A method for quantifying changes in the epicuticular wax structure of Norway spruce needles

A method for quantifying changes in the epicuticular wax structure of spruce needles (Pieea abies) has been developed for the scanning electron microscope. This evaluation system, based on a five-point scale, classifies only the epistomatal waxes of current-year needles. Two criteria, the different crystal wax forms and the amount of changed wax as a percentage of the total stomatal area have been used for classification. Statistically significant results (accuracy below ± 10% at 5% error level) were obtained under the following conditions. Mixed needle samples were taken from two adjacent trees per site. These were in a dominant and predominant social position in the stand. The needles were collected from the 7^th whorl of sun crowns exposed to all wind directions. The wax quality was determined by evaluating three stomata per needle. One stoma was investigated at the needle base, one m the middle and the third at the apex of the needle. 24 needles were evaluated per site. SEM-Investigations of needle waxes of 25 Austrian forest sites with no local emission source (background sites) showed, that the mean wax quality ranged from 1.6 to 4.1, according to this classification method. Stepwise multiple regression analyses with site characteristics and element contents of the needles (nutrient elements, heavy metals) confirmed correlations between the wax quality and the manganese- and sulphur-content of the needles and also the average degree of crown defoliation.     

Evidence for the accelerated micromorphological degradation of epistomatal waxes in Norway spruce by motor vehicle emissions

The epistomatal wax crystalloids of potted spruce plants exposed for 20 weeks to motor vehicle emissions along roadside and in a fumigation chamber were studied in the scanning electron microscope. An accelerated structural degradation of the wax crystalloids was observed in comparison with control plants. This structural degradation is considered to cause a structural obstruction of the stomatal antechambers and to contribute to the observed reduction of gas exchange.     

Effects of nursery environment on needle morphology of Pinus monticola Dougl. and implications for tree improvement programs

Statistically significant differences were found in 14 needle traits of western white pine (Pinus monticola Dougl.) seedlings grown from the same seed orchard source in the three nurseries in northern Idaho. Traits with significant variation included needle length and width, number of stomatal rows, number of stomata per row, total stomata per needle, adaxial surface area, stomatal density, major axes of stomata, stomatal shape, stomatal area, stomatal occlusion, epistomatal wax degradation, weight of wax per dry weight of needle, and the contact angles of water droplets placed on adaxial needle surfaces. Wax crystallites on needle surfaces were hollow and tubular and the amount of surface wax appeared to be associated with surface wettability. Our results may have important implications for tree improvement programs that require successful inoculation of nursery-grown seedlings with spores of Cronartium ribicola J. C. Fisch. ex Rabenh. to reliably screen white pines for resistance to blister rust.     

Environmental Effects on Norway Spruce Needle Wax

In spring, tubular wax structures were observed on the needle surfaces of new Norway spruce needles and also on previous-year needles. In young plants, as in mature trees, the fusing and eroding of the wax tubes on needles of increasing age had taken place in relation to their exposure, particularly to wind and precipitation. The quantity of needle wax and certain fractions of the extracted wax differed in mature trees at two field sites and in young clonal plants. No difference in wax quantity and only small differences in wax composition occurred among young plants which had undergone different treatments (fumigation with O³, SO², ambient air, filtered air, or planting at the sites). Environmental effects on wax structure, wax quantity and the presence of certain compounds in the wax were identified.     

Vascular tissue anatomy of Norway spruce needles and twigs in relation to magnesium deficiency

Vascular tissues of needles and twigs of Norway spruce with low foliar magnesium concentrations were examined by light microscopy. Observations were made on samples from (1) apparently healthy trees, (2) trees exhibiting progressive symptoms of decline, including the yellowing and fall of needles and the death of twigs and branches in the subapical canopy, and (3) trees recovering from symptoms of decline after fertilization with magnesium sulfate. Abnormalities in cambium and phloem anatomy, which were apparent in 2-year-old needles of declining trees, were seen only in needles at least 4 years old in healthy trees, suggesting that needles of declining trees are susceptible to precocious aging. Abnormalities in xylem anatomy were observed in needles 3 years or more in age in declining trees, but were never seen in needles of healthy trees. Over time, anatomical abnormalities in declining trees were seen in progressively younger twigs, which may explain the acropetal development of decline symptoms. After fertilization with magnesium sulfate, normal phloem and xylem were observed in the newly formed tissues.     

Abscisic acid in needles of Pinus cembra in relation to ozone exposure

Ozone pollution was analyzed in arolla pine (Pinus cembra L.) forests growing over two mountain ranges located in southern France by using specific ozone-sensitive tobacco plants as bio-indicators and a physico-chemical analyzer. Concentrations of abscisic acid (ABA) were determined in needles of healthy and declining trees in a massif with a declining forest and in a massif with a healthier forest. In addition, ABA was quantified in needles of trees exposed to either charcoal-filtered air or unfiltered air supplemented with ozone in open-top chambers located at the Col du Donon. The concentration of ABA in needles of injured trees increased when the trees were exposed to ozone either under field conditions or in open-top chambers; however, the difference in ABA concentration between control and ozone-exposed needles was less in the open-top chambers, where ozone was the sole variable, than in the field. The results are discussed in the context of the effects of ozone on plant water relations and hormone-mediated cell defense.     

Effects of Filtered Air and Misting Treatments on Cuticles of Red Spruce Needles on Whiteface Mountain,N.Y.

Two sets of large (8-20 m tall) red spruce (Picea rubens Sarg.) trees growing on Whiteface Mountain, N.Y., were used in branch chamber experiments. In the summer of 1988, the treatments were made on four healthy trees and consisted of: (1) open branches (N), and in chambers that were supplied with either: (2) ambient air (A); (3) charcoal-filtered air (T); or (4) charcoalfiltered air and deionized water misting when the forest was immersed in ambient cloud water (M). Each tree had all of the treatments. The treatments for the second year (summer of 1989) were made on four declining trees and consisted of: (1) open branches (NC) and chambers supplied with either (2) ambient air and mist (AA), (3) synthetic acid mist and ambient air (SA), (4) distilled water mist and ambient air (DA), (5) synthetic acid mist with filtered air (SF), and (6) distilled water mist with filtered air (DF). Foliar properties measurcd included: (1) microreflectivity, a measure of surface wax properties; (2) cuticle thickness; (3) cutinized cell wall thickness; (4) total cuticular layer thickness: (5) the mass of surface wax extracted from needle samples; and (6) contact angles, a measure of surface wetting. In addition, needles were collected and measured from healthy trees at lower and higher elevations. In the first experiment, reflectance from the wax in the stomata1 antechambers in treatment M was statistically significantly greater than all the other treatments. The cuticles of needles in treatment M were also statistically significantly thicker than the cuticles measured in all the other treatments (40% thicker than for the open branches). A plot of cuticular layer against elevation showed that the two filtered chambers (M and T) provided environments for cuticle development that mimic lower elevations. In 1989 the weather was cooler and more moist, and although the trees used in 1989 were declining, the results were similar to those of 1988. However, the additional treatments with synthetic acid mist resulted in reduced cuticle thickness. While the cuticles of the chamber trees growing at 1,170 m were, except for treatment M and T, generally thicker in 1989 than in 1988, they were still considerably thinner than those of spruce trees growing at the lower elevations. These results suggest regional scale air and precipitation quality have detrimental effects on red spruce needles at Whiteface Mountain.     

Co‐occurrence of the ascomycete Lophodermium piceae and the rust fungus Chrysomyxa abietis in Norway spruce needles

The frequency of needles and the proportion of needle segments infected by Lophodermium piceae were compared in symptomless and Chrysomyxa abietis‐infected, 1‐year‐old needles of Picea abies. In late spring, symptomless needles from both rust‐infected and healthy saplings were sampled. In addition, rust‐infected, totally chlorotic needles and needles with chlorosis along about half their length from the diseased trees were examined. In all three stands, the proportion of segments infected by L. piceae was larger in the rust‐infected half of the needle than in the symptomless half; but the difference was statistically significant in only one of the stands. The proportion of L. piceae‐infected segments among the nonrust‐infected needles was the same as that found for the uninfected half of rust‐infected needles (after correction for size differences). No differences in the proportion of L. piceae‐infected segments were found between the totally chlorotic, rust‐infected needles and the green needles of diseased or healthy trees.     

Über die Eignung von Phosphatase- und Esteraseaktivitätsbestimmungen an Fichtennadeln und Birkenblättern zum Nachweis „unsichtbarer physiologischer” Fluorimmissionsschädigungen

Measurement of phosphatase and esterase activity in Norway spruce needles and birch leaves to detect “hidden” F-injury . Potted Norway spruce and birch were exposed at various distances from an industrial fluoride source. The needles and leaves were analysed periodically during a year for their enzymatic activities. In contrast to phosphatase, increased esterase activities were found to be a possible indicator of “hidden” F-injury to the trees.     

Osmotic potential of spruce,fir and beech as a contribution to water budget in connection with forest decline (“Waldsterben”)

Osmotic cell sap potentials of diseased and healthy spruce, fir and beech leaves, fine roots and cortes were determined with the aid of capillary cryoscopy. With one exception (fir needles) the diseased trees showed no reduction in osmotic potential compared to healthy trees.     

Industrial air pollution and peroxidase activity in Scots pine needles – two case studies

The peroxidase activity (EC 1.11.1.7) in homogenates from Scots pine needles (Pinus sylvestries L.) were studied in relation to needle age and sampling locations around two different sources of industrial air pollution. Increased enzyme activity was associated with both increased needle age and proximity to the emission sources. Fluorine contamination in one of the cases was not correlated with enhanced enzyme activity. Enzyme activity levels were considered in relation to variations between trees and between different parts of the same trees.     

Within-crown structural variability of dwarfed mature Abies mariesii in snowy subalpine parkland in central Japan

We investigated mature dwarf Abies mariesii trees growing in conifer thicket–meadow parklands on a snowy subalpine plateau, where these dwarf trees are buried in the accumulated snow in winter. We focused on structural variation in the needles, shoots, and branchlets within different crown positions (leader crown vs lower crown) of the dwarf trees. In the leader crown, which appears above the snow surface earlier than the lower crown, current-year shoots and branchlets had greater total biomass, and foliage was more closely packed along the stem axis than in the lower crown, whereas current-year shoots in the leader crown had a lower needle mass ratio than in the lower crown. These results suggest that current-year shoots and branchlets in the leader crown have a specific structure that allows them to harvest more light, although construction and maintenance costs would be higher. In contrast, the structural characteristics of current-year shoots and branchlets in the lower crown efficiently concentrate incoming light by avoiding mutual shading within foliage, thus leading to increased biomass of photosynthetic needles within shoot and branchlet biomass. Such within-crown variability at various hierarchical levels from needles to branches in mature, but very dwarf, A. mariesii trees maintains the crown and allows survival within conifer clumps in areas of subalpine parklands that receive heavy snowfall.     

Effect of sulfur-dioxide on protein-SH in needles of Picea abies1

The effect of SO₂ on the SH-groups of proteins in needles of Picea abies is studied. The content of total protein SH and glutathione is estimated with 5.5′-Dithio-bis-nitrobenzoic-acid (Ellman reagent). In addition structural protein SH is measured microspectrophotometrically in sections stained with the SH reagent, mercurochrome. The results indicate that GSH and also total protein SH and structural protein SH are increased in needles of Picea abies growing in SO₂ polluted areas. Compared to needles of trees in relatively unpolluted areas average increases of 2. 33 (GSH), 1.22 (total protein SH) and 1.55 (structural protein SH) are found.     

The relationship between Swiss needle cast symptom severity and level of Phaeocryptopus gaeumannii colonization in coastal Douglas‐fir (Pseudotsuga menziesii var. menziesii)*

This study examined 108 15‐year‐old Douglas‐fir (Pseudotsuga menziesii var. menziesii) trees to investigate whether trees exhibiting less severe Swiss needle cast (SNC) symptoms were more resistant (had less fungal colonization) or more tolerant (maintained healthy foliage under similar infection levels). Trees were sampled from six open pollinated families that were categorized into three disease severity groups (two families for each group; mild, moderate and severe disease symptoms). The amount of retained foliage and level of discoloration were visually assessed on trees in the field. Fungal colonization (as determined by proportion of stomata occluded with pseudothecia and by amount of Phaeocryptopus gaeumannii DNA in sampled needles) was measured on 1‐ and 2‐year‐old needles in the laboratory. Trees in the different disease severity groups were similar with respect to amount of fungus in their needles, yet the trees in the mild symptom group retained higher proportions of needles and maintained greener foliage. The relationship between amount of P. gaeumannii in needles and SNC symptom severity was statistically significant (p < 0.05) for amount of fungal DNA in 1‐year‐old needles and average needle retention (NR) over the last four growing seasons. Average NR decreased with increased amount of pathogen DNA in the mild disease symptom families. This relationship was reversed in the severe disease symptom group and there was no relationship in the moderate disease symptom group. Because the amount of P. gaeumannii DNA in foliage did not differ significantly among the groups, differences in symptom severity were attributed to tolerance, not resistance. Visual scoring of individual trees for average NR over the past four growing seasons could be used to effectively assess for SNC tolerance in Douglas‐fir.     

Needle nutrient status of Sirococcus shoot blight‐diseased and healthy Norway spruces

In this study the needle nutrient status of Sirococcus shoot blight‐diseased and healthy Norway spruces (Picea abies) was investigated. Element contents were determined in the current year and 3‐year‐old needles collected in December 2000 from 72 mature trees randomly distributed in the investigated stand. Half of the trees were severely affected by Sirococcus conigenus and had a reduced crown whereas the other trees were unaffected and vigorous. Compared with the uninfected trees, contents of Mg, Ca, P and Mn were significantly lower in the current year and 3‐year‐old needles of diseased trees. Furthermore, analyses of the nutrient contents of needles from severely affected trees revealed insufficient Mg and Ca supply and enhanced N/Mg and N/Ca ratios, when compared with threshold values. The results of this study suggest that imbalanced tree nutrition either has a significant impact on the expression of Sirococcus disease symptoms or fungal infection itself is affecting needle nutrient contents.     

Morphology of epicuticular waxes in Pinus pinea needles in relation to season and pollution-climate

Micromorphological change of the epicuticular wax structure in Pinus pinea needles was analysed by scanning electron microscope and the relationships between the rates of wax weathering over seasons and the pollution-climate at one urban and two rural sites arediscussed.     

Endophytische Pilze in Nadeln von gesunden und geschädigten Fichten (Picea abies [L.] Karsten)

Endophytic fungi in needles of healthy-looking and diseased Norway spruce (Picea abies [L.] Karsten). Endophytic fungi were isolated from surface-sterilized, 5 to 6 year old needles of healthy-looking and diseased trees. Two fungal species could be isolated frequently: Lophodermium piceae and Tiarosporella parca. At any site neither L. piceae nor T. parca could be isolated more frequently from needles of diseased trees. The possible types of relationship between these two fungi and Norway spruce are discussed.     

Effects of Atlas cedar (<Emphasis Type="Italic">Cedrus atlantica</Emphasis>) defoliation on performance of the pine processionary moth (<Emphasis Type="Italic">Thaumetopoea pityocampa</Emphasis>)

The pine processionary moth (Thaumetopoea pityocampa) is an important defoliating insect of native cedar stands in Northern Africa. In 2002 and 2003, we studied the size of needles of Atlas cedar trees that had been defoliated or not in the previous year, and compared the oviposition preference and larval performance of processionary moth on these two types of trees in cedar stands of central Algeria. Needle length and their number per needle cluster were twice as high on non-defoliated trees than on defoliated trees. There were about ten times fewer egg batches on defoliated than on non-defoliated trees in both study years. Young larvae raised in the laboratory on the foliage of previously defoliated trees were smaller compared to those fed on the foliage from healthy trees. Larval colonies transferred to trees in the field showed two times higher mortality on defoliated trees. It was concluded that the decline in population density in defoliated stands often observed after outbreaks results both from the fact that the female moths avoid laying their eggs on defoliated trees and the lower performance of larvae which later feed on the new-grown needles.     

Rasterelektronenmikroskopische Untersuchungen an Stomata von Fichten- und Tannennadeln nach Begasung und saurer Beregnung1

Scanning electron microscopical investigations on stomatal wax plugs of fir and spruce needles after fumigation and acid rain treatment Alterations of stomatal wax plugs of fir and spruce needles have been investigated in order to demonstrate the effects of different air pollutants. After acid rain treatment, and in addition to SO₂ fumigation, heavily melted wax crystals were observed. It is assumed that acid rain causes mainly the changes of the stomatal wax plugs.     

Chemical and structural characteristics of conifer needles exposed to ambient air pollution

Conifer needles exposed to ambient air pollutants were observed by a scanning electron microscope (SEM). Predominant changes on needles were the breakdown and the aggregation of wax structures on stomatal chambers. However, the mode of destruction in stomatal wax structures was dependent on the pollutants. Ginkgo biloba seemed to be resistant to air pollutants despite higher amounts of sulfur in the foliage.