نتایج جستجو برای: birch tree
تعداد نتایج: 174023 فیلتر نتایج به سال:
Betula platyphylla var. japonica (white birch) has heterophyllous leaves (i.e., early and late leaves) and is a typical pioneer tree species in northern Japan. Seedlings of white birch were exposed to ozone during two growing seasons, and measurements were carried out in the second year. Early leaves did not show an ozone-induced reduction in photosynthesis because of lower stomatal conductance...
The aim of the study was to determine the concentrations of selected trace elements in needles and bark of Scots pine (Pinus sylvestris L.), leaves and bark of silver birch (Betula pendula L.), and Norway maple (Acer platanoides L.), as well as in the soil in which the trees grew, depending on their localization and hence the distribution of local pollution sources. The content of trace element...
A deciduous tree has broad, flat leaves which it sheds in the autumn. Its seeds are enclosed in ordinary cases as for example, the oak, birch and walnut. Timber from deciduous trees is said to be 'hardwood'. It can be seen, therefore, that the term 'softwood' and 'hardwood' apply to the family or type of tree and do not necessarily indicate the density of the wood. That is why balsa, the lighte...
Deciduous tree species throughout the boreal forest of North America have lighter-coloured bark than do species restricted to more southern forests. We tested the hypothesis that light-coloured bark minimizes the thawing and freezing of cambium tissue during winter that could contribute to sunscald injury. During mid-winter, maximum midday cambium temperatures of south-exposed bark of white bir...
Atmospheric chemical composition affects foliar chemical composition, which in turn influences the dynamics of both herbivory and decomposition in ecosystems. We assessed the independent and interactive effects of CO2 and O3 fumigation on foliar chemistry of quaking aspen (Populus tremuloides) and paper birch (Betula papyrifera) at a Free-Air CO2 Enrichment (FACE) facility in northern Wisconsin...
Lowland boreal forest ecosystems in Alaska are dominated by wetlands comprised of a complex mosaic of fens, collapse-scar bogs, low shrub/scrub, and forests growing on elevated ice-rich permafrost soils. Thermokarst has affected the lowlands of the Tanana Flats in central Alaska for centuries, as thawing permafrost collapses forests that transition to wetlands. Located within the discontinuous ...
The paper describes an approach that may lead to a proof that the Birch and Swinnerton-Dyer conjecture fails.
In the present experiment, the single and combined effects of elevated temperature and ozone (O(3)) on four silver birch genotypes (gt12, gt14, gt15 and gt25) were studied in an open-air field exposure design. Above- and below-ground biomass accumulation, stem growth and soil respiration were measured in 2008. In addition, a (13)C-labelling experiment was conducted with gt15 trees. After the se...
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