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Platforms mounted in rope parks cause injuries to trees. A new method for mounting platforms uses clamps, which are theoretically less damaging to trees. The aim of the study was to determine changes in the vitality of Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) in response to both old and new platform mounting systems. In the old system, wooden brackets are embedded in the cut fragments of tree trunks. The new system utilizes clamps that hug the trunks. A vitality assessment was carried out for control trees and trees with platforms on the basis of changes in the assimilation apparatus and the degree of thinning of the outer parts of the tree crowns. The visual assessments differentiated between four classes 0–3. We conducted the visual assessment of tree vitality four years after the installation of the platforms. The level of trunk circumference damaged at the platform attachment point was determined using photogrammetric measurements and laser scanning technology. The obtained results were compared to the vitality recorded for the control trees. Trees that initially had better vitality showed a clear decrease in vitality of ~0.5 class. Trees that initially had worse vitality showed a clear increase in vitality, ranging from 0.25 class for pines to 1 class for beeches. Pine and beech trees reacted differently to injuries caused by platform installations. Pine trees responded with a slight increase in vitality, while beech trees experienced a decrease of over a hundred percent. The reactions were more pronounced for the new type of platform. Although the new method of platform installation caused more damage to the surface of tree trunks, its impact on tree vitality was not significantly greater than that of the old system. Since the new system allows, in the long term, to change the position on the tree and adjust the clamping force to the trunk, it can be recommended for use in practice despite the overall slightly worse state of the trees when compared to trees with the old mounting system. [ABSTRACT FROM AUTHOR]

Common beech is a shade-tolerant tree species that can adapt to varying light intensities at the level of whole plants, crown fragments, and individual leaves. The acclimation abilities of the morphological, physiological, and biochemical characteristics of beech leaves were experimentally determined in tree crowns for different levels of light availability. About 24% higher length, width, and area and about 35% higher thickness were recorded in the sun leaves compared with shade leaves. Lower and earlier maximum leaf pigment levels, a faster degradation of leaf pigments during senescence, and a higher chlorophyll a/b ratio were observed in fully sun-grown leaves compared with leaves growing deeper in the canopy. Changes in the intensity of oxidative stress and the differential ability of developing and senescing leaves to defend against this effect under different light conditions were determined. This resulted in a higher redox imbalance and faster senescence in the outer parts of the tree crowns. Due to higher ascorbic acid and glutathione content and slower activity loss of antioxidative enzymes involved in superoxide anion and hydrogen peroxide decomposition, better control over the redox balance, oxidative stress, and senescence induction was noted in the sun leaves. [ABSTRACT FROM AUTHOR]

The induction and course of autumn leaf senescence in early, intermediate and late phenological forms of beech (Fagus sylvatica L.) was studied by analysing the contents of chlorophyll a and b, chlorophyll degradation products and the activities of chlorophyllase and Mg-dechelatase. Studies were conducted in two beech stands differing in the date of senescence onset. Leaf samples were collected from July to October in 2007 and 2009. The main trigger of leaf senescence in beech was a temperature drop occurring in parallel with the appropriate photoperiod. The early phenological form was the most sensitive to temperature. Chlorophyll degradation in senescing leaves of this form occurred in three stages, which strongly coincided with the dates of sudden temperature drops. These stages were less visible in the intermediate form, whereas chlorophyll degradation in the late form was the most stable and occurred in two stages. The fraction of chlorophyllides and phaeophytin in relation to chlorophylls in the early phenological form was significantly higher than that in the late form. Biochemical analyses indicate that pigment dephytylation associated with an increase in chlorophyllase activity is an early reaction of chlorophyll degradation, whereas the Mg-dechelating reaction was much less important. The correlation coefficients between the proportion of chlorophyllides and chlorophyll content for the early, intermediate and late phenological forms were -0.90, -0.87 and -0.72, respectively, providing evidence of chlorophyllase activity in vivo. The activity of chlorophyllase depended significantly on the phenological form. All chlorophyll degradation parameters were highly correlated with temperature changes during senescence. The early phenological form was characterised by the highest correlation coefficients. [ABSTRACT FROM AUTHOR]

Leaf senescence allows plants to remobilise and use the same nitrogen repeatedly and is closely linked to autumn phenology. The timing of leaf senescence affects the growth rate and survival of trees due to the association between senescence and the remobilisation of nutrients, particularly nitrogen. The present study compares protein degradation dynamics and nitrogen remobilisation in early, intermediate and late phenological forms of beech trees (Fagus sylvatica L.). Specimens of phenological forms were marked and examined in 2005 and 2008. Leaf samples were collected from August to October during each of these years, and a biochemical analysis and a determination of proteolytic enzyme activity were conducted. The early phenological form showed protein degradation with three clearly indicated phases, whereas in the late form, protein degradation was stable with a constant decrease. The phenological forms differed significantly in their C/N ratios, which increased from approximately 20 in August to 37.5, 35 and 32 for the early, intermediate and late forms, respectively, at the end of leaf senescence. The date of the sudden drop in temperature had a decisive effect on the beginning of leaf senescence. Temperature has a greater effect on protein degradation and the protein and nitrogen resorption efficiency in the early form than in the late form. The trees that began to senesce the earliest exhibited the highest resorption of nitrogen compounds. Senescence led to an increase in proteolytic activity. Aminopeptidase activity was highest at the beginning of senescence, while endo- and carboxypeptidase activity was highest in the middle of senescence. The early form had the highest activity levels for all peptidase types. These results indicate that beech trees that differ in their autumn senescence timing display different nitrogen remobilisation efficiencies. This efficiency depended on the length of leaf senescence, peptidase activity and the sensitivity of particular phenological forms to temperature changes. [ABSTRACT FROM AUTHOR]

High-altitude tree populations are exposed to severe natural environmental conditions. Among abiotic factors, variable temperatures, early frosts, and high radiation are the factors affecting tree growth at high altitudes. Fagus sylvatica L. exhibits a variety of physiological and genetic traits that allow it to adapt to different forest habitats. This study examines the differences in the biochemical properties of senescing beech leaves between populations originating from different altitudes using a common-garden experiment. Leaves were collected from five-year-old plants from the beginning of August to the end of October for two years. Based on the changes in senescence marker levels the genetic differences and significant correlations between populations' altitude origin and their biochemical characteristics were identified. According to the free radical theory of leaf senescence, reactive oxygen species (ROS) and senescence markers were highly correlated. In this study, populations from higher altitudes were characterized by earlier and greater increases in ROS content and oxidative stress, which resulted in higher antioxidative system activity. Increases in ROS in high-altitude populations play a controlling role to initiate earlier senescence processes that allow the trees to adapt to harsh climatic conditions. Earlier senescence allows beech trees to maintain a balance between nitrogen metabolism and photosynthetic activity. It allows for remobilization of nitrogen compounds more efficiently and protects the trees from nitrogen loss and prepares them for winter dormancy. [ABSTRACT FROM AUTHOR]

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