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Floral sex allocation (weight of male flower buds over weight of female flower buds) was examined at the levels of current-year shoot, individual tree and population, and the tree individual level and population level floral sex ratio was explained as a consequence of the behavior of current-year shoots in the shoot-level monoecious (flowering current-year shoots have both male and female flowers)...
The effect of short-term flooding was examined in 2-year-old apricot trees (Prunus armeniaca cv. Búlida). Six apricot trees of similar appearance were submitted to two treatments: three were irrigated daily, while the others were flooded for a period of 50 h by submerging the pots in plastic water tanks. The trees were removed from the water, drained and then placed in the same conditions as the control...
We investigated the response of the photosynthetic apparatus during an episode of extreme low winter temperature in Quercus ilex subsp. ballota (Desf.) Samp., a typical Mediterranean evergreen species in the Iberian peninsula. Both plants in a woodland located at high altitude (1,177 m. a.s.l.) and potted plants obtained from acorns of the same populations grown at low altitude (225 m. a.s.l.) were...
Western redcedar (Thuja plicata Donn) populations were planted out on a reforestation site and measured, during the summer, to define their gas exchange processes in relation to evaporative demand under non-limiting light and edaphic conditions. These populations came from various locations across a longitudinal transect representing various biogeoclimatic subzones, differing in annual and summer...
Differences in δ15N among ten white spruce [Picea glauca (Moench) Voss] families were examined in hydroponic experiments testing (1) three N sources [100 μM N as (i) NH4+, (ii) NO3− or (iii) NH4NO3] and (2) two supply regimes [200 μM NH4+ (i) maintained steadily or (ii) recurrently drawn-down]. In the N-source experiment, the NH4+ treatment resulted in superior growth and lower C/N ratios. Whole...
The effects of elevated CO2 and N-fertilization on the architecture of Pinus ponderosa Dougl. ex P. Laws & C. Laws fine roots and their associated mycorrhizal symbionts were measured over a 4-year period using minirhizotron tubes. The study was conducted in open-top field-exposure chambers located near Placerville, Calif. A replicated (3 replicates), 3×3 factorial experimental design with three...
Fourteen morphometric variables of silver birch (Betula pendula Roth) leaves from two sites in the Upper Silesia province were analyzed to establish the pattern of intrapopulational and interpopulational relations. The leaves were collected from ten trees growing on a zinc–lead dump as well as from ten trees in the unpolluted area of Mirów within the same bioclimatic region. Leaf samples were collected...
Measurements taken from trees growing in exposed and sheltered areas within two structurally similar forests were used to investigate the influence of wind on branch characteristics of mature New Zealand-grown Pinus radiata. A widely used branch model was used to remove the influence of treatment and site differences in tree stem diameter and height, so that the influence of wind on branch diameter...
This study examines the effect of chilling and photoperiod on rest completion and bud burst in Norway spruce [Picea abies (L.) Karst.] using twigs from both 15-year-old (“young trees”) and 56-year-old (“old trees”) trees. The material was transferred between September and May from outdoors to experimental forcing conditions with four different photoperiods. The bud burst percentage of the twigs from...
Some tropical trees with indistinct growth rings have a distinct interlocked grain that reveals their internal growth rhythm. To determine their growth rhythm, it is necessary to accurately measure the wood grain angle. The usual methods for grain angle measurement are radial splitting using wood disks, which occasionally provides inaccurate data, and serial tangential sectioning, which requires preparation...
The singular umbrella-like crown shape of Stone pine can be interpreted as a consequence of primary shoot-growth patterns and posterior axis differentiation due to differential secondary growth and down-bending of branches. This paper centres on the first aspect, analysing the growth, branching and flowering behaviour of about 5,000 individual shoots on 27 grafted Stone pines. The data measurement...
Foresters have produced many measures of stand density. Yet, none of these is entirely satisfactory. A majority of the measures (stand density index, basal area, and leaf area) present number of trees per unit area as a function of one factor: average tree size. This paper identifies the second factor driving self-thinning: the accumulation of gaps between tree crowns inevitable even in dense stands...
We investigated the potential links between stomatal control of transpiration and the risk of embolism in root and shoot xylem of seedlings of three Mediterranean conifers (Cupressus sempervirens, Pinus halepensis and P. nigra) grown in a greenhouse under semi-controlled conditions. We measured the intrinsic vulnerability to embolism in roots and current year shoots by the air injection method. Root...
Populus × euramericana, P. alba, and P. nigra clones were exposed to ambient or elevated (about 550 ppm) CO2 concentrations under field conditions (FACE) in central Italy. After three growing seasons, the plantation was coppiced. FACE was continued and in addition, one-half of each experimental plot was fertilised with nitrogen. Growth and anatomical wood properties were analysed in secondary sprouts...
Schinus terebinthifolius Raddi (Schinus) is an invasive exotic species widely found in disturbed and native communities of Florida. This species has been shown to displace native species as well as alter community structure and function. The purpose of this study was to determine if the growth and gas exchange patterns of Schinus, under differing salinity conditions, were different from native species...
Previous studies on the mechanisms of birch resistance to herbivores and foliar micro-fungi (both pathogenic and endophytic) have focused mainly on the role of internal leaf chemistry. In the present study, we examined genetic correlations between leaf surface traits (glandular trichome density and total concentrations of surface flavonoid aglycones) and occurrence of three species of foliar micro-fungi,...
Sulfate transport processes and its regulation were studied in roots of poplar trees (Populus tremula x P. alba). From the exponential increase in sulfate uptake with temperature an activation energy (Ea) of 9.0±0.8 kJ mol−1 was calculated. In the concentration range 0.005–10 mM sulfate uptake showed biphasic Michaelis-Menten kinetics with a Km of 3.2±3.4 μM and a Vmax of 49±11 nmol SO42− g−1...
The effects of two boron (B) levels on growth, shoot water potential, gas exchange and nutrient accumulation in Norway spruce [Picea abies (L.) Karst.] seedlings were studied in a growth room experiment lasting 22 weeks which included well-watered control seedlings and seedlings exposed to one (8 days) or two (6+8 days) periods of drought and a rewatering period (8 days) at the end of the experiment...
We investigated leaf and shoot architecture in relation to growth irradiance (Qint) in young and mature trees of a New Zealand native gymnosperm Agathis australis (D. Don) Lindl. to determine tree size-dependent and age-dependent controls on light interception efficiency. A binomial 3-D turbid medium model was constructed to distinguish between differences in shoot light interception efficiency due...
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