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Mycorrhizal syntheses of pine seedlings were conducted with Suillus luteus (L.) S.F. Gray, a strain No 14 characterised by high tolerance to Al3+ ions and a strain No 62, sensitive to aluminium. The experiment was performed as a semi-sterile culture in a peat-perlite medium with Al3+ ion concentration of 11 mM. Abundant coralloid and cluster mycorrhizas of S. luteus were formed on roots of the inoculated plants at the beginning of the experiment. Aluminium treatment limited mycorrhizal morphotypes to single and dichotomous and significantly reduced the total number of mycorrhizal tips but had no effect on extramatrical mycelium development in the potting substrate. Al treatment did not affect growth of the above-ground part of the tested plants but significantly reduced root growth of mycorrhizal seedlings. The effect of Al on the internal nutrient status was variable and not very much pronounced. A considerable amount of Al was absorbed by the roots and translocated to the shoots. Mycorrhiza formation with both strains of S. luteus did not prevent Al3+ translocation to the upper parts of the tested seedlings. The results suggest that low pH and high Al availability may harmfully influence mycorrhizal symbiosis of Scots pine (Pinus sylvestris L.) by anega tive effect on fine-root production and fewer short root tips available for colonisation rather than through a direct negative effect of Al3+ ion concentrations on extramatrical mycelium in the soil.
Using the characteristic of accumulated woody debris, data on vegetation, and data on previous climate fluctuations, we reconstructed the history of Scots pine (Pinus sylvestris L.) encroachment and retreat in a raised bog. The available patchy information on plant cover allowed us to pinpoint events in the development of pine seedlings and the first cases of trees dying off on the time scale. The results obtained show that the process of natural bog afforestation and deforestation was very dynamic and lasted only 22 years. These short-term changes in the tree populations were clearly linked to short-term climate fluctuations. The annual precipitation and mean temperature of winter months were the most important variables and the main factors directly influencing the young woodland. We assumed that the woody remnants represent the last stage of the contemporary phase of high germination and dying-off (GDO) of pine trees. The spatial distribution of woody debris and its characteristics indicate the naturalness of vegetation during this temporary ‘woodland phase’. The study show that the investigation of woody debris can be used to further improve our understanding of bog vegetation dynamics, especially with regard to the influence of periodical climate fluctuations on transitions between open and forested peatland.
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