1,124 research outputs found
How does climate influence xylem morphogenesis over the growing season? Insights from long-term intra-ring anatomy in Picea abies
No full textDuring the growing season, the cambium of conifer trees produces successive rows of xylem cells, the tracheids, that sequentially pass through the phases of enlargement and secondary wall thickening before dying and becoming functional. Climate variability can strongly influence the kinetics of morphogenetic processes, eventually affecting tracheid shape and size. This study investigates xylem anatomical structure in the stem of Picea abies to retrospectively infer how, in the long term, climate affects the processes of cell enlargement and wall thickening
Giangiacomo Panessa. — Fonti greche et latine per la storia dell'ambiante e del clima nel mondo greco, 1991. (Pubblicazioni della classe di Lettere e Filosofia, VIII et IX)
No full textCounillon Patrick. Giangiacomo Panessa. — Fonti greche et latine per la storia dell'ambiante e del clima nel mondo greco, 1991. (Pubblicazioni della classe di Lettere e Filosofia, VIII et IX). In: Revue des Études Anciennes. Tome 96, 1994, n°3-4. p. 578
Giangiacomo Panessa. — Fonti greche et latine per la storia dell'ambiante e del clima nel mondo greco, 1991. (Pubblicazioni della classe di Lettere e Filosofia, VIII et IX)
No full textCounillon Patrick. Giangiacomo Panessa. — Fonti greche et latine per la storia dell'ambiante e del clima nel mondo greco, 1991. (Pubblicazioni della classe di Lettere e Filosofia, VIII et IX). In: Revue des Études Anciennes. Tome 96, 1994, n°3-4. p. 578
New research perspectives from a novel approach to quantify tracheid wall thickness
No full textThe analysis of xylem cell anatomical features in dated tree rings provides insights into xylem functional responses and past growth conditions at intra-annual resolution. So far, special focus has been given to the lumen of the water-conducting cells, whereas the equally relevant cell wall thickness (CWT) has been less investigated due to methodological limitations. Here we present a novel approach to measure tracheid CWT in high-resolution images of wood cross-sections that is implemented within the specialized image-analysis tool 'ROXAS'. Compared with the traditional manual line measurements along a selection of few radial files, this novel image-analysis tool can: (i) measure CWT of all tracheids in a tree-ring cross-section, thus increasing the number of individual tracheid measurements by a factor of ~10-20; (ii) measure the tangential and radial walls separately; and (iii) laterally integrate the measurements in a customizable way from only the thinnest central part of the cell walls up to the thickest part of the tracheids at the corners. Cell wall thickness measurements performed with our novel approach and the traditional manual approach showed comparable accuracy for several image resolutions, with an optimal accuracy-efficiency balance at 100× magnification. The configurable settings intended to underscore different cell wall properties indeed changed the absolute levels and intra- and inter-annual patterns of CWT. This versatility, together with the high data production capacity, allows to tailor the measurements of CWT to the specific goal of each study, which opens new research perspectives, e.g., for investigating structure-function relationships, tree stress responses and carbon allocation patterns, and for reconstructing climate based on intra- and inter-annual variability of anatomical wood density
Fennoscandian tree-ring anatomy shows a warmer modern than medieval climate.
No full textEarth system models and various climate proxy sources indicate global warming is unprecedented during at least the Common Era1. However, tree-ring proxies often estimate temperatures during the Medieval Climate Anomaly (950-1250 CE) that are similar to, or exceed, those recorded for the past century2,3, in contrast to simulation experiments at regional scales4. This not only calls into question the reliability of models and proxies but also contributes to uncertainty in future climate projections5. Here we show that the current climate of the Fennoscandian Peninsula is substantially warmer than that of the medieval period. This highlights the dominant role of anthropogenic forcing in climate warming even at the regional scale, thereby reconciling inconsistencies between reconstructions and model simulations. We used an annually resolved 1,170-year-long tree-ring record that relies exclusively on tracheid anatomical measurements from Pinus sylvestris trees, providing high-fidelity measurements of instrumental temperature variability during the warm season. We therefore call for the construction of more such millennia-long records to further improve our understanding and reduce uncertainties around historical and future climate change at inter-regional and eventually global scales
An insight in tree-water-relation responses to climate from 13-years of sap flow and dendrometers daily cycles
No full textWood anatomical responses to long-term enrichment and soil warming in Larix decidua treeline trees
No full textAnatomical responses to long-term co2 enrichment and soil warming in Larix decidua trees at the alpine treeline
No full textConduit-size based comparison of present and past tree height growth rates at two treeline sites in the Alps
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