Academic literature on the topic 'Pressler's law'

In this study, the relationships between crown development and stem volume increment of ash (Fraxinusexcelsior L.) were considered in the framework of a project where modelling and computer simulation should be used to gain insight into the dynamics of even-aged ash stands. Twenty trees, of various development stages and competition status, were felled and subjected to stem and branch analysis. The relationships established in a previous study between stem elongation, branch growth, and branching angle (based on these measurements), together with the characteristic pattern of variation of stem cross-sectional area increment along the stem (Pressler's Law), allowed the reconstruction of the past development of tree crowns. The quantity of foliage in tree crowns was estimated by a "foliar volume" calculated as the product of crown surface projection area and height growth, for each growing year considered. This foliar volume was used together with a relative foliar volume based on the stem surface area to obtain a prediction equation for annual stem volume increment.

El estudio de las especies que presentan potencial dendrocronológico es importante y es la base para investigaciones más complejas que ayuden a entender los bosques mediante técnicas dendrocronológicas. Evaluamos la especie Zanthoxylum rhoifolium Lam. y su potencial para estudios dendrocronológicos en la Amazonía peruana. Para dicho fin, fueron utilizados 10 árboles de Zanthoxylum rhoifolium, de ocurrencia natural en el fundo El Bosque de la Universidad Nacional Amazónica de Madre de Dios - UNAMAD, la colecta fue realizada a través del método no destructivo con el auxilio del barreno de Pressler. Se caracterizaron los anillos de crecimiento en la sección transversal de la especie, su potencial dendrocronológico, la relación de la cronología con el clima local (precipitación y temperatura) y la temperatura de la superficie del mar (SST) HadlSST1. Los resultados de la caracterización anatómica de los anillos de crecimiento de la especie de Zanthoxylum rhoifolium mostraron tener un gran potencial para estudios en dendrocronología por presentar una buena delimitación del anillo de crecimiento. Se logró construir una cronología de 32 años (1985-2017). Finalmente se pudo comprobar que la especie Zanthoxylum rhoifolium presentó respuesta significativa al clima local e influencia a SST.

The ongoing climatic changes are causing the extinction of numerous species or their withdrawal from previously occupied areas. The environmental and economic significance of introduced species may increase. The aim of the present study was to examine the rate of growth of coniferous species growing in northwestern Poland and to analyze the tree ring width–climate relationships. Six tree species were selected for this study. Two of these species have natural occurrences in Poland: Pinus sylvestris and Larix decidua. The remaining four species were introduced from North America: Chamaecyparis lawsoniana, Thuja plicata, Pseudotsuga menziesii, and Pinus strobus. Samples were collected from 131 trees using a Pressler borer at 1.3 m above ground. Tree ring widths were measured down to 0.01 mm. Climatic data were retrieved from a weather station located 23 km from the study plot. The average tree ring width reaches the lowest value for the P. sylvestris chronology (1.62 mm/year) and for P. strobus (1.69 mm/year), and the highest value is reached for T. plicata (2.80 mm/year) and P. menziesii (2.56 mm/year). The analysis of weather conditions in the designated pointer years and the response function analysis indicate that winter and early spring air temperature is the factor responsible for the formation of wide tree rings in the following species studied: P. sylvestris, C. lawsoniana, P. menziesii, and T. plicata. For L. decidua and P. strobus, the climate–growth relationships are different: weather conditions in the previous growth year are important, and it is the weather in the late spring and summer months. Two of the investigated introduced species (T. plicata and P. menziesii) are characterized by very good acclimatization and are best adapted to the new habitat during the current climate changes. These tree species can constitute a basis for replacing native species, which, due to increasingly severe droughts and higher temperatures, are doing less and less well in their current habitats. Foresters wanting to conduct sustainable forest management will look for replacement species that are well adapted to new habitat conditions in order to maintain the continuity of forest cover.

Si l'accès aux ressources telles que la lumière ou l'eau détermine le potentiel de croissance des arbres, l'allocation de la biomasse produite est fortement influencée par les stimulus mécaniques perçues par la plante. La réponse des arbres aux stimulus mécaniques tels que ceux induits par le vent est appelée thigmomorphogénèse. Cette réponse a surtout été étudiée sur de très jeunes plants en conditions contrôlées, et seulement peu en conditions naturelles. Cette étude est la première à étudier la croissance d'un arbre dans un peuplement de feuillus ayant pour objectif de quantifier l'importance de l'effet thigmomorphogénétique en tant que facteur de croissance dans un contexte sylvicole. Pour ce faire, quarante arbres répartis en quatre groupes de dix arbres chacun ont été sélectionnés dans un peuplement dense de F. sylvatica L. âgé de 35 ans. Chaque groupe était soumis à un des traitements suivants : éclaircie sans haubanage, éclaircie avec haubanage, haubanage et témoin.En ce qui concerne l'allocation de la croissance, les résultats montrent que 45% de la croissance volumique du tronc ainsi que 61% de la croissance radiale des racines des arbres éclaircis sont dus aux stimuli mécaniques induits par le vent. Par ailleurs, la distribution de la surface des cernes suivant la hauteur de l'arbre est sous un fort contrôle mécanosensitif. A l'opposé, aucun effet des sollicitations mécaniques ni de l'éclaircie n'a été observé sur la croissance axiale. Concernant l'anisotropie circonférentielle de la croissance, l'étude ne permet pas de mettre en évidence un effet thigmomorphogénétique, malgré l'identification des secteurs dominants pour les vents et les déformations fortes. L'hypothèse avancée est que la variabilité directionnelle des déformations perçues est trop grande pour induire une réaction de croissance orientée dans une direction précise comme c'est le cas en conditions contrôlées
While the tree growth potential is mainly determined by access to resources such as light or water, the distribution of produced biomass is under strong biomechanical control. The tree response to mechanical stimuli such as those induced by wind is called thigmomorphogenesis. This response has been mainly studied on very young trees under controlled condition, and only rarely in natural condition. This is the first study dealing with the tree growth in a broadleaf stand aiming to quantify the importance of thigmomorphogenetic effect as a growth factor in the silvicultural context. The experimental set-up includes forty trees divided into four groups of ten trees selected in a dense 35yrs old F. sylvatica L .stand. Each group was submitted to one of following treatments: thinning without guying, thinning with guying, guying only and controls.Considering the thigmomorphogenetic effect on the biomass allocation inside the tree, our results show that 45% of the stem volume growth and 61% of the root radial growth of thinned trees are due to wind-induced mechanical stimuli. Further, the distribution of tree ring area along the tree stem is under strong mechanosensitive control. In contrast, no effect of mechanical stimuli or thinning was observed on axial growth. Considering the explanation of the circumferential growth anisotropy, our results do not highlight a thigmomorphogenetic effect despite the identification of dominant sectors for strong winds and strains. The hypothesis put forward is that the directional variability of perceived strains is too high to induce a strongly directional growth response as it is usually the case under controlled conditions

Twenty elements of the wooden structure inside the Sigismund Tower and the Sigismund Bell Bed were selected for dendrochronological studies. All analysed the constructional elements made of oak wood. Twelve elements with the sapwood layer retained were sampled with a Pressler increment borer, whereas analysis of the remaining eight elements, with more or less legible cross-sections, was based on macrophotographs. Absolute dating was carried out on the basis of standard chronologies developed for oaks from southern Poland. The dating results of samples from the bell suspension structure, with the last, underbark rings retained, allowed to conclude that the trees for its construction were felled during vegetation breaks in a few consecutive seasons, from 1515/16 to 1519/20 AD. Assuming that the wood from the structure analysed was used without prolonged seasoning, which in principle is the rule, it could be stated that it was erected in 1520 AD from wood accumulated over three successive seasons. The exceptions are some beams with notches difficult to explain from the point of view of their functional purpose, which were dated to the first half of the 15th century. These elements should be interpreted as re-used, probably coming from the previous structure, completely dismantled in 1520 AD.