Daily patterns of stem size variation in irrigated and unirrigated Eucalyptus globulus
David M. Drew (1, 2), Anthony P. O’Grady (3), Geoffrey M. Downes (4, 5), Jennifer Read (1) and Dale Worledge (4)
1. School of Biological Sciences, Monash University, Clayton Victoria 3800, Australia / 2. Corresponding author () / 3. University of Tasmania, Private Bag 55, Hobart Tasmania 7001, Australia / 4. CSIRO Forest Biosciences, Private bag 12, Hobart Tasmania 7001, Australia / 5. Co-operative Research Centre for Forestry, Private bag 12, Hobart Tasmania 7001, Australia / Received April 20, 2008; accepted June 22, 2008; published online August 1, 2008
Summary
High resolution measurements of stem diameter variation provide a means to study short-term dynamics of tree growth and water
status. In this 14-month study, daily changes in stem radius of Eucalyptus globulus Labill. seedlings were measured with electronic point dendrometers in a plantation in southern Tasmania, Australia. The daily
patterns of stem expansion and shrinkage were classified into three phases: shrinkage; recovery; and increase in diameter
from one maximum to the next, or increment. This study showed that rapid onset of even mild drought in irrigated trees caused
distinct changes in daily patterns of stem diameter variation, particularly the duration of daily stem increment. The duration
of the daily increment phase was directly related to increment magnitude. The dynamics of daily increment were significantly
affected by mean minimum temperature, indicating a temperature limitation on metabolic processes underlying diameter growth
in these trees. Most likely due to differences in conductance, the duration but not rate of the incremental daily expansion
was greater in fast- than in slow-growing trees.
Keywords:
dendrometer, leaf water potential, size class distributions.
