Anthony P. O’Grady, Xinyin Chen, Derek Eamus, Lindsay B. Hutley
Tóm tắt
Savanna communities dominate the wet–dry
tropical regions of the world and are an important community type in monsoonal
northern Australia. As such they have a significant impact on the water and
carbon balance of this region. Above the 1200-mm isohyet, savanna’s are
dominated by Eucalyptus miniata–E. tetrodonta open
forests. We have described in detail the composition and structure as well as
seasonal patterns of leaf area index and above-ground biomass in the
E. miniata–E. tetrodonta open forests of the Gunn
Point region near Darwin in the Northern Territory of Australia. In all, 29
tree species from four phenological guilds were recorded in these forests.
Stand structure suggests that the forests were still recovering from the
impacts of cyclone Tracy and subsequent frequent fires.
Eucalyptus miniata and
E. tetrodonta were significant contributors to
overstorey leaf area index and standing biomass (>70%), and both
leaf area index and biomass were strongly correlated to basal area. Leaf area
index was at a maximum (about 1.0) at the end of the wet season and declined
over the dry season by about 30–40%. There were proportionally
greater changes in the understorey reflecting the greater contribution of
deciduous and semi-deciduous species in this strata. Standing biomass was
about 55 t ha –1 . Detailed descriptions of leaf
area index and biomass are important inputs into the development of a water
and carbon balance for the savanna’s of northern Australia.