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Evidence of threshold temperatures for xylogenesis in conifers at high altitudes

Rossi Sergio, Deslauriers Annie, Anfodillo Tommaso et Carraro Vinicio. (2007). Evidence of threshold temperatures for xylogenesis in conifers at high altitudes. Oecologia, 152, (1), p. 1-12.

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Temperature is the most important factor affecting growth at high altitudes. As trees use much of the allocated carbon gained from photosynthesis to produce branches and stems, information on the timing and dynamics of secondary wood growth is crucial to assessing temperature thresholds for xylogenesis. We have carried out histological analyses to determine cambial activity and xylem cell differentiation in conifers growing at the treeline on the eastern Alps in two sites during 2002-2004 with the aim of linking the growth process with temperature and, consequently, of defining thresholds for xylogenesis. Cambial activity occurred from May to July-August and cell differentiation from May-June to September-October. The earliest start of radial enlargement was observed in stone pine in mid-May, while Norway spruce was the last species to begin tracheid differentiation. The duration of wood formation varied from 90 to 137 days, depending on year and site, with no difference between species. Longer durations were observed in trees on the south-facing site because of the earlier onset and later ending of cell production and differentiation. The threshold temperatures at which xylogenesis had a 0.5 probability of being active were calculated by logistic regressions. Xylogenesis was active when the mean daily air temperature was 5.6-8.5°C and mean stem temperature was 7.2-9°C. The similar thresholds among all trees suggested the existence of thermal limits in wood formation that correspond with temperatures of 6-8°C that are supposed to limit growth at the treeline. Different soil temperature thresholds between sites indicated that soil temperature may not be the main factor limiting xylogenesis. This study represents the first attempt to define a threshold through comparative assessment of xylem growth and tissue temperatures in stem meristems at high altitudes.

Type de document:Article publié dans une revue avec comité d'évaluation
Pages:p. 1-12
Version évaluée par les pairs:Oui
Identifiant unique:10.1007/s00442-006-0625-7
Sujets:Sciences naturelles et génie > Sciences appliquées > Climatologie et météorologie
Sciences naturelles et génie > Sciences appliquées > Foresterie et sciences du bois
Sciences naturelles et génie > Sciences naturelles > Biologie et autres sciences connexes
Département, module, service et unité de recherche:Départements et modules > Département des sciences fondamentales
Unités de recherche > Centre de recherche sur la Boréalie (CREB)
Mots-clés:Alps, cambial activity, cell differentiation, tree ring, treeline
Déposé le:26 mai 2023 13:47
Dernière modification:26 mai 2023 13:47
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