PARENT SESSION
Organized Oral Session 11: Hydraulic limitations in vascular plants
Organizer(s): F Berninger, L Lauzon, and E Nikinmaa
Monday, August 8, 1:30 PM - 5:00 PM, Meeting Room 511 C, Level 5, Palais des congrès de Montréal
Size, not cellular senescence, explains reduced vigour in tall trees.
Mencuccini, Maurizio1, Martinez-Vilalta, Jordi1, Vanderklein, Dirk 2, Hazandy, Hamid1, Korakaki, Evangelia1, 1 University of Edinburgh, Edinburgh, UK2 Montclair University, Montclair, NJ, USA
ABSTRACT- Carbon sequestration by forests usually decreases after a peak at mid-age. Reduced growth in old trees has been shown to be one of the main contributors to this decrease, but explanations for the reduced growth are debated. One theory proposes that reduced growth after the start of the reproductive phase is caused by cellular senescence. A second set of theories has focussed on plant size and the role of an increased respiratory burden or excessive height. We report on experimental manipulations to separate the effects of size from those of age for four tree species of contrasting life history. For all species, evidence indicates that size, not cellular senescence, accounts for the observed age-related decline in tree growth. These findings are discussed in the context of current theories on the evolution of senescence in trees.
Key words: age-related decline, hydraulic limitation, senescence