Trees
AbstractSeedlings of Picea sitchensis, Thuja plicata and Tsuga heterophylla were supplied N hydroponically at one of four exponentially increasing rates of addition (0.09, 0.07, 0.05, or 0.025 gN1 day1) for up to 3 months in a naturally illuminated glasshouse. Relative growth rates (RGR) were analyzed as a function of N uptake, the allocation of assimilated N to foliage (LNFR), foliar N concentrations...
AbstractThe effects of differing, exponentially increasing rates of N addition (0.025, 0.05, 0.07 and 0.09 gN gN1day1) on photosynthesis, discrimination against 13C and partitioning of foliar N to chlorophyll and major photosynthetic proteins were compared in seedlings of the evergreen conifers Picea sitchensis, Thuja plicata and Tsuga heterophylla. T. heterophylla had the lowest range of foliar N...
AbstractEthanol synthesis was induced in stem segments from greenhouse-grown conifer seedlings by placing them in a N2 atmosphere at 30C for 24 h. Stems from ponderosa pine, Pinus ponderosa Dougl. ex Laws., sugar pine, Pinus lambertiana Dougl., Pacific silver fir, Abies amabalis Dougl. ex Forbes, and lodgepole pine, Pinus contorta Dougl. ex Loud, produced the highest quantities of ethanol. This group...
AbstractThe dormancy status of Fraxinus excelsior embryos at different developmental stages under environmental conditions was examined over a period of 2 years. For each sampling date the length of the fruit, of the seed, and of the embryo were measured, and the embryological stage determined. The depth of dormancy was assayed by the germination behaviour of isolated embryos under aseptic conditions...
AbstractNorway spruce [Picea abies (L.) Karst.] seedlings were grown in greenhouses with two supplemental levels of ultraviolet-B (UV-B) radiation. Photochemical efficiency of photosystem II and vitality index were determined monthly. At the end of the experiment, growth, chlorophyll content and photosynthetic rates were measured. The data indicate that low temperature in winter affected light dependent...
AbstractFrom April 1988 to October 1991 3-year-old seed propagated beech (Fagus sylvatica L.) trees were exposed in open-top chambers to four different levels of air pollution: (1) charcoal filtered air, (2) ambient air, (3) ambient air plus 30 nl l1 ozone during the summer, and (4) ambient air plus 30 nl l1 ozone during the summer and 20 nl l1 SO2 and NO2 during the winter. Leaf colour was studied...
AbstractEffects of SO2, aqueous fluoride (NaF) and a solution of nitrogen compounds (NH4NO3) on the visible symptoms, pollutant accumulation and ultrastructure of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst.] seedlings were studied in an open-air experiment lasting for 3 consecutive years. Visible injury symptoms were most pronounced in combination exposures and whenever...
AbstractOne-year-old Scots pine (Pinus sylvestris L.) seedlings were grown for 9 weeks in nutrient solutions containing 0, 0.5, 1, 2 and 4 mM aluminum nitrate (Al(NO3)3) at pH 4.2. Nine weeks exposure to Al significantly reduced total plant, shoot and root mass and caused a linear decline in proportional allocation of biomass to roots. Relative growth rate of roots declined to as low as zero. Aluminum...
AbstractThree different experiments in birch (Betula pubescens Ehrh. and Betula pendula Roth) stands were conducted during summer 1991: an evaluation of the accuracy of the vertical tube method measuring crown free projection (CFP) in four birch stands; a study of relative irradiance (RI; photosynthetically active radiation, PAR), in birch stands differing in stem density and basal area; and an estimation...
AbstractPolylepis sericea trees grow well above the continuous forest line in the Venezuelan Andes. In these environments, extreme daily temperature ranges can occur at any time of the year and trees experience a 4 month dry period. The purpose of this work was to study carbon and water relations of this species in the field during wet and dry seasons in order to understand this species success at...
AbstractScots pine (Pinussylvestris L.) seedlings were fumigated with 1.21.5 ambient ozone over 2 seasons in an open-air experiment. Fumigation started in the early spring and continued into late autumn during both years. Needle and root cell structures were analyzed in the summer, autumn and early winter following the second fumigation period. Under the light microscope an increase in the intercellular...
AbstractA glasshouse experiment investigated the effect of bending stress on stem radial and height growth and stem taper of Eucalyptus regnans seedlings. Eighteen-week-old, potted seedlings were bent continuously for 8 weeks with a static bending stress. The bending treatment was then removed and the seedlings grown for another 12 weeks. Other seedlings were stayed vertically throughout the experiment...
AbstractCloned Sitka spruce grafts were subjected to NH4NO3 mist (1 mm day1 equivalent) acidified with H2SO4, for 4 days a week, from April until November. Three N treatments at pH 5.0 used 0.01 mol m315NH4 15NO3, 1.6 mol m315NH4 NO3 or 1.6 mol m3 NH415NO3. At pH 2.5, the treatments were 15NH415NO3, 15NH4NO3 and NH415NO3 all at 1.6 mol m3. At the end of the growing season, 15N was found in every part...
AbstractThe distribution of the above-ground and below-ground biomass of Scots pine in southern Finland were investigated in trees of different ages (18212 years) from two types of growth site. Secondly, some structural regularities were tested for their independence of age and growth site. Trees were sampled from dominant trees which could be expected to have a comparable position in stands of all...
AbstractThe seasonal fluctuation of N, P, K, Ca and Mg in leaves, young stems and fruits of young and mature Quercus suber trees growing at the same site was studied. Nutrient dynamics within the tree appeared to be linked to phenological events. Leaves maximized their nutrient contents throughout summer whereas stems maintained rather constant values during most of the year. Before the spring growth...
AbstractMicroautoradiography indicated that 1-year-old Fraxinus excelsior L. stem chlorenchyma assimilated external 14CO2 in mid-April, when buds were swollen, but before bud-break. The lenticel regions showed the highest amount of radioactively labeled assimilates. Labeled assimilates declined in the tangential direction with increasing distance from lenticels, suggesting that 14CO2 entered the stem...
AbstractAn exposure - response study with proportional-to-ambient ozone levels was conducted in closed chambers on 3-year-old European beech (Fagus sylvatica L.) of montane origin. The fumigation started in April 1990 and lasted for a single growing season. Climate data and ozone concentrations monitored at an experimental station of the Institute for Applied Plant Biology, Schnenbuch, Switzerland...
AbstractThe nutrient concentrations and contents of needles and shoots of 22-year-old European larch (Larix decidua Mill.) were evaluated with respect to crown position, age of tissues and sampling date during a complete growing season. Concentrations of N, P, K, Ca, Mg and Zn in the needles and of N, P and K in the shoots differed significantly among the dates of sampling. The concentrations of N...
AbstractDespite the importance of the vascular cambial differentiation, little is known about its regulation. In order to address this problem we attempted to biochemically characterize differentiating xylem and phloem elements during the early stages of development. By applying techniques of quantitative histochemistry we show that the total pool size of pyridine nucleotides is similar in the phloem...
AbstractDeciduous larches, Larix spp., and evergreen pines, Pinus spp., are sympatric Pinaceae conifers. Adjacent monocultures of 10-year-old Larix decidua Mill. and Pinus resinosa Ait. were subjected to single-season artificial defoliation by clipping from 0% to 99% of each needle. Survival, above-ground productivity, and architecture were measured for 36 months. P. resinosa and L. decidua exhibited...