Ba. Myers et al., DOES IRRIGATION AFFECT LEAF PHENOLOGY IN DECIDUOUS AND EVERGREEN TREES OF THE SAVANNAS OF NORTHERN AUSTRALIA, Australian journal of ecology, 23(4), 1998, pp. 329-339
Soil moisture was augmented experimentally during two successive dry s
easons and the intervening wet season in a humid tropical savanna in D
anwin, northern Australia. Leaf phenology was monitored in four common
tree species Terminalia ferdinandiana and Planchonia careya (both dec
iduous species), and Eucalyptus miniata and Eucalyptus tetrodonta (bot
h evergreen species). Irrigation produced consistently significant eff
ects in only T. ferdinandiana. In this species leaf-flush was signific
antly earlier, canopy decline and leaf-fall were significantly later a
nd the attainment of full canopy was earlier in irrigated compared wit
h non-irrigated trees. Litterfall, and the seasonal patterns of contra
ction and expansion of stems (a measure of stem water status or storag
e) were not significantly affected by irrigation in any species. Leaf
longevity in the deciduous species was 6-8 months; some eucalypt leave
s lived for approximately 1 year, but none lived longer than 18 months
. Irrigation had relatively little effect on leaf longevity. While var
iation in soil moisture is a potentially important cue to both leaf-fa
ll and leaf-flush, stem water status and climatic factors such as vapo
ur pressure deficit may also be important climatic cues to phenologica
l behaviour.