development of appropriate deposition models, and their relevance to using throughfall as an estimate of total S deposition.     

Dynamics and stratification of bacteria and fungi in the organic layers of a scots pine forest soil

The abundance and micro-stratification of bacteria and fungi inhabiting the organic layers of a Scots pine forest (Pinus sylvestris L.) were investigated. An experiment using stratified litterbags, containing organic material of four degradation stages (fresh litter, litter, fragmented litter and humus) was performed over a period of 2.5 years. Dynamics and stratification of fluorescent stained bacteria and fungi, ratios between bacterial and fungal biomass, and relationships with moisture and temperature are described. Average bacterial counts in litter and fragmented litter were similar, i.e., approximately 5×10⁹ bacteriag^–1 (dry weight) organic matter, and significantly exceeded those in humus. The mean bacterial biomass ranged from 0.338 to 0.252mg carbon (C) g^–1 (dry weight) organic matter. Lengths of mycelia were significantly below the usually recorded amounts for comparable temperate coniferous forests. The highest average hyphal length, 53mg^–1 (dry weight) organic matter, was recorded in litter and decreased significantly with depth. The corresponding mean fungal biomass ranged from 0.050 to 0.009mg Cg^–1 (dry weight). The abundance of bacteria and fungi was influenced by water content, that of fungi also by temperature. A litterbag series with freshly fallen litter of standard quality, renewed bimonthly, revealed a clear seasonal pattern with microbial biomass peaks in winter. The mean hyphal length was 104mg^–1 (dry weight) and mean number of bacteria, 2.40×10⁹ bacteria g^–1 (dry weight). Comparable bacterial and fungal biomass C were found in the freshly fallen litter [0.154 and 0.132mgCg^–1 (dry weight) organic material, respectively]. The ratio of bacterial-to-fungal biomass C increased from 1.2 in fresh litter to 28.0 in humus. The results indicate the existence of an environmental stress factor affecting the abundance of fungi in the second phase of decomposition. High atmospheric nitrogen deposition is discussed as a prime factor to explain low fungal biomass and the relatively short lengths of fungal hyphae in some of the forest soil layers under study. Received: 26 June 1997     

Photosynthesis of a scots pine shoot: Test of a shoot photosynthesis model in a direct radiation field

The photosynthetic light curves of eight Scots pine (Pinussylvestris L.) shoots, each with a different structure, were measured in a direct radiation field at different positions relative to the radiation beam. Using a model of shoot geometry, the irradiance distributions on the needle surface area of the same shoots were simulated in each position. Using measurements of shoot photosynthesis, the photosynthetic light curve for a needle surface area element (a small area on the needle surface) was estimated indirectly for each shoot. Shoot photosynthesis was then calculated from the estimated photosynthetic light response curve of a needle surface area element and the irradiance distribution on the surface area of needles. Calculated rates for shoot photosynthesis agreed well with the measured rates. The mean irradiance on the needle surface area was the major component causing variation in the light response of a shoot irradiated from different directions, but the shape of the irradiance distribution on the needle surface area had a considerably smaller effect.     

Reduction of decomposition rates of scots pine needle litter due to heavy-metal pollution

Decomposition of unpolluted Scots pine needle litter was studied in two heavy-metal-pollution gradients in Sweden; one near a brass mill and the other around a primary smelter. In the latter area locally collected polluted Scots pine needle litter was also incubated. Decomposition rates were strongly influenced by the metal pollution and a decrease in the rate of mass-loss occurred. In the brass-mill gradient this occurred until about 1 km from the pollution source which corresponded to about 500 µg Cu and 1 000 µg Zn g^?1 soil. Data are presented to indicate that lignin decomposition was more sensitive to pollution than decomposition of whole litter and affected further away from the pollution sources. At the smelter sites, the metal-polluted needle litter decomposed more slowly than the unpolluted needle litter, and this difference was enhanced close to the smelter. The results indicate that heavy metals accumulated in needles prior to shedding have a long-term impact on the subsequent decomposition of the litter. Both litter quality and soil factors thus contribute to the reduced litter decomposition rate in metal-polluted forests. A new non-linear model with decreasing decay rate was used in the statistical evaluation. The model can be used to characterize the effects of pollution on decomposition rate.     

Bioelement content and biomass in scots pine: Effect of acidification and liming

Dry weights and bioelement contents in biomass of Scots pine (aboveground) were estimated on some differently treated plots from one acidification experiment in North Sweden. Dry weight estimates of Scots pine biomass showed relatively small differences between treatments. The content of N, P, K, Ca, Mg, Mn, and S showed significant differences in a number of cases. The amount of N in different crown components increased; fertilizer-N recovered in the biomass was up to 10% of that added (in total, the NPK-plots received 1260 kg N ha^?1). The concentration of other elements (P, K, Ca, Mg, Mn and S) showed some effect of the treatments, but was not as marked as that of N. Especially interesting is a decrease in the level of Mg in needles and shoots on the NPK-treated plots. The concentration of S was influenced by application of acid, but much more by NPK-fertilization throughout the period.     

Bioelement content and biomass in scots pine: Effect of acidification and liming

Dry weights and bioelement contents in biomass of Scots pine (aboveground) were estimated on some differently treated plots from one acidification experiment in North Sweden. Dry weight estimates of Scots pine biomass showed relatively small differences between treatments. The content of N, P, K, Ca, Mg, Mn, and S showed significant differences in a number of cases. The amount of N in different crown components increased; fertilizer-N recovered in the biomass was up to 10% of that added (in total, the NPK-plots received 1260 kg N ha^?1). The concentration of other elements (P, K, Ca, Mg, Mn and S) showed some effect of the treatments, but was not as marked as that of N. Especially interesting is a decrease in the level of Mg in needles and shoots on the NPK-treated plots. The concentration of S was influenced by application of acid, but much more by NPK-fertilization throughout the period.     

Photosynthesis of a scots pine shoot: simulation of the irradiance distribution and photosynthesis of a shoot in different radiation fields

Using a model of shoot geometry the distribution of irradiance at the needle surface area of a shoot in different radiation conditions is simulated and shoot photosynthesis calculated. It is shown that the distribution of irradiance is very sensitive to radiation field geometry, affecting the efficiency of the utilization of radiant energy in photosynthesis. As a result, the photosynthetic response of a shoot in natural conditions is, for instance, highly dependent on the proportions of direct and diffuse solar radiation, being higher the greater is the proportion of diffuse radiation.     

The effect of nitrogen and potassium availability on scleroderris canker of scots pine seedlings

Scots pine seedlings were grown in quartz sand and were given N and K in different ratios with irrigation water. Fifty percent of the seedlings were inoculated with a conidial suspension ofAsoocalyx abietina (Lagerb.) Schlaepfer-Bernhard. The amount of damage caused by the pathogen was surveyed by measuring the specific symptoms on each seedling. The results suggest that an increased availability of N increases the degree of scleroderris canker damage in Scots pine seedlings. The possible connection between N-fertilization, deposition of N containing compounds in forests and the abundance of the disease is discussed.     

Decomposition of root litter and some factors regulating the process: Long-term root litter decomposition in a scots pine forest

Decomposition of root litter was studied using Scots pine roots (six diameter classes) and rhizomes from heather (three diameter classes) and cowberry (one diameter class). For Scots pine roots, root diameter was correlated with initial concentrations of N, P, S and Mg but not with organic-chemical composition. The highest nutrient concentrations were found in Scots pine roots and the lowest in heather rhizomes, with cowberry rhizomes intermediate. The highest lignin concentrations were in heather and cowberry rhizomes. In the early decomposition stages diameter and nutrient concentration correlated with mass loss rate in Scots pine roots: in a comparison Scots pine roots were degraded faster than cowberry rhizomes which, in turn, were degraded faster than heather rhizomes. Root diameter, however, may not be important in decomposition of cowberry and heather rhizomes but nutrient and lignin concentrations appear important in all three species. In the late decomposition stages only Scots pine roots could be compared and it appeared that there was a negative correlation with lignin concentration and mass loss, and no correlation with any nutrient.     

Injuries to scots pine mycorrhizas and chemical gradients in forest soil in the environment of a pulp mill in central Finland

The occurrence and condition of Scots pine mycorrhizas were studied at different distances from a pulp mill in Central Finland. The chemical analyses of the soil humus layer in the vicinity of the mill revealed increased levels of ammonium-nitrogen, sulphur and calcium but unaltered concentrations of phosphorus and magnesium. Higher nitrate levels and nitrification were clearly detected at some sites which had recently been limed. Significant decreases in root ramification index and number of living mycorrhizas were found in a zone 0–0.6 km zone surrounding the factory but these parameters increased with increasing distance. Within a 2 km zone around the mill there were abundantCenococcum geophilum andPaxillus involutus-type mycorrhizas while lowered frequencies of several other mycorrhizal types were detected. An ultrastructural study revealed changes in several types of mycorrhizas, the clearest of which were increased tannin deposition in cortical cells, intracellular growth of hyphae in cortical cells and the appearance of electron dense accumulations in the vacuoles of the fungal cells. The ultrastructural changes observed were distributed at least to a distance of 3 km from the mill and occurred in the roots of trees that had only a slight loss of needle mass. Nitrogen deposition is suspected to be the primary cause of root decline but atmospheric S0₂ through the tree crown is also likely to be a contributing factor.     

The role of nitrogen in declining scots pine forests (Pinus sylvestris) in the lowland of East Germany

Over the last decade, N inputs in pine ecosystems on the lowland of the former GDR have clearly increased. Agriculture plays a special role as a NH_x emitter, because the whole lowland is covered with a network of large livestock farms. High N inputs cause an overnutrition of the pine stands with N, an accumulation of N in the soils, and as a consequence of the ensuing eutrophication, a drastic modification of the ground vegetation with a luxuriant growth of weeds and shrubs or of the vital herbaceous cover. The fine root quantity is reduced, also the mycorrhiza and the growth of pine. In many cases pine stands show a dramatical decrease of Mg nutrition. Finally, the limited range of silvicultural options is discussed, which are available to limit the progress of damage.     

Effects of ammonia,ammonium sulphate and sulphur dioxide on the frost sensitivity of scots pine (Pinus sylvestris L.).

The deterioration of forest vitality has been at least partly attributed to air pollution. Especially NH₃, originating from intensive livestock farming and locally deposited in high concentrations, may contribute to forest decline in The Netherlands. Therefore, the effect of NH₃ and SO₂ fumigations on cold stress and water stress of Pinus svlvestris were examined. P. sylvestris trees (3 yr old) were exposed to ambient air supplemented with several NH₃ concentrations, with SO₂ or a combination of NH₃ and SO₂.Tops of branches were then exposed to various subzero temperatures and the effect of air pollution on frost damage was examined. Neither ambient air, NH₃ or SO₂ significantly influenced from sensitivity at –4 or –7°C. Following freezing treatments of –10°C, the influence of NH₃ and SO₂ became apparent. The effect of the combination of these pollutants is synergistic. Exposure to NH₃ alone followed by freezing temperatures lower than –10°C resulted in more severe frost damage in early autumn and spring than in the winter. It also increased the susceptibility of P. sylvestris to water stress. A greater loss of water was observed in NH₃-fumigated needles following drought stress, suggesting increased cuticular transpiration. Bud burst and subsequent shoot growth was also strongly reduced by NH₃ fumigations.     

Comparison of proanthocyanidins in commercial antioxidants: grape seed and pine bark extracts

The major constituents in grape seed and pine bark extracts are proanthocyanidins. To evaluate material available to consumers, select lots were analyzed using high-performance liquid chromatography, gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), gel permeation chromatography (GPC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Atmospheric pressure chemical ionization (APCI) LC/MS was used to identify monomers, dimers, and trimers present. GC/MS analyses led to the identification of ethyl esters of hexadecanoic acid, linoleic acid, and oleic acid, as well as smaller phenolic and terpene components. The GPC molecular weight (MW) distribution indicated components ranging from approximately 162 to approximately 5500 MW (pine bark less than 1180 MW and grape seed approximately 1180 to approximately 5000 MW). MALDI-TOF MS analyses showed that pine bark did not contain oligomers with odd numbers of gallate units and grape seed contained oligomers with both odd and even numbers of gallate. Reflectron MALDI-TOF MS identified oligomers up to a pentamer and heptamer, and linear MALDI-TOF MS showed a mass range nearly double that of reflectron analyses.     

Bacterial numbers in a pine forest soil in relation to environmental factors

Numbers of soil bacteria stained with acridine orange (AO) or fluorescein diacetate (FDA) were studied for 3 and 2 yr respectively. Three pine forest sites were used and both organic and mineral soil layers were included. Different patterns of fluctuation in bacterial numbers were found each year. Significant correlations were demonstrated between AO-stained bacterial numbers and soil moisture content and between FDA-stained bacteria and the accumulated precipitation during a week before the sampling date. In multiple regression analyses 60–80% of the variation in numbers of AO-stained bacteria could be accounted for by soil moisture and numbers of bacterial-feeding nematodes at the sampling dates, and 30–45% of the variation in numbers of FDA-stained bacteria was accounted for by precipitation.     

Preclinical evaluation of rapeseed, raspberry, and pine bark phenolics for health related effects

Rapeseed, raspberry, and pine bark are promising bioactive sources of plant phenolics selected from among ca. 100 previously screened plant materials for in vitro preclinical evaluation of health related effects. Phenolic extracts and isolated fractions of the selected materials were investigated for antioxidant, antimicrobial, antiinflammatory, and antimutagenic properties as well as for cell permeability. It was shown that rapeseed and pine bark phenolics and raspberry anthocyanins were good or excellent antioxidants toward oxidation of phosphatidylcholine membrane (liposomes), rapeseed oil (crude) phenolics were effective radical scavengers (DPPH test), and both raspberry and pine bark phenolics inhibited LDL oxidation. Rapeseed oil phenolics, principally vinylsyringol, raspberry anthocyanins, and pinoresinol and matairesinol, the principal components of pine bark phenolic isolate, were effective against formation of the proinflammatory mediator, prostaglandin E(2). Raspberry ellagitannins inhibited the growth of Proteus mirabilis and Klebsiella oxytoca. Pine bark and rapeseed had minor effects on the permeability of model drugs in Caco-2 experiments. None of the tested extracts were mutagenic nor toxic to Caco-2 cells or macrophages. Thus, phenolic isolates from rapeseed, raspberry, and pine bark and are safe and bioactive for possible food applications including functional foods intended for health benefit.