Daily stem growth patterns in irrigated Eucalyptus globulus and E. nitens in relation to climate

Abstract

Daily increments in stem radius were determined from hourly dendrometer measurements in each of three irrigated Eucalyptus nitens and E. globulus trees. Multiple regressions determined from daily weather variables accounted for 40-50% of the variance in increment. The use of weather variables lagged by 1-2 days increased the variance explained. The diurnal variation in stem radius was resolved into three mathematically defined phases: shrinkage, recovery and increment. The positive daily net increment in stem radius, by definition, occurred in the increment phase. Average weather conditions during this phase (predominantly night-time) did not explain any more variance in increment than the average daily conditions, determined over a 24 h period. Daily increment was resolved into a rate of stem radius increase during the increment phase and the duration (hours) of that phase. Significant species by month interactions were evident with growth in summer characterised by faster rates of stem expansion over shorter time periods within each diurnal cycle. E. nitens tended to have longer increment phases in spring and autumn, and faster phase rates in autumn than E. globulus. Interactions between weather variables and cambial growth were complicated and varied over the year. The correlation between temperature and stem growth varied from positive in spring to zero or negative during summer. The data indicate a need to understand weather-byclimate interactions at the level of whole tree physiology in order to fully understand the effect of weather on cambial activity and therefore stem increment and wood properties.

High-resolution analysis of radial growth and wood density in Eucalyptus nitens, grown under different irrigation regimes

“…Specific software procedures were written in IDL (RSI Inc.) to handle hourly dendrometer data, extracting rates and duration of stem shrinkage and expansion in each 24 hour period, as shown previously in Downes et al [5,6]. The trees commonly experienced a shrinkage phase during the early part of the day followed by an expansion phase during the afternoon and evening.…”

“…The "recovery" phase was defined as that portion of the cycle during which the radius increased until it reached the position observed previously. Finally, the "increment" phase was defined as the period during which the stem radius continued to increase until the shrinkage phase commenced in the next diurnal phase [5]. By processing the measured data the shrinkage, recovery and increment were resolved into a rate (µm h -1 ) and duration (h).…”

“…These dendrobands have been prominent in different studies, such as investigating tree water status [22], drought effects [14] or ozone and climate effects on tree growth [25]. An alternative to bands are point dendrometers to monitor the radial movements of tree stems [5,16,41]. Point dendrometers are usually mounted on stainless steel rods that are inserted into the wood.…”

Dynamique de la croissance radiale et influence météorologique quotidienne chez le sapin baumier (Abies balsamea (L ) Mill ) en forêt boréale

“…Les analyses anatomiques permettent de caractériser précisément la dynamique de la formation cellulaire du xylème durant une saison de croissance (Deslauriers 1999). La dendrométrie, soit l'utilisation des dendromètres électroniques, permet de suivre les variations radiales du tronc des arbres en temps réel et d'enregistrer les données dans des intervalles de temps très courts (Downes et al 1999). À l'aide des dendromètres, seuls les phénomènes de divisions et d'élargissement des cellules composant le cerne en formation peuvent être enregistrés.…”

“…Even though dendrometers are widely used recording instruments (Clark et al 2000), only a small number of studies have used dendrometers to measure tree-ring development in order to understand the growth-climate relationship (Downes et al 1999;Kozlowski and Winget 1964;Pietarinen et al 1982;Worbes 1999). The main objective of this study was to determine the most important weather factors influencing radial growth of balsam fir in Québec boreal forests, hi order to evaluate correctly the results of this study, two important aspects should be clearly defined, i) Since true daily radial growth is linked to the reversible stem motions and is estimated by extraction methods it is more appropriate to refer to it as stem radius increment (SRI), ii) Biologically, tree growth does not react directly to meteorological events (Schweingruber, 1996), but combined with synchronous SRI estimates, important information on intra-annual tree-ring dynamics may be provided.…”