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Abstract. Mining activities in the boreal regions can increase levels of Na+, Cl and SO42 in the forest soil. In the present study, we compared the effects of NaCl and Na2SO4 on the nutrient status of jack pine (Pinus banksiana). Germinated seedlings were grown in sand culture for 28weeks before adding salts over a period of 3days to treatment concentrations of 60mM NaCl and 60mM Na2SO4, which were...
Abstract. The ecophysiological development of two competitive species naturally regenerated after partial cutting was studied in a boreal mixed stand of eastern Canada. Photosynthetic light response curve and growth analyses were performed on balsam fir [Abies balsamea (L.) Mill.] and trembling aspen (Populus tremuloides Michx.) natural regeneration growing at different light intensities. Five levels...
Abstract. We describe the secondary xylem anatomy of three types of roots produced by Laguncularia racemosa (cable roots, pneumatophores and pneumathodes). Formation of lateral roots (pneumathodes) by pneumatophores causes structural modifications in their secondary xylem, like circular vessels, which may have consequences for water transport. These modifications are not found in the secondary xylem...
Abstract. Wild-type hybrid poplar (Populus tremula P. alba) plants and transgenic lines over-expressing glutathione reductase (GR) either in the cytosol (ca. 5-fold) or in the chloroplast (150- to 200-fold) or glutathione synthetase (GSS) in the cytosol (ca. 200-fold) were exposed for 3days to ambient air or air containing 300 nl l1 ozone for 7h day1. The contents and oxidation state of antioxidants...
Abstract. Previous studies have shown that root system asymmetry can greatly affect the stability of trees. In this study mechanical investigations of the stability and anchorage symmetry of suppressed crown Scots pine (Pinus sylvestris) trees growing in clay soil were combined with morphological investigation of the lateral root system. It was found that most of the trees showed different resistance...
Abstract. In cambium producing wood of increasing spirality, the angle of inclination of fusiform cells to the stem axis is augmented with time. Frequently, events such as pseudotransverse anticlinal divisions and intrusive growth between radial walls do not explain the relatively large rate of change in the angle. The present analysis of the cambium of Pinus sylvestris L. indicates that the large...
Abstract. Beech (Fagus sylvatica L.) seedlings growing under contrasting canopy closure conditions (gaps vs closed canopy) were collected in a naturally regenerating stand of northeastern France. Seedling morphology [total height, basal diameter, number of growth units (GUs), length of GUs] and anatomy (width of the pith and width of the annual rings at seedling base and at various levels along the...
Abstract. Carbohydrate stores may hold the answer to the old question whether treeline trees are carbon limited. However, it is still unknown how sensitively mobile carbon pools reflect the carbon supply status of trees in cold climates. There may be an inherent lower limit to the depletion of these pools, which could restrict their usefulness as indicator values. Here we examined the responsiveness...
Abstract. Transgenic trees are major products of tree biotechnology. This relatively young field of both plant biotechnology and tree biology concentrates on (1) improvement of pathogen, pesticide, and stress resistance, (2) manipulation of lignin content and composition, and (3) improvement of growth. Transgenic trees also have a great potential in other areas of applied and environmental research,...
Abstract. Leaf-level gas exchange and leaf water potential (leaf) measurements were made over a diurnal time-course in multi-aged and even-aged stand structures of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) in central Oregon (June) and western Montana (July) to test for differences in physiological performance due to stand structure. Total site occupancy was similar between the geographic regions...
Abstract. It is a widely held view that plantations of exotic tree species in the tropics are harmful to the environment. Arguments are collected here from experience in tropical countries, showing that the canopies of exotic trees can exert protective functions and have a nurse effect for the regeneration of natural forest. This counterbalances the opinion that exotic tree plantations generally are...
Abstract. Seeds of Scots pine provenances originating from all over Russia were planted in the Boguchany provenance trial at a central Siberian location (southern taiga) in 1974. Eight tree-ring density and width parameters for 16 different provenances were measured with densitometric techniques. The tree-ring data were recorded from 1982 to 1996. Correlation analysis calculated by raw series showed...
Abstract. Branch development of silver birch (Betula pendula Roth) was studied in a planting-design experiment in central Finland. Data was collected from 18 trees growing in stand densities of 400, 1,600 and 5,000stems ha1. Annual radial increments were measured from branches systematically sampled between the stem apex and crown base. Sawn specimens that included the thickest branch or knot were...
Abstract. Pinus cembra (L.) trees growing at an elevation of 1,800m in the Mercantour Alps National Park in southern France have shown various degrees of damage (yellowing and needle loss) since the early 1980s. Two stands were selected, one populated by healthy and the other by damaged trees, and 1-year-old needles were analysed. The needles of the declining trees displayed chlorotic mottled patterns...
Abstract. The acclimation of leaf pigments and antioxidative systems along the vertical canopy light gradient was determined in mature European beech (Fagus sylvatica L.) and sessile oak [Quercus petraea (Matt.) Liebl.] trees in a mixed beech/oak forest in northwest Germany. The aim of the study was to investigate if the higher shade tolerance of beech, relative to oak, is correlated with characteristics...
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