Differences in daily stem size variation and growth in two hybrid eucalypt clones

Abstract

Understanding daily stem size variation is important as the net increment of a forest stand is ultimately determined by the accumulation of daily increment events. In this study, measurements of stem size at high spatial and temporal resolution were made using two commercial hybrid Eucalyptus clones [E. grandis 9 urophylla (GU) and E. grandis 9 camaldulensis (GC)] over a period of more than 3.5 years in order to better understand how daily stem growth is effected by variations in environmental conditions. It was evident that GU had fewer days on which net growth occurred than GC. However, when growth did occur, GU grew for longer each day and at a higher rate than GC. Thus, it still had an overall larger net stem increment during the study period. The GU clone had a markedly intermittent pattern of growth, such that growth essentially ceased under drought conditions, but responded rapidly when water became available. This confirms other findings that E. grandis 9 urophylla is more susceptible to drought stress than E. grandis 9 camaldulensis, but emphasizes that a strategy of ''rapid response'' when environmental conditions become temporarily non-limiting is a good one in terms of net increment at sites such as in this study.

Intra-Annual Variation of Stem Radius of Larix principis-rupprechtii and Its Response to Environmental Factors in Liupan Mountains of Northwest China

“…After the drought period, a rapid stem radius increment was observed in response to a precipitation event (48 mm, DOY 246). This result supports the conclusion by Drew et al [41] that continuous rapid stem radius increment for days can be measured immediately when drought ends after sufficient rainfall and soil moisture recovery. Zweifel et al [42] suggested that this rapid growth could be explained by the release of the low pressure conditions in the cambium by a sudden enlargement of the already existing cells to their mature stage.…”

Cambial growth dynamics and climatic control of different tree life forms in tropical mountain forest in Ethiopia

“…The diurnal cycle of stem diameter change can be divided into three distinct phases (Downes et al 1999;Deslauriers et al 2007;Drew et al 2009;Volland-Voigt et al 2010): (1) the contraction or shrinkage phase is the period during which the stem diameter decreases from the morning maximum to the daily minimum normally set in the afternoon; (2) the recovery or recreation phase is defined as the part of the cycle in which the diameter expands from the minimum until it reaches the value of the morning maximum again; and (3) the increment phase is the period in which the stem diameter exceeds the maximum of the morning to reach a new maximum. Afterwards, the stem starts to shrink again.…”

Short-term growth responses and associated wood density fluctuations in variously irrigated Eucalyptus globulus

“…These tools allowed the daily growth to be associated with radial wood increments (Drew and Downes 2009). As dendrometers measure ''distance over time'' (the change in stem radius), there is a common axis with measured wood properties from SilviScan.…”

“…As dendrometers measure ''distance over time'' (the change in stem radius), there is a common axis with measured wood properties from SilviScan. E. globulus does not produce clear rings to help to ''anchor'' the re-scaled data, thus a relative correction to deal with extra-cambial effects, like bark thickness, was applied to each tree individually to optimise the re-scaling (Drew and Downes 2009).…”

“…The use of point dendrometers that record stem growth at high resolution to provide the basis for this rescaling has been successfully used in the previous studies (Drew and Downes 2009). Point dendrometers provide a linear measure of the stem size change that can be related to processes in the cambium, at a particular point on the stem, at a given point in time.…”